Release of natural radionuclides
from NORM-residues
caused by sewage
J. Dilling1, K. Flesch2, R. Gellermann3, J. Gerler1, H. Hummrich2,
V. Neumann4, R. Knappik5, H. Schulz2
1Federal
Office for Radiation Protection, Berlin
2IAF - Radioökologie GmbH, Dresden
3FUGRO-HGN GmbH, Magdeburg
4BGD, Dresden
5VKTA, Rossendorf
2nd Workshop of the European ALARA Network for NORM, Dresden 2009
Legal Framework
Radiation Protection Ordinance  Positive List
Introduction of surveillance limits depending on the
recycling or disposal option
If exceeding SLs
formal release of surveillance necessary
Precondition: D < 1mSv/a (members of the public)
joint disposal depending on specific activity and landfill
parameters
site specific dose assessments (realistic scenarios, parameters,
models)
Dose assessment
Pathways of concern
— inhalation of Radon and its decay products
— inhalation of contaminated dust
— direct ingestion of contaminated soil
— exposure to external gamma radiation
— ingestion of locally produced food (incl. drinking water)

grown on contaminated sites

irrigation with contaminated water
Dose assessment
Pathway: Ingestion of locally produced food
focussing on water
disposed or recycled NORM
seepage water
well
surface water
ground water
source term: which radionuclide concentrations will be released?
Approach
Crosslink conventional hazards
Standard methods for assessing waste and contaminated soil
regarding potential groundwater contaminations
— soil saturation extract
— pH-Stat
— elution with water (1:10, 1:2 respectively)
— column experiments
Present study  Feasibility study regarding methodical approaches
Approach
Soil saturation extract (technical realisation)
original sample + deion. water to moisten completely ,
keeping 24 h at 5°C
adding water until flow limit is reached,
keeping another 24 h at 5°C
centrifugation and filtration with membrane filters
(pore size 0,45 µm)
Approach
Soil saturation extract
original sample + deion. water to moisten completely ,
keeping 24 h at 5°C
Methodical advantages and disadvantages
— close to reality material/water ratio (+)
adding
until
flow
— no fixed
waterwater
/ solid
ratio
(-) limit is reached,
keeping another 24 h at 5°C
— small sample volume (5-30ml /100g) (-)
— not convenient for very fine and very coarse
textured material (-)
centrifugation and filtration with membrane filters
(pore size 0,45 µm)
Approach
pH-Stat (technical realisation)
field moist sample + deion. Water (1:10),
24 h stirring, adding HNO3 by means of an
automatic titrator until pH 4
filtration with membrane filters
(pore size 0,45 µm)
Approach
pH-Stat
Methodical advantages and disadvantages
field moist sample + deion. Water (1:10),
— determination of the leachable contaminants
according to a worst-case scenario (+)
24 h stirring, adding HNO3, by means of an
— information of buffering capacity (+)
automatic titrator until pH 4
— no pH-Stat experiment at low pH value (<4) (-)
filtration with membrane filters
(pore size 0,45 µm)
Approach
Elution with water 1:10 and 1:2 (technical realisation)
field moist sample + deion. Water (1:10, 1:2 respectively)
24 h overhead-rotating shaker at room temperature
filtration with membrane filters
(pore size 0,45 µm)
Approach
Elution with water 1:10 and 1:2
Methodical advantages and disadvantages
— leachate
volume+large
enough
the following
field
moist sample
deion.
Waterfor
(1:10,
1:2 respectively)
analysis (+)
24 h overhead-rotating shaker at room temperature
— abrasion of particles during the extraction
procedure (-)
filtration with
filters
— 1:10 material/water
ratio:membrane
excess water
1:2 material/water
ratio
closer
reality (see soil sat.
(pore
size
0,45toµm)
Extract)
Approach
Column experiment – experimental setup
insert sample in column, wetting
from downside up within 24 h
keeping 24 h at 10°C
6-20x
exchange of one pore volume
within 24 h
intermittently driven
Approach
Column experiment – end of experiment
„quasi steady state“ situation
 no alteration in physico-chemical properties like pH, redox-potential
EC
pH
Redox I
Pi/Pi 1
1,2
0,8
„steady-state“
0,4
0,0
0
5
10
PV
15
20
Approach
Column experiment – end of experiment
„quasi steady state“ situation
 no alteration in physico-chemical properties like pH, redox-potential
EC
pH
Redox I
Redox II
Pi/Pi 1
1,2
0,8
„steady-state“
0,4
0,0
0
5
10
PV
15
20
Approach
Determining the source term
C
soil saturation extract
different concentration
levels expected !!
