Literature Review of the Potential Application
of Metal Melting in the UK Nuclear Sector
by
M. Buckley, B. Handy and Z.K. Hillis
11426/TR/001
Issue 04
November 2004
The work described in this report was carried out by NNC Ltd under contract to the Health and Safety
Executive (HSE). Any views expressed have not been adopted or in any way approved by the HSE and
should not be relied upon as a statement of the HSE’s views.
© NNC Limited 2004
All rights reserved. No part of this document, or any information or descriptive material within it may be
disclosed, loaned, reproduced, copied, photocopied, translated or reduced to any electronic medium or machine
readable form or used for any purpose without the written permission of the Company
Table of Contents
List of Tables .............................................................................................ii
List of Figures...........................................................................................iii
Summary ...................................................................................................iv
Acronyms ..................................................................................................vi
Note on Definitions................................................................................ viii
1
Introduction.....................................................................................1
2
Waste Issues....................................................................................3
2.1
2.2
2.3
2.4
2.5
UK Market Potential............................................................................. 3
Recycling of Metals Outside the Nuclear Industry (Public Domain) ........ 8
Recycling Within The Nuclear Sector .................................................. 10
Melting as Part of a Disposal Strategy ................................................ 15
Summary - Waste Issues.................................................................... 16
3
Melting Technology .......................................................................17
3.1
3.2
3.3
3.4
3.5
3.6
Introduction ...................................................................................... 17
Overview of the Process Of Melting Radioactively Contaminated Metals17
Proven Technology Used For Melting Radioactively Contaminated Metals
................................................................................................... 20
Current Non-Nuclear Technologies ..................................................... 23
Developing and Emerging Nuclear Melting Technologies...................... 25
Summary - Melting Technology ........................................................... 28
4
Policy & Regulatory Control .........................................................28
4.1
4.2
4.3
4.4
4.5
Introduction ...................................................................................... 28
International Policy with Regard to Clearance .................................... 28
UK Policy and its Implications for Melting ........................................... 30
Implications of Recent UK Decommissioning Policy Developments ....... 32
Summary – Policy.............................................................................. 33
5
Constraints on the Implementation of UK Melting Facilities ....34
5.1
5.2
5.3
Regulatory Controls........................................................................... 34
Stakeholder Issues............................................................................ 38
Summary – Constraining Issues ......................................................... 41
6
Conclusions ....................................................................................43
7
Recommendations.........................................................................45
8
References......................................................................................49
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List of Tables
Table 1
Industrial scale melting facilities
Table 2
Chemical components in LLW from all sources (Electrowatt-Ekono, 2002)
Table 3
Chemical components in ILW from all sources (Electrowatt-Ekono, 2002)
Table 4
Metal Wastes at UK sites (Electrowatt-Ekono, 2002)
Table 5
Status of UK sites (http://www.dti.gov.uk/nuclearcleanup/tl.htm)
Table 6
Requirements for drums, boxes, reinforcement, grouts in UK disposal facilities
currently in operation (European Commission, 1998a)
Table 7
Partitioning factors for BOFs and EAFs (NCRP, 2002: Cheng et al, 2000; Nieves
et al, 1995; NRC, 1999)
Table 8
Summary of issues and recommendations
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Page (ii)
List of Figures
Figure 1
Radioactively contaminated metal arisings in the UK
Figure 2
Estimate of Metal Arisings from UK decommissioning
Figure 3
Scrap metal for steel-making (NCRP, 2002)
Figure 4
GERTA (Siempelkamp, 2004)
Figure 5
Blast Furnace – Basic Oxygen Furnace (www.atsiinc.com)
Figure 6
Plasma Arc Furnace (Fentiman et al.)
Figure 7
IET Plasma Enhanced Melter
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Summary
Large quantities of radioactively contaminated waste metal are currently, and will continue to
be, generated during decommissioning of nuclear facilities in the UK. The waste producers
currently manage these wastes generally on a “project”, or on occasion, a site-wide basis.
There is currently no UK-wide strategy for coordinating or integrating management of
contaminated metallic wastes, other than for disposal at Drigg.
Other countries, including France, Germany and Sweden, have developed more integrated
strategies for managing radioactiv ely contaminated metal wastes through the operation of
central metal melting facilities. These strategies take advantage of economies of scale to
process a wide range of metallic waste streams, which produce either metals ‘cleared’ for
unrestricted use in the scrap metal market, for recycling within the nuclear industry or
material for disposal.
This review examines the opportunities for developing similar integrated strategies in the UK
for managing contaminated metal wastes arising from across UK nuclear sites, and
compares with the experience of operating facilities internationally. It considers:
•
A review of the UK waste market
-UK arisings of radioactively contaminated metal waste
-Review of the available metal “reuse” market
•
A review of melting technologies
-Proven metal melting technology in the nuclear market
-Proven metal melting technology in the non-nuclear market
-Developing and emerging nuclear melting technologies
•
Review of Regulatory Policies and Principles
•
Review of Barriers to implementing integrated melting technologies in the UK,
including stakeholder issues.
The conclusions of the review are as follows.
1
In the UK there is a significant inventory of unconditioned waste radioactive metals
(70,000 tonne of ILW and 383,000 tonne of LLW), which will require management.
2
There are a number of proven technologies for melting radioactively contaminated
metals operating in a number of countries including France, Germany and Sweden.
These facilities manage a number of different radioactive waste streams arising from a
range of nuclear sites.
3
Induction melting is the chosen technology for existing industrial radioactive metal
melting facilities. Further developing technologies are also emerging, such as cold
crucible and plasma arc technology.
4 Metal melting can be used to achieve three aims:
•
•
Size or volume reduction of waste
Segregation or separation of contaminants
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•
5
Homogenisation of contaminants within the bulk metal.
Following processing in these melting facilities, the metals can follow one of three paths:
I. Release outside the nuclear sector (clearance)
II. Reuse within the nuclear sector
III. Disposal, having achieved a reduction in disposal volume and activity
concentration.
6
The establishment of melting facilities for radioactive waste metals is consistent with UK
government decommissioning policy and the principles of:
•
•
•
•
7
8
Waste minimisation
Reuse and recycle
Sustainability
Environmental impact & resource management
There are a number of drivers for reviewing the need for melting facilities:
•
Economic
o Reducing waste disposal costs
o Recovering costs through reuse and recycling
o Conserving natural resources
o Conserving the UK’s LLW disposal resources
•
Policy
To comply with government policy, guidance and principles including:
• Waste minimisation
• Reuse and recycle
• Sustainability
• Environmental impact & resource management
•
Strategic
To review application of a proven technology for radioactive waste metals on a
“national” rather than project or site basis.
There are significant stakeholder issues that must be considered and managed in order
to implement an integrated metallic waste management strategy. These include:
•
•
•
Public and (non-nuclear) metal industry unease with regards to reuse of
previously radioactively contaminated metals and
Public concern over the transport of radioactive waste
Concern over new waste or radioactive management facilities involving “heat
treatment”
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Acronyms
AC
Alternating Current
AEAT
AEA Technology (UK)
AISI
American Iron and Steel Institute (USA)
BAT
Best Availa ble Technique
BF-BOF
Blast Furnace – Basic Oxygen Furnace
BMRA
British Metals Recycling Association
BNFL
British Nuclear Fuels plc (UK)
BREF Note
Best Available Technique Reference Note
BSS
Basic Safety Standards
CEA
Commissariat à l'énergie atomique / Atomic Energy Commission (France)
CSSIN
Nuclear Information and Safety Council (France)
DC
Direct Current
DRIRE
Direction régionale de l'industrie, de la recherche et de l'environnement /
Regional directorate of industry, of research and of the environment
(France)
DSIN
Direction de la sûreté des installations nucléaires / Nuclear installation safety
directorate (France)
DTI
Department of Trade and Industry (UK)
EA
Environment Agency (England & Wales)
EAF
Electric Arc Furnace
ENRESA
Empresa Nacional de Residuos Radiactivos SA (Spain)
EPA
Environment Protection Act (UK)
EU
European Union
EUROFER
European Confederation of Iron and Steel Making Industries
HLW
High Level Waste
HPICCM
Hybrid Plasma Induction Cold Crucible Melter
HSE
Health & Safety Executive (UK)
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IAEA
International Atomic Energy Agency
IET
Integrated Environmental Technologies
ILW
Intermediate Level Waste
IPPC
Integrated Pollution & Prevention Control (UK)
IRR99
Ionising Radiations Regulations 1999
JPDR
Japanese Power Demonstration Reactor
LLRC
Low Level Radioactivity Campaign (UK)
LLW
Low Level Waste
LSA
Low Specific Activity
MIRC
Metals Industry Recycling Coalition (USA)
NCRP
National Council on Radiation Protection and Measurements (USA)
NDA
Nuclear Decommissioning Authority (UK)
NEA
Nuclear Energy Agency (part of the OECD)
NII
Nuclear Installations Inspectorate (UK)
NORM
Naturally Occurring Radioactive Material
OCNS
Office of Civil Nuclear Security (UK)
OECD
Organisation for Economic Co-operation and Development
OPRI
Office de protection contre les rayonnements ionisants / Office for
protection against ionizing radiation (France)
PET
Plasma Enhanced Melter
PICCM
Plasmatron with Induction Cold Crucible Melter
RBMK
Large Power Boiling Reactor of Soviet Union design
R&D
Research and Development
RSA93
Radioactive Substances Act 1993 (UK)
SCS
Site Condition Survey
SCO
Surface Contaminated Objects
SEPA
Scottish Environment Protection Agency
SOCODEI
Société pour le conditionnement des déchets industriels / Company for the
conditioning of the industrial waste
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conditioning of the industrial waste
SoLA
Radioactive Substances (Substances of Low Activity) Exemption Order 1986
UKAEA
UK Atomic Energy Authority
US DOE
Department of Energy (USA)
Note on Definitions
In the literature both terms ‘smelting’ and ‘melting’ are used in relation to metal furnaces.
The term smelting is most correctly reserved for the extraction of metals from their ores.
This report focuses upon the recycling of scrap metal and so the term ‘melting’ is used as
the furnaces are being used to convert metal into the liquid phase as opposed to metal
extraction and refinement.
For the purpose of this study, “contamination” refers to radioactive contamination.
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1
Introduction
Overview of Report
Large quantities of radioactively contaminated waste metal are currently and will
continue to be, generated during decommissioning of nuclear facilities in the UK. The
waste producers currently manage these wastes generally on a “project”, or on
occasion, a site-wide basis. There is currently no UK-wide strategy for coordinating
or integrating the treatment of contaminated metallic wastes, other than for ultimate
disposal at Drigg.
Other countries, including France, Germany and Sweden, have developed more
integrated strategies for managing radioactively contaminated metal wastes through
the provision of proven, operating central metal melting facilities. These strategies
take advantage of economies of scale to process a wide range of metallic waste
streams which produce either metals ‘cleared’ for unrestricted use in the scrap metal
market, for recycling within the nuclear industry or material for disposal.
A summary of operating metal melting facilities is shown in Table 1.
There are a number of drivers for a review of UK radioactive metal waste
management:
Economic
- In order to review the most cost effective strategy for UK
management of radioactive waste metal liabilities.
Policy
- To comply with government policy, guidance and principles of waste
minimisation and sustainability.
Strategic
- To review the application of proven technology of waste radioactive
metals on a “national” rather than project or site basis.
This review examines the opportunities for developing similar integrated strategies for
managing contaminated metal wastes arising from across all UK nuclear sites, and
compares with the experience of operating facilities internationally. It considers:
NNC Limited
11426/TR/0001
Issue 04
•
A review of the UK waste market
-UK arisings of radioactively contaminated metal waste
-Review of the available metal “reuse” market
•
A review of melting technologies
-Proven metal melting technology in the nuclear market
-Proven metal melting technology in the non-nuclear market
-Developing and emerging nuclear melting technologies
•
Review of regulatory policies and principles
•
Review of the constraints to implementing melting technologies for
contaminated metals in the UK, including stakeholder issues.
•
Conclusions and Recommendations.
Page 1
Table 1
Industrial scale melting facilities
Sources: (NEA, 1999) [1], (Byrd Davis, 2003) [2], (Powell, 1999) [3], (Worchester et al, 1995) [4], (MSC, 2004) [5], (Byrd
Davis, 2004) [6], (Greppo et al, 1998) [7], (Faugieres J., 2000) [8].
Furnace
type
Types of
metal
treated
Charge
size (t)
Products
Radiologica
l limitations
INFANTE
Plant,
Marcoule,
France (start
1992 now
shutdown)
[1], [2]
STUDSVIK
Melting
Facility,
Sweden
(start 1987)
[1]
CARLA Plant,
Siempelkamp,
Germany
(start 1989)
[1]
Electric arc
melting
furnace
Carbon
steel,
stainless
steel
12
Ingots,
shield
blocks,
waste
containers
Max.
250 Bq/g for
Co-60, other
limits for
other
nuclides
Induction for
steel, small
electric arc
for aluminium
Carbon
steel,
Stainless
steel,
Aluminium
3
Ingots
No specified
limits
1500
230 t released,
remaining stored for
decay (or disposal)
Induction
Carbon
steel,
stainless
steel,
aluminium,
copper, lead
(R & D)
3.2
Ingots,
shield
blocks,
waste
containers
7000
6800 t recycled in
nuclear industry, 50 t
free release
SEG Plant,
Oak Ridge,
USA (start
1992) [1]
Induction
Carbon
steel,
stainless
steel,
aluminium,
(planning to
melt copper
and
titanium)
20
2000
Recycling in the
nuclear industry
Capenhurst
Melting
Facility, UK
(start 1994)
[3]
MSC, Oak
Ridge, USA
(start 1996)
[4], [5]
Induction
Aluminium,
(brass,
copper,)
steel
4
Ingots and
shield
blocks at
present,
waste
containers
and
reinforcing
steel after
1994
ingots
Max 200 Bq/g
for betagamma
nuclides, Max
100 Bq/g for
alpha
nuclides,
separate
limits for
uranium
Normally <
2 mSv/hr,
greater dose
rates with
prior review
and approval
7000
For unrestricted use
Centraco,
France (start
1999)
[6], [7], [8]
Page 2
Reverberator
y
Induction
Induction
Quantity
of scrap
melted
(t)
In excess
of 5000t
Recycled/released
Facility
Stored/recycling in
nuclear industry
MSC's manufacturing plant is a fully integrated manufacturing facility with the capacity to melt,
cast, roll or machine products from many specialty metals such as steel, aluminium, uranium,
tantalum, and niobium. The company's facilities and equipment are ideally suited for small and
medium batch sizes that are uneconomical for large metal producers to process. One of its key
services is the recycling of depleted uranium.
