Reactor No 4 of the Beloyarsk nuclear power plant in the in the Sverdlovsk region of Russia has started commercial operation, state nuclear corporation Rosatom announced Monday.

The reactor is a powerful sodium-cooled fast-breeder and its operation marks a step by Russia toward developing a closed nuclear fuel cycle, a subject of concern among some environmentalists and nonproliferation experts.

Rosatom described the achievement as “one of the most important events of the year for Russian nuclear power.”

Beloyarsk No 4 has been billed in the Russian media as being capable of using waste from traditional nuclear reactors, thus reducing the amount of radioactive waste that needs to be stored in a permanent sealed repository.

The Beloyarsk No 4 reactor. (Photo: Rosatom)

Russian media has also touted the reactor as being capable of burning surplus Soviet weapons grade plutonium, though Rosatom has yet to endorse it for that purpose.

The reactor likewise receive accolades from Power, an influential industry publication in the United States, which gave the reactors isotope production and safety features high grades.

Nils Bøhmer, Bellona’s executive director and nuclear physicist said he was concerned that the reactor’s reliance on mixed uranium oxide fuel fashioned from plutonium could–if such reactors found their way to worldwide use – pose serious nuclear proliferation problems.

Bøhmer was also keeping an eye on the reactors sodium coolant system.

“Sodium is very reactive when it comes into contact with water,” he said. “Other sodium-cooled reactors have had large challenges with its coolant. This could also happen with the BN-800 reactor.

Andrey Petrov, general director of Rosatom’s civilian nuclear power plant operator subsidiary Rosenergoatom, signed the order giving permission for the start of operations of Beloyarsk’s No 4 reactor on Monday, World Nuclear News reported.

Before go-ahead from Petrov, regulator Rostekhnadzor completed all the required checks of the unit and issued a “certificate of compliance with design documentation, technical regulations and regulatory legal acts, including the requirements of energy efficiency”, Rosatom said.

The 789 MWe BN-800 Beloyarsk 4 is fuelled by a mix of uranium and plutonium oxides arranged to produce new fuel material as it burns, WNN said.

Construction of BN-800, the fourth reactor at the Beloyarsk plant, began in 1984. But it saw significant delays after the Chernobyl disaster in 1986, after which an overhaul of the reactor’s design was undertaken to boost safety. It ran into further delays when it was plagued by funding shortfalls in the wake of the Soviet collapse.

The project was reinvigorated in 2006, during a period Russian economic growth.

Beloyarsk 4’s capacity exceeds that of the world’s second most powerful fast reactor – the 560 MWe BN-600 Beloyarsk 3.

WNN reported that Beloyarsk 4 brings the total of Russia’s operating nuclear power units to 35 with a combined installed capacity of 27,127 GWe. These 35 do not include Novovoronezh 6, which is undergoing trial operation.