WM’01 Conference, February 25-March 1, 2001, Tucson, AZ
REMOTE-HANDLED DISPOSAL OF THE INTERMEDIATE STORAGE SITE FOR
SOLID, RADIOACTIVE WASTES OF VKTA (DRESDEN GERMANY) WITH
ELECTRICAL MASTER-SLAVE MANIPULATORS
U.Helwig (VKTA)
A. Kiolbassa (ANSA)
ABSTRACT
The paper will present the potential applications for EMSM-E lectro Master Slave
Manipulators and other remote controlled equipment with the intention of reducing
radiological exposure to personal.
INTRODUCTION
Special radioactive wastes that arose in the past in the Mo-99, the Fe -59 and the Co-60 source
production were put into intermediate storage at the former Rossendorf nuclear research site.
Since 1991 the Nuclear Engineering and Analytics Rossendorf Inc. (VKTA) is responsable
for decommissioning of the nuclear facilities. Expert reports of the relevant authorization
officials already recommended the immediate development and implementation of plans for
safeguarding and disposal of the radioactive wastes in 1991/1993.
A plan for remote-handled processing, removal and packing of the radioactive wastes
emerged from this recommendation.
STRUCTURE OF THE INTERMEDIATE STORAGE SITE
The intermediate storage site for special solid wastes consists of a concrete monolith
embedded in the ground in which six cylindrical pits (Containers 1 to 6) are located.
The containers, lined with steel in the interior in part, were closed up with shielding plugs
made of concrete. A bridge crane for handling the shielding plugs, as well as for relocating
waste containers, was located over the concrete monolith (Figure 1).
2
3
3000
ca. 6000
6
1300
5
1
4
ca. 9000
Fig. 1. Intermediate Storage Site for Special Solid Wastes (Concrete Monolith with Containers 1 to 6)
WM’01 Conference, February 25-March 1, 2001, Tucson, AZ
DESCRIPTION OF THE RADIOACTIVE WASTES
The high overall activity of the wastes, as well as the fact that the storage of the waste was
only documented in an incomplete way in the initial years, had the effect of making the
removal and packing of the wastes more difficult:
Table I: Characterization and Distribution of the Wastes in the Containers 1 to 6
Cont.
No.
1
Waste Type
Metal parts, ionexchange resins,
concrete
2, 3, 5 Empty
4
Co-60 sources,
irradiated uranium,
europium wastes,
hardened cement
paste
6
Radiation boxes,
neutron-activated
metal parts
Packing
Steel barrels,
PVC containers
Total
Lead
Volume nuclides
/m³/
2.5 m³ Co-60
Cs-137
Activity
(1995)
Approx. 24
GBq
Dose Rate
at an Open
Container (1993)
2.9 mSv/h
Approx.
800
pieces of metal
cladding
0.9 m³
Co-60
Eu-154
Cs-137
Sr-90
Approx. 20
TBq
257 mSv/h
3 pieces
200-l barrels
0.6 m³
Co-60
Approx. 46
TBq
2600 mSv/h
WM’01 Conference, February 25-March 1, 2001, Tucson, AZ
Container 1
The container was completely sealed
with concrete. Water was discovered
under the concrete layer during the
remote -handled removal.
In total,
approx. 500 l of weakly radioactive
water was pumped out. The majority of
the wastes existed in a heterogeneous
form (sludge, concrete, metal parts).
Fig. 2. Container 1
Container 4
Metal cladding was stored from around
1965 to 1978. Due to the external
storage, condensation water forme d in
the container that repeatedly set because
of the addition of cement. As a result of
this, a cement matrix with the integrated
metal cladding arose.
Fig. 3. Container 4
Container 6
Three waste packing drums were located
in Container 6; two of those were
preconditioned and sealed. The third
waste packing drum was open and filled
over the top in part with bulky metal
pieces.
DISPOSAL PLAN
Fig. 4. Container 6
The goal of the disposal measures was the removal of all waste, its packing and its
intermediate storage in the location's own intermediate storage site.