elution with water 1:2
elution with water 1:10
column experiment
t
Approach
28 different NORM residues investigated
— slags from primary metallurgic processes in the raw iron and nonferrous metallurgy
— sludges and dust from the smoke gas filtering with the primary
metallurgic processes in the raw iron and non-ferrous metallurgy
— sludges and sediments from the recovery of oil and natural gas
(Scales)
— red mud from the extraction of bauxite
— tailings from the extraction of uranium
— residues of water treatment facilities
Approach
Analysed parameters
• Residue
— U-238 series: U-238, Th-230, Ra-226, Pb-210, (Po-210)
— U-235 series: Ac-227
— Th-232 series: Ra-228, Th-228, (Th-232)
— K-40
• Leachate
— U-238, Ra-226, Pb-210, Ra-228 (Th-228, Ac-227, Po-210)
— Major ions: Cl-, HCO3-, SO42-, Na+, K+, Ca2+, Mg2+
— pH, electrical conductivity
• Analysing methods
— Gamma spectrometry
— Alpha spectrometry
— Liquid Scintillation Counting (LSC)
— ICP-MS
Results
Data mining
Different water / solid ratios  results not comparble
normalisation required
activity-concentration scaled on pore
volume aiPV of undisturbed soil:
a iPV 
i
a ileachate  WF   d
n
a leachate: activity-concentration in leachate [Bq/l]
WF:
Water/material ratio [l/kg]
d:
oven-dry density [g/cm³]
n:
porosity
leachable fraction Ri:
i
aleachate
 WF
Ri 
Ai
Ai:
specific activity [Bq/kg]
Results
U-238 activity concentration scaled on pore volume
1E+7
U-238 (1+10)
U-238 (pH-Stat)
U-238 (SSE)
U-238 (1+2)
1E+6
1E+5
mBq/l
1E+4
1E+3
1E+2
1E+1
ww filter
gravel
ww filter
gravel
ww filter
gravel
tailings
tailings
tailings
red mud
scales
dem.
residues
dem.
residues
phosphate
slag
Theisen
sludge
furnace
gas
furnace
sludge
gas
sinter dust
Cu-slag
Ni-slag
1E+0
1.1 1.2 1.10 2.5 2.9 2.15 3.2 3.4 3.13 4.1 5.1 5.2 5.4 6.1 6.6 6.7
Due to the acidification during the pH-Stat experiment trends
to result in highest concentration
Results
U-238 leachable fraction
U-238 (1+10)
U-238 (pH-Stat)
U-238 (SSE)
U-238 (1+2)
1E+0
1E-1
1E-2
1E-3
1E-4
1.1 1.2 1.10 2.5 2.9 2.15 3.2 3.4 3.13 4.1 5.1 5.2 5.4
Tailings: close to 100% release feasible
ww filter
gravel
ww filter
gravel
ww filter
gravel
tailings
tailings
tailings
red mud
scales
dem.
residues
dem.
residues
Cu-slag
Ni-slag
1E-6
phosphate
slag
Theisen
sludge
furnace
gas
furnace
sludge
gas
sinter dust
1E-5
6.1 6.6 6.7
Results
Ra-226 activity concentration scaled on pore volume
1E+6
Ra-226 (1+10)
Ra-226 (pH-Stat)
Ra-226 (SSE)
Ra-226 (1+2)
1E+5
mBq/l
1E+4
1E+3
1E+2
ww filter
gravel
ww filter
gravel
ww filter
gravel
tailings
tailings
tailings
red mud
scales
dem.
residues
dem.
residues
Cu-slag
Ni-slag
1E+0
phosphate
slag
Theisen
sludge
furnace
gas
furnace
sludge
gas
sinter dust
1E+1
1.1 1.2 1.10 2.5 2.9 2.15 3.2 3.4 3.13 4.1 5.1 5.2 5.4 6.1 6.6 6.7
Due to the acidification during the pH-Stat experiment trends
to result in highest concentration
Results
Ra-226 leachable fraction
Ra-226 (1+10)
Ra-226 (pH-Stat)
Ra-226 (SSE)
Ra-226 (1+2)
1E+0
1E-1
1E-2
1E-3
1E-4
1.1 1.2 1.10 2.5 2.9 2.15 3.2 3.4 3.13 4.1 5.1 5.2 5.4
ww filter
gravel
ww filter
gravel
ww filter
gravel
tailings
tailings
tailings
red mud
scales
dem.
residues
dem.
