Russian accident tolerant fuel (TVEL)The first fuel assemblies (FAs) for the VVER-1000 reactor with experimental accident tolerant fuel rods manufactured at Russia’s Novosibirsk Chemical Concentrates Plant (NZHK) have passed acceptance tests, Russian fuel company Tvel has announced.
Rosatom plans to load the fuel assemblies into one of the reactors at the Rostov nuclear plant in the first quarter of 2020.

Each of the three experimental fuel assembly-2M design contains 12 fuel rods with two different options for the cladding material, made using either a chromium-plated zirconium alloy or 42XNM chrome-nickel alloy. Both options make the cladding more heat-resistant.

Full-size cladding for the chrome-nickel alloy fuel rods was manufactured at Mashinostroitelny Zavod (MSZ) in Elektrostal. A chrome coating was applied to the standard zirconium cladding manufactured at Chepetsk Mechanical Plant (ChMZ) in Glazov by specialists of the Moscow Power Engineering Institute (NRU MEI). The designer of the fuel rods is the AA Bochvar Research Institute of Inorganic Materials (VNIINM) Moscow.

The composition of the acceptance committee, in addition to the specialists from Tvel and VNIINM, included representatives of various enterprises of the nuclear industry, including OKB Gidropress (designer of the VVER-1000 reactor and TVS-2M fuel), as well as an authorised quality control organisation of nuclear utility Rosenergoatom, VPO Zarubezhatomenergostroy.

Tvel is on schedule with its tolerant fuel programme. “Next year, we have to take an important step and start parallel testing of samples not only in a research reactor, but also in a commercial high-power reactor,” said  Alexander Ugryumov, vice president for Scientific and Technical Activities at Tvel. 

“Having all the necessary calculations and justifications for the reactor core, we will test the fuel element cladding at an existing power unit without changing the traditional fuel composition – uranium dioxide. At the same time, in the research reactor, we will continue to irradiate fuel rods with various combinations of cladding materials and fuel pellets, as well as simulate various operating conditions, including power variation modes. The results of these tests will help in selecting the best technological solution."

Earlier in 2019, the first phase of reactor tests of tolerant fuel for light-water reactors was completed. In separate water loops of the MIR reactor at the Research Institute of Atomic Reactors (NIIAR) in Dimitrovgrad, two experimental fuel assemblies with fuel elements of VVER and PWR design were irradiated – each comprising 24 fuel elements with four different combinations of cladding materials and fuel composition. Fuel pellets were made from traditional uranium dioxide, as well as a uranium-molybdenum alloy with increased density and thermal conductivity. Then, several fuel rods from each fuel cartridge were removed for further post-reactor material science research and new non-irradiated samples were installed.

Photo: Russian designed ATF has been loaded into MIR (Credit: Tvel)