One of the most radioactively dangerous ship in the whole of Northern Europe, the Lepse stores in its hold tonnes of spent nuclear fuel, or SNF—much of it damaged and therefore extremely dangerous to move—from Russia’s civilian fleet of nuclear icebreakers.

The ship was used actively from 1963 until 1981 as a fuel storage and reactor reloading vessel for the icebreaker fleet run by the Murmansk Shipping Company, or MSCo, and serviced the Lenin, Sibir and Arktika icebreakers. After the commissioning of a similar ship called the Imandra, the Lepse became a permanent SNF storage ship. It is currently moored at the docks of Atomflot, the service base for the MSCo’s nuclear icebreakers, located 2 kilometers north of the densely populated Arctic city of Murmansk.

The Chernogorov report
In June, Bellona published in Russian a report, written by Yuri Chernogorov, who was the chief of the Special Technical Supervision group at MSCo from 1980 to 1991, and dealt with the decommissioning of Lepse.

It was Chernogorov’s assertion in hiss report that, in order to secure the Lepse from posing further radioactive hazards to the Murmansk region, it should simply be filled with a special radiation resistant concrete mixture, leaving the SNF onboard in storage.

The concrete block that would then comprise the SNF storage section of the Lespe would then be cut from her hull. Then, because of the specially designed radiation containing cement, the hull could be stored in the open for 500 years, or at least until a suitable underground nuclear waste repository is constructed, Chernogorov’s plan asserts. In dry storage, says Chernogorov, this special concrete mixture will remain stable for thousands of years.

Other variants that have been considered include unloading spent nuclear fuel from the Lepse and sending it to dry storage. But this would be extremely hazardous for the personnel involved because of both the fragile condition of damaged fuel on board and the high radiation levels measured at the Lepse. According to Chernogorov, the Lepse’s SNF storage hold reached 20 sieverts per hour. A dose of one sievert is enough to cause radiation sickness. The absolute maximum permissible dosage per nuclear worker in Russia has been established to be 0.05 sieverts.

“The suggested variant of Lepse decommissioning without unloading of SNF beyond the bounds of the Atomflot docks and Murmansk is in our opinion more preferable,” reads the conclusion compiled by the Northern European Inter-regional Department of the Federal Service for Nuclear Oversight—or FSAN in its Russian abbreviation—in reference to the Chernogorov report published by Bellona Web.

“One of the problems possible is the lack of personnel to carry out the direct works,” continued FSAN’s document. “Having soon received the annual radiation dosage norm, they would not only be prevented from continuing to unload SNF, but would also be unable to fulfill any of their service duties for maintaining the nuclear fleet.”

Tank of the Lepse spent nuclear fuel storage (vertical section): 1-Plug for caissons, 2-Dash plate, 3-Feathering float of indexing revolving station. 4-Plug for channel, 5-Tank frame, 6-Caisson, 7-Channel with a spent fuel assembly.

Taken together the Lepse contains 260 kilograms of uranium-235, 156 kilograms of is fission products, and 8 kilograms of plutonium-239. The Lepse’s starboard storage tank contains 144 kilograms of uranium-235 and its port tank contains 116 kilograms. Also in the starboard storage tank are 99 kilograms of uranium 235’s fission products and 57 of the same in the port tank. The port tank also contains the plutonium.

As measured on January 1st, 2002, the radioactivity of the fission products in the Lepse’s starboard tank was approximately 16,500 tera-becquerels, and about 7,500 in the port tank. About 70 percent of the radioactivity on the Lepse is represented by caesium-137 and strontium-90. Radioactivity of alfa-emitting nuclides was 210 tera-bequerels on the starboard side and 755 tera-bequerels in the port tank.

Of the 639 assemblies stored in the Lepse’s caissons, 206 were brought from the icebreaker Lenin.

The caissons also contain 18 defective assemblies that were broken during unloading from the Sibir in 1980 and from the Lenin in 1981.

The Lenin’s fuel assemblies had expanded as a result of the reactor accident and would not fit into the Lepse’s storage channels and so were stored in the Lepse’s caissons instead. Others were further damaged by mishandling. This is similar to the situation with the Sibir assemblies.

The remaining assemblies are in slightly better repair, but have been held in these corrosive conditions for so long that it is impossible to remove them using the technologically proscribed methods.

Unloading dangers already apparent
In 1997, an attempt to unload defective SNF assemblies from a caisson in the Lepse storage area resulted in severe radioactive contamination of the Lepse itself, the neighbouring Rossiya icebreaker, and the berth at which the Lepse is moored. Personnel managed to unload only two out of five planned SNF assemblies.