1366 (in
For restricted use:
4
Ingots and
370 Bq/g
Stainless
2000)
manufacture of
tubes
alpha,
steel,
storage drums or
20,000 Bq/g
carbon steel
biological shield
beta/gamma
and to the
materials.
lesser
extent nonferrous
metals
NNC Limited
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2
Waste Issues
This section describes the potential market in the UK for melting of metals from the
nuclear industry. It covers:
•
•
•
•
2.1
UK Market Potential;
Recycling of the metals outside of the nuclear industry (public domain);
Recycling within the nuclear industry and,
Melting as part of a disposal strategy.
UK Market Potential
2.1.1 Quantities of Contaminated Metals
Melting technology is most readily applicable to metal wastes. In the UK over 90%
of the radioactively contaminated metal waste is ferrous, with lead, Magnox,
aluminium and copper comprising most of the remainder. 85% of this metallic
radioactive waste in the UK is categorised as low-level waste (LLW) with the
remaining 15% being intermediate level waste (ILW). Some High Level Waste
(HLW) also includes scrap plant items from vitrification plant maintenance that have
been contaminated. The sources of radioactively contaminated metals are not
confined to licensed nuclear operations; the oil and gas industry also routinely
generate Naturally Occurring Radioactive Material (NORM) contaminated material
(Electrowatt-Ekono, 2002).
The extent of potential source material for a radioactively contaminated metal melter
is outlined in Figure 1.
Figure 1
Radioactively contaminated metal arisings in the UK
(Derived from Electrowatt-Ekono, 2002)
Metallic Radioactive Waste
LLW (85%)
ILW (15%)
446 000t
70 000t
Quantity awaiting
conditioning:
Source:
(O)
Decommissioning (D) /
66 000t
Operational (O)
(D)
(O)
383 000t
39 000t
(D)
31 000t
More detailed information as to the breakdown by individual metals is provided in
Table 2 and Table 3.
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Table 2
Chemical components in LLW from all sources (Electrowatt-Ekono,
2002)
Weight (tonnes) (2) (3)
Material (1)
METALS:
Ferrous metals
Aluminium
Copper
Lead
Zinc
Magnox/Magnesium
Zircaloy/Zirconium
Boral
Brass
Bronze
Dural
Inconel
Monel
Nimonic
Stellite
Others
Stocks at 1.4.2001
Operational Decommissioning
Total
Stocks and arisings
Operational Decommissioning
Total
2,171
61
39
303
2
4
6
0
2
2
0.2
0.2
0.2
0
0.2
15
2,400
2,423
178
19
15
0
0
0
6
0
0
0
0
0
0
410
4,571
2,484
217
323
17
4
6
0
8
2
0
0.2
0
0
0
425
52,167
1,531
1,578
6,236
88
7
13
538
980
5
0.3
112
2
0
0.3
53
376,978
4,853
4,166
3,944
265
186
15
0
42
0
0
4
0
0
0
1,776
429,144
6,384
5,744
10,180
353
192
28
538
1,022
5
0
116
2
0
0.3
1,829
STABLE ELEMENTS:
Nickel
Tin
Niobium
Selenium
Molybdenum
38
0.7
4
0.1
11
517
5
0
0
23
555
6
4
0.1
34
2,051
6
29
1
78
5,600
118
147
3
797
7,650
123
176
4
876
INORGANIC ANIONS:
Fluorides
Chlorides
Iodides
Cyanides
Carbonates
Nitrates
Phosphates
Sulphates
Sulphides
Other anions
3
3
0
0
22
0
3
3
0
9
1
0
0
0
0
0
0
0
0
0
4
3
0
0
22
0
3
3
0
9
20
16
12
2
54
16
15
15
12
32
1,326
1,325
1,325
0
2,652
1,325
1,325
2,649
1,325
16
1,347
1,341
1,337
2
2,706
1,341
1,340
2,664
1,337
49
ORGANICS:
Cellulosics
Halogenated plastics
Non-halogenated plastics
Ion exchange materials
Rubbers
Other organics
162
72
152
72
85
258
46
17
17
0.3
6
6
208
89
169
73
91
264
86,501
10,607
8,142
523
8,450
1,729
8,422
8,437
5,623
15
3,240
123
94,923
19,044
13,765
538
11,690
1,852
COMPLEXING AGENTS
6
0
6.5
126
80
206
TOXIC METALS AND COMPOUNDS:
Cadmium
Lead
Mercury
Beryllium
Other toxic metals
0.4
303
0.3
0.3
0
0
19
0.3
0.3
0.3
0
323
1
1
1
1
6,233
4
1
0
2
3,819
9
9
282
3
10,052
14
11
282
OTHER HAZARDOUS MATERIALS:
Combustible metals
Low flash point liquids
Explosive materials
Phosphorus
Hydrides
Materials reactive with water
Strong oxidising agents
Pyrophoric materials
Generating or evolving toxic gases
Putrescible wastes
Biological, pathogenic materials
Asbestos
Free aqueous liquids (4)
Free non-aqueous liquids (4)
Powder (4)
9
0.7
0
0.09
0
3
0
42
0
0
0
13
544
136
5
0
0
0
0
0
0
0
0
0
0
0
11
0
0
0
9
0.7
0
0.09
0
3
0
42
0
0
0
25
544
136
5
35
3
0
0.45
0
3
0
42
0
0
0
109
631
512
79
0
0
0
0
0
0
0
0
0
0
0
1,103
0
0
0
35
3
0
0.45
0
3
0
42
0
0
0
1,212
631
512
79
Notes:
(1) The materials listed do not include all components of the wastes, e.g. soil.
(2) Note that care needs to be taken if summing material weight as certain materials
appear in more than one category
(3) Only waste streams with a quantified material concentration contribute to this
table.
(4) Potentially hazardous for the process of supercompaction
Page 4
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Table 3
Chemical components in ILW from all sources (Electrowatt-Ekono,
2002)
Weight (tonnes) (2) (3)
Material (1)
Stocks at 1.4.2001
Stocks and arisings
Operational
Decommissioning
Total
Operational
Decommissioning
Total
METALS:
Ferrous metals
Aluminium
Copper
Lead
Zinc
Magnox/Magnesium
Zircaloy/Zirconium
Boral
Brass
Bronze
Dural
Inconel
Monel
Nimonic
Stellite
Others
19,659
728
89
368
17
5,300
767
0
0.2
0.04
0
13
0
91
0.5
861
1,694
28
21
2
0.2
0.2
0
0
0
0
0
0
0
0
0
0
21,353
756
110
370
17
5,300
767
0
0
0
0
13
0
91
1
862
29,826
913
204
633
41
7,037
2,338
73
0.3
0.1
0
45
0
194
1
944
30,318
323
201
189
6
42
12
0
4
0
0
0
0
4
0
94
60,144
1,236
405
822
48
7,079
2,351
73
5
0.1
0
45
0
199
1
1,038
STABLE ELEMENTS:
Nickel
Tin
Niobium
Selenium
Molybdenum
1,403
12
41
0.8
215
45
0
0.08
0
12
1,448
12
41
0.8
227
2,367
37
52
3
231
735
0.02
5
0.01
103
3,102
37
57
3
334
INORGANIC ANIONS:
Fluorides
Chlorides
Iodides
Cyanides
Carbonates
Nitrates
Phosphates
Sulphates
Sulphides
Other anions
54
49
23
0
51
1,232
29
87
126
41
0
0.002
0
0
0.4
0
0
0.002
0
0
54
49
23
0
52
1,232
29
87
126
41
112
97
66
0
114
1,372
81
140
169
43
0.3
0.3
0.3
0
1
0.3
0.3
0.3
0.3
0.3
112
97
66
0
115
1,373
81
140
169
43
ORGANICS:
Cellulosics
Halogenated plastics
Non-halogenated plastics
Ion exchange materials
Rubbers
Other organics
1,030
2,033
1,018
509
536
176
59
64
50
4
52
0
1,089
2,096
1,068
513
588
176
1,251
2,663
1,202
617
741
379
404
595
374
9
401
0
1,655
3,258
1,576
625
1,143
379
COMPLEXING AGENTS
5
0
5
9
0
9
TOXIC METALS AND COMPOUNDS:
Cadmium
Lead
Mercury
Beryllium
Other toxic metals
2
342
2
1
549
0.06
2
0
0.3
0.1
2
344
2
1
549
2
611
2
1
644
7
189
0.1
38
2
9
799
2
39
646
OTHER HAZARDOUS MATERIALS:
Combustible metals
Low flash point liquids
Explosive materials
Phosphorus
Hydrides
Materials reactive with water
Strong oxidising agents
Pyrophoric materials
Generating or evolving toxic gases
Putrescible wastes
Biological, pathogenic materials
Asbestos
Free aqueous liquids (4)
Free non-aqueous liquids (4)
Powder (4)
4,222
0.8
0.09
0.09
0.3
3,586
1,239
6
1,239
152
21
44
12,410
6
66
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
4,222
0.8
0.09
0.09
0.3
3,586
1,239
6
1,239
152
21
44
12,410
6
66
6,390
1
0.09
0.09
0.5
4,216
1,250
7
1,250
152
22
80
14,876
9
71
41
0
0
0
0
42
0
0
0
0
0
0
0
0
0
6,431
1
0.09
0.09
0.5
4,258
1,250
7
1,250
152
22
80
14,876
9
71
Notes:
(1) The materials listed do not include all components of the wastes, e.g. graphite.
(2) Note that care needs to be taken if summing material weight as certain materials
appear in more than one category
(3) Only waste streams with a quantified material concentration contribute to this
table.
(4) Potentially hazardous for the process of supercompaction
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Table 4, derived from (Electrowatt-Ekono, 2002) shows predicted arisings of
radioactive metal waste from the major nuclear operators. The evaluation of the
application of metal melting technologies should therefore consider the timescales
and policy governing these arisings. Table 5 produced by the Department of Trade
and Industry (DTI) shows the status of UK nuclear sites and it can be seen that of
the 20 sites listed, 13 are currently undergoing some form of decommissioning. The
geographical location of the arisings will be a consideration for melting operators and
waste owners for the siting of any proposed melting facility.
Table 4
Metal Wastes at UK sites (Electrowatt-Ekono, 2002)
Weight of Metals Stocks
and Arisings
ILW
LLW
Operational
Decommissioning
Operational
Decommissioning
26,077
6,505
44,624
80,855
4,008
6,206
732
124,679
1,711
6,209
1,401
65,109
7,282
6,126
4,043
96,473
378
4,166
2,872
8,698
39
0
5138
0
(Tonnes)
Operator
Site
BNFL
Capenhurst
Sellafield
Springfields
Calder Hall
Chapecross
Berkeley
Bradwell
Dungeness A
Hinkley Point A
Oldbury
Sizewell A
Trawsfynydd
Wylfa
Hunterston A
Berekeley Centre
Dungeness B
Hartlepool
Heysham 1
Heysham 2
Hinkley point B
Sizewell B
Hunterston B
Torness
Dounreay
Harwell
Windscale
Winfrith
Culham
Aldermaston
Devonport
Rosyth Royal
Dockyard
HMNB Clyde
Rosyth and
Devonport
Eskmeals
DSTL Fort
Halstead
DSDC North
Defence Estates
Organisation
NRTE Vulcan
Amersham
Cardiff
Harwell
Capenhurst
(Also minor
producers)
BNFL Magnox
British Energy
Generation
Ltd
UKAEA
Ministry of
Defence
Amersham
Plc
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Table 5
Status of UK sites (http:/ / w w w .dti.gov.uk / nuclearcleanup/ tl.htm)
RESPONSIBLE
SITE
ORGANISATIONS
Sellafield
Operational and decommissioning - fuel
reprocessing and storage and management of
nuclear wastes and materials
Capenhurst
Works
Decommissioning/waste management and
storage
Springfield
Works
Operational and Decommissioning - fuel
manufacture, nuclear services and
decommissioning of redundant historic
facilities
Drigg Disposal
Site
Operational - low level waste disposal
Dounreay
Decommissioning
Windscale
Decommissioning
Harwell
Decommissioning
Winfrith
Decommissioning
Culham
Operational
Wylfa
Operational
Oldbury
Operational
Sizewell A
Operational
Dungeness A
Operational
BNFL
UKAEA
STATUS
Hinkley Point A Defuelling & Decommissioning
Magnox
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Bradwell
Defuelling & Decommissioning
Hunterson A
Decommissioning
Trawsfynydd
Decommissioning
Berkeley
Decommissioning
Chapelcross
Operational (will shut down by March 2005)
Calder Hall
Defuelling & Decommissioning
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2.1.2 Nature of the Radioactive Contamination
Metal contamination can be of two forms, either bulk or surface contamination.
Bulk contamination usually arises from neutron activation of nuclides during the
service life of the component. These components will usually be in-core components
i.e. will have experienced high neutron fluxes. The main activation products will be
Co-58, which arises from the nickel content of the metal (Inconel alloys and stainless
steel), and Co-60, which arises from cobalt impurity. Other activation products of
shorter half -life include Cr-51, Fe-55 and Mn-54.
Surface activity can be loose contamination arising from deposition of nuclides from
the interfacing medium, i.e. aqueous phase or gas phase during service. The
deposited nuclides will depend on the environment of the component during service.
