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FINAL CLEAN-UP OF THE PIVER PROTOTYPE VITRIFICATION FACILITY: DECONTAMINATION OF THE HOT CELL

Objective

The PIVER pilot vitrification facility at Marcoule was operated between 1969 and 1980, first using a batch process to vitrify Gas-Cooled Reactor fuel element reprocessing waste, and then to develop a continuous process to vitrify Fast Breeder Reactor (FBR) fuel reprocessing waste. A total of 12 t of glass was treated. It was then decided to remove the equipment and clean up the cell in order to install new equipment for continuous vitrification of waste generated by reprocessing FBR fuel (PIVER II).

PIVER is the first vitrification cell for fission product solutions to be decommissioned. Under a previous contract (FI1D0057), all process equipment items of the main cell were removed, followed by preliminary decontamination carried out in remote operation. So, the internal radiation level was reduced from several Gy/h to less than 10 mGy/h. The remaining radioactivity inventory is estimated at about 1.1E13 Bq (300 Ci). At this level, access to the cell is now possible for durations not exceeding about one minute; the cell remains highly contaminated and requires the use of ventilated protective clothing under severe working conditions.

The work to be carried out under this contract is aimed at continuing decontamination and dismantling work enabling further dismantling of in-cell equipment with hands-on techniques and finally to reach a radiation level allowing the installation of new equipment with standard working conditions for controlled zones. 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 contractual work will result in assessed decontamination procedures for highly contaminated cells.
PIVER is the first vitrification cell for fission product solutions to be decommissioned. Under a previous contract, all process equipment items of the main cell were removed, followed by preliminary decontamination carried out in remote operations.

The work to be carried out under this contract is aimed at continuing decontamination and dismantling work enabling further dismantling of in cell equipment with hands on techniques and finally to reach a radiation level allowing the installation of new equipment with standard working conditions for controlled zones.

Dismantling and decontamination of the PIVER cell reduced the in cell radiation level to 0.1 mGy/h. Research and development work on enhanced decontamination processes was carried out. 4 mature processes (electrolytic, shot peening, cryogenic and gel) were tested under actual, representative hostile conditions to assess their advantages, drawbacks and effectiveness. The final decontamination operations were carried out on only a portion of the cell wall, and did not significantly affect the overall ambient radiation level in the cell. The dismantling and decontamination operations in the PIVER cell have been successfully terminated and quantitatively assessed.
WORK PROGRAMME

1. Dismantling of the telemanipulators in the PIVER cell including 2 MT200 master-slave manipulators, a robot manipulator (CAROLINE) and a pantograph manipulator (ANTOINE).

2. Further decontamination of the PIVER cell with various decontamination techniques (chemicals using liquids, foams and gels, electropolishing, and cryogenics), accompanied by radiological measurements.

2.1. First stage decontamination by short time in-cell work, aimed at strongly reducing the dose rates.
2.2. Second stage decontamination by long time in-cell operators' work.
2.3. Final decontamination aimed at obtaining standard working conditions for controlled areas in the cell (dose rate < 0.1 mGy/h).

3. Dismantling of the remaining pipes not needed for the future use of the cells.

4. Identification of the remaining cell internals by photogrammetry for facilitating design work for the reuse of the cell.

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

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Commissariat à l'Energie Atomique (CEA)
Address
Centre D'études Nucléaires De La Vallée Du Rhône Cité De Marcoule
30205 Bagnols-sur-cèze
France