Similar contamination occured during the unloading of 2000 defective SNF containers from a similar nuclear waste ship, the PM-80 in the Pacific: In this case, the ship and water near the bays of Konyushkovo and Sysoyeva were contaminated. There are eight more ships similar to the Lepse—projects 326 and 326M—all of them, unlike the Lepse, run by the Navy. The engineered lifespan for all of them expired long ago.

“An estimation of the radiation impact, in the case of incidents, on local inhabitants living in close proximity to the place where decommissioning works are carried out, is needed, as well as [an estimation] of radioactive contamination of the environment in the area,” reads the FSAN document, adding that “before the beginning of operations, it is necessary to elaborate on different variants of decommissioning.”

Other support for Chernogorov’s proposal
The technology of the Lepse’s decommissioning, proposed in the report by Chernogorov is supported by a number of specialists.

“In our opinion, the proposed approach to the Lepse’s decommissioning deserves rapt attention of specialists,” reads a statement from the Institute of Industrial and Marine Medicine of the Russian Ministry of Health, signed by the institute’s director, Vitaly Dovgusha. “This approach can be applied to decommission other similar vessels, while SNF unloading from them poses a high risk of radioactive danger.”

Bellona’s Position
Bellona’s position is that a competition of projects aimed at solving the conundrum of decommissioning the Lepse should be held. The solution variants should concern both ecological and economical sides. Alternative projects suggesting both that the SNF be unloaded or left in place and sealed—as Chernogorov proposes—should be examined. Alongside this, it is necessary to carry out a public environmental evaluation of the project according to Article 13 of the Russsia Federal Law “On Environmental Protection.”

Yuri Chernogorov shows a design of one of the Lepse’s storage tanks.

Rashid Alimov

Four decommissioning projects that are currently underway—which were worked out by the MSCo, the Institute of Shipbuilding technology, or TSNII TS, the Institute for energy technology, or VNIPIET, and by the French nuclear company SGN—were conceived within this framework.

But Chernogorov claims that such operations may lead to over-irradiation of the personnel, possible irradiation of Murmansk’s inhabitants, and water contamination that would be measurable in Finland and Norway.

“The Lepse is a unique vessel,” Chernogorov said in an interview with Bellona Web. “All its SNF is defective, and it is impossible to unnload it in a conventional way.”

From 1980 to 1996, when Chernogorov was the chief engineer of the Special technical supervision group of the MSCo, he was responsible for de-fuelling and refuelling the reactors of the nuclear icebreakers. From 1963 to 1981, all spent fuel from icebreakers was delivered to the Lepse for storage.

“It was in 1989 when I was charged with the Lepse’s decommissioning, but due to a lack of funds, I could implement only the first stage,” Chernogorov said.

A concrete mixture being plugged into the spaces between the tanks of the Lepse in October 1991. The numbers show: 1-truck mixer, 2-truck concrete-pump, 3-concrete-pump manipulator.

Courtesy of Yuri Chernogorov

This was done to immobilize radioactive water, which spilled from the caisson and channels during a heavy storm in the Kara Sea, an arm of the Arctic Ocean between Novaya Zemlya and the Russian Far North. The concrete ensured radiation protection and also strengthened the tanks.

Aside from the radiation risks described by Chernogorov, the Minatom-developed concept of dismantling the Lepse’s storage area into fragments would fail precisely because of this concrete—the storage area is packed with 500 tonnes of concrete and its walls are very thick as a result. Likewise, cutting the storage area off the Lepse and putting it into a large container is impossible for the simple purpose that there is no crane in the surrounding area powerful enough to handle the load.

Defective SNF
Some SNF came to Lepse storage after accidents aboard nuclear ice breakers. In February 1965 an accident occured on the Lenin: a fault of the operators left the active zone in one of the ships reactors without cooling water and about 60 percent of fuel assemblies were damaged. Only 95 fuel assemblies were unloaded and transfered the Lepse storage — where the still sit. An additional 111 would arrive from the Lenin in 1981. In 1967 another 125 defective assemblies were dumped into Tsivolki Bay of the Kara Sea near Novaya Zemlya.

Another similar accident that resulted in defective SNF getting sent for storage onboard the Lepse occurred in 1980 when the active zone of the second reactor on the icebreaker Sibir was pushed beyond the limits of is energy producing capacity. Eleven of the assemblies in the icebreaker’s reactor were impossible to unload normally, recalled Chernogorov, who was in charge of the operation. The fuel claddings on the assemblies had swollen terrifically.

