Rosatom plans REMIX fuel fabrication at Seversk facility

27 August 2020

Rosatom has approved a project to upgrade an experimental shop-floor for nuclear fuel fabrication at the site of the Siberian Chemical Combine (SCC), which is in Seversk, in the Tomsk region of Russia. The move will enable SCC to manufacture fuel assemblies with uranium-plutonium REMIX (regenerated mixture) fuel matrix for VVER-1000 reactors.

TVS-2M fuel model (Image: TVEL)

A subsidiary of TVEL, Rosatom's nuclear fuel manufacturer, SCC is the "centre of expertise" for handling plutonium, having manufactured experimental fuel assemblies with dense mixed nitride uranium-plutonium fuel (MNUP fuel) for the BN-600 fast neutron reactor operated at the Beloyarsk nuclear power plant.

REMIX fuel is made from a mixture of reprocessed uranium and plutonium, extracted from used nuclear fuel, with the addition of small volumes of enriched uranium. Distinct from uranium-plutonium fuels for fast reactors (such as MNUP and mixed-oxide fuel), REMIX fuel has low plutonium content (up to 1.5%).

Modernisation of the shop-floor will result in the launch of a new production line for assembling VVER-1000 fuel rods and fuel bundles of the TVS-2M model. REMIX fuel fabrication will be carried out in cooperation with the Mining and Chemical Combine in Zheleznogorsk, in the Krasnoyarsk region, which will produce uranium-plutonium fuel pellets. The project is scheduled for completion in 2023.

The neutron spectrum of REMIX fuel does not vary from common lightwater reactor fuel with enriched uranium, and fuel assembly behaviour in the reactor core and the amount of plutonium bred from uranium from irradiation are generally similar, TVEL said.

For nuclear power plant operators, this means that REMIX fuel may be introduced without any changes in reactor design or additional safety measures. Introduction of such fuel would enable to "boost exponentially" the feedstock for nuclear power plants thanks to the closing of the nuclear fuel cycle, and also to recycle used nuclear fuel instead of its storage, it added.

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 unit 3 of the Balakovo nuclear power plant. The third 18-month cycle of their irradiation started this year.

Alexander Ugryumov, TVEL's vice-president for research and development, said: "The bundles with the experimental REMIX fuel rods have successfully completed two micro-campaigns and continue the full irradiation cycle. The next step should be loading of fully fledged REMIX fuel assemblies in a reactor. For this purpose, it is planned to launch fabrication of such fuel at the Siberian Chemical Combine; the capacity of this production line will be sufficient to manufacture experimental REMIX fuel bundles for pilot operations in required numbers."

He added: "This is the first stage necessary for testing the technology, afterwards it will be possible to consider creation of industrial batch production facility of REMIX fuel in Rosatom. These prospects also depend on the results of the pilot operation of the REMIX fuel produced in Seversk."

Researched and written by World Nuclear News