Russia has launched its third cycle of testing modern uranium-plutonium REMIX gas on the Balakovo Nuclear Energy Plant in Saratov Oblast, a key step that advances the closed nuclear gas cycle expertise. Designed to recycle spent nuclear gas (SNF), the REMIX assemblies may considerably increase the uncooked materials base for nuclear power whereas decreasing radioactive waste, in line with nuclear gas producer TVEL.
The third 18-month cycle of pilot industrial operation of REMIX-based gas assemblies started at Balakovo Unit 1, TVEL introduced on Dec. 2. Rosatom subsidiary Rosenergoatom initially loaded six TVS-2M gas assemblies into the lively zone of the VVER-1000 reactor in late 2021. Since then, the assemblies have accomplished two customary working cycles below the strict oversight of federal nuclear watchdog Rostekhnadzor.
“At the start of 2026, in the course of the scheduled preventive upkeep on the energy unit, assemblies with REMIX gas will probably be lastly unloaded from the reactor core into the spent gas pool, after which the gas will probably be despatched for post-reactor research,” TVEL stated.
Multi-Recycling to Enhance Closing the Gas Cycle
Rosatom has been pursuing verification of REMIX gas use of VVER-1000 reactors as a strategic funding mission since 2014. A key side of this system envisions integrating reprocessed uranium and plutonium from SNF into Russia’s nuclear power ecosystem. An specific aim is to shut the nuclear gas cycle for derivatives of the VVER-1000, a pressurized water reactor (PWR) design that varieties the cornerstone of Russia’s flagship Era II+ nuclear energy fleet and is a key export product for Rosatom.
Conventional efforts to reuse SNF have targeted closely on blended oxide (MOX) gas, which mixes regenerated plutonium with depleted uranium to supply a viable gas for thermal and quick reactors. Whereas MOX gas has been broadly deployed in Europe and Japan and has confirmed efficient, its method inherently requires separate recycling streams for uranium and plutonium, including processing steps and specialised infrastructure.
REMIX gas (REgenerated MIXture of uranium and plutonium oxides) introduces an modern method to closing the nuclear gas cycle by enabling a number of recycling of reprocessed uranium and plutonium right into a single gas kind for thermal reactors. “Its gas composition is produced from a combination of reprocessed uranium and plutonium, which is fashioned in the course of the processing of spent nuclear gas, with the addition of enriched uranium,” TVEL defined.
The enriched uranium correction, containing about 16–17% uranium-235, ensures that REMIX gas matches the power potential of recent uranium gas. That functionality permits for the repeated recycling of all recovered uranium and plutonium. After irradiation, the gas undergoes a cooling interval of 5 years in a storage pool earlier than being reprocessed. Every cycle produces gas containing roughly 4% uranium-235 and 1–2% plutonium, which may allow 5 to seven recycling iterations with recent additions of pure or reprocessed uranium.
As crucially, REMIX gas requires no modifications to reactor design or important extra security measures. “Not like uranium-plutonium gas for ‘quick’ reactors (blended nitride uranium-plutonium [MNUP] and MOX), REMIX gas is characterised by a decrease plutonium content material (as much as 5%). Its neutron spectrum doesn’t differ from customary gas with enriched uranium. Subsequently, the conduct of the gas within the reactor core and the quantity of plutonium fashioned from uranium on account of irradiation are usually similar,” TVEL famous.
TVEL prompt REMIX guarantees a “a number of enlargement of the uncooked materials base of nuclear energy engineering because of the closure of the nuclear gas cycle, in addition to the reuse of irradiated gas as a substitute of storing it,” the agency says.
REMIX Approaching the Finish of a 10-12 months Testing Program
Russia’s ongoing pilot industrial operation of TVS-2M gas assemblies primarily based on REMIX gas at Balakovo Nuclear Plant displays years of growth and collaboration amongst key nuclear enterprises. In 2016, the nation loaded three experimental gas assemblies—with six REMIX gas rods every and customary gas parts—as a part of a trial operation at Balakovo 3 and efficiently wrapped up three 18-month irradiation cycles in 2021. The following five-year testing stage, which kicked off in December 2021, has concerned loading lead check rods to guage the operation of full-fledged REMIX-TVS gas design to acquire knowledge for licensing full reloads.
TVEL famous it made the REMIX gas pellets on the Zheleznogorsk Mining and Chemical Mix and manufactured the gas assemblies on the Siberian Chemical Mix in Seversk to the identical exterior specs because the TVS gas.
After the primary and second operation cycles, specialists from Rosatom’s Gas and Power Divisions inspected the gas and structural parts of TVS-2M with REMIX gas utilizing a regular reloading machine digicam, TVEL reported. Based mostly on the inspection outcomes, “no obstacles” to additional gas operation had been recognized. “Through the interval of operation of two TVS-2M gas masses with REMIX gas, there have been no deviations from regular operation, the neutron-physical and useful resource traits didn’t exceed the justified limits of secure operation,” stated Yuri Ryzhkov, Deputy Chief Engineer for Security and Reliability of the Balakovo NPP.
