REMIX fuel pilot testing starts at Balakovo reactor

Russia has started pilot testing of its new type of nuclear fuel, REMIX, at unit 3 of the Balakovo nuclear power plant. Rosenergoatom said on 1 July the unit is being loaded with a number of fuel elements containing the fuel, and that the use of REMIX "will increase the efficiency of uranium use in the nuclear industry".

Development of REMIX (from Regenerated Mixture) fuel is part of state nuclear corporation Rosatom's strategy to enable better use of recycled uranium and plutonium on an industrial scale in pressurized water reactors. All four units at Balakovo are of the Russian V-320 PWR design. Rosatom has said the ultimate aim of REMIX is closure of the nuclear fuel cycle by minimising Russia's accumulation of used nuclear fuel.

Loading of REMIX fuel elements was carried out during scheduled maintenance work at the Balakovo unit, which is scheduled to be restarted on 9 August, Rosenergoatom said. The pilot fuel elements will remain in the unit for about three years - two fuel campaigns - after which they will then be subjected to post-irradiation analysis, it added. Rosenergoatom is Rosatom's civil nuclear power plant operator subsidiary.

REMIX fuel is produced directly from a non-separated mix of recycled uranium and plutonium from reprocessing used fuel, with a low-enriched uranium (LEU, up to 17% U-235) make-up comprising about 20% of the mix. This gives fuel initially with about 1% Pu-239 and 4% U-235 which can sustain burn-up of 50 GWd/t over four years.

The used REMIX fuel is then reprocessed and recycled again, after low-enriched uranium top up. The wastes (fission products and minor actinides) are vitrified, as today from reprocessing for MOX, and stored for geological disposal. REMIX fuel can be repeatedly recycled with 100% core load in current VVER-1000 reactors, and correspondingly reprocessed many times - up to five times according to Tenex, 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.

"Just three fuel assemblies have been loaded in the reactor along with standard fuel, in each of which, together with the conventional uranium fuel rods (of which there are 300 in an assembly), there are six REMIX fuel elements," said Alexander Ermolaev, head of nuclear safety and reliability at the Balakovo plant, which is located south of Moscow. "This amount is sufficient to confirm the properties of the design of the new type of fuel elements from their pilot operation," he added.

More than a dozen Russian nuclear industry enterprises are involved in the REMIX project, according to the 1 July statement. These include the Khlopin Radium Institute, the Kurchatov Institute, Gidropress, TVEL and Rosenergoatom. TVS-2M fuel assemblies for VVER-1000 reactors have been manufactured and retrofitted with the new type of fuel rods by Novosibirsk Chemical Concentrates Plant.

Balakovo 3 entered commercial operation in April 1989. It has a net capacity of 988 MWe.

Researched and written
by World Nuclear News