Russia has begun tests of its new Remix (Regenerated Mixture) nuclear fuel at the MIR research reactor at the Research Institute of Atomic Reactors (NIIAR) in Dimitrovgrad. Development of REMIX fuel is part of state nuclear corporation Rosatom's strategy to enable better use of recycled uranium and plutonium on an industrial scale in pressurised water reactors.
Rosatom said on 3 November that Remix fuel rods manufactured in July had been placed in the core of MIR, a loop-type research reactor designed mainly for testing fuel elements, fuel assemblies and other core components of different types of operating and promising nuclear power reactors.
The first data from testing the fuel in MIR will include the "swelling, gassing and distribution of fission products and, of course, the isotopic composition of the used fuel rods," the head of innovation at the Khlopin Radium Institute, Andrey Belozub, said in the Rosatom statement. Use of the MIR research reactor is an "extremely important step", Rosatom said, towards full implementation of the project to introduce Remix into the Russian fuel cycle.
In July, Rosatom announced that it had started pilot testing Remix at unit 3 of the Balakovo NPP.
REMIX fuel is produced directly from a non-separated mix of recycled uranium and plutonium from reprocessing used fuel, and a low-enriched uranium (LEU, up to 17% U-235) comprising about 20% of the mix. This results in fuel with about 1% Pu-239 and 4% U-235 which can sustain burn-up of 50 GWd/t over four years. The used Remix is then reprocessed and recycled again, after being topped up with more LEU.
The wastes (fission products and minor actinides) are vitrified and stored for geological disposal. Remix fuel can be repeatedly recycled with 100% core load in current VVER-1000 reactors, and reprocessed many times (up to five times according to Russian nuclear fuel manufacturer TVEL), so that with less than three fuel loads in circulation a reactor could run for 60 years using the same fuel, with LEU recharge and waste removal on each cycle.