Rosatom completes dismantling of floating technical base Lepse

29 November 2023

Rosatom has finally completed dismantling of floating technical base (FTB) Lepse after 10-years of work. Construction of the Lepse began in 1934 at the Nikolaev shipyards as a regular timber transport (dry cargo carrier). However, it was never used for its intended purpose – it was scuttled when the Germans attacked the city during World War II. Attempts to restore the ship after the war proved difficult and it was handed over to Leningrad shipbuilders, where, in 1961, it was reconstruction of as a FTB for servicing the Russian nuclear fleet. The ship was equipped with a storage facility for used nuclear fuel, tanks for the collection and temporary storage of liquid radioactive waste, and production facilities for carrying out technological operations with reactor equipment.

From 1964 to 1988, the Lepse FTB not only served the nuclear power plants of the nuclear icebreakers Lenin, Arktika and Sibir, but also carried out transports with radioactive cargo to their disposal sites in the Barents and Kara Seas. In 1981, Lepse was replaced by the Imandra FTB and was then used only for temporary storage of radioactive waste. In 1988 it was decommissioned and in 1990 it was anchored near Murmansk.

Used fuel was stored at Lepse using a method whereby the canisters were filled with water. Long-term storage of fuel assemblies in water resulted in their corrosion. In 1991, in order to create an additional engineering barrier, the inter- tank space of the used fuel storage facility at Lepse was filled with special concrete mixtures. A survey of the vessel and the development of a recycling project began in 2005. The radiation and engineering surveys were completed, in 2012 and and the vessel was towed from FSUE Atomflot in Murmansk to the Nerpa shipyard for subsequent disposal.

The Lepse was gradually dismantled between 2012 and 2017, and scrap metal was disposed of. The used fuel was transported to the Mayak production association in Ozersk for reprocessing. In April 2022, the last batch of fuel was removed. In November 2023, the bow unit, the last part of the ship itself was sent to the long-term storage facility for radioactive waste in Saida Bay.

The main source of radioactive hazard from the Lepse was the used fuel storage facility. The work of unloading and transporting 639 fuel assemblies from the floating base, some of which were damaged and could not be removed by conventional means required special technical solutions from nuclear industry specialists. To unload the fuel, Lepse was placed in a specially designed and constructed ground shelter area to protect it from the weather and rough seas. New technologies were devised to unload fuel along with the shell of storage cells in order to prevent the assemblies from collapsing during the unloading process. This required the design and manufacture of special tools and equipment. The work was carried out using a remote-controlled robotic complex. Disposal of the Lepse cost about €60m ($65.6m). Various organisations of the nuclear industry and enterprises of the North-Western region took part in the implementation of the Lepse project.

At the gala event dedicated to completion of the project, Rosatom Deputy Director General for Mechanical Engineering & Industrial Solutions Andrey Nikipelov noted that Rosatom develops solutions for of the most complex environmental problems. “We are engaged in the elimination of the nuclear legacy and the legacy of toxic industrial production, and we are creating an infrastructure in the country for the management of radioactive and chemical waste.” He said. “For more than 20 years, we have been systematically clearing the coast of the Arctic and Far East from radiation hazardous objects - we are disposing of decommissioned nuclear submarines and support vessels. And this is a special day for us: one of Rosatom’s landmark environmental projects of has been completed …. There is one less dangerous object in the Arctic.”

Vasily Tinin, Director of Public Policy for Rasdwaste, Used Fuel & Decommissioning of Nuclear and Radioactive Facilities, said Rosatom had something to be proud of. “The most complex project - the recycling of Lepse - was implemented for the first time in the world. There were simply no existing solutions. And the people here have applied all their strength and knowledge to ensure that this story had a happy ending…. Together we will make the nuclear industry “greener” and safer.”

Dmitry Titorenko, Deputy Minister for Arctic Development & Economy of the Murmansk Region said the problems of eliminating accumulated environmental damage and the nuclear legacy in the Arctic zone remained the focus of both federal and regional executive authorities. “Undoubtedly, the completion of such a large-scale project makes a huge contribution to ensuring environmental, nuclear and radiation safety in the Arctic,” he noted. “Disposal of Lepse became a challenge for engineering and would have been impossible without the well-coordinated work of a team of professionals. This unique experience will definitely be used in other projects.”

Rosatom continues to clear the waters of the Arctic and Far East from radiation hazardous objects. To date, 202 decommissioned nuclear submarines have been dismantled and all accumulated used nuclear fuel has been removed from the Far East. In the Murmansk region, the removal of used fuel is proceeding as planned. From 2002 to 2023, the total volume of accumulated used fuel decreased by half. The remaining used fuel is being removed from the storage facility in Gremikha and all work is expected to be completed in 2025. More than half of the used fuel has already been removed from the facility in Andreeva Bay, and the entire removal work is planned to be completed by 2028.

Images courtesy of Rosatom

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