Russian accident tolerant fuel (ATF) is undergoing a second cycle of trial operation at unit 2 of the Rostov NPP. In 2021, three combined TVS-2M design fuel assemblies were loaded into the reactor core for the first round of testing. Each contained 12 innovative fuel rods. Six were made using chromium-nickel alloy 42KhNM as a structural material and six with claddings made of zirconium alloy with a chromium coating. This aims to eliminates or significantly slow down the development of the zirconium vapour reaction in the reactor core in the event of an emergency.

“Fuel replacement at NPPs is carried out during the scheduled repair and maintenance outages,” said Rostov NPP Director Andrey Salnikov. “New generation fuel elements with improved safety were loaded into Rostov unit 2 18 months ago. They worked normally, and now the second of the three operating cycles designated for pilot operation has begun.”

Alexander Ugryumov, Senior Vice President for Scientific & Technical Activities at Rosatom’s Fuel Company TVEL, explained further. “In 2023, at the Chepetsk Mechanical Plant in Glazov, a pilot plant for applying chromium coatings to claddings made of a traditional zirconium alloy will be installed. While fuel assemblies with experimental fuel rods of ‘tolerant’ design will continue the test programme at the Rostov NPP, we will begin to manufacture fuel rods with chromium-plated cladding in a quantity sufficient for several complete fuel assemblies. Their operation in a high-power power reactor will be the next, and final, a step towards the qualification, commercialisation and widespread introduction of Russian ATF fuel,” he said

At the same time, the Research Institute of Atomic Reactors (NIIAR) in Dimitrovgrad is undertaking a large-scale programme to test a wide range of different fuel cladding materials and ATF fuel pellets in the MIR research reactor. In 2022, this research programme was expanded. Reactor tests of new fuel elements with uranium-silicide fuel for VVER and other pressurised water reactors has begun. TVEL is the main organisation working on the development of innovative types of fuel in co-operation with the AA Bochvar Research Institute of Inorganic Materials (VNIINM).

Image: TVEL's accident-tolerant fuel assembly (courtesy of TVEL)