Surface contamination can also be tightly bound, and this usually arises from the
adsorption of deposited nuclides into the oxide layer formed on the metal. These
require more aggressive decontamination techniques to remove such as melting.
Much of the metallic waste arising during decommissioning is only surface
contaminated rather than activated. As melting causes a homogenisation of the
radionuclides mentioned above, the removal of surface contamination should be
actively considered by waste owners and melt operators prior to melting if the aim is
to reduce activity of the waste to as low as is possible.
As will be later described in Section 3, melting redistributes radioactivity between the
slag, the metal and off-gases depending on the radionuclides present. The
radionuclides generally present within the radioactively contaminated scrap metal are
Co-58, Cr-51, Fe-59, Ni-58, Zn-65 and Mn-54. These appear in combination with the
main fission products Cs-134 and Cs137. The more volatile nuclides such as
strontium and caesium leave the melt and are essentially transferred to the slag and
the fumes. These are then retained by special filter systems. Other radionuclides
such as cobalt, nickel, chromium, iron, zinc and manganese remain within the melt
with only a small transfer to the slag (European Commission, 1998a).
2.2
Recycling of Metals Outside the Nuclear Industry (Public Domain)
In order for material from the nuclear sector to enter the public domain it must be
released from regulatory control i.e. it must be ‘cleared’. In the UK this is by means
of the Radioactive Substances (Substances of Low Activity) Exemption Order.
In addition to demonstrating compliance with these objective regulatory criteria,
there are a number of ‘subjective’ obstacles that must first be overcome. These
include for example, the concerns of the scrap metal industry and the general public
over radioactivity in the environment. These issues are discussed in more detail in
Section 5.
Assuming the barriers to recycling of radioactively contaminated material and its later
use in the non-nuclear market can be addressed, there are two main options for
release into the general scrap market:
1. Surface contamination is removed. The metal is authorised for release from
the nuclear site to a commercial non-nuclear metal melting facility for
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recycling along with ‘normal’ scrap metal. After melting the ingots are free to
be sold on the open market. This follows the route of ‘specific’ or ‘conditional’
clearance foreseen in RP 89 (see European Commission, 1998b).
2. Surface contamination is removed and the metal is melted at a
designated/separate melting facility specifically for radioactive scrap metal.
The resulting ingots are then cleared for the open market.
2.2.1 Specific Clearance
The advantage of using existing operational (non-nuclear) melting facilities where
radioactive waste metal is mixed with “normal” metal is that the expense of
construction is avoided. In addition there are savings in efficiency as the plant will be
able to operate at near-full capacity. There will be a dilution effect from the mixture
of charges, as a result of mixing contaminated material from the nuclear industry
with non-nuclear sourced scrap in the melting load.
However, all waste metals would have to meet stringent specific clearance levels
such as those recommended by the European Commission in RP 89 before release
from a nuclear site could be authorised. RP 89 gives clearance levels for surface
contamination in Bq/cm2 as well as Bq/g limits. These specific clearance levels are
radionuclide specific. They were derived on the basis of radiological assessments
that assumed only a fraction of the scrap in the furnace came from cleared scrap
(European Commission, 1998b). Specific or conditional clearance is where the
material is released for a specific purpose e.g. for melting. In the case of general or
unconditional clearance material is released from regulatory control without any
future controls or restrictions. In UK legislation there are no specific clearance levels.
Traceability and controls to ensure the material reached its defined destination, i.e.
the melting facility, would have to be in place. Agreements also would have to be
reached with furnace operators to accept the waste. Finding a commercial melting
facility willing to melt material meeting the specific clearance standards is likely to
prove difficult. In Germany there has been a reluctance from the non-nuclear steel
industry to accept material from nuclear facilities even when the material is below the
more restrictive general clearance criteria (European Commission, 1998a). In France
a programme of recycling ran into problems due to the commercial steelm aker
partner not wishing to be associated with the nuclear industry.
The details of the French example are that the Atomic Energy Commission (CEA)
set up a pilot program for recycling decontaminated scrap metal using a commercial
steelworks. The key aspects of the system included:
•
•
•
•
•
•
•
•
•
•
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the choice of operators,
the identification of objects,
traceability with regard to operations and operators,
the contractual basis of the services provided,
the contracts between the owner of the containers,
the decontamination contractor and the steelmaker,
documentary control of operations,
verification inspections and measurements,
second-level supervision,
auditing of operators,
Page 9
•
environmental impact calculations and public information (Bordas, 2000).
Despite a unanimous favourable decision from the Public Health Commission for the
region which followed 3 years of reviews by the French authorities including the
OPRI, DSIN, CSSIN, DRIRE, the Ministries of Health, Industry and the Environment
and a public consultation, the operation has stalled due to the concerns of a key
stakeholder, namely the steelmaker. A foreign owner bought the steelmaker
partner, and was afraid of the consequences of adverse media publicity and refused
to get involved (Bordas, 2000).
2.2.2 General Clearance
The alternative is to set-up a licensed melting facility dedicated to the melting of
scrap metal from the nuclear industry. The melting would still be subject to
regulatory control thus metals of higher activity could be melted. There is the
opportunity to reduce the level of segregation and sorting on the basis of activity
levels required in advance of melting. It may be possible also to reduce the extent
of the surface decontamination and its verification. After melting, ingots could then
be sorted into those that can be cleared, those that should be recycled within the
nuclear industry and those that require disposal.
There is no guarantee that after melting and after achieving radioactive
decontamination below the general clearance levels such that the metal ingots can
be sold on the open metal market that a buyer will be found. As mentioned
previously, in Germany steel companies continued to be reluctant to take material
from nuclear facilities even when the material is below clearance levels (European
Commission, 1998a). As later described in Section 5, cleared material can set off
gate alarms on the entrance to the steel facilities which steel producers procedures
dictate they will reject; there is also a concern that the acceptance of cleared
material into the system will have an adverse effect on the industry commercially by
reducing demand for metal amongst consumers due to a nervousness regarding
radiation. There have been some notable successes, including the aluminium melter
at Capenhurst, UK where 7000 t of aluminium has been melted for unrestricted use
(See Table 1).
A matter for consideration by the melter operators in conjunction with the waste
owners in this approach is achieving a cost efficie nt use of the facility i.e. maximising
its use.
2.3
Recycling Within The Nuclear Sector
2.3.1 Availability And Potential Usage Of The Recycled Material Within The
Nuclear Sector
Uses of recycled metals within the nuclear sector other than in radioactive waste
disposal or storage facilities are limited, an example being in shielding blocks. A
review of the amounts of waste steel, concrete, copper and aluminium generated
from the decommissioning and normal operations of nuclear facilities in the EU from
1998 to 2050 was made in EUR 18041 (European Commission, 1998a). Twelve
scenarios for the recycling and reuse of these materials within the controlled nuclear
sector were analysed. The intended final product dictates the scrap grade that can
be used. Product specifications and the inherent radioactivity must be appropriate to
the intended future use. Thin cold rolled products (e.g. for waste drums) will require
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higher purity steel to prevent surface defects and stress cracking during fabrication,
whereas rebar and structural steel only requires lower quality steel. The report,
(European Commission, 1998a), concluded that steel recycling by melting, and
concrete recycling by crushing were the most likely forms of controlled release
recycling that could be carried out economically.
Copper and aluminium recycling within the nuclear sector was considered unfeasible.
With respect to copper, refining processes are most likely to yield copper suitable for
clearance. It was estimated by ENRESA and AEAT, the authors of the European
Commission report, that there is insufficient copper arising as waste in the nuclear
sector to run a plant dedicated to its refinement at full capacity. With respect to
aluminium, recycling for unrestricted release (as demonstrated by operations at
Capenhurst) would be the most likely form of recycling.
Following a review of existing European radioactive waste disposal facilities by AEAT
and ENRESA, the requirements for steels for rebars, boxes, drums, and concrete for
boxes and grouts across Europe have been calculated (European Commission,
1998a), and the estimated UK requirements have been reproduced in Table 6. In
the UK the final decommissioning of stations is delayed for around 100 years to take
advantage of the decay of some radionuclides and thus reduce the amount of
waste that may require final disposal in controlled facilities. Thus in the UK the large
amounts of waste generated from decommissioning of nuclear power plants were
outside the timescale being considered for the European Commission study.
Table 6
Requirements for drums, boxes, reinforcement, grouts in UK
disposal facilities currently in operation (European
Commission, 1998a)
Type of container
used
UK Total/ yr
6 600
Total Steel
requirements
(t)
858
500 litre drums
(requires 0.13 t of
stainless steel)
200 litre drums
Concrete boxes
(requires 0.62 t of
carbon steel for
reinforcing bars)
3m 3 boxes
(requires 0.63 t of
stainless steel)
ISO containers
(require 2.5 t steel
plate)
2010 - 2060
162 000
61
38
1997 – 2050
2010 – 2060
423
266
2010 – 2060
600
1500
1997 – 2050
Timescale
In the UK the waste container which will be in greatest demand is the 200 litre drum.
The estimated annual arisings of metals are presented in Figure 2.
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Figure 2
Estimate of metal arisings from UK decommissioning
SOURCE DATA: European Commission, 1998a based upon figures from the 1994
United Kingdom Radioactive Waste Inventory. DOE/RAS/96.001, UK Nirex Report
No. 695.
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Figure 2 cont’d
The LLW arisings of aluminium within the UK are plotted above. Although it appears
that there are significant arisings of aluminium in general it arises as only a small
percentage of waste within any waste stream.
As for aluminium the copper waste generally arises as a small percentage of a waste
stream e.g. electrical components and cabling.
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The data suggests that the arisings of material will always exceed the possible uses
of that material identified for disposal facilities. Around 40 % of Europe-wide arisings
of carbon steel could be recycled into waste containers and rebars. For stainless
steel the fraction of material generated that could be recycled is smaller at around
20 % of arisings. For stainless steel it is suggested that in some cases storage of
metals for later use should be considered, especially if disposal plans for the second
half of the 21st century indicate that large quantities of stainless steel containers
would be required for disposal or storage of ILW or spent fuel (European
Commission, 1998a).
The use of recycled metallic materials in the manufacture of spent fuel storage
disposal containers is an attractive scenario because the activity of the final
containers will be dominated by the activity of the waste contained therein rather
than any residual activity in the recycled product. The review of practices in spent
fuel management reveals several opportunities for the use of recycled steel for the
manufacture of containers. For example, casks such as the CASTOR type used in
Finland could be easily made at a plant similar to that proposed for the manufacture
of cast boxes for disposal of LLW/ILW. However, Given that the plans for dealing
with spent fuel are at an early stage in many countries, this gives suitable scope for
examining the possibility of incorporating a controlled release strategy in this area.
2.3.2 Necessary Additional Processing Facilities
One of the problems in the reuse of stainless steels that cannot be sold to the scrap
market for unrestricted release is the requirement for processing of the metal into
plate. Due to the high value of the material and its anti-corrosive properties,
stainless steel products used in the nuclear industry are essentially formed and
welded from plate. For production of containers such as a 500 litre drum used for
disposal of ILW in the UK, a rolling mill would be required. If material is of an activity
higher than that suitable for unrestricted release then a nuclear installation rolling mill
would be required. Any facility of this nature would have to address operational
complexities including maintenance of potentially contaminated equipment and the
possible requirements for remotely operated machinery. Even mini-mills used in
conventional industry have annual capacities of 200,000 tonne meaning that a
nuclear facility of this type will be operating significantly under capacity. This raises
problems in finding suitable sources of material for processing within the country of
location of such a facility, and with it problems in transportation and legislation
regarding movement of material across borders.
The alternative of using the facility to also roll plate for unrestricted release may not
be acceptable to the conventional market. Investment in such a facility for a short
lifetime and the siting of a large facility may mean that this scenario may not be
feasible within Europe. The alternative manufacturing process of back-extrusion
instead of forming from plate, raises further possibilities for stainless steel controlled
release recycling. However, further evaluation of this method of manufacture and
analysis of the economics would be required (European Commission, 1998a).
With respect to carbon steel used for the production of 200 litre / 220 litre drums
from plate, the same problems of processing of the metal into plate would be
encountered as those for stainless steel recycling. It should be noted, however,
that because of the extensive use of such drums around the EU, the production of
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these drums would provide a larger market for carbon steel. The requirement for
drums in a single country would be much larger than for stainless steel containers,
and may therefore support a facility dedicated to arisings from a single country.
This would reduce problems in transportation, but those of siting of such a facility
would still have to be resolved.
The adoption of a strategy of recycling within the nuclear sector may require
considerable collaboration between several organisations e.g. the waste owners,
melter operator, disposal facilities and the regulators. In cases where the
decommissioning operations, construction and placement of waste materials are
carried out by the same organisation, the availability of disposal facilities (and thus
options for restricted release recycling) and the arisings of materials suitable for
recycling can be easily matched. Where this is not the case there is need for
considerable collaboration (European Commission, 1998a).
2.3.3 Experience
Facilities in France, Sweden, Germany and the USA are currently melting material
and producing waste containers and shielding. (See Table 1).
2.4
Melting as Part of a Disposal Strategy
In addition to facilitating recycling as described above melting can be advantageous
for disposal. SOCODEI in France has operated a contaminated scrap metal melting
unit at CENTRACO since February 1999. CENTRACO has achieved volume reduction
ratios from ten to one to twenty to one (Faugieres, 2000). However, this may take
into account a degree of reuse of the metal for shielding blocks and packaging. A
more conservative estimate of volume reduction is that Electric Arc Furnace (EAF)
and induction furnaces can achieve a reduction factor of 4 – 6 (ISTC, 2004). The
reduction in volume will be dependent on the geometry and form of the metal. It
may be possible to redistribute activity of a number of ILW waste streams by
combining them such that the eventual waste is a single waste stream reduced to
it’s maximum density with the volume of the waste reduced when compared to that
of the initial separate waste streams.
If the melter’s purpose is purely to reduce the volume prior to disposal (i.e. there is
no intention to recycle the material), there will be no requirement to decontaminate
or sort the metals (other than to ensure there are no water containing vessels in the
load). Melting technology can be chosen to avoid the production of slag or the slag
can be added back into the melt and disposed of together.
