Final cycle of REMIX nuclear fuel trial under way
The third 18-month phase of the pilot operation of innovative REMIX fuel has begun at Russia's Balakavo nuclear power plant's first unit. The aim is to be able to close the fuel cycle for VVER reactors.
Instead of standard enriched natural uranium, the REMIX fuel assemblies contain pellets of a mixture of enriched uranium with recycled uranium and plutonium obtained from used nuclear fuel at VVER reactors.
Six fuel assemblies of the TVS-2M design, equipped with the pilot fuel elements, were loaded into Balakavo 1 in 2021. They are undergoing a standard operating cycle for VVER-1000 reactor fuel, of three 18 month campaigns. Following the first two of those three operating cycles, specialists from TVEL, Rosatom's fuel division, did video inspections of the fuel elements and structural elements of the TVS-2M with no obstacles identified to moving on to the final stage.
The third of the 18 month operating campaigns is now under way, with the REMIX (from Regenerated Mixture) fuel due to be unloaded in 2026 into the used fuel pool before being closely studied.
Alexander Ugryumov, Senior Vice President for Scientific and Technical Activities at TVEL, said: "After completing the pilot programme and post-reactor studies of REMIX fuel, Rosatom will have sufficient justification to offer the market a new product in the Balanced Fuel Cycle concept. At the next stage, we expect to move on to the phased introduction of such fuel at one of the high-capacity VVER power units."
The REMIX fuel cycle would see used fuel assemblies reprocessed so that uranium and plutonium can be recycled as an unseparated mixture. They are topped up with some freshly enriched uranium and made into new fuel, which goes back to be used again. This cycle 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, with 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.
Compared with uranium-plutonium fuel for fast reactors - such as MOX fuel - REMIX has a lower plutonium content of up to 5% and the fuel 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.
Rosatom said: "In the future, the introduction of uranium-plutonium fuel will allow not only fast neutron reactors to be involved in the closed nuclear fuel cycle, but also classical light-water thermal reactors, which form the basis of modern nuclear energy. This will allow the raw material base of nuclear energy to be expanded many times over by closing the nuclear fuel cycle, as well as reusing irradiated fuel instead of storing it."
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