The first Russian-made nuclear fuel assemblies with experimental accident-tolerant fuel rods (ATF) for commercial reactor have been manufactured and passed acceptance inspection at Novosibirsk Chemical Concentrates Plant, a fabrication facility of ROSATOM’s TVEL Fuel Company.
Already in the first quarter of 2020, they should be loaded into one of VVER-1000 reactors at Rostov NPP.
Each of the three TVS-2M model fuel assemblies contains twelve ATF fuel rods with two different options for the cladding material, which is either zirconium alloy with chromium coating, or chrome-nickel alloy. Both options make claddings more heat-resistant.
“The fuel division of ROSATOM has fulfilled on schedule all the plans within the ATF program for 2019. Next year, we are committed to make another important step and start parallel testing of samples not only in a research reactor, but also in a commercial high capacity reactor. Having all necessary validations for the reactor core, we will test rod claddings at a functioning power unit without changing the traditional fuel pellets composition, which is uranium dioxide. At the same time, in the research reactor, we will continue to irradiate fuel rods with various combinations of cladding and fuel pellets materials, as well as simulate different operational conditions, including load changing modes. The results of these tests will help to choose the best technological solution,” said Alexander Ugryumov, Vice President for Research and Development at TVEL JSC.
Earlier in 2019, TVEL had fulfilled the first phase of ATF testing in MIR research reactor at the State Research Institute of Atomic Reactors. In separate water loops, two experimental fuel assemblies with fuel elements of VVER and PWR type fuel rods were irradiated. Each of them consisted of 24 fuel rods with four different combinations of cladding materials and fuel composition. Fuel pellets were made of traditional uranium dioxide, as well as uranium-molybdenum alloy with increased density and thermal conductivity. Afterwards, several fuel rods from each fuel assembly were removed for further post-irradiation studies, and new non-irradiated samples were installed instead.
ATF is nuclear fuel resistant to severe beyond-design basis accidents at NPPs with loss of coolant in a reactor. Even in case of heat removal failure in the reactor core, ATF is supposed to keep its integrity for a long enough time without a zirconium-steam reaction inducing hydrogen release. ATF is of critical importance for further elevating the integral safety and reliability of nuclear power. Research, design and testing of the accident tolerant fuel in TVEL Fuel Company is provided and coordinated by the Bochvar High-Technology Scientific Research Institute of Inorganic Materials.