In addition to volume reduction melting provides:
•
•
A homogeneous waste form which makes characterisation simpler and easier;
A stabilised final waste package (Faugieres, 2000).
It may be possible that once the metal is melted and formed into easily stacked
ingots the need for further packaging for disposal could be avoided as the
radioactivity is stabilised within the bulk metal. As a consequence of homogenisation
during melting the activity concentration will fall which may affect the categorisation
of the radioactive waste and thus the correct disposal facility for it.
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2.5
Summary - Waste Issues
There is a large quantity of metal in the UK that could be melted. The majority of
this radioactively contaminated metal is LLW. 90% of the metal is ferrous.
There are three main melting strategies for these wastes:
•
Melting for release to the open market:
Melting for release to the open market will require the product to meet stringent
clearance criteria. There will also be exacting controls for the verification and
monitoring of the process. There also remains the issue of whether there is a
market for the material due to continuing nervousness amongst the public and steel
producers over radiation.
•
Melting for reuse within the nuclear sector,
Melting for reuse within the nuclear market will permit the recycling of metals which
would not achieve the more stringent clearance levels required for free release. It is
likely that the UK supply of contaminated metal generated within the nuclear sector
would outstrip the demand for recycled materials within this sector.
•
Melting for disposal.
Melting for size reduction, would require no prior surface decontamination and very
little sorting of the waste material. Melting can achieve a volume reduction factor of
4 –6, thus significantly reducing the disposal cost accordingly. Melting will
homogenise and stabilise the waste reducing packaging requirements.
These strategies have been described as three separate approaches. There is
opportunity however to integrate the strategies such that were possible material can
be cleared, reused within the nuclear sector or disposed of at Drigg or Nirex
depending on the activity of the product and the available markets. Whatever the
strategy or approach each will require to a lesser or greater extent the co-operation
and acceptance by the public and the non-nuclear steel industry:
•
•
•
•
•
Acceptance of metal products containing recycled metal from the nuclear
sector (public),
Acceptance of cleared material (steel maker),
Acceptance of radioactive metals/ingots for controlled melting/rolling for the
nuclear sector (steel maker),
Acceptance of a melting facility for radioactive material (public),
Acceptance of a variation in source material at an existing melter (public and
steel maker).
The issues which arise for each strategy are summarised in Table 8.
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3
Melting Technology
3.1
Introduction
In Section 2, the extent of available radioactively contaminated metal in the UK was
explored and the potential strategies for melting and their implications discussed.
Section 3 concentrates upon the available technology for the achievement of those
strategies.
The section addresses:
• Overview of the process of melting radioactively contaminated metals,
• Proven technology used for melting radioactively contaminated metals,
• Current non-nuclear technologies,
• Developing and emerging nuclear melting technologies.
3.2
Overview of the Process Of Melting Radioactively Contaminated Metals
In the 1990s, the melting of contaminated steel in purpose built plants for recycling
developed as a new industry (NEA, 1999). Seven plants have been identified as
having melting facilities or having melted contaminated metals on an industrial scale
(see Table 1). The plants are located in France, Germany, Sweden, UK and the
USA. Six out of seven of the facilities use induction melting, and the remaining plant
used electric arc melting (see Section 3.3). To date, available information suggests
that scrap metal has largely been recycled within the nuclear industry.
A review of the feasibility of recycling and/or reuse of non-releasable components
and materials arising from nuclear operations within the European Community has
been undertaken by ENRESA and AEAT on behalf of the European Commission.
The study concluded that the recycling of radioactive steels (carbon and stainless) is
an already well researched area which requires no further development as regards
the melting and refining of steel arising from nuclear facilities (European Commission,
1998a).
3.2.1 The Treatment Process
The treatment of radioactively contaminated steels will depend on whether the
contamination lies within the bulk of the steel or on the surface.
Surface Contamination
In the case of surface contamination, the melting process will distribute the activity
within the bulk. Consequently, if melting technologies are used to process steels and
the aim is to maximise the reduction of activity, it is important to remove surface
contamination before treatment if the reduction/removal of radioactivity is to be
achieved (See Section 3.2.2). A pre-treatment, surface decontamination process will
generate secondary waste arisings, which may require further treatment prior to
disposal.
Bulk Contamination
A generic flow diagram for bulk-contaminated scrap is given in Figure 3. Prior to
melting, items have to be size reduced to allow charging of the furnace through a
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suitable air-lock which prevents the escape of aerosols during the loading process.
The material must be sorted, for steel melting for example there must be no
copper, lead or cadmium entering the melt, as this would result in an unacceptable
final product for recycling. Sorting is also necessary to ensure there are no bodies
containing water as this leads to formation of vapour in the melt and presents an
explosion risk (European Commission, 1998a).
Figure 3
Scrap metal for steel-making (NCRP, 2002)
Melting
The metal is melted usually either by heating by means of electrical induction heating
or by electric arc in the furnace and flux potentially added, a slag phase containing
the bulk of the contamination forms and floats on top of the metal phase. Fluxing
agents may be added to im prove the slag separation; flux is a mixture of oxides
added to the molten metal to enhance the capture of impurities (NCRP, 2002). Any
combustible and volatile materials including volatile metals and metal oxides are either
contained by vacuum melters and enter into the slag, or they enter an off-gas
system (Garcia, 1996).
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3.2.2 Distribution of Radioactive Material in the Metal-Melting Process
When the aim is to maximise the reduction of activity, the first step is to remove as
much surface contamination as possible. Melt refining can then be used to remove
radionuclide contaminants from metals or alloys by preferential oxidation, and the
oxidized contaminants are then separated from the metal.
The removal of impurities can be achieved by vaporisation if they have a low boiling
point. The vapours can be removed in the off-gas system or reacted with oxygen
to form an oxide fume. For high boiling point impurities, they are combined with flux
components and removed in the slag. The mode of removal is therefore a function
of the chemistry of the furnace (acidic or basic), the thermodynamics of the
system, and the chemistry of the impurities. Table 7 presents ranges of partitioning
data for various radionuclides when melted in the electric arc furnace (EAF) steelmaking furnaces.
Table 7
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Partitioning factors for BOFs and EAFs (NCRP, 2002: Cheng
et al, 2000; Nieves et al, 1995; NRC, 1999)
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A study by the US National Commission for Radiation Protection and Measurement
(NCRP) indicated that steel refining processes are successful in removing
lanthanides, actinides, and other fission products that are easily oxidised from
ferrous metals. However, results are poor for removing transition elements such as
cobalt and technetium from stainless steel, and carbon steel (NCRP, 2002).
The fate of contaminants during melting processes can be summarised as follows.
•
•
•
•
3.3
Transition metals that readily alloy with steel (eg Ni, Co) will remain within the
bulk metal – this means the resulting metal may be unsuitable for clearance
and may have to be disposed of or undergo a period of decay storage.
Cs, Pb and Zn and other contaminants of relatively low vapour pressure are
captured in the emission control system – any filters would therefore, be likely
to be disposed of as radioactive waste
Owing to their volatility, iodine or tritium escape through the stack – such
emissions may require the use off-gas treatment
Transuranics (eg U) are readily oxidised and will remain in the slag and can
be removed from steel completely under some conditions – the slag may
require further treatment before being disposed of.
Proven Technology Used For Melting Radioactively Contaminated Metals
3.3.1 Electric Arc Melting
In a three-phase arc furnace the charge is heated and melted by an electrical
current passed indirectly between three electrodes. The furnace consists of a
refractory lined hearth and a water-cooled roof section, with holes to allow the
electrodes to be lowered into place. The roof section may be lifted or swung away
to permit feedstock to be loaded into the furnace. The roof section is then
replaced, the electrodes are lowered, and power is applied to melt the charge. After
melting, the furnace is tilted, the slag is tapped, and the molten metal is poured into
a ladle. A three phase, 15 tonne arc furnace, INFANTE, commenced operation in
April 1992 for the melt consolidation in the treatment of ferrous materials recovered
from the dismantling of the CO2 systems from the plutonium production and power
generation reactors at Marcoule, France (Schlienger et al, 1997). The CEA has since
shut down the furnace and is sending or planning to send any metal to the induction
melting unit at Centraco (Byrd Davis, 2003). The disadvantages of the system
have been identified as the following (Schlienger et al, 1997):
•
•
•
•
a great deal of dust and fume is produced,
the furnaces are difficult to enclose,
spent refractory from the furnace hearth and from the ladles used to
transport molten metal becomes a radioactive waste stream, and
slag handling is complex, because it must be handled in a molten condition.
The ferrous melting facility in France had a 2.5 m opening diameter, allowing a
nominal maximum charge piece size of 1.7 m X 1.7 m X 1.3 m. The installation was
sized for two 12.5 t taps per shift with the nominal product being 25 kg cast iron
ingots produced on a continuous casting line (Worchester et al, 1995). Arc melting
was selected over induction melting for ease of operation, greater safety,
acceptance of large feed piece sizes, and ease of modifying the charge composition.
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Production of cast iron was chosen as the product over steel because of its lower
melting temperature and casting ease (Worchester et al, 1995).
The advantages of EAF are (Worchester et al, 1995):
•
•
•
•
lower costs are incurred with increasing heat requirements,
accommodates larger scrap section sizes,
allows for easier modification of melt composition, and
provides a greater margin of reliability and safety because of the absence of
the water cooled induction coil.
3.3.2 Induction Melting
An induction furnace is an AC electric furnace in which the primary conductor
generates, by electromagnetic induction, a secondary current that develops heat
within the metal charge. It can be performed in a vacuum, and hence it is usually
done without a slag layer. Vacuum induction melting is the optimum
decontamination strategy for removal of volatile radionuclides but does not provide a
mechanism for the removal of non-volatile radionuclides.
The Siempelkamp facility in Germany has employed induction furnaces since 1984
(Schlienger et al, 1997). There are two melting plants, namely CARLA and GERTA.
CARLA was commissioned in 1990 and is an authorised recycling facility for nuclear
applications employing a 3.2 t 300-500 Hz coreless induction furnace with a melting
capacity of 2 tonne/hr. It is equipped with a negative pressure fume system.
GERTA is a development of CARLA commissioned in 1998 for the treatment of
naturally occurring radioactive material (NORM) and toxic/chemical contaminated
material. GERTA (Figure 4) uses an 8 t line frequency induction furnace
(Siempelkamp, 2004).
Figure 4
GERTA (Siempelkamp, 2004)
Sweden also has a radioactive metal melting facility (Studsvik AB), which also uses
an induction furnace (Schlienger et al, 1997). There is a further induction furnace
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facility at Centraco in France which began processing radioactive material in February
1999 (Byrd Davis, 2004). A coreless induction furnace was also used in the
decommissioning program of the Japanese Power Demonstration Reactor (JPDR).
This method was selected because it allows melting of both stainless and carbon
steel, it produces less secondary wastes (aerosols, dust, etc), and fume hooding is
easier (Worchester et al, 1995).
The advantages and disadvantages of induction melting systems are:
Advantages
•
•
•
the system permits but does not require the use of a slag
the system exhibits good melt agitation, rela tively easy fume control and
rapid heat-up
it is not as inherently dusty as electric arc melting, producing only 20% as
much effluent dust
Disadvantages
•
•
there is an increased risk of cross-contamination between melts due to
reactions between refractory lining and the metal and also the slag.
molten slag is removed by skimming for which the furnace may be opened
releasing fumes and dust.
3.3.3 General Aspects of Proven Nuclear Melting Technologies
As described in Table 1 plants in Germany, Sweden, USA and the UK have selected
induction melting as their preferred technology.
The main factors favouring coreless induction over electric arc furnace are:
•
•
•
Better melt agitation,
Easier fume control, and
Rapid heat-up (Worchester et al, 1995).
The above factors are particularly important when considering an initial
consolidation/homogenisation melt of radioactively contaminated metals, and are the
primary reasons why induction has been selected for most of the existing large scale
melting programmes (Worchester et al, 1995).
Concerns relating to the process raised in the past include the stratification of
residuals because it could result in ‘hot spots’ of concentrated radioactivity in the
finished product. Causes include:
•
•
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Temperature stratification within the vessel that prevents the free movement
of convective currents. It has been observed in some EAF furnaces when
low-power current reduces the convective mixing of the liquid bath in the
furnace.
Induction furnaces are more likely to experience temperature and chemistry
stratification due to overall lower melting and refining temperatures and lower
occurrence of physical mixing.
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In practice it has been demonstrated that the application of electrical arc and airinduction installations gives rise to serious problems in collecting and processing dust
and slag; the gas clean-up system is cumbersome and expensive. However,
induction vacuum furnaces also suffer from substantial disadvantages, i.e. the low
service-life (= 50 runs) of melting crucibles and moulds resulting in additional
secondary waste that cannot be processed (Pastushkov et al, 2001).
The benefits of the melting process are that as quantities of contaminated waste
continue to increase, while the space available for disposal decreases, melting
provides a mechanism for both simple volume reduction and also for the avoidance
of disposal by means of recycling. During the melting process volatile nuclides such
as Cs-137 volatilise from the metal. And so in most reactor scrap metal, the
remaining radioactive elements have relatively short half -lives (eg Co-60), permitting
material to be reused at some predetermined time in the future. The process of
melting and casting into ingots of convenient shape reduces the volume of the
material thus saving on the high cost of disposal and storage (Schlienger et al,
1997). Melting eliminates the problem of inaccessible surfaces, and the remaining
radioactivity content is homogenised over the total mass of the ingot (NEA, 1999).
This results in no surface contamination, and the measurement of activity after
melting is easier. Furthermore as previously stated, the redistributing of
radionuclides in ingots, slag and dust results in an effective decontamination.
