The AT-1 Pilot Dismantling Project

The European Commission selected AT-1 as a pilot dismantling project for its R&D programme on the decommissioning of nuclear installations.

The AT-1 pilot facility was built to reprocess fuel coming from fast breeder reactor (Rapsodie and Phenix).

It was situated near Cherbourg on the site of COGEMA La Hague.

Short history

• 1969-1979: Operation
• 1979: Decommissioning of the workshop
• 1979-1981: Decontamination and flushing of the reactor coolant system
• 1981: Preliminary studies and dismantling
• 1982-1985: Cleaning operations, Development of specific apparatus
• 1990-1993: Dismantling of the process in the high activity cells using the ATENA machine, operated by remote control
• 1993-1997: Dismantling of the containers barriers

Figure 1. Situation of the AT-1 pilot Facility at the site of COGEMA La Hague.

It was in activity for 10 years from 1969 to 1979 and produced 1.094 kg of Pu.

At the beginning this facility had three reprocessing cycles. A 4th cycle of U/Pu separation and a complementary fission product storage were created in 1972 in the Extension Building.

After the definitive shut down in 1979, the operations were pursued as follows:

• A one year period of rinse has allowed to collect 600 g of Pu and 1.700 g of U.
• A 18 months period of decontamination.

The UDIN (Unité de Démantèlement des Installations Nucléaires) has been in charge of the reprocessing plant AT-1 since 1982 for the dismantling of the facility: stage 3 decommissioning excluding civil works:

• The dismantling and removing of all the circuits and equipment contaminated.

• The cleansing of the different cells at a level as low as possible in order to allow the reuse of the building without being force to control it permanently.

Figure 2. Functions of the cells of the AT-1 facility

The functions of the cells of AT-1 facility are summarised in Figure 2 as follows:

• The fuel pins transported in lead casks were introduced into the cell 901, then conveyed into cell 902 to be cut into pieces and placed into baskets.
• From cell 902 the baskets were sent down into the dissolver located in cell 903.
• The nitric solutions coming from the dissolver were then clarified and sent to the first, second and third extraction cycles in cells 904 and 905.
• After segregation from the fission products, the fissile material was routed to the end of the process: separation between U and Pu, concentration and transformation into uranyl solution and PuO2 located in alpha cells and glove boxes without heavy shielding (cells 950, 951, 952 and 906).

Some other cells were devoted to fission products storage (cells 908 and 909, extension building), liquid waste storage (cell 907), off gas treatment (filtration cell) and glove boxes for sampling, analysing.

Figure 3. Cutaway view illustrating the dismantling of cell 905 and maintenance cell

Further information

• Dismantling Operations and Main Results
• Pictury Gallery
• Drawing Gallery

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