At unit 1 of Russia’s Balakov NPP, the third 18-month cycle of experimental industrial operation of fuel assemblies using Remix uranium-plutonium fuel has begun. Six TVS-2M fuel cassettes were first loaded into the core of the VVER-1000 at the end of 2021 in which all 312 fuel elements were completely composed of Remix fuel. This does not use standard enriched natural uranium, but a mixture of regenerated uranium and plutonium obtained from used nuclear fuel from VVER reactors.
In future, such fuel will not only be used in fast neutron reactors, but also classical light-water thermal reactors, Rosatom’s fuel company TVEL noted. This will expand the raw material base of nuclear energy by closing the nuclear fuel cycle, and will reuse irradiated fuel instead of storing it.
The experimental industrial use of the Remix fuel at the Balakov NPP is carried out in strict coordination with regulator Rostekhnadzor in accordance with amendments to the terms of the current operating licence for unit 1. The innovative fuel cassettes will undergo the standard operating cycle for nuclear fuel at VVER-1000 reactors – three fuel campaigns of 18 months each. At the beginning of 2026, during scheduled maintenance outage, they will be finally unloaded from the reactor core to the used fuel pool, after which the fuel will be transferred for post-reactor studies.
According to the results of the first and second operating cycles, specialists from the Fuel and Energy Divisions of Rosatom inspected the fuel and structural elements of the TVS-2M assemblies with Remix fuel using the regular television camera of the refuelling machine. Based on the results of the inspection, no obstacles to the further operation of the fuel were identified.
“During the operation of the two fuel loads of TVS-2M Remix assemblies, there were no deviations from normal operation. The neutron-physical and resource characteristics did not exceed the reasonable limits of safe operation,” said Balakov NPP’s Deputy Chief Safety Engineer, Yuri Ryzhkov.
“After completion of the pilot industrial operation programme and post-reactor research, Rosatom will have sufficient justification to offer a new product to the market as part of the concept of a closed fuel cycle. At the next stage, we expect to move on to the phased implementation of such fuel at one of the VVER high-power units,” said Alexander Ugryumov, Senior Vice President of Scientific & Technical Activities at TVEL.
Remix fuel for light-water thermal reactors is made from a mixture of regenerated uranium and plutonium, which is formed during the reprocessing of used nuclear fuel, with the addition of enriched uranium. Unlike uranium-plutonium fuel fast reactors – mixed dense nitride uranium-plutonium (SNUP) and mixed oxide (MOX), Remix is characterised by a lower plutonium content (up to 5%). Its neutron spectrum does not differ from the standard fuel with enriched uranium, so the behaviour of the fuel in the reactor core and the amount of plutonium generated from uranium as a result of radiation are generally identical. Remix fuel can be implemented without changes in the design of the reactor and significant additional safety measures.
The closed nuclear fuel cycle sets as its main objective the fundamental reduction in the volume and activity of radioactive waste sent for disposal. It will increase the safety of nuclear waste management and reduce environmental risks; solve the problem for future generations and ensure a sustainable model of consumption and production; minimise the volume and degree of danger of waste to be disposed of; and re-engage valuable raw materials by recycling nuclear materials.
Experimental assembly production of uranium-plutonium TVS for VVER-1000 began in 2021 at the Siberian Chemical Combine in Seversk, Tomsk Region in cooperation with the Mining & Chemical Combine in Zheleznogorsk Krasnoyarsk Territory, which made fuel pellets using a uranium-plutonium mixture.