3.4
Current Non-Nuclear Technologies
The non-nuclear metal melting industries serve a vast market. In 1997 the steel
industry of the 15 countries of the EU produced almost 160 Mt of crude steel. The
technology is well developed, typically the large producers operate integrated mills
located near coastal waters or large rivers operating Blast Furnace – Basic Oxygen
Furnaces (BF-BOF). Smaller steel mills are located close to demand, using Electric
Arc Furnaces, installations of this type account for over a quarter of steel production
in the UK and more than a third of the world production capacity.
In the next two decades the European Confederation of Iron and Steel Making
industries (EUROFER) anticipate that between 50-60% of steel will be produced via
BF-BOF. EUROFER also expect the main technological developments will be
focussed on improving process control and efficiency, product quality, environmental
and safety performance. Some developmental work has been carried out assessing
the impact of using waste or by-product gas, oil and in some cases plastics, to
reduce the proportion of coke consumed and to harness the energy potential of
wastes through reuse. Assessment has also been made of the effect of preheating
feedstocks on reducing energy consumption (Manning & Fruehan, 1999).
Many derivative processes exist though these are based on the same principle
furnace technology but with adaptations to suit the use of different reduction
processes to meet the individual needs of producers or to meet the steel quality
needs of the consumers. Examples of these processes include HIsmelt, COREX,
FINEX, FINMET and MIDREX.
The Electric Arc Furnace is detailed in Section 3.1.1.
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3.4.1 The Blast Furnace – Basic Oxygen Furnace
The blast furnace, see Figure 5, is a refractory lined steel vessel which is charged
from the top with iron-ore, coke and flux materials. The iron-ore feed stream is in
the form of small pellets or fragments up to 4 cm across. The coke is produced
from crushed coal which is heated until most of the volatiles such as oil and tar are
removed. The flux is usually limestone which again must be crushed before it can
be charged into the furnace. In addition to these streams the furnace requires air
supply at a rate of 2300 m3/min to 6500 m3/min. Air is introduced at the lower
region of the furnace at high temperature and pressure. Gas temperatures are
typically 1,800° to 2,200°F at 30 to 60 psig, the resulting flame temperatures are
typically 2400° to 2500°F [www.atsiinc.com].
Figure 5
Blast Furnace – Basic Oxygen Furnace (www.atsiinc.com)
The molten metal and slag passes through the coke bed to the bottom of the
furnace where the slag floats on top of the liquid iron. Iron and slag are tapped
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through notches at the base of the furnace shell. The high temperature exhaust
gases exit the top of the blast furnace with considerable energy value. These gases
are burned to preheat the blast air, any surplus is used to generate steam which
turns a turbo blower to compress the blast air.
According to the British Metals Recycling Association (BMRA), the UK steel industry
BF-BOF process incorporates approximately 25% secondary metal in each furnace
charge. The use of a BF–BOF design in the treatment of radioactive contaminated
scrap would require significant pre-treatment of wastes to size reduce the feed
stream (BMRA – www.recyclemetals.org).
3.5
Developing and Emerging Nuclear Melting Technologies
3.5.1 Cold Crucible Technology
Cold Crucible melters have been used for the melting of high purity and reactive
metals and the technology is now being developed for use in the nuclear sector for
the treatment of metallic waste. At Marcoule in France a cold crucible has been
developed to melt waste from fuel decladding operations (Byrd Davis, 2003).
Developmental work is ongoing in France, Russia and Japan. This follows on from its
implementation in waste vitrification (www.entech.org.uk/). The technology utilises
the induction furnace but replaces the ceramic crucible with a water-cooled crucible
typically made of copper. Electrical currents are induced in the crucible’s outer
surface and transferred to its inner surface, generating currents in the charge which
(depending on the shape of the crucible) can cause the molten metal to rise leading
to enhanced mixing within the melt (as a result cold crucible melters are sometimes
referred to as levitation melters).
As the crucible is water cooled, the crucible itself remains cold, thus a ‘skull’ of
solidified material forms between the crucible and the molten metal. The advantage
of this is that crucible lifetime is prolonged as the cooled solid skull protects the liner
by insulating it from the melt and minimising corrosion. In addition, the copper
crucible is less susceptible to contamination than the ceramic crucible.
Demonstration facilities have been constructed, the US DOE have collaborated with
the Russian Institute of Chemical Technology in Moscow to develop a Hybrid Plasma
Induction Cold Crucible Melter (HPICCM) for waste recycling applications. The pilotscale Plasmatron with Induction Cold Crucible Melter (PICCM) has been successful in
laboratory and pilot scale tests. Additional work is in progress and the technology is
being considered for application at US DOE sites (Plodinec, 1998).
In common with other melting techniques, waste volume reduction factors are
typically 5-6 and the process is capable of removing surface contamination and
contamination from within the bulk metal. Cold Crucible melting can achieve
decontamination of over 98% for Caesium, Strontium and alpha emitting
radionuclides (Pashtukov, 2001).
The main advantages include:
• compact facility with low resource requirements,
• crucible life-span of 10 years is possible,
• compact and simple offgas treatment,
• low consumption of fluxes (3-5% of the metal mass),
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•
•
•
•
low production rates of slag for subsequent cementation or vitrification,
no mould or casting device required,
high quality of decontaminated metal, and
remote operation is possible.
3.5.2 Plasma Arc Furnace
A plasma arc furnace consists of a melt chamber with a feed entry route and output
route for the waste material. Within this chamber an electrical charge is passed
through high temperature gas to create the arc which can reach temperatures of
7,000 to 12,000 degrees Celsius. Outside of the arc, temperatures typically reach
1100 to 1400 degrees Celsius. The plasma-based technologies include plasma torchbased systems and plasma arc melters. Originally plasma torches were developed in
1960s for plasma-cutting and plasma-spraying equipment. More recently plasma
technologies were developed for the treatment of municipal, medical, hazardous
chemical and nuclear wastes. Figure 6 shows a simplified schematic of a Plasma Arc
Furnace for the treatment of LLW.
Figure 6
Plasma Arc Furnace (Fentiman et al .)
The Plasma Arc Furnace could be described as an emerging technology, although
Plasmas have been used for decades in many industrial metal processing applications
it is more recently being used to treat hazardous waste including metals at a number
of facilities worldwide.
A Model 10 IET Pla sma Enhanced Melter, has been recently installed in Japan. The
Integrated Environmental Technologies Plasma Enhanced Melter (PEM) system,
illustrated in Figure 7, uses a dual heating system to optimise operations and
minimise energy use. A DC arc plasma is used for waste destruction and
gasification. The DC plasma destroys the organic materials and reacts with the
carbon. An independent joule heated AC electrode is used to heat a molten glass
bath, which incorporates the inorganic residues from the waste into the glass matrix.
In most cases, the glass also immobilises hazardous metals and nuclear
contaminants into a leach resistant final waste form. The melter performs three
function simultaneously:
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•
•
•
thermal treatment,
vitrification and
metal melting.
Depending on the waste stream, most of the waste is converted into either glass or
metal waste form.
Figure 7
IET Plasma Enhanced Melter
The advantages of this system include:
•
•
•
•
•
No metal waste separation,
Off-gas volume less than conventional incinerators,
Low releases of chemical and radiological pollutants,
Possible to obtain stable final waste form with correct feed mix,
Can process higher temperature melting materials and improve transfer of
heat.
The disadvantages of this system include:
•
•
•
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Plasma has limited history in the nuclear industry,
Short electrode life affects system’s operating time,
Partitioning of radionuclides into slag must be verified,
Attentive operational control required.
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3.6
Summary - Melting Technology
There are a number of proven metal melting technologies operating around the
world for processing radioactive metal wastes. The majority of these are based on
induction melting technologies.
The removal of surface contamination prior to melting is necessary if total bulk
activity of the metal is to be reduced following processing.
In addition, there are some developing and emerging technologies, notably plasma
arc and cold crucible technology which may play a future role in radioactive metal
management.
4
Policy & Regulatory Control
4.1
Introduction
This section seeks to explore international and UK policy that is likely to influence
future application of melting technology in the UK. Experience internationally has
shown that melting plays a role in the clearance of metals and so international
guidance in relation to clearance is considered. Interest with regard to international
policy is focussed upon the European Union as the UK being a EU Member State is
most directly affected by the guidance of the EU through the European Commission.
In the UK there are a number overarching principles applied in the area of waste
management and decommissioning. These key principles are considered where
melting of radioactively contaminated scrap metal may be relevant.
This section covers:
•
•
•
4.2
International policy with regard to clearance
UK policy and its implications for melting
Implications of recent developments in UK decommissioning policy
developments
International Policy with Regard to Clearance
4.2.1 European BSS & Clearance
Under Title III of the European Basic Safety Standards (European Commission,
1996) there is provision for Member States to remove material from regulatory
control, namely clearance. The concept of clearance is for the purpose of releasing
material with low levels of radionuclide contamination from a regulated practice or
work activity. Clearance is seen as a means of saving valuable natural resources
and avoiding unjustified allocation of resources for controlled disposal of low activity
waste.
Guidance
The European Commission has further facilitated clearance by providing various
guidance documents on the implementation of the concept. The decision to apply
the clearance criteria set out in the guidance below remains the responsibility of the
competent authorities in Member States, however, it was concluded in RP 89
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(European Commission, 1998b) that slightly radioactive metal scrap, components
and equipment from nuclear fuel cycle installations can be authorised for clearance to
the public domain whenever recycling within the nuclear industry is not appropriate
subject to meeting the clearance criteria.
In the context of metals relevant European Commission guidance includes:
1. RP 89 which recommends radiological protection criteria for the recycling of
metals for the decommissioning of nuclear installations and,
2. RP 122 Part I (European Commission, 2000a) which provides guidance on
general clearance levels for practices.
There are also technical reports including:
1. RP 101 (European Commission, 1999) which relates to the definition of
surface contamination clearance levels for the recycling or reuse of metals
2. RP 117 (European Commission, 2000b) provides the methodology for the
dose calculations for the recycling of metals.
Both of the above reports were the basis of the recommendations provided in RP
89.
4.2.2 The IAEA Clearance Strategy
The IAEA supports the use of clearance and has proposed a tiered system for the
recycling and reuse of materials and components from the nuclear sector. For
steels these tiers comprise the following
1. Direct release for recycling or reuse,
2. Recycling by melting at a commercial foundry for subsequent unrestricted
release or reuse,
3. Recycling by melting at a controlled facility followed by remelting at a nonnuclear facility,
4. Recycling by melting at a controlled facility for specified industrial use,
5. Recycling by melting at a controlled facility for reuse within a controlled
environment.
The decision whether to recycle (or reuse) materials and/or components for
restricted or unrestricted use depends on many factors, some of which are specific
to a facility or a country and others which are international (IAEA, 1988). These
include:
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•
•
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•
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The availability of regulatory criteria giving activity levels for unrestricted use
and those which may only be released of restricted use
The availability of technology and facilities to recycle the items
The availability of instrumentation to measure regulatory activity levels and
quality assurance programs to assure compliance with the criteria.
The effect that recycling of materials will have on the extension of natural
resources
The economic implications including cost of decontamination, waste disposal,
market value of recycled materials.
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•
The socio-political attitudes in the affected country or industry regarding the
recycling/reuse of materials or components.
Although there is support for recycling and clearance of scrap metals it is not without
its problems. In the US the programmes for the recycling of scrap metal from the
nuclear industry ran into resistance from the steel industry and the public resulting in
a moratorium in 2000.
4.3
UK Policy and its Implications for Melting
In a review of UK waste management and decommissioning policy there are a
number of common themes. Of particular resonance for the consideration of
melting technology are:
•
•
•
•
•
Sustainable development
Waste minimisation
Characterisation and segregation
Waste in a passively safe state
Compatibility with future management and disposal options
Consideration is also given to the UK government’s policy towards ‘clearance’ and the
implications of the recent developments in UK decommissioning programme on the
application of metal melting techniques in the UK decommissioning programme.
4.3.1 Sustainable Development
The Environment Agency’s vision calls for wiser, sustainable use of natural
resources. Waste minimisation and increasing recycling is part of UK sustainability
strategy. Melting and recycling of metal from the nuclear sector can make a
significant contribution to achieving this vision of sustainable development.
Recyclable materials, such as metals, that are sent for disposal rather than being
recycled must be replaced by newly mined material if society is to continue using
metal for drums, pipes and other uses. Wider issues other than simple economic
factors need to form part of the criteria for recycling and replacement.
In assessing the merits of recycling metal, it is important that adverse health and
environmental impacts from mining and milling processes associated with the
replacement of these materials are considered adequately. This point has been
emphasised in a NEA study where it was found that environmental and socioeconomic impacts attributable to disposal and replacement exceed those for
recycling and reuse (NEA, 1996a). Melting technology offers a means of recycling
metals affording savings through reductions in both the amounts of raw material
required and the energy necessary to process the metal. In addition it reduces the
amounts of pollution and waste generated by mining activities required for replacing
the discarded scrap metals (NEA, 1996b).
4.3.2 Waste Minimisation
Waste minimisation is a recurring theme in UK policy. It is one of the four
fundamental expectations stated by the NII: ‘production of radioactive waste should
be avoided. Where radioactive waste is unavoidable, its production should be
minimised’ (HSE, 2001a). The EA has expressed its support for the ‘waste
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hierarchy’ as a general guide to selecting the best option for dealing with waste:
reduce, re-use, recycle, recover, dispose.
Melting technology can minimise the waste requiring disposal by promoting recycling
as well as reducing waste volume by the removal of voidage. In Germany it was
estimated that melting and recycling 12,000 t of steel scrap resulted in saving a final
repository volume of 80% compared to direct disposal without any pre-treatment
(Hamm et al, 2000). Melting is an effective means to reduce or eliminate the waste
volume, mass or toxicity content that requires disposal (NCRP, 2002).
4.3.3 Characterisation and Segregation
The NII, in its guidance (HSE, 2001a) in relation to radioactive waste requires
characteris ation and segregation to facilitate safe and effective management and
disposal. Melting of metals complies with this requirement. Scrap metal often
presents measurement difficulties due to problems in reaching all the internal
surfaces and the possible presence of hot spots. However, by melting,
characterisation is greatly simplified by the elimination of inaccessible surfaces, and
the remaining radioactivity content is homogenised over the total mass of the ingot.
