Cleaning up the Arctic

Photo: Andreeva Bay (credit: EBRD)

RUSSIA’S LEPSE FLOATING TECHNICAL BASE, which had served as a used fuel storage facility for the nuclear icebreaker fleet, was decommissioned in 1988.

For more than 20 years the floating technical base was afloat near Murmansk, awaiting disposal, where it posed an environmental and radiation threat to the entire Northwest region. Now Russian state nuclear corporation Rosatom has said that the Lepse base will be sealed and transferred from the Murmansk region to long-term storage at the village
of Sayda Guba, where there is a long-term ground storage facility for reactor compartments.

There were 639 used fuel assemblies in storage. Some of the fuel assemblies were damaged, which made extraction very difficult.

Work started in May 2019, since when 620 used fuel assemblies have been cut out and unloaded from the base’s bow package using specially developed technologies and unique equipment. In July, the last of six batches of used fuel assemblies was loaded into TUK-18 transport packaging containers and delivered to the special storage site at Atomflot by the motor ship Serebryanka. This left 19 assemblies, which pose particular difficulties, to be removed in 2021.

How it started

The dry cargo ship Lepse was built in 1934, and converted into a floating technical base in 1961. Until 1981, it supported the refuelling of Russia’s nuclear icebreakers and after 1981 it served as a storage facility. In 1996, a project to deal with Lepse was included in the European Union’s TACIS programme (the CIS technical assistance programme) with funding allocated for inspection of the used fuel.

In 2008, an initial executive grant agreement was concluded for the disposal of the Lepse. The recipient of the grant was LC NFC, and the European Bank for Reconstruction and Development (EBRD) acted as the administrator. After 2011, with funding from Russia’s federal target programme (Ensuring Nuclear and Radiation Safety for 2008 and for the Period Until 2015), a comprehensive radiation survey of the vessel was undertaken and preparatory work began. This included docking, partial conversion of the ship’s hull, removing some radioactive material, decontamination and installation of additional equipment. In 2012 Lepse was towed to the Nerpa shipyard.

Defuelling

In September 2018, EBRD announced it had built a shelter for the vessel, which was intended to create safe conditions in which to cut out the used fuel from the onboard storage tanks, transfer the nuclear material into new canisters and transport it for further storage at Mayak.

The EBRD said the €23 million shelter was financed through the Nuclear Window of the Northern Dimension Environmental Partnership (NDEP) Support Fund, an international fund with contributions from Belgium, Canada, Denmark, the European Union, Finland, France, Germany, the Netherlands, Norway and the UK, managed by the EBRD.

“The next stage will be the preparation of the storage facility for long-term storage. The roof, from where the canisters with fuel are cut, will be sealed and brought into compliance with Russian standards to natural radiation levels. The facility will be moved to Sayda Guba and placed there,” Rosatom said.

Before the start of conservation in 2021, the last 19 fuel assemblies will be removed. “These 19 fuel assemblies are stored in caissons, where they were once placed for temporary storage. They will be unloaded using a separate technology developed jointly with the EBRD. it will be necessary to practice the actions of the personnel using the test bench,” Rosatom noted.

Andreeva Bay

Rosatom said unloading of used nuclear fuel from storage facilities at the former onshore naval technical base in Andreeva Bay near Murmansk is planned to be completed by 2027. The Andreeva Bay storage facility, established in the 1960s, is the largest such facility in Northwest Russia and one of the biggest in the world.

The Andreeva Bay base was built to service nuclear submarines. The storage facility contained about 22,000 used fuel assemblies in three containers, which corresponds to the contents of 100 nuclear reactors. It also stored radioactive waste from nuclear submarines, and the base hosted surface ships with nuclear power plants and ships to support the operation of nuclear submarines.

Following an accident in Building 5 in 1982, water leakage from one of the used fuel pools caused widespread contamination. In 1988/9, the majority of fuel from Building 5 was transferred to three dry storage tanks at the site and the building was abandoned.

The base was closed in 1992, by which time the radiation situation had significantly deteriorated. To remove waste for reprocessing, it was necessary to improve the radiation situation on the territory and in the storage facilities but preparatory work was stopped in the early 1990s. It was resumed only in 2001, after the transfer of storage bases to Minatom.

Rosatom noted that the radiation situation in the building where the main storage was located significantly improved in 2020. “When Rosatom began to work on the Andreeva Bay, about 40% of the base and technical area were contaminated with radionuclides. Now the area is mostly cleaned up,” Rosatom said, adding that the schedule for unloading used fuel is determined in accordance with safety requirements — risks for personnel, the population of adjacent territories and for the environment are excluded as much as possible.

