REMIX fuel ready for final test

Thursday, 11 November 2021

A batch of six REMIX fuel assemblies has been made by Rosatom subsidiary TVEL at the Zheleznogorsk Mining and Chemical Combine, Rosenergoatom announced yesterday. They are planned to undergo a full operation cycle in one of Russia's VVER-1000 reactors.

Doing this "will give us more information about REMIX fuel behaviour in the reactor core and its influence on reactor physics," said Alexander Ugryumov, vice president for research, development and quality at TVEL. "Thus, we would obtain the necessary data for licensing full refuelling of the core with REMIX assemblies, as well as a reference experience for commercialisation and introduction of such fuel."

This builds on the successful trial of three fuel assemblies, each containing a few REMIX rods at the Balakovo nuclear power plant, which concluded in September after five years. Those assemblies are in storage while high levels of radioactivity dissipate enough for them to be examined in detail.

"Introduction of [REMIX fuel] would enable to boost exponentially the feedstock for nuclear power plants due to closing the nuclear fuel cycle, and also to recycle spent nuclear fuel instead of its storage," said Rosatom.

REMIX (from Regenerated Mixture) fuel is made from uranium and plutonium recovered as an unseparated mixture from previously used fuel. They are topped up with low-enriched uranium to give a fuel that performs within the same parameters as fuel made only from fresh low-enriched uranium. This means a reactor would not need any modification to start using REMIX.

The cycle of reprocessing, recycling and top-up can be repeated as many as five times, with waste fission products removed each time and vitrified in glass ready for permanent geological disposal. In theory, a new reactor could operate for its whole design life of 60 years on just three REMIX fuel loads, circulating them continuously.

In August last year, Rosatom approved investment to set up a full manufacturing line for REMIX fuel. The uranium-plutonium fuel pellets will be made at the Mining and Chemical Combine in Zheleznogorsk, in the Krasnoyarsk region, where there is already a large storage facility for VVER-1000 fuel. The pellets will be manufactured into finished fuel assemblies at the Siberian Chemical Combine in Seversk in the Tomsk region of Russia.

While REMIX fuel is manufactured at the Mining and Chemical Combine in Zheleznogorsk, the fuel pellets themselves are made at the Siberian Chemical Combine in Seversk, 640 km to the east, where Russia has a large storage facility for used VVER-1000 fuel.