The various storage conditions, which were only known in part, as well as the high inventory
of active substances, required the use of a flexible remote-handling technique that was able to
not only operate within the containers, but was also able to take on packing and measurement
tasks. The conditions in the container were simulated in a model test at the company ANSA
in Bouzonville, France, the use of Electrical Master-Slave Manipulators was tried and its
suitability was verified.
WM’01 Conference, February 25-March 1, 2001, Tucson, AZ
A prerequisite for the reliable use of the electrical master-slave manipulators was the setup of
a disposal facility, consisting of a reinforced concrete hall and comprehensive technical
systems over the concrete monolith.
The overall process was divided up into the following sub-steps:
•
•
•
•
•
•
•
•
•
Dismantling of the existing bridge crane
Setup of a hall over the concrete monolith
Installation of the technical equipment for the emptying of Container 6
Emptying of Container 6
Installation of the technical equipment for the emptying of Containers 1 and 4
Emptying Container 1
Emptying Container 4
Decontamination of Containers 1 to 6 and of the concrete monolith
Decontamination and dismantling of the technical equipment no longer needed
DESCRIPTION OF THE DISPOSAL FACILITY
The disposal facility for the emptying of Container 6 consisted of
•
•
•
•
•
•
•
a reinforced concrete hall (LxW: 22.9 x 13.0 m),
a 10-ton bay crane with camera equipment,
mobile shielding walls,
ventilation and air -conditioning systems,
a fire alarm system,
a local dose-rate measurement system and
a control container and an operational container for the remote-handling equipment.
The removal of the two sealed tension-ring cover barrels took place with the aid of a barrel
container of the type FC-100 under the view of a camera. The contents of the open barrel
were distributed over two Type -A barrels with a crane -guided electrical master-slave
manipulator. The intermediate storage of all waste packing drums takes place in shielded
containers in the newly-built intermediate storage site Rossendorf ZLR II.
After the conclusion of the waste removal from Container 6, the setup of the additional
technical equipment required for the removal process from Containers 1 and 4 took place,
consisting of:
•
•
•
•
•
•
•
•
a sheet-steel caisson (L x W x H: 9.8 x 6.9 x 5.7 m) with a connection to the ventilation
and air-conditioning systems,
a caisson crane with three sets of hoisting equipment (2.5 tons and 2 x 0.5 tons),
a movable container seal,
a transport system for 200-liter barrels, consisting of a double -cover material lock and
barrel transport carriages,
a dust-suctioning system,
camera equipment on the caisson crane and in the area of the transport system,
a three-partition material transfer tent for the access into the caisson,
measurement equipment for radiation protection and monitoring.
WM’01 Conference, February 25-March 1, 2001, Tucson, AZ
The handling, removal and packing of the wastes in Containers 1 and 4 took place in a way
analogous to that for Container 6 with an electrical master-slave manipulator, as well as
various resources or tools, such as special shovels, an electrical chisel hammer, abrasive
cutting machines and the like, for example. The individual metal cladding was evaluated with
gamma spectrometry in the caisson; its local dose rate was determined and documented in a
database. The sorted wastes were put into 200-l, Type-A barrels through a double-cover
material lock. After this, the storage in the intermediate storage site Rossendorf ZLR I took
place.
DISPOSAL STEPS
Table II: Result of the Disposal of the Intermediate Storage Site for Special
Radioactive Wastes (As of April of 2000)
Disposal Step
Time Period
200-l MAW Packing
Drums Created
Emptying of Container 6
Sept. 23 - Sept. 30, 1998
5
Emptying of Container 1
July 15 - Aug. 08, 1999
2
Emptying of Container 4
Start: Sept. 23, 1999
65
End: 04/2000
CONCLUSION
100% of the total inventory of active substance was thereby removed and put into safe
intermediate storage.
The execution of the work showed that the selected remote-handling technique of the
company ANSA was optimally suited to the solution of the problem described. The whole
wor k was done within the proposed time schedule and the calculated cost frame.