From Andreeva Bay, the fuel is transported to FSUE Atomflot, and from there it is delivered by special trains to PA Mayak in the Chelyabinsk region for reprocessing.

Experts from international environmental organisation Bellona, which are conducting their own environmental nuclear project and monitoring the situation in Andreeva Bay, positively assess the work being done. In their opinion, some of the problems with the accumulated Soviet legacy have already been either resolved or are in the process of being liquidated.

A modern complex for long-term storage of reactor compartments of nuclear submarines and parts of civil nuclear fleet ships has already been created; in Andreeva Bay, the dismantled nuclear submarines are being systematically unloaded and sent for reprocessing.

Andrei Zolotkov, head of Bellona’s offices in Murmansk, told Tass that at present all territories where spent fuel storage facilities are located are well guarded, and there are qualified personnel. Although potentially dangerous works are regularly carried out in these areas, they have no serious impact on the environment outside the perimeter.

“When I saw with my own eyes the state of the facility in Andreeva Bay in 1990, and then more than 25 years later, we can undoubtedly talk about progress in this direction...

“There is a hope that, despite various political conflicts in the modern world, Murmansk region, SevRAO (part of RosRAO) and Rosatom will continue international cooperation, because there is the next goal ahead — disposal of sunken and dumped nuclear hazardous objects in the Arctic seas,” Zolotkov said.

In April 2017, the construction and commissioning of infrastructure facilities for the management of the fuel and its transportation for subsequent reprocessing were completed and work began the following month. Nuclear waste management company RosRAO (part of Rosatom) began unloading spent nuclear fuel from the Andreeva Bay base in May 2017. To date more than 30% of the fuel has been removed and sent for processing.

However, a significant volume of radionuclides remained in the sludge at the bottom of the pools and six used fuel assemblies remained at the bottom of one of the pools in Building 5. Following a radiological survey of the storage facility, urgent repairs of the building’s roof were performed and shielding was installed.

Tackling the removal of the remaining spent fuel was complicated, as the damaged assemblies required special operations. Dedicated remote handling equipment had to be manufactured. After tests on a mock-up facility the removal was completed by the end of October 2019.

The assemblies are being retrieved, packaged and removed from the site by SevRAO as part of an international initiative financed by NDEP.

Arctic retrieval

Rosatom has also recently confirmed plans to raise sunken nuclear objects from the Arctic.

It said in August that it expects to raise six of the most radiation-hazardous objects from the bottom of the Arctic zone of the Russian Federation in the next eight years — sunken parts of an icebreaker, nuclear submarines and reactors with used fuel. Although these are a small fraction of those located in the Russian Arctic, they are responsible for 90% of the radiation background in these places, Rosatom told Tass.

This is a longstanding problem. After the arms race, nuclear weapons and the nuclear fleet had to be disposed of. Several bases were deployed in the Murmansk region, in Andreeva Bay, Saiga Bay and near the village of Gremikha. But during the transport of nuclear submarines and icebreakers for decommissioning, accidents occurred and a number were sunk.

“According to research estimates, about 95% of the 18,000 flooded objects are now in a safe state naturally, they are silted and the levels of gamma radiation around them correspond to natural background indicators,” Rosatom said. “The remaining 5% (1000 objects) are characterised by higher levels of gamma radiation. The greatest danger could be posed by six of these objects, namely reactors with used fuel from submarines K-11, K-19 and K-140, two intact submarines K-27 and K-159 and used fuel from the reactor of the icebreaker Lenin. These contain more than 90% of the total activity of sunken objects.”

Rosatom says even the extremely low probability of leakage of radioactive materials from these facilities is an unacceptable risk for the Arctic ecosystems.

“We consider it necessary to raise all six objects, including K-159 and K-27. The lifting of all six objects, their safe transportation to the disposal site and their preparation for long-term storage will take at least eight years.”

The research data was obtained at the end of 2019, following the work of an international consortium that included Italian company Sogin, the Norwegian radiation protection agency NRPA (now DSA), UK company Nuvia and Germany’s EWN.

Based on the results of hazard modelling of all the listed objects, the consortium concluded that “at the moment these objects are only potentially dangerous and do not pose a real threat. ” It recommended raising two submarines (K-159 and K-27). For the rest, constant monitoring of the situation is currently sufficient.

Author information: Judith Perera, Contributing Editor, Nuclear Engineering International