residues
Cu-slag
Ni-slag
1E-6
phosphate
slag
Theisen
sludge
furnace
gas
furnace
sludge
gas
sinter dust
1E-5
6.1 6.6 6.7
Low leachable fraction for demercurised residues and scales
Results
1E+9
1E+8
1E+7
1E+6
1E+5
1E+4
1E+3
1E+2
1E+1
1E+0
ww filter
gravel
ww filter
gravel
ww filter
gravel
tailings
tailings
tailings
red mud
scales
dem.
residues
dem.
residues
phosphate
slag
Theisen
sludge
furnace
gas
furnace
sludge
gas
sinter dust
Cu-slag
Pb-210 (1+10)
Pb-210 (pH-Stat)
Pb-210 (SSE)
Pb-210 (1+2)
Ni-slag
mBq/l
Pb-210 activity concentration scaled on pore volume
1.1 1.2 1.10 2.5 2.9 2.15 3.2 3.4 3.13 4.1 5.1 5.2 5.4 6.1 6.6 6.7
Highest concentration due to the acidification during the pHStat experiment are evident
Results
Pb-210 leachable fraction
Pb-210 (1+10)
Pb-210 (pH-Stat)
Pb-210 (SSE)
Pb-210 (1+2)
1E+0
1E-1
1E-2
1E-3
1E-4
1.1 1.2 1.10 2.5 2.9 2.15 3.2 3.4 3.13 4.1 5.1 5.2 5.4
ww filter
gravel
ww filter
gravel
ww filter
gravel
tailings
tailings
tailings
red mud
scales
dem.
residues
dem.
residues
Cu-slag
Ni-slag
1E-6
phosphate
slag
Theisen
sludge
furnace
gas
furnace
sludge
gas
sinter dust
1E-5
6.1 6.6 6.7
Elevated leachable fraction for sinter dust and water work
residues
Results
Data mining column experiments
total leached load Ain,abs
Ani ,abs 
 a
n
i
leachate,n
 Vleachate,n
relative leached load Firel

1
i
a leachate,n: activity conc. in n-th leachate [Bq/l]
Vleachate,n: volume n-th leachate [l]
i
A
i
Frel
 n,abs
m  Ai
m: mass of material in column [kg]
Ai: specific activity [Bq/kg]
Results
Theisen sludge – intermittently driven column experiment
activity concentrationen
1E+4
Ra-226
Pb-210
1E+1
U-238
3,7
Ra-226
Pb-210
1E+0
Bq
1E+3
mBq/l
leached activity (accumulated)
1E+2
1E-2
1E+0
1E-3
2
8
6
4
pore volume
10
12
0,14
1E-1
1E+1
0
U-238
0,025
0
2
8
6
4
pore volume
10
12
Results
Theisen sludge – comparison between different leaching
methods
U-238
Ra-226
Pb-210
rel. leached load
1E-2
1E-3
1E-4
1E-5
1E-6
1E-7
SSE
CE
1.leachate
CE
10.leachate
pH-stat
1+10
1+2
Results
Tailings – intermittently driven column experiment
activity concentration
leached activity (accumulated)
1E+5
1E+2
92
Ra-226
U-238
1E+1
1E+3
Bq
mBq/l
1E+4
1E+2
1,7
1E+0
1E+1
Ra-226
U-238
1E+0
0
2
4
6
pore volume
8
10
1E-1
0
2
4
6
pore volume
8
10
Results
Tailings – comparison between different leaching methods
1E+0
U-238
Ra-226
rel. leached load
1E-1
1E-2
1E-3
1E-4
1E-5
1E-6
1E-7
SSE
CE
1.leachate
CE
10.leachate
pH-stat
1+10
1+2
Conclusions
— This present study is the first complex investigation about the
release of radionuclides by sewage from NORM .
— The soil saturation extract offers only a marginal sample volume,
meaning the determination of radionuclides is in many cases
impossible.
— The elution with water is easy to handle and gives qualitative
informations about the radionuclides released.
— Caused by the lowered pH of 4 the results of pH-Stat experiments
show, as expected, higher activity concentrations compared to
other methods.
Conclusions
— The realisation of intermittently driven column experiments is
more sophisticated compared to batch experiments, but the
results offer informations about time depending leaching of
radionuclides.
— No alteration in the physico-chemical properties (e.g. pH and
redox-potential) assumed the electric conductivity is a suitable
parameter to determine „quasi steady-state“ conditions.
— The transferability of the well-established methods (elution with
water, the pH-Stat, intermittently driven column experiments)
from waste legislation on radiological purposes could be shown.