Deliberate dilution by mixing of different arisings to achieve clearance is not an
acceptable practice (Nuclear Industry Safety Directors Forum, 2003).
4.3.4 Passively Safe State of Waste
Part of the NII’s strategy for decommissioning of nuclear sites is for any proposed
decommissioning programme to achieve a systematic and progressive reduction of
the hazards presented by the nuclear facilities or site (HSE, 2001b). Furthermore
radioactivity should be immobilised and packaged in a form that is physically and
chemically stable as soon as it is reasonably practicable (HSE, 2001a).
Melting provides a stable product in which the radioactivity is immobile in the slag and
the metal (see Section 2). Furthermore the recycling of radioactive steels (carbon
and stainless) is an already well researched area which requires no further
development as regards the melting and refining of steel arising from nuclear facilities
(European Commission, 1998a).
4.3.5 Compatibility with Future Management and Disposal Options
Waste conditioning/processing should minimise the need for future processing and
not create wastes that cannot be managed using current or existing developmental
technologies (HSE, 2001a).
If contaminated metal can be cleared through melting there is no requirement for
future processing. Melting does not foreclose future disposal and is likely to make
storage easier due to the more convenient shapes for packing for any remaining
material that continues to require management.
4.3.6 Clearance
Clearance or clearance levels do not appear explicitly in UK legislation but Schedule 1
of the RSA93 and the Exemption Order for Substances of Low Activity contain levels
that could be used for unconditional clearance of large volumes of materials on
agreement with the EA/SEPA.
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Description of process of clearance:
In the UK disposal of radioactive waste is controlled and regulated under the
Radioactive Substances Act 1993 (RSA93). Under RSA93 in order to dispose of
registered radioactive material an authorisation must be obtained. An application
must be made to the appropriate agency (EA in E&W). Proforma exist for small
users but larger sites must negotiate with the EA to determine what can be
discharged/released and how. There is a requirement for a radiological impact
assessment and a statement of expected amounts of waste needing disposal.
Before the granting of an authorisation the chief inspector and the appropriate
Minister shall consult with the Local Authority, relevant water bodies or other public
bodies, as he feels appropriate. The authorisation will lay down maximum discharge
limits and disposal routes. It will also set monitoring requirements and record keeping
conditions. Each authorisation is set on a case-by-case basis. On granting of the
authorisation a copy shall be supplied to the Local Authority of the area where the
disposal or accumulation will occur.
The only use of ‘clearance’ levels as such would be through the application of the
Exemption Orders, in particular, the Radioactive Substances (Substances of Low
Activity) Exemption Order 1986 (SoLA). Under this Order, an insoluble solid other
than a closed source, can be excluded from the requirement for authorisation for
disposal, provided that its activity does not exceed 0.4 Bq/g when it becomes a
waste.
There is no surface contamination clearance criteria given in the RSA93. However in
practice in the UK, material with surface contamination of below 4 Bq/cm2 β and
0.4 Bq/cm2 α goes to free release. All solid wastes that contain radioactive material
above the levels in Schedule 1 of RSA93, which includes only natural radionuclides,
and those that cannot be shown to be ‘substantially insoluble’, must be disposed of
under specific authorisations regardless of the quantities involved (Gerchikov et al,
2003).
Hence it is reasonable to infer that if melting through the redistribution of
radionuclides will result in radioactivity levels below 0.4 Bq/g, clearance may be
achieved.
4.4
Implications of Recent UK Decommissioning Policy Developments
The UK policy on decommissioning was set out in 1995 in the Government White
Paper “Review of Radioactive Waste Management Policy: Final Conclusions” herein
referred to as [Cmd 2919]. This policy concerns the decommissioning of all nuclear
facilities and calls for the production of site-specific decommissioning strategies for
redundant plant. Site operations are regulated by the HSE’s NII who are responsible
for quinquennial review of the decommissioning strategies in conjunction with the
EA/SEPA who regulate discharges to the environment. The Office of Civil Nuclear
Security (OCNS) are responsible for site security and will also be involved in the
approval of decommissioning strategies on a case-by-case basis.
Since the introduction of Cmd 2919 in 1995, some important changes have taken
place in the UK nuclear industry. These include notably the formation of the Nuclear
Decommissioning Authority (NDA) planned for 2005 and the government review of
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the policy for managing the UK’s solid radioactive waste. As part of this process, in
November 2003, the DTI published “A Public Consultation on Modernising the Policy
for Decommissioning the UK’s Nuclear Facilities” (DTI, 2003). This document invites
opinion on a proposed decommissioning policy to replace that set out in Cmd 2919.
In the government’s proposed new decommissioning policy statement, the following
principles are highlighted and are of particular relevance to this study:
•
•
•
•
•
•
•
minimising waste generation and providing for effective and safe
management of wastes which are created,
minimising environmental impacts including reusing or recycling materials
whenever possible,
maintaining adequate site stewardship,
using resources effectively, efficiently and economically,
using existing best practice wherever possible,
conducting R&D to develop necessary skills or best practice and,
consulting appropriate public and stakeholder groups on the options
considered and the contents of the strategy.
From the above it can be seen that the technique of metal melting is consistent with
principles of the proposed new policy, in terms of volume reduction for disposal and
recycling. The formation of the NDA brings an opportunity to co-ordinate
decommissioning and specifically the treatment of contaminated scrap metal, taking
an integrated approach.
4.5
Summary – Policy
Internationally clearance is favoured as a means of saving valuable natural resources
and avoiding unjustified allocation of resources for controlled disposal of low activity
waste. In the UK there is support for sustainable development and waste
minimisation including reusing or recycling materials whenever possible. Melting of
contaminated metals is compatible with these goals. The formation of the NDA
brings an opportunity to co-ordinate decommissioning and specifically the treatment
of contaminated scrap metal, taking an integrated approach.
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5
Constraints on the Implementation of UK Melting Facilities
Although sections 3 and 4 demonstrated that there are proven technologies which
can be used for metal melting in the UK, consistent with UK government policy,
there are a number of hurdles which must be overcome before any large scale
central facility can be implemented.
This section discusses a number of the key issues which must be addressed as part
of any development strategy, addressing:
•
•
5.1
Regulatory Controls
Stakeholder Issues
Regulatory Controls
There are two main areas of regulation for consideration when implementing a
melter for radioactively contaminated metals:
•
•
Radiation Protection legislation and control including transport and
Non-nuclear environmental protection controls.
5.1.1 Radiation Protection legislation
(a)
Authorisation and Licensing Issues
The OECD/NEA co-operative Programme on Decommissioning chartered a task
group on recycling and reuse in 1992 to conduct an examination of the nuclear
industry in order to identify obstacles to recovering scrap metals generated from
decommissioning nuclear facilities. This task group also was to identify and
determine the effectiveness of methods for overcoming these obstacles (NEA,
1996a). Its findings included:
•
•
•
•
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The most significant impediment to increasing the use of recycle and reuse
practices is the absence of consistent release standards within the
international community. Currently, material is either released under varying
criteria or on a case-by-case basis, frequently prohibiting countries from best
utilising the available recycling technologies and facilities.
Recycling and reuse initiatives were further complicated by variations in the
quality requirements, sampling protocols, required instrumentation, and
documenting practices used by the 25 completed and ongoing
decommissioning projects which were surveyed in the study.
A number of ‘clearance’ levels have been proposed by various international
organisations. However, currently proposed clearance levels focus almost
entirely on unconditional clearance.
The absence of an international conditional clearance standard is a hindrance
to the transport and melting of scrap metal, particularly if implementing such
an option requires movement of the material across national boundaries.
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Case-by-Case Approach
In the UK, the SoLA Exemption Order is used for clearance i.e. 0.4 Bq/g for solids
that are substantially insoluble in water. However, this is applied on a case-by-case
basis and particularly for the large sites is a process of authorisation and negotiation
between waste producer and regulator. Factors that can hinder or discourage
innovative approaches such as utilising melting technologies in the waste
management process include:
•
•
Uncertainty and/or variation in what procedures and quality assurance
requirements will be required by regulatory inspectors and,
Divergent approaches to clearance applied from one project or plant.
Safety Cases & Authorisations
Melting facilities built on exis ting nuclear licensed sites would require compliance with
nuclear site license regulations, including conditions for provision of safety cases and
accumulation of radioactive waste.
An operator of a facility who is not the main site licensee would in addition need to
demonstrate compliance with RSA93 requirements with regards to the accumulation
of radioactive wastes (HSE, 2001a).
Costs
Savings on disposal costs, either through the use of melting to reduce voidage and
ease packing or using it to achie ve clearance of material, can provide a considerable
economic benefit to waste owners.
However, this must be balanced against a number of costs, which, as well as capital,
operating and transport costs, include those associated with regulatory control such
as the above authorisations.
In general, clearance offers the least expensive option if potentially radioactive scrap
metal can be readily characterized and certified. Avoiding disposal as LLW at a Drigg
would substantially reduce disposal costs, and conserve a valuable national resource.
Sale of scrap metal for recycling could help in cost recovery. However, such cost
saving incentives may diminish if extensive decontamination efforts were required to
certify the metal for clearance (NCRP, 2002).
The indicative charge for grouting and disposal of uncompactable waste at Drigg up
until 2005 is £1795/m3. In addition there are radiological activity charges (for
example, C-14 £52.43/MBq (BNFL, 2002)) as well as costs for packaging and
transport. Assuming a conservative volume reduction factor of 4 (See Section 2.4)
that is a potential saving of around £1350 /m3 of metallic waste. There is also likely
to be additional savings due to the redistribution of activity during the melting
process.
The availability and cost of LLW disposal site capacity is one of the most critical
socio-economic issues related to recycling of steels. If the total inventory of scrap
steel is disposed of as LLW it would require greater LLW disposal capacity than is
currently available or planned at Drigg. In contrast recycling would require much less
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disposal capacity. Recycling and disposal activities are likely to take place in the
countries in which sources of suitable material are located (European Commission,
1998a). The European Commission has carried out a study to compare locally
installed and centralised treatment systems for contaminated metals (Andreani &
Bailo, 2000). The report focussed upon the decommissioning of an RBMK reactor, it
is recommended that a similar cost –benefit analysis is conducted for the UK.
(b)
Radiation Protection Controls
The definition of what constitutes a radioactive material for regulatory control is
different under different regulations. Under the Ionising Radiations Regulations 1999
(IRR99) a ‘radioactive substance’ is defined as ‘any substance which contains one or
more radionuclides whose activity cannot be disregarded for the purposes of
radiation protection’.
The threshold radioactivity concentrations for regulation under IRR99 for some
isotopes of the specified radioelements in Schedule 1 of RSA93 are slightly lower than
those permitted under RSA93; for the non-specified radioelements only Cm-250 is
lower than the 0.4 Bq/g SoLA Exemption Order Limit.
The implications are that any operator of a melter (off a licenced site) may be
subject to regulation 6 of IRR99 to report their activities to the regulator (Nuclear
Industry Safety Directors Forum, 2003).
(c)
Transport Implications
The transport of radioactive material in the UK is regulated under the Radioactive
Materials (Road Transport) Regulations 2002. The regulations cover the type of
packaging, consigning and carriage of radioactive materials.
Transport regulations are always applicable when transporting radioactive materials.
No new measurements are required if the material or waste is cleared under RSA93,
it is excluded under regulation 17 and can be transported as not radioactive (Nuclear
Industry Safety Directors Forum, 2003). However, this is unlikely to apply in the
case of material being sent for melting for decontamination purposes. Thus, the
transport regulations must be applied.
The first step in determining the correct packaging of a consignment for transport is
to assess the material for its radioactive content (in terms of both activity and
radionuclides present). Depending on the activity content of the steel being
transported there are several possibly applicable classifications of package type. The
packaging for transport of contaminated steel is likely to be as Excepted or as LSA-I
(Low Specific Activity) or SCO-I (Surface contaminated objects) material.
Excepted Packages would be applicable to contaminated steel that contains limited
quantities of activity restricted to 1/1000 * A2 (Regulation 30, Schedule 4 Paragraphs
1 and 2). A2 values are activity levels of radioactive material based on hazard e.g.
A2 for Co-60 is 0.4 TBq. Excepted packages are only subject to a limited number of
provisions under the regulations relating to dose limits and design and manufacture
of the package. These are specified in regulation 41 of the regulations.
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If the activity content of the steel exceeds the limits for Excepted Packages, it is
likely that the material will need to be consigned under the provisions for either LSA
or SCO-I. This class of radioactive steel can be transported unpackaged under
certain conditions; for example, it can be consigned as unpackaged as long as no
material can escape from the conveyance. If the conditions cannot be met then
the steel would be transported in an IP-1 industrial package. These can be
purchased from a number of reputable specialist manufacturers.
5.1.2 Implications of Non-Nuclear Environmental Controls
There are two main areas from a non-radiological perspective that will be restrictive
for those wishing to start up a melting plant for contaminated metals. These are
regulation and cost. These are not mutually exclusive, as the level of regulation will
ultimately determine cost.
(a)
Regulatory Requirements
The Integrated Pollution Prevention & Control Directive came into EU legislation in
1999; this was then transposed into UK law in 2000 in the form of the Pollution
Prevention & Control (England & Wales) Regulations 2000 (IPPC). Metal melting of
both Ferrous and Non-Ferrous metals come within the scope of these regulations.
The level of regulation is based mainly on tonnage and in some instances on the
percentage levels of certain pollutants. Schedule 1 should be consulted to determine
which level of regulation can be expected for any proposed melter.
Within Schedule 1 of the Directive and Regulations the levels of regulation are split
into three:
•
•
•
A(1) regulated by the EA
A(2) regulated by the installations Local Authority with input by the EA
Part B regulated by the installations Local Authority
By whom an installation is regulated is determined by the particulars of the site such
as the production on a daily or annual basis. However, some operations have no
thresholds and are regulated at the highest levels due to their perceived
environmental impact.