“On the subsequent stage, we anticipate to maneuver on to the phased introduction of such gas at one of many high-capacity VVER energy items,” stated Alexander Ugryumov, TVEL senior vice chairman for Scientific and Technical Actions.
A Focused ‘Balanced Nuclear Gas Cycle’ Product
TVEL expects the completion of the pilot program and post-reactor research to present it “adequate justification” to supply REMIX to the market as a part of Rosatom’s Balanced Nuclear Gas Cycle (BNFC) product. The brand new line developed by Rosatom subsidiaries TVEL and TENEX search to offer “sensible options” to closing the nuclear gas cycle, “permitting for the environment friendly reprocessing of irradiated nuclear gas and making certain rational dealing with of the reprocessing merchandise, each helpful (uranium, plutonium) and people despatched for disposal (fission merchandise).” The initiative’s important goal “is to basically scale back the amount and exercise of radioactive waste despatched for disposal,” TVEL stated.
The BNFC encompasses 4 key companies: SNF reprocessing and high-level radioactive waste fractionation; uranium-plutonium gas manufacturing (together with REMIX gas); transmutation of minor actinides in quick reactors; and options for long-term SNF storage and transportation. “These 4 companies cowl your complete spectrum of duties associated to the administration of spent nuclear gas from business reactors. Clients can order both particular person companies or the total package deal. The companies are designed for the operators of water-cooled water-moderated reactors (appropriate for various modifications of VVERs, PWRs, BWRs, and many others.). Particular designs could also be custom-made to satisfy the client’s wants and constraints,” Rosatom stated.
How the Balanced Nuclear Gas Cycle WorksRosatom subsidiaries TVEL and TENEX are growing the Balanced Nuclear Gas Cycle (BNFC), a brand new product line primarily based on the idea of recycling nuclear gas. By reprocessing spent nuclear gas (SNF), BNFC seeks to drastically scale back waste quantity and disposal prices whereas maximizing useful resource reuse. For instance, in line with preliminary Rosatom estimates, whereas a two-unit VVER-1200 plant generates 7,000 cubic meters of SNF, seven occasions much less SNF will stay after reprocessing. That quantities to a 23% discount in storage and disposal prices. Moreover, the Balanced NFC aligns with inexperienced finance standards. “Normally, the introduction and broad use of the Balanced NFC companies will make it potential to chop down on spent gas accumulation and reaffirm the standing of nuclear as a clear and renewable power supply,” Rosatom says.
Spent Nuclear Gas (SNF) Removing and Reprocessing Fabrication of Recent Gas Transmutation of Minor Actinides Storage and Transportation |
An Added Concentrate on Quick Reactors
Nonetheless, Russia’s efforts to shut the nuclear gas cycle additionally notably embody the Proryv Mission, which is targeted on the event of quick neutron reactors. Since Russia put on-line the 800-MWe (2,100-MWth) BN-800 at its Beloyarsk nuclear plant in 2016, it has absolutely loaded its BN-800 with uranium-plutonium MOX gas. It has additionally begun pilot operation at that reactor of gas assemblies holding a gas matrix comprising plutonium in addition to different transuranic parts—americium-241 and neptunium-237.
Nuclear engineering firm OKBM Afrikantov, in the meantime, is growing BN‑1200M, a 1.2-GWe/2.8-GWth sodium-cooled reactor, to be put in at Beloyarsk Unit 5. In tandem, Rosatom, in January 2024, kicked off building of the 300-MWe/700-MWth lead-cooled BREST-OD-300 quick reactor at TVEL’s Siberian Chemical Mix in Seversk, with commissioning anticipated in 2027. The reactor will run on dense uranium-plutonium nitride (SNUP) gas.
“The BREST-OD-300 reactor will present itself with its important power part—plutonium-239—reproducing it from the isotope uranium-238, which has a relative abundance of greater than 99% (it’s the isotope uranium-235, which makes about 0.7% of pure uranium, that’s presently used to supply power in thermal reactors). The introduction of such applied sciences will enhance exponentially the effectivity of pure uranium,” Rosatom stated in January.
“The manufacturing of MOX and SNUP fuels makes it potential to contain depleted uranium into the nuclear gas cycle, steadily eliminating its collected stockpiles, whereas MOX gas makes use of extremely radioactive plutonium obtained by reprocessing spent nuclear gas from VVER‑440, VVER‑1000 and BN reactors,” Rosatom famous.
TVEL, Rosatom’s gas division, has been growing a expertise for producing regenerated uranium gas for RBMK and VVER reactors. Whereas the gas is already commonly equipped to Kola NPP Unit 2 within the Murmansk Area, Russia has determined to transform Novovoronezh II and Leningrad II energy items with VVER‑1200 reactors to regenerated uranium gas by 2027–2028.
—Sonal Patel is a POWER senior editor (@sonalcpatel, @POWERmagazine).
