BN-800 fast reactor at Beloyarsk (credit: Rosatom)The first serial batch of uranium-plutonium mixed oxide (mox) fuel was loaded into Russia's Beloyarsk 4 BN-800 fast reactor on 28 January, according to a joint statement by Rosenergoatom and fuel company TVEL.

The batch comprised 18 fuel assemblies manufactured at the Mining and Chemical Combine (MCC) in Zheleznogorsk, Krasnoyarsk Territory using depleted uranium and plutonium.

The raw materials for the production of the mox fuel pellets are plutonium oxide produced in power reactors and depleted uranium oxide (obtained by defluorising depleted uranium hexafluoride – DUHF – the secondary tailings of the enrichment process).

In 2020, Rosatom’s electricity and fuel divisions plan to add another 180 fuel assemblies to the reactor at Beloyarsk 4, the statement said.

In 2021, the BN-800 core is planned to have a full load of uranium-plutonium fuel for the first time in the history of Russian nuclear energy to verify the operation of a fast reactor using exclusively mox fuel.

“Rosatom’s strategic line for the creation of a two-component nuclear energy system with thermal and fast neutron reactors, as well as the closure of the nuclear fuel cycle will help solve a number of critical tasks,” said Vitaliy Khadeev, vice president for technology development and the establishment of closed nuclear fuel cycle facilities at TVEL.

“First, to multiply the raw material base of nuclear energy. Second, to reuse (after reprocessing) used nuclear fuel instead of storing it. Third, to incorporate into the fuel cycle and utilise the stockpiles of DUHF and plutonium accumulated in the warehouses.”

Beloyarsk NPP Director Ivan Sidorov said: “At power unit 4, we carried out the first overhaul in four years of its operation in the power system. Let me remind you that this unit has two tasks: not only to produce electricity, but also to work out elements of a promising technology that is important for the future of all nuclear energy. The work performed during the overhaul are designed to ensure the long-term safe operation of the power unit as a whole, the reliability of the equipment and maintain the specified life of its work. ”

In addition to fuel reloading, maintenance and preventive maintenance works were performed during outage. These included replacement of a generator rotor. The rotor, which has worked for four years, will go to the manufacturer, where it will be refurbished and inspected before being returned to the Beloyarsk NPP as a backup.

The industrial fabrication of mox fuel began at the end of 2018 at MCC following extensive cooperation with TVEL, which supplies the mox assemblies to Beloyarsk NPP.

The basic technology for manufacturing the MOX fuel pellets was developed by TVEL subsidiary AA Bochvar Research Institute of Inorganic Materials.

Initially, when the BN-800 reactor was launched, it had a hybrid core comprising both uranium fuel produced by Mashinostroitelny Zavod in Elektrostal and mox assemblies manufactured at the Research Institute of Atomic Reactors (NIIAR) in Dimitrovgrad.

Fast neutron reactors using a mixture of uranium and plutonium oxides as fuel will produce enough plutonium to provide themselves with new fuel and, if necessary, produce a certain amount of fuel for other reactors.

The Beloyarsk 4 BN-800 reactor was brought to minimum controlled power for the first time in 2014. Commercial operation was also planned in 2014, but in December Rosenergoatom announced that nuclear fuel for the unit needed further development.

Beloyarsk 4 achieved minimum controlled power in August 2015, and again in November 2015, followed by grid connection in December 2015. The BN-8000 entered commercial operation in October 2016.

Photo: Russia's BN-800 reactor, Beloyarsk 4 (Credit: Rosatom)