The Investment Committee of Russia's Rosatom has approved a project to modernise the experimental shop-floor for nuclear fuel fabrication at the Siberian Chemical Combine (SCC), in Seversk, West Siberia.

The upgrade will enable SCC, part of TVEL Fuel Company, to manufacture fuel assemblies with uranium-plutonium REMIX fuel matrix for VVER-1000 reactors.

It will allow the launch of the new production line for assembly of VVER-1000 fuel rods and TVS-2M fuel bundles, with associated quality control, Rosatom said.

REMIX fuel fabrication will be carried out in cooperation with the Mining and Chemical Combine located in Zheleznogorsk, East Siberia, which will produce uranium-plutonium fuel pellets. The project is planned for completion in 2023.

REMIX (regenerated mixture) fuel is an innovative Russian product for light-water reactors. Its fuel matrix is made from a mixture of reprocessed uranium and plutonium, extracted from spent nuclear fuel, with addition of small volumes of enriched uranium. Distinct from uranium-plutonium fuels for fast reactors (such as MNUP and MOX fuel), REMIX fuel has low plutonium content (up to 1.5%). Its neutron spectrum does not vary from common LWR fuel with enriched uranium, therefore, fuel assemblies behaviour in the reactor core and the amount of plutonium bred from uranium due to irradiation are generally similar.

"For nuclear power plant operators, this means that REMIX fuel may be introduced without any changes in reactor design or additional safety measures," Rosatom said.

Since 2016, three TVS-2M fuel assemblies, each containing six experimental REMIX fuel rods (among the total 312 rods in one fuel bundle), have been undergoing pilot operation at Balakovo 3 in Russia. In 2020, the third 18-month cycle of their irradiation started.

"The bundles with the experimental REMIX fuel rods have successfully completed two micro-campaigns and continue the full irradiation cycle," said Alexander Ugryumov, vice-president for research and development at TVEL Fuel Company (part of Rosatom).

"The next step," he added "should be loading of full-fledged REMIX fuel assemblies in a reactor."

The capacity of the production line at the SCC "will be sufficient to manufacture experimental REMIX fuel bundles for pilot operations in required numbers," Ugryumov said. Afterwards, depending on the results of pilot operation, it will be possible to consider creation of an industrial batch production facility for REMIX fuel in Rosatom.

Photo: TVS-2M fuel model (Credit: TVEL/Rosatom)