Decommissioning of the Lepse FTB

Lepse ship was built more than 70 years ago to carry cargo, but in 1958 it was rebuilt as a service ship, or Floating Technicial Base, for refuelling the first nuclear powered icebreaker - Lenin - and later for the next generation of icebreakers: Arktika and Sibir. In 1988 it was taken out of service and in 1990 Lepse was officially declared as a 'laid-up' vessel although its storage compartments still contained spent fuel and radioactive waste.

The vessel, laid up in the Kola Bay near Murmansk, contains two storage tanks for spent nuclear fuel (SNF) from the icebreakers with 639 spent fuel assemblies (SFAs) on board. A considerable amount of high and intermediate-level liquid radwaste (LRW) is stored in the SNF storage tank tubes, in special tanks and in the cooling circuit.

The decommissioning of Lepse was identified as an important task 20 years ago and the work was initiated by the Murmansk Shipping Company (MSCo) but was abandoned in 1994 when funds ran out. Lepse was then brought to the attention of the international community and received great support from the European Commission, NEFCO and the governments of Norway and France.

The majority of the SFAs stored in the Lepse are categorised as damaged and the use of regular procedures and practices for defuelling is impossible in its current state. Therefore the unloading of the SFAs from the storage facility on the ship requires the use of specialised equipment and procedures which need to be developed. The approved concept design for the dismantling of Lepse requires that the ship is transported to Nerpa shipyard where the specialist infrastructure will be constructed and equipment installed.

The preparation for transportation included the removal of radioactive waste,decontamination of the vessel and the provision of radiation protection and ventilation systems. Lepse also underwent repairs in the floating dock to close or seal all the openings in the hull and the deck prior to transportation and on 14 September 2012 she was towed to Nerpa shipyard.

Considerable progress has been made in the design development of the SNF and RW management processes and associated infrastructure. Procurement activities are under way for Nerpa shipyard infrastructure requirements which will allow placement of Lepse on the slipway in late 2013 and for the detailed design and manufacture of the specialised equipment.

This NDEP project continues to build on the extensive joint cooperation of the international community and the Russian experts from Rosatom, MSCo and the Russian Ministry of Transport and on the results of the ongoing TACIS funded project.