Specialists at Russia’s AA Bochvar Research Institute of Inorganic Materials (VNIINM, part of Rosatom’s TVEL fuel company) have developed a technology and manufactured experimental fuel pellets from uranium disilicide for light water reactors (VVERs and PWRs).
Part of a comprehensive programme for the development of accident tolerant fuel (ATF), the new development was presented to TVEL President Natalya Nikipelova during a working visit to VNIINM.
The uranium disilicide fuel has a number of advantages. These are high density and uranium content, which enables longer fuel cycles without increasing uranium-235 enrichment, as well as high thermal conductivity combined with low heat capacity, which means less heat stored in the reactor core and lower fuel cladding temperatures in emergency situations. Another advantage is the lower operating temperature of the fuel pellet compared with uranium dioxide, which improves the performance of the fuel.
Nikipelova was shown areas for developing technology, for manufacturing fuel pellets, and for melting and casting uranium disilicide ingots. The introduction of this technology at TVEL’s Mashinostroitelny Zavod in Elektrostal (MSZ) made it possible to launch the production of fuel pellets from uranium disilicide and experimental fuel elements for subsequent tests in a research reactor.
Rosatom has been undertaking reactor tests of Russian ATF fuel for light water reactors since early 2019. Experimental fuel assemblies, which have passed three full cycles of reactor tests in the MIR research reactor at the Research Institute of Atomic Reactors (NIIAR) in Dimitrovgrad contain fuel elements with four combinations of cladding and fuel pellet materials. In September 2021, the commercial VVER-1000 reactor at Rostov 2 began operation of combined TVS-2M, each containing 12 ATF fuel rods.