1- Feathering float of index revolving station, 2- Rotary actuator of the station, 3-Channel plug.

Bellona archive

After several vain attempts to squeeze the assembly into a channel, it was placed in a caisson. About 600 components of the defective assemblies were left in the reactor of Sibir. Similar problems arose during the 1981 SNF unloading from the icebreaker Lenin.

“We put nine assemblies into one caisson. They didn’t want to go in—we had to hammer them against the grain with a sledge hammer. Surely bundles of the nuclear fuel elements were destroyed,” said Chernogorov..

In his report Chernogorov argues that unloading defective spent nuclear fuel assemblies both from the channels and from caissons without breaking their active parts containing nuclear fuel cannot be done.

The bundled fuel elements would break and fall back into caissons and channels. Then, it would be impossible to remove them because of the exteremly high doses of radiation present over the channels and caissons.

Atomflot docks near Murmansk. Here, nuclear ice-breakers are technically serviced.

Alexander Raube

“After pouring the radiation-resistant concrete mixture into the caissons and between the channels, and then the blocking the SNF storage unit, a neighbouring tank full of low-activity waste would be cut out of the hull,” Chernogorov said. In this manner, blocks of the hull, from side to side, would be put on special carts—thus eliminating the problem of the absence of powerful cranes in the vicinity of the Lepse.

Cherngorov’s cement
Chernogorov realized that concrete was the key to solving the problem but that regular concrete would not do the job as it was not sufficiently porous, and thus had to be improved with sand and water. Gamma radiation causes radiolysis and water decomposes into gases. According to Avagadro’s law, 18 grams of water produce 22.4 litres of gas, Chernogorov said.

A cubic meter of concrete contains 120 litres of water, meaning that every cubic meter of concrete produces 150,000 litres of gas. This gas, said Chernogorov, cannot escape after it has accumulated there. This results in hairline cracks and breaches of the concrete block from within.

“All Russian radioactive waste storage facilities and nuclear power plants, such as Mironova hill, in Arkhangelsk region, and Leningrad NPP near St Petersburg face this problem,” Chernogorov said.

The secret lies in the shugite
The special concrete mixture, he advocates, is permeable for gas but not for water — because of the shungisite it contains.

Shungisite is a burnt form of shungite—an elementary non-crystalline carbon with a meta-stable structure incapable of graphitization—which is abundant in rocks of the Karelia region of Russia, south of Murmansk. In Chernogorov’s mixture, shungisite is used instead of quartz.

Also boron carbide is distributed equally in the mixture. This carbide is a neutron absorber and would render impossible both a self-sustaining chain reaction and leakage of radio-nuclides into the environment. The mixture had been tested for absorbed dose of 6000 Mrad if gamma irradiation is 110-86 rad/sec. Such a material could prove extraordinarily beneficial for nuclear storage facilities dealing with radioactive waste and SNF.

Paldiski
Pouring concrete into the Lepse would be similar to another operation Chernogorov performed to decommission the radioactive heritage of the Soviet Union.

In 1994, Lennart Meri, president of the former Soviet Rebulic of Estonia met Russian president Boris Yeltsin in Moscow and they agreed to secure Soviet nuclear reactor submarine compartments in the former 93rd training unit of the Soviet Navy in the Estonian town of Paldiski, 50 kilometers west of Tallinn. Chernogorov, as the leading engineer in this field, participated in developing the technology for the decommissioning operation.

“This mixture and the technology of its usage were worked out based on the experience we gained in 1991 during concrete grouting in the spaces between the tanks of the Lepse. A similar mixture was used in Paldiski,” Chernogorov said.

Two surface prototypes of reactor compartments of first and second generation nuclear submarines with functioning nuclear energetic installations were secured and laid up using the concrete mixture.

“The other variant was using not the concrete mixture, but a mixture based on furfural,” said Chernogorov. “That’s what NIKIET Institute of Minatom proposed, but furfural is a paralyzing poison, and its application is dangerous for health—at furfural producing plants workers usually faint away at the end of their shift. Moreover, furfural mixture would be almost one hundred times more expensive.”

When the operation was finished in September 1995, Estonian President Meri, standing without remarks on the concrete sarcophagus over one of the reactors, confirmed, more articulately than words could have, that the operation had been a success.

“In my opinion, the question of Lepse decommissioning requires a wide discussion with participation of environmentalists, physicists, specialists on radiation safety, officials from the Murmansk administration and Minatom,” Chernogorov said.

“And I hope we won’t leave this problem to our grand-children.