Rosenergoatom said the move to MOX fuel at Beloyarsk-4 brings the Russian nuclear industry “one step closer” to its goal of closing the fuel cycle.
It said that for the first time during a planned outrage, which began on 8 January 2021 and concluded this week, only MOX fuel was loaded into the reactor.
Staff loaded 160 MOX fuel assemblies to complement the first 18 which were loaded in January 2020. There are now 178 MOX assemblies from a total of 565 in the reactor core.
The 820-MW BN-800 reactor began commercial operation in October 2016 with a hybrid core, partially loaded with uranium fuel produced by state nuclear fuel company Tvel and partially with experimental MOX fuel bundles manufactured at the Research Institute of Atomic Reactors in Dimitrovgrad, southwest Russia.
In July 2020, Tvel said it had produced a full batch of 169 uranium-plutonium MOX assemblies for use at Beloyarsk-4.
Rosenergoatom said this week that from now on only MOX fuel will be added to the BN-800 core. This is expected to lead to full MOX operation in 2022.
MOX fuel contains more than one oxide of fissile material, usually plutonium oxide blended with natural uranium, reprocessed uranium or depleted uranium oxide. MOX fuel can also use weapons-grade plutonium from military sources.
The industrial production of MOX fuel in Russia is part of a federal programme to develop a new generation of nuclear technologies. The MOX fuel project was led by Tvel. Production began in late 2018.
State nuclear corporation Rosatom has said the fuel pellets in the MOX assemblies were made of a mixture of depleted uranium oxides accumulated from enterprises connected to Tvel and plutonium oxides separated during the reprocessing of spent nuclear fuel.
Recycling fissile material in this way is known as closing the nuclear fuel cycle. The overall toxicity, fissile content and volume of the waste produced is reduced while the fissionable residuals are recycled for energy production.
The Beloyarsk nuclear power station is near Yekaterinburg in central Russia. Apart from the BN-800 at Beloyarsk-4, there is another commercially operational fast reactor unit at the site – the Beloyarsk-3 BN-600, a smaller version of the BN-800, and two permanently shut-down light-water cooled graphite moderated reactors.