Thank you for your attention
Legal Framework
List of residues requiring surveillance (Radiation Protection
Ordinance – RPO): “Positive List”
— sludges and sediments from oil and natural gas extraction
— unconditioned phosphor gypsum, dust, sludges and slags occurring
during processing of raw phosphate
— waste rock, sludges, sands, slags and dusts from the extraction and
preparation of bauxite, columbite, copper shale, tin…
— dust and sludge from smoke gas filtering within primary metallurgic
processes in the raw iron and non-ferrous metallurgy
Exception:
• C < 0,2 Bq/g
• Introduced in technological processes specified in the positive list
as raw material
Legal Framework
— Based on Directive 96/29 EURATOM (European Basic Safety Standards)
— Systematic research for identifying relevant processes and materials
— Radiological criterion:
1 mSv/a to members of the public (added to the natural background level)
— Results:
• fate of particular industrial residues of concern
• U-238 and Th-232 series relevant
List of residues needing surveillance – Radiation Protection Ordinance
(RPO 2001)
NORM residues
Slags from primary metallurgic processes in the raw iron and nonferrous metallurgy
P1.1 Ni-Slags
P1.2 Cu-Slags
P1.3 Sandy residues from tin
ore prosessing
P1.8 Casting cinder
P1.10 Phosphate slags
P1.10
5 cm
NORM residues
Sludges and dust from the smoke gas filtering with the primary
metallurgic processes in the raw iron and non-ferrous metallurgy
P2.5 Theissen sludge
P2.9 Furnace gas sludges
P2.13 Sinter dust
P2.14 Furnace gas sludges
P2.15 Sinter dust
NORM residues
Sludges and sediments from the recovery of oil and natural gas (Scales)
P3.3
P3.2
P3.2 to P3.5 demercurised residues
P3.6 & P3.13 dry Scales
5 cm
5 cm
P3.5
P3.4
5 cm
P3.6
5 cm
P3.13
2 cm
2 cm
 Not considered: oily sludges
NORM residues
Red Mud from the extraction of bauxite
P4.1 Red mud Lauta
P4.2 Red mud AOS Stade
NORM residues
Tailings from the extraction of Uranium
P5.1
P5.2
5 cm
5 cm
P5.3
P5.4
5 cm
5 cm
P5.1, P5.3 & P5.4 silt-dominated Tailings
P5.2 sand-dominated Tailings
NORM residues
Residues of water treatment facilities
P6.1, P6.3, P6.6 & P6.7
different filter gravel
P6.9 Filtrolite
P6.11 powdered immobilisate
(mine water clean up from
former uranium mining)
1E-06
Immobilisat 2
filtrolite
ww-filter gravel 4
ww-filter gravel 3
ww-filter gravel 2
ww-filter gravel 1
tailing 4
tailing 3
tailing 2
tailing 1
red mud 2
red mud 1
scale 2
scale 1
dem. residue 4
1E-02
dem. residue 3
1E-01
dem. residue 2
1E+00
dem. residue 1
sinter dust 2
furnace gas sludge 2
sinter dust 1
furnace gas sludge 1
Theisensludge
phosphate slag
casting cinder
sandy tin ore residue
Cu-slag
Ni-slag
i
a PV (mBq/l)
Results
Activityconcentration normalised to porevolume
U-238 (1+10)
U-238 (ph-stat)
U-238 (SSE)
U-238 (1+2)
1E-03
1E-04
1E-05
1E-06
Immobilisat 2
filtrolite
tailing 4
ww-filter
gravel 1
ww-filter
gravel 2
ww-filter
gravel 3
ww-filter
gravel 4
tailing 3
tailing 2
tailing 1
red mud 2
red mud 1
PV
(mBq/l)
1E-01
scale 2
i
1E+00
sinter dust 2
dem. residue
1
dem. residue
2
dem. residue
3
dem. residue
4
scale 1
sinter dust 1
furnace gas
sludge 2
Cu-slag
sandy tin ore
residue
casting cinder
phosphate
slag
Theisensludge
furnace gas
sludge 1
Ni-slag
a
Results
Activityconcentration normalised to porevolume
Ra-226 (1+10)
Ra-226 (ph-stat)
Ra-226 (SSE)
Ra-226 (1+2)
1E-02
1E-03
1E-04
1E-05
1E-06
water work
filter gravel 3
water work
filter gravel 2
water work
filter gravel 1
tailing 3
tailing 2
1E-01
tailing 1
1E+00
red mud 1
scale
dem. residue 2
dem. residue 1
sinter dust
furnace gas
sludge
Theisen sludge
phosphate slag
Cu-slag
Ni-slag
i
a PV (mBq/l)
Results
Activityconcentration normalised to porevolume
Pb-210 (1+10)
Pb-210 (ph-stat)
Pb-210 (SSE)
Pb-210 (1+2)
1E-02
1E-03
1E-04
1E-05