(b)
Cost
The size and scale of the facilities will affect the costs of regulation of the facility in a
number of areas:
•
•
•
The Application process for authorisation under IPPC regulation
The Application fee and subsistence fees
BAT (Best Available Technique) (Abatement techniques)
The application process for A(1) and A(2) installations can cost between £15-£60k
(excluding phase 2 intrusive work) depending on the size and complexity of the
process. Unlike regulation under the Environmental Protection Act and Part B
installations a number of issues need to be covered in the application, which require
expertise that is not usually available in the operators direct employment, e.g.
Energy Survey, Noise & Vibration Survey, Resources & Waste Audits and Site
Condition Survey (SCS).
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A SCS is one of the most important sections of the application and the Phase 2 –
Intrusive Survey of this can be very expensive (anywhere between £10-£150k+).
The cost is dependent on the size of the site but also its past and current
contamination/usage. The SCS provides the site with a ‘clean slate’ in terms of
contaminated land and therefore the survey needs to be thorough.
In the case of BAT the regulatory level is again the deciding factor, along with date
on which the installation became operational. New installations will have to comply
with the BREF Note (Best Available Technique Reference Note) from the date it is
commissioned or provide evidence to indicate that the techniques used are as good
or better than those laid down by the EU. Existing plant will eventually have to
comply with the BAT guidance and these are timetabled into the sectors guidance
notes.
The BREF Notes provide details not only on how the installation should be managed
and run but also the abatement techniques to be used.
5.2
Stakeholder Issues
There are a number of key stakeholders who may have different concerns with
regard to implementing radioactive melting facilities, including:
-The metals industry
-General public
5.2.1 Policy Issues
Preventing any radiation contamination from orphan sources from entering the scrap
metal stream is essential in maintaining the quality of the metal products and is an
important economic issue to the metals industry (NCRP, 2002: Nieves et al, 1995).
There are growing efforts by the industry in recent years to guard against
inadvertent or illicit inclusion of radioactive materials in the scrap metal supply. A
general lack of support by metal-producing mill operators for contaminated scrap
clearance has been reported (NCRP, 2002).
In the USA, the public and the metal recycling industry have expressed strong
opposition to any new rule or practice that allows release for the commercial recycling
of metals containing any residual radioactivity (NCRP,2002: MIRC, 1999). Similar
resistance on the part of non-nuclear steel industry has been experienced in
Germany and other European countries.
5.2.2 Cost/Quality Aspects
The UK steel industry consumes more than 4 million tonnes of steel scrap per year.
Scrap metal is a commercial commodity, and hence the criteria of supply, demand
and quality apply. Because of the potential liabilities, the operators’ reluctance to
purchase contaminated scrap metal is likely to increase in low price periods i.e. when
scrap is plentiful or the demand is low (NCRP, 2002).
The cost of refining metal scrap increases as the residual impurities increase, thus it
is important for mill operators to know the chemical composition of the scrap. This is
especially important for medic al stainless steel and other specialty alloy producers.
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Because of the need for documented chemical quality assurance for such products,
demolition scrap is not purchased for these products, and there is a preference to
use in-house scrap. Thus, there is little likelihood that stainless steel from demolition
projects will find its way into medical products such as hip replacements or
pacemakers (NCRP, 2002).
Scrap from the nuclear industry may not be considered negatively in all situations. If
the supply is large, the chemistry is known, and the metal is free of hard to refine
residuals, it could be seen as desirable by scrap buyers, provided the metal can be
certified to be free of radioactive contamination (or meets the clearance criteria)
(NCRP, 2002).
Should the scrap metal be melted and recycled within the nuclear industry there are
issues in relation to the level of demand for the materials (see Section 2) and also
the cost of controlled recycling (NCRP, 2002).
5.2.3 Monitoring
There are radiation monitors at the gates to many steel and aluminium mills. It is
important to ensure that the sensitivity of radiation monitors intended to intercept
orphan sources (often shielded by large scrap metal piles) would not lead to the
inadvertent rejection of potentially radioactive scrap metal released through
clearance. Detector limits are presently set below the clearance levels, which creates
a barrier to metal scrap recycling of clearable material (Hamm et al, 2000). Failure
to harmonise will impede progress and erode public support for scrap metal
clearance.
Once scrap has triggered the gate alarm, the waste is segregated as radioactive.
Even if further investigation has determined that it can be categorised as nonradioactive, it is regarded as unacceptable for the steel plant to melt these pieces of
steel owing to the fact that they have already been segregated as radioactive
(Harvey, 2002).
5.2.4 Public Perception
The main public concern is about the final product in which the recycled metal will end
up. This has obvious health and safety implications if the material is used in food
containers, or items with which children have contact (eg buggies etc). In order for
recycling and reuse to become acceptable, the negative stigma associated with the
nuclear industries of most countries must be overcome (NEA, 1996a).
(a)
Attitude
In the USA, three issues were found to reflect the general attitude of the American
public toward recycling of radioactive scrap metal:
1. Clearance of metals containing low levels of radioactive contamination, even if
deemed acceptable by regulatory agencies, “….would undermine public trust in
the safety of consumer and commercial products containing steel, nickel, and
other metals” (MIRC, 1999). In addition, the American Iron and Steel Institute
(AISI), commissioned a public opinion poll which indicated that significant public
opposition existed to the concept of clearance, even if governmental regulatory
agencies declared the practice to be safe. Opposition increased from 61 to 74%
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when those polled were told that a government agency had determined that
clearance posed no health risk (MIRC, 1999).
2. A policy of clearance for metals “….would adversely affect consumer acceptance
of products having a recycled metal content, even if radioactively contaminated
metal was not actually used to produce the product.” The concern is that
adverse perception would result in the ‘de-selection’ of metal and metal
containing products (MIRC, 1999).
3. An adverse impact would be incurred at those facilities receiving radioactively
contaminated scrap. The concern is that clearance “….would increase
substantially the volume of scrap metal in commerce having above-background
levels of radioactivity” (MIRC, 1999). Segregation by monitors would have the
effect of increasing the frequency that the gate monitors are triggered. This
would have a number of impacts:
•
•
•
•
•
Diversion of personnel to respond to alarms and to complete paperwork to
reject the scrap.
Numerous alarms may desensitise staff resulting in an orphan source getting
through.
Numerous alarms may create anxiety amongst staff over exposure to
radiation.
Shifting of disposal costs from nuclear industry to the metals industry.
The metals industry has no guarantee that low-level contamination in dust
and slag would not require remediation in later years, or that a government
agency would not eventually require a recall of metal products containing lowlevel concentrations of radioactive material that were once considered
‘acceptable’ (MIRC, 2002).
There is simila r opposition in the UK to clearance. The Low Level Radiation
Campaign has stated its opposition to clearance of contaminated materials ‘even at
400 Bq/kg’ (LLRC, 2004). There is concern amongst many stakeholders over the
cumulative effect of clearance of large quantities of material even if it contains only
low levels of radioactivity.
(b)
Social Factors
Socio-political factors must also be considered by melting policy makers. In the UK,
there have been many public and stakeholder consultation exercises carried out
examining attitudes to nuclear and radioactive waste issues (including PASCALEA,
Managing Radioactive Waste Safely, ISOLUS). Public concern can be expected
relating to a number of key areas:
-Building of new waste management facilities, particularly involving heat
treatment (links with incineration)
-Unrestricted release of previously contaminated materials
-Transport of radioactive material
Although melting of components or materials from decommissioning or refurbishment
of nuclear installations is not a routine activity at present, considerable public concern
may be anticipated in the case of unrestricted release of substantial amounts of
materials. Even if the radiological risks from unrestricted release are negligible, public
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and government concern may force nuclear operators to recycle for restricted use
or alternatively to dispose of the items. Recycling for restricted use should not
experience the same level of opposition. Similarly, when deciding upon the future
use of a site of a decommissioned installation, public acceptance of a new nuclear
facility on the same site may be easier than elsewhere. This is a point in favour of
continued nuclear use, especially if such sites are scarce (European Commission,
1998a).
Within the UK, it will be essential to engage the public and other stakeholders in a
participative decision making process, rather than the old “decide-announce-defend”
model of decision making which has proved unsuccessful in the nuclear industry in
recent years.
(c)
Transport and Location
Within the UK the general public have historically been hostile to significant or new
movements of radioactive waste. This has been seen both as a fear of risk of
accident or terrorist attack, but also from an underlying principle which many people
feel that radioactive waste should be managed where it is generated (UKAEA LLW
BPEO Dounreay). Transport of significant amounts of scrap radwaste to a central
melting facility may be expected to face some resistance as a result.
The location of a facility will be of importance and great interest to the local public,
with minimisation of transport requirements of particular interest. It has already been
suggested that a combined plant for production of steel products for use in the
nuclear industry (such as stainless steel drums), and the facility for melting of
materials for unrestricted release would give more favourable economics due to
increasing the plant throughput to near design capacity.
5.3
Summary – Constraining Issues
Regulatory issues:
•
•
•
There is currently a case-by-case approach to clearance regulation making a
national co-ordinated or long-term approach difficult.
There are no specific clearance levels in the UK, which may hinder the
transport of contaminated metal off-site to a central melting facility.
A melting facility will require extensive authorisations including safety cases,
RSA authorisations and IPPC authorisations.
Economic issues:
•
•
There is potentially insufficient demand for recycled metals either within the
nuclear sector because of insufficient need or outside the nuclear industry
because of stakeholder acceptance issues (see below).
Melting and associated facilities to manage radioactively contaminated waste
will be capital intensive.
Stakeholder issues:
•
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There is a lack of support amongst the non-nuclear metals industry for
recycling of radioactively contaminated metal.
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•
•
•
•
•
•
•
The steel industry has installed gate monitors to prevent the contamination
of their products by orphan sources, these radiation monitors are set below
current clearance levels. As a consequence, cleared metals may trigger the
alarms and be rejected as a matter of policy from non-nuclear facilities.
Steel producers have a fear of adverse publicity and negative reaction by the
public to their products should they become involved with the nuclear sector.
There is a fear that the clearance of potentially radioactive metals will
undermine the metal industry.
Concern amongst the public over the safety of releasing metals previously
considered radioactive. Uncertainty and fear over where the metal will end
up such as in medical tools or in food containers.
Some stakeholders fear that accepted opinion over safety may change in the
future resulting in a recall of previously cleared metals.
There has been historical objections to “heat generating” waste facilities such
as incinerators
Public objections to the transport of radioactive waste.
Whilst there are strong drivers for metal melting and recycling, the barriers should
not be underestimated. In particular public and stakeholder concerns must be fully
taken into account and stakeholders engaged at an early stage of any participative
decision making process. Full and extensive public and stakeholder engagement
exercises will be required.
Table 8 summarises these issues.
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6
Conclusions
At present, UK decommissioning project or site managers will often determine the
management of potentially contaminated scrap metal. Decision makers must take
into account a number of relevant factors, including regulatory requirements,
availability of facilities, cost constraints and stakeholder concerns.
There are a number of drivers for reviewing melting as an alternative and/or
complimentary strategy to disposal:
•
Economic
o Reducing waste disposal costs
o Recovering costs through reuse and recycle
o Conserving natural resources
o Conserving UK LLW disposal resources
•
Policy
o To comply with government policy, guidance and principles including:
• Waste minimisation
• Reuse and recycle
• Sustainability
• Environmental impact & resource management
•
Strategic
o To review the application of a proven technology for radioactive waste
metals on a ‘national’ rather than project or site basis.
In the UK there is a significant inventory of unconditioned waste radioactive metals
(70,000 tonne of ILW and 383,000 tonne of LLW), which require management.
There are a number of proven technologies for melting radioactively contaminated
metals is operating in a number of countries including France, Germany and Sweden.
These facilities manage a number of different radioactive waste streams arising from
a range of nuclear sites. Induction melting is the chosen technology for existing
industrial radioactive metal melting facilities. Further developing technologies are also
emerging, such as cold crucible and plasma arc technology.
Metal melting can be used to achieve a number of aims:
•
•
•
Size and volume reduction of waste
Segregation or separation of contaminants
Homogenisation of contaminants within the bulk metal.
Following melting, the metals can follow one of three paths:
1. Release outside the nuclear sector (clearance),
2. Reuse within the nuclear sector,
3. Disposal, having achieved a reduction in disposal volume and activity
concentration.
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The decision whether to recycle (or reuse) materials and/or components for
restricted or unrestricted use depends on many factors, some of which are specific
to a facility or a country and others which are international (IAEA, 1988). These
include:
•
•
•
•
•
•
The availability of regulatory criteria giving activity levels for unrestricted use
(general clearance levels) and those which may only be released of restricted
use (specific clearance levels)
The availability of technology and facilities to recycle the items
The availability of instrumentation to measure regulatory activity levels and
quality assurance programs to assure compliance with the criteria.
The effect that recycling of materials will have on the extension of natural
resources
The economic implications including cost of decontamination, waste disposal,
market value of recycled materials.
The socio-political attitudes in the affected country or industry regarding the
recycling/reuse of materials or components.
Many of the above factors are more important for the release of materials from
regulatory control as opposed to their recycling and reuse within the nuclear sector.
There are significant stakeholder constraints that must be considered and overcome
in order to implement an integrated radioactive metals strategy. These include:
•
•
•
Public and (non-nuclear) metal industry unease with regards to reuse of
previously radioactively contaminated metals.
Public concern over the transport of radioactive waste.
Concern over new waste or radioactive management facilities involving “heat
treatment”
There are also technical and economic matters that must be addressed:
1. There is a limited demand for metals within the nuclear sector. Metal
arisings are expected to exceed demand for disposal packaging, which is the
anticipated key use of the material.
2. Cost effective use of any facilities must be addressed
3. Stainless and also in some circumstances carbon steel products are formed
from plate. Therefore the recycled metal must be rolled or an alternative
manufacturing process identified. Investment in a mini-rolling facility for
restricted metal is likely to be unfeasible.
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7
Recommendations
1. An economic analysis covering a range of metallic radioactive waste management
strategies in the UK should be carried out, building on the qualitative analysis completed in
this study.
