The Lepse nuclear service ship, long one of the most radioactive heirlooms of the Soviet Era, has finally been emptied of all 639 spent nuclear fuel assemblies that for decades laid dangerously in its holds, marking a major milestone in an international cleanup effort that Bellona helped bring to the fore.
The fuel removal effort, which took place at the Nerpa shipyard near Murmansk, Russia, has been one of the most technically demanding nuclear legacy cleanup operations in modern history, representing decades of preparation and the coordination of numerous international partners in often troubled political circumstances.
“It is difficult to comment on the project, which has been going on for 27 years, but for me personally, the end of the process of handling spent nuclear fuel that was in the storage facility of the Lepse is a significant event,” said Andrei Zolotkov, head of Bellona’s Murmansk offices, who once worked aboard the vessel. “I would like to congratulate my former colleagues at Atomflot [Russia’s nuclear icebreaker port] on the successful completion of the most important stage of this work – the unloading of spent nuclear fuel. Now we can put an end to the history of a nuclear ship.”
The Lepse was built in 1934 as a dry cargo ship. Later, in 1961, with the development of nuclear technologies and the construction of the first Soviet nuclear icebreaker, the Lenin, the Lepse was converted into a floating technical base for refueling icebreakers at sea and storing the spent nuclear fuel and radioactive waste they offloaded.
Between the 1960s and the 1980s, the Lepse refueled not only the Lenin, but the Arktika and the Sibir as well. But beginning 1981, the Lepse was relieved of its refueling duties and was used exclusively to store spent fuel.
Eventually, in 1988, it was finally decommissioned and moored at Atomflot, only a few kolometers from Murmansk, where it posed an environmental threat to the 400,000 residents of Russia’s Arctic capital. To make matters worse, the Lepse had during one of its missions run into heavy weather, which caused radioactive water to slosh into its spent fuel storage holds, complicating later decontamination.
At one point, during icebreaker refueling operations, a number of spent fuel assemblies wouldn’t fit into storage cases. As a result, significant force was used to shove them in, with some even packed in with sledgehammers, which later made their removal problematic.
“I started my work in the civil nuclear fleet in 1974 with this very vessel,” said Zolotkov.: And I remember very well that when I began to measure the radioactivity of the cooling water in the storage, I was very surprised by the readings of the device. I have never met such values – close to one Curie per liter; this is 100,000 times more than the radioactivity of the coolant of the primary circuit of the reactor of an atomic icebreaker during regular work.”
Six hundred twenty of the 639 fuel assemblies onboard were stored in canisters in two of the ship’s storage tanks, with the remained damaged or corroded assemblies placed in caissons. These were the assemblies that were forced into their storage chambers, which caused spillage of the fuel compositions and made their removal impossible by conventional means.
In the early 1990s, the Bellona Foundation learned of the issues surrounding the Lepse, particularly how there were no funds or technological know how to safely dispose of it.
Since then, Bellona has made every effort to help coordinate the funding and the political will to address the hazard. As a result of those initiative, the Lepse project was included in the 1994 Barents Euro-Arctic Region Work Plan as a priority. In 1995, the Advisory Committee for the Lepse international environmental project was established.
“During this period of time, there were a lot of events, both encouraging and dubious, and there was a period when the project simply stalled and became bogged down in bureaucratic discussions. The works have been carried out at the Nerpa Shipyard for the ninth year already,” Zolotkov said.
In 2012, the Lepse was finally towed from the Atomflot base to the Nerpa shipyard, a naval facility near Murmansk were dismantling works on the vessel finally began. It wouldn’t be until 2019 that technicians began sawing the vessel up and extracting the first canisters containing spent nuclear fuel.
How the work progressed
Anatoly Grigoriev, head of international technical assistance projects at Rosatom, Russia’s state nuclear corporation, told Bellona that last year that, despite the pandemic, the unloading of the 620 spent fuel assemblies stored in two storage tanks was completed.
The spent nuclear fuel was then transported from Nerpa to Atomflot aboard a specialized vessel called the Serebryanka, which made a total of six voyages – three in 2019 and three in 2020. After that, all spent fuel assemblies were shipped by rail to Mayak, Russia’s main nuclear fuel reprocessing center near Chelyabinsk
The work was funded by the European Bank for Reconstruction and Development and the Environmental Partnership Fund.
Nevertheless, the 19 defective spent fuel assemblies in caissons remained in the storage facility, and extracting them was carried out on funding from Russia.
“The caisson is a cylinder with a wide neck, where defective spent fuel assemblies were placed that did not fit into standard storage cells,” Sergei Zhavoronkin, secretary of the Public Council for the Safe Use of Atomic Energy in the Murmansk Region, told Bellona.
According to Grigoriev, unloading the caissons required different technology, different equipment, and a different methodology to extract them.
“Each spent fuel assembly was unloaded separately, put into a canister, which was then loaded into a container,” Grigoriev explained.
What remains of the Lepse itself will be packed into block packaging and sent to Sayda Bay in Russia’s northwest for storage.
“We can say with confidence that colossal work has been successfully carried out, work of global significance, which shows the success of both Russia and international cooperation,” said Grigoriev. “As a result, a long-term problem was solved, which manifested itself in the 80s of the last century. We searched for a solution for a long time, but now the whole world can calmly let out its out – this problem has been solved.”