It is the oldest nuclear powered submarines that are in danger of sinking, says report titled “Nuclear and Radiation Safety in Russia”, produced by the Russian Ministry of Nuclear Energy (Minatom). The report, released to public at a nuclear safety conference in Moscow, ranks the risk, emanating from laid-up nuclear powered submarines, as one of the major challenges for the nuclear safety priorities in Russia. Today, a total of 183 nuclear powered submarines are taken out of operation in the Russian Navy. 120 of them still have spent nuclear fuel in their reactors and pose the highest safety risk.

110 nuclear powered submarines are taken out of operation in the Northern Fleet, 72 of them still have spent nuclear fuel onboard. Since most of the submarines have two reactors, the total number of reactors with spent nuclear fuel in the Northern Fleet is 135. In the Pacific Fleet, 73 submarines are taken out of operation, of which 48 still have spent fuel onboard. The total number of reactors with spent nuclear fuel is 91 in the Pacific Fleet.

Corroded submarine hulls

According to Minatom, 30 submarines that have been laid up for as long as 15 years mostly without any kind of repair or maintenance might sink at its piers. These submarines belong to both first and second generations. Years of corrosion have led to a situation where the hulls of the submarines are no longer hermetic, downgrading the submarines’ capability to remain afloat. All 30 submarines in question have spent nuclear fuel in their reactors.

The report also says that a leakage from primarily cooling circuit in the reactors has been detected onboard several first generation submarines. Such leakage is detected on board of at least six nuclear submarines at the remote naval base Gremikha in the eastern part of the Kola Peninsula. Gremikha hosts submarines of November- and Victor-class. A total of 17 submarines are laid-up at Gremikha, and Minatom suggests it is necessary to build a facility at Gremikha to decommission the submarines, fearing that towing them to other naval yards pose a high risk of an accident.

Risky operation to remove spent fuel

As Bellona Web reported last week, a pad for storage of spent nuclear fuel containers from retired submarines is to be built at Gremikha. Removal of spent nuclear fuel from the first generation submarines is a risky operation. The condition of reactors has not been monitored for years that makes it hard to predict the state of the fuel elements. The risk for the fuel elements to go critical in their current position is low due to the design particularities of a naval reactor. But the Navy fears a steam explosion that can occur during lifting the reactor lid at the oldest submarines to get access to fuel. To avoid the steam explosion, the cooling water can be tapped out, but that would give higher radiation doses to the personnel involved in such operation.

The first generation submarines that are in danger of sinking is not a problem related only to Gremikha. At the Sevmorput naval yard in Murmansk, two such submarines are anchored at piers, and some few more are located at naval shipyard no. 10 in Polyarny. Similar trouble submarines are scattered at various naval yards and bases in the Pacific Fleet as well. The report by Minatom, however, does not give any risk assessments of what might happened should one or more of the submarines actually sink with spent nuclear fuel inside.