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PILOT DISMANTLING OF THE FBR-FUEL REPROCESSING FACILITY AT-1. DISMANTLING OF DISSOLUTION AND EXTRACTION SYSTEMS AND OF FISSION PRODUCT STORAGE TANKS; DECONTAMINATION AND REMOTE DISMANTLING OF CONCRETE WALLS

Objective

The pilot facility AT-1 for the reprocessing of FBR-fuel had a capacity of 2 kg/day and had been operated from 1969 to 1979. Dismantling of the plant has started and is planned to be completed by 1992.

Considering that the experience to be gained from the dismantling of the first representative nuclear installations in the Community should be made available to all Member States, the Commission selected AT-1 as a pilot dismantling project for the 1989-93 R&D programme on the decommissioning of nuclear installations. The Commission, through shared-cost participation in specific parts of the project, intends promoting the use of advanced techniques and the performance of collateral investigations, in order to enhance the generation of useful knowledge and experience to serve in subsequent decommissioning tasks. In particular, the generation of specific data on costs, working hours and job doses as well as on the amount of created secondary waste is considered as an important objective of this project.

The dismantling of the AT-1 facility is concerned by specific problems associated to the reprocessing of irradiated fuel, namely the presence of a mixture of alpha, beta and gamma emitters. This necessitates the use of remotely operated and controlled equipment for the dismantling and decontamination, partly due to the specific conception of the cells, without direct viewing. For this, the carrier ATENA is used (telescope plus polyarticulated arm) supporting the telemanipulators MA 23 or RD 500.

Specific problems are also encountered with radioactive measurements needed for the sorting and preconditioning of the arising dismantling waste.

The contract started with Phase 1 work involving the dismantling and waste assaying and conditioning of cells 903, 904, 905 and the dismantling of fission product storage cells. The subsequent Phase 2-work is devoted to the remote dismantling of a concrete wall and to the decontamination of the concrete walls and floors in the dismantled cells.

Estimated maximal values for the specific contamination and for dose rates are in the order of 10,000 Bq/square cm and 1 Gy/h, respectively.
The dismantling of the AT-1 facility is concerned with specific problems associated with the reprocessing of irradiated fuel, namely the presence of a mixture of alpha, beta and gamma emitters. This necessitates the use of remotely operated and controlled equipment for the dismantling and decontamination, without direct viewing.

The contract started with phase 1 work involving the dismantling and waste assaying and conditioning of cells 903, 904, 905 and the dismantling of fission product storage cells. The subsequent phase 2 work is devoted to the remote dismantling of a concrete wall and to the decontamination of the concrete walls and floors in the dismantled cells.

The dismantling of the high activity cells has almost been totally completed using the ATENA machine. To enter cell 903 (dissolution cell), it was necessary to make an access through the concrete wall separating cell 903 from cell 904. This operation was remotely carried out with the ATENA machine equipped with a diamond tipped saw. The cell used for the conditioning of waste was put into service and used to remove almost half of the waste bulk from cell 904. After 2 years of operation, the experience gained with the remote equipment, used to dismantle the high activity cells of AT-1 and to remove waste, was investigated.
WORK PROGRAMME

1. Remote-operated dismantling of equipment out of the strongly contaminated cell 903 (used for dissolution), and of cells 904 and 905 (used for extraction).

2. Measurement of the radioactivity and conditioning of the waste arising from 1.

3. Dismantling of tanks for the storage of fission products.

4. Generation of specific data on costs, radioactive job doses, working time and secondary waste arisings, derived from the execution of items 1, 2, 3, 5 and 6.

5. Remote dismantling of a reinforced concrete wall

6. Semi-automatic decontamination and contamination measurements of concrete walls and floors

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

COMMISSARIAT A L'ENERGIE ATOMIQUE
Address
Rue De La Federation 31-33
75015 Paris
France