Uranium-plutonium nitride fuel tested for BN-1200 fast reactor

The BN-1200 is a fast sodium reactor - the plan is to build the first power unit at the Beloyarsk nuclear power plant where the BN-600 and BN-800 units are already operating.

Fast neutron reactors are capable of operating on plutonium and are able to help close the fuel cycle, Rosatom said, which makes a uranium-plutonium mixture "the optimal fuel". The fuel elements contain mixed dense nitride uranium-plutonium fuel (MNUP) fuel.

Rosatom said: "The BN-800 reactor was switched to oxide MOX [mixed oxide] fuel in 2022. Another type of uranium-plutonium fuel for fast reactors is nitride SNUP fuel, which will be used in the first innovative lead-cooled reactor BREST-OD-300, under construction in Seversk.

Alexander Ugryumov, Senior Vice President for Scientific and Technical Activities of TVEL JSC, said: "Both options are being considered for the BN-1200M core - both oxide and nitride fuel. In the case of MOX fuel, we have worked out the entire production technology and are accumulating experience in operating the BN-800 with a full core load of uranium-plutonium fuel."

Experimental fuel assemblies with MNUP fuel manufactured by the Siberian Chemical Combine in Seversk have been tested in the BN-600 reactor since 2014, with ever higher burn-up of nuclear fuel gradually achieved, Rosatom said.

As part of Rosatom's Proryv, or 'Breakthrough' initiative, a programme is being implemented to gradually increase the burnup of SNUP fuel to an average value of 12%. For this purpose, the BN-600 also provides irradiation of assemblies with removable containers, which will allow testing nitride fuel to the limiting design parameters, the company says.

The sodium-cooled BN-series fast reactor plans are part of Rosatom's project to develop fast reactors with a closed fuel cycle whose MOX fuel will be reprocessed and recycled. In addition to the BN-600 reactor, the 789 MWe BN-800 fast neutron reactor - constructed as Beloyarsk unit 4 - entered commercial operation in October 2016. This is essentially a demonstration unit for fuel and design features for the larger BN-1200.