2. A facilitated, multi-stakeholder seminar to discuss radioactive metallic waste strategies
should be held to review and consider the issues raised in this study. A proposed agenda
could include for example:
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•
Framing of issues (summary of this report)
•
Examples of proven operating melting technology
-Technology vendors
-Operators experience
•
UK Waste management issues, project experience and current practice
Eg
-BNFL
-UKAEA
•
Regulatory Perspective
-NII
-EA
•
Stakeholder Issues
-Metal industry
-Public engagement experience
-Siting issues
•
Strategy and way forward
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Approach
Recycling for
use outside the
nuclear industry
Table 8
Melting inside the
nuclear industry
e.g. UK, BNFL
Capenhurst
Aluminium melting
and Sweden,
STUDSVIK
Melting outside the
nuclear industry
e.g. French CEA
pilot programme
(Bordas, 2000)
Issues
Adverse
• Metals will require careful decontamination and sorting prior to
transport off-site: must meet specific clearance criteria
• ‘Contamination’ of steelworks equipment
• ‘Tainting’ of any scrap metal from the steelworks with the poor
nuclear image
• Transfer of disposal costs e.g. disposal costs for slags and
filters.
• Fears/concerns of staff over exposure
Benefits
• No need to build a new furnace/facility
• Plant can operate at full capacity
Neutral
• Require authorisations and regulatory supervision
• Steelworks are likely to require radiation protection expertise
Adverse
• Cost of furnace/facility
• Lack of a market for material
• Cleared material sets off gate monitors at steelworks/mills
• Change of clearance levels in the future resulting in a recall of
metal products
• Adverse public reaction to the possibility of cleared metal in their
products results in damage to the metal industry.
Benefits
• A lesser need to decontaminate and sort material
• Can melt a greater range of metals and determine destination of
material i.e. extent of clearance, after melting
Neutral
• IPPC authorisation required
• Require specialist staff skilled in furnace operation
Summary of Issues and Requirements
•
•
•
•
Development of national
clearance criteria.
Take steps to enhance public
understanding of the
clearance process.
Tighten up orphan source
control nationally and
internationally. Engage with
the metals industry with
regard to the setting of gate
monitor alarms.
Stakeholder engagement
and participation
Requirements
• Development of national
specific clearance criteria
• Take steps to enhance public
understanding of the
clearance process
• Stakeholder engagement
and participation
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Approach
Recycling for use
inside the nuclear
industry
Table 8 cont’d
Melting by on a
site by site basis
Manufacturing
Sciences
Corporation, USA
for depleted
uranium recycling
Melting by a
central specialist
facility
e.g. Germany,
CARLA and
France, Centraco
and INFANTE
(Byrd Davies, 2003
and 2004),
Issues
Adverse
• Cost of furnace/facility
• Inadequate demand for materials
• Cost of milling equipment to convert ingots into usable
drums etc
• Public opposition to transport of contaminated materials to
the site from other locations
• Public opposition to building the facility
Benefits
• Maximise quantity of metals available thus maximise
efficiency
• Reduce the use of natural resources
• Radioactivity of drums would be small compared to the
radioactivity of the filled drums.
• Avoids public concerns over release of materials
Neutral
• IPPC authorisation required
• Require specialist staff skilled in furnace operation
• Need for an authorisation to accumulate and keep
radioactive material
Adverse
• Cost of obtaining furnaces for each site
• Need to find suitably qualified specialised staff to operate
the furnaces for short/limited periods of operation
• Increase in furnaces which must be decommissioned
• Unlikely to be sufficient metals on a single site in one time
period to keep the melter operating at full capacity
Benefit
• Reduced transport
Neutral
• IPPC authorisation required
• Need for a safety case
•
•
Evaluate the cost-benefits of a
site-by-site approach.
Stakeholder engagement and
participation
Requirements
• Integrate waste management
strategy from waste arising to
disposal facilities packaging
requirements.
• Consider location of arising in
the site selection process to
minimise transport.
• Stakeholder engagement and
participation
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Approach
Melting for disposal
Table 8 cont’d
Issues
Adverse
• No saving of natural resources
• Creation of secondary wastes
• No opportunity to recuperate costs by selling the metals
Benefits
• Avoids public concerns over release of material
• Reduces volume for disposal, thus creating disposal cost
savings
• Creates a homogenous and stable waste form
• Conserves UK LLW disposal resources
Neutral
• IPPC authorisation required
• Need for a safety case
Requirements
• Evaluate the cost savings.
• Stakeholder engagement and
participation
8
References
Andreani & Bailo, Comparative Cost Assessment of Locally Installed versus
Centralised Facilities for Radioactive Waste Thermal Treatment Systems. European
Commission Directorate General for the Environment. EUR19257, 2000.
BNFL, Drigg Starter Pack – Indicative Unit Charges for H.F.C., Grouting and Disposal
Standard Services, Issue 7, October 2002.
Bordas F., ‘Recycling Decontaminated Scrap Metal From the Nuclear Industry’,
Safewaste 2000: Nuclear Waste: from Research to Industrial Maturity, 1 –5 October
2000, Vol. 1 pp55 – 62.
Byrd Davis M., ’Marcoule’, Nuclear France: Materials and sites, Updated 3 July 2003,
http://www.francnuc.org/en_sites/langue_cea_e.htm
Byrd Davis M., ’Centraco’, Nuclear France: Materials and sites,
http://www.francnuc.org/en_sites/langue_codo_e.htm, accessed 9th March 2004.
Cheng J.J., Kassas, B., YU, C., Lepoire, D., Arnish, J., Dovel, E.S., Chen, S.Y.,
Williams, A., Wallo, A., and Peterson, H., RESRAD-Recycle: A Computer Model for
Analyzing the Radiological Doses and Risks Resulting from the Recycling of
Radioactive Scrap Metal and the Reuse of Surface-Contaminated Material and
Equipment, ANL/EAD-3, Argonne National Laboratory, Argonne, Illinois, 2000.
Department of Trade and Industry, A Public Consultation on Modernising the Policy
for Decommissioning of the UK’s Nucle ar Facilities. November 2003.
Electrowatt-Ekono (UK) Ltd. The 2001 United Kingdom Radioactive Waste
Inventory – Main Report. DEFRA/RAS/02.004, Nirex Report N/042, October 2002.
EUROFER, 1999. Technology Roadmap to Determine the Research Priorities of the
European Steel Industry
European Commission, Council Directive 96/29/EURATOM of 13 May 1996 laying
down basic safety standards for the protection of the health of workers and the
general public against the dangers arising from ionizing radiation, Official Journal of
the European Communities, OJ L159 29/06/1996, p0001 – 0114, 1996.
European Commission, Recycling and Reuse of Radioactive Material in the Controlled
Nuclear Sector’, EUR 18041, ISBN 92-828-3464-6, 1998a.
European Commission, ‘Recommended Radiological Protection Criteria For The
Recycling Of Metals From The Dismantling Of Nuclear Installations’, Radiation
Protection 89, European Commission, 1998b.
European Commission, ‘Basis for the definition of surface contamination clearance
levels for the recycling or reuse of metals arising from the dismantling of nuclear
installations’, Radiation Protection 101, Luxembourg, 1999.
NNC Limited
11426/TR/0001
Issue 04
Page 49
European Commission, ‘Practical Use of the Concepts of Clearance and Exemption –
Part I Guidance on the General Clearance Levels for Practices’, Radiation Protection
122, European Commission, 2000a.
European Commission, ‘Methodology and models used to calculate individual and
collective doses from the recycling of metals from the dismantling of nuclear
installations’, Radiation Protection 117, Luxembourg, 07/2000b.
Faugieres J., ‘SCODEI Melting, Recycling and Incineration Facilities’, Safewaste 2000:
Nuclear Waste: from Research to Industrial Maturity, 1 –5 October 2000, Vol. 1
pp49 – 54.
Fentiman, A. W., Karam, A., Meyers, R. B., What Is Being Done to Reduce the
Volume of Low-Level Radioactive Waste? RER-50. Ohio State University
Garcia S.R., Commercially Available Low-Level Radioactive And Mixed Waste
Treatment Technologies’, DOE/LLW-240, October 1996.
Gerchikov M.Y., Hillis Z.K., Meijne E.I.M, Oatway W., Mobbs S., Weers van A.,
Evaluation of the Application of the Concepts of Exemption and Clearance for
Practices According to Title III, of Council Directive 96/29/EURATOM of 13 Many
1996 in EU Member States, Volume 2: Appendices , Radiation Protection Series
Issue 134, European Commission, 2003.
Greppo J.F., Faugieres J., ‘Socodei Melting – Recycling and Incineration Facilities’,
Fifth International Nuclear Conference on Recycling, Conditioning and Disposal,
RECOD 98, Nice, 25 –28 October 1998.
Hamm M., Kreh R., Quade U., ‘Recycling of Contaminated Scrap by Melting 10
Years of Experience in Germany’, Safewaste 2000: Nuclear Waste: from Research
to Industrial Maturity, 1 –5 October 2000, Vol. 1 pp995 – 103.
Harvey D., ‘Natural Radioactivity in Steel Scrap’, Natural Radiation and NORM
Conference, IBC, 22-23 April 2002.
HSE, Nuclear Safety Directorate, Guidance for Inspectors on the Management of
Radioactive Materials and Radioactive Waste on Nuclear Licensed Sites, Health &
Safety Executive, 13 March 2001a.
HSE, Nuclear Safety Directorate, Guidance for Inspectors on Decommissioning on
Nuclear Licensed Sites, Health & Safety Executive, 13 March 2001b.
IAEA, Factors Relevant to the Recycling or Reuse of Components Arising from the
Decommissioning and Refurbishment of Nuclear Facilities, IAEA Technical Reports
Series No. 293, 1988.
ICTC, ‘ISTC Project 1713 Cold Crucible Technology for Waste Treatment’,
http://www.tech-db.ru/istc/db/projects.nsf/prjn/1713, accessed 2nd March 2004.
LLRC. Low Level Radioactivity Campaign, ‘Clearing the under radioactive waste
mountain – under the ‘Basic Standards Directive’,
http://www.llrc.org/regulation/subtopic/clearance.htm, March 2004.
Page 50
NNC Limited
11426/TR/0001
Issue 04
Manning, C. P., Fruehan, R. J. Emerging Technologies for Iron and Steelmaking,
Journal of Materials, 53(10) 2001 pp. 20-23, 2001
.
MIRC. Metals Industry Recycling Coalition. ‘’Comments of the American Iron and
Steel Institute, the Nickel Development Institute, the Nickel Producers Environmental
Research Association, and INCO, US Inc., in the matter of the US Nuclear
Regulatory Commission’s “Issues paper, scoping process for environmental issues
relative to the release of solid materials at licensed facilities,” 64 FR 35090, US
Nuclear Regulatory Commission, Washington, 1999.
MSC. Manufacturing Sciences Corporation, http://www.mfgsci.com/, accessed 17th
March 2004.
NEA. Nuclear Energy Agency. The NEA Co-operative Programme on
Decommissioning, The First Ten Years 1985-95. OECD 1996a.
NEA. Nuclear Energy Agency. Nuclear Decommissioning: Recycling and Reuse of
Scrap Metals , Task Group of the Co-operative Programme on Decommissioning,
OECD 1996b.
NEA. Nuclear Energy Agency. Decontamination Techniques Used in
Decommissioning Activities – A report by the NEA Task Group on Decontamination,
OECD 1999.
Nieves, L.A., Chen, S.Y., Kohout, E.J., Nabelssi, B., Tilbrook, R.W., and Wilson,
S.E. Evaluation of Radioactive Scrap Metal Recycling, ANL/EAD/TM-50, National
Technical Information Service, Springfield, Virginia, 1995.
NRC, U.S. Nuclear Regulatory Commission, Radiological Assessments for Clearance
of Equipment and Materials from Nuclear Facilities, Draft Report for Comment,
NUREG/CR-1640, Vol.1, U.S. Nuclear Regulatory Commission, 1999.
NCRP. Managing Potentially Radioactive Scrap Metal – Recommendations of the
National Council on Radiation Protection and Measurements, NCRP Report No. 141,
19 November 2002.
Nuclear Industry Safety Directors Forum, Clearance and Exemption Principles,
Processes and Practices for Use by the Nuclear Industry – A Nuclear Industry Code
of Practice, Interim Issue, May 2003.
Pastushkov V.G., Molchanov A.V., Serebryakov V.P., Smelova T.V., Shestoperov
I.N., ‘Technology and Equipment Based on Induction Melters With ‘Cold’ Crucible For
Reprocessing Active Metal Waste’, WM’01 Conference, February 25 – March 1,
Tucson AZ, 2001.
Plodinec, J. Hybrid Plasma Induction Cold Crucible Melter. DIAL’s Research
highlights, United States Department of Energy, 1998.
Powell F.R., ‘Practical Experience In The Decontamination And Melting Of Low Level
Waste With Particular Reference To Radiological, Safety And Environmental Matters ’,
British Nuclear Fuels plc, http://www.srp-uk.org/srpcdrom/p8-18.doc, 2 July 1999.
NNC Limited
11426/TR/0001
Issue 04
Page 51
Quapp W., Application of the Plasma Enhanced MelterTM to the Processing of
Radioactive Waste. Integrated Environmental Technologies, Richland, USA, 2002.
Secretary of State for the Environment (1995). Review of Radioactive Waste
Management Policy. Cmd 2919, July 1995.
Schlienger M.E., Buckentin J.M., Damkroger B.K., ‘Melting Processing of Radioactive
Waste: A Technical Overview’ CONF-970335-44, SAND-97-0811C, 1997.
Siempelkamp, http://www.siempelkamp.de/en/index.html, 2004.
Worchester S.A., Twidwell L.G., Paolini D.J., Weldon T.A., Mizia R.E.,
Decontamination of Metals by Melt Refining/Slagging – An Annotated Biblography:
Update on Stainless Steel and Steel, INEL-95/0123, January 1995.
Page 52
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