Siberian Chemical Combine
A Russian nuclear-fuel-cycle complex in Seversk that originated in the Soviet weapons program and now supports uranium enrichment, fuel production, isotope work, and radioactive-material management.
Last updated August 31, 2026
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Overview
The Siberian Chemical Combine, commonly abbreviated SKhK, is a large Russian nuclear-industrial complex in Seversk, Tomsk Oblast. Established in 1953 in the closed Soviet city then known as Tomsk-7, it was created as an integrated enterprise for the nuclear weapons program. Its original mission covered the production and processing of fissile materials, including highly enriched uranium and plutonium, together with the fabrication of components and other special products used in nuclear weapons. During the Cold War, SKhK combined several technically distinct activities that elsewhere might have been distributed among separate plants. Its isotope-separation facilities enriched uranium, while its radiochemical operations processed irradiated uranium and recovered uranium, plutonium, and other radionuclides. A chemical-metallurgical operation handled plutonium and produced components, special items, magnetic alloys, and ultrafine powders. The complex also operated a group of production reactors. These reactors supplied fissile-material production and, in some cases, generated heat and electricity for the surrounding industrial site. The end of the Cold War changed the enterprise's role. Production of highly enriched uranium ceased, and the final plutonium-production reactor was shut down in 2008. The five reactors associated with the complex—EI-1, EI-2, ADE-3, ADE-2, and another reactor identified in historical accounts—were progressively retired; the remaining reactor infrastructure had been decommissioned by 2023. The closure of the production reactors did not eliminate the site's strategic importance. SKhK continued to store and handle weapon-usable materials and nuclear components, while its industrial facilities were adapted for civilian and commercial nuclear work. In its contemporary role, the combine is part of Russia's Rosatom system through the TVEL nuclear-fuel division. Its activities include uranium isotope separation, supply of low-enriched uranium for Russian nuclear fuel requirements, enrichment of reprocessed uranium for foreign customers, uranium refining, production of selected stable isotopes, and management of radioactive materials. The site is also associated with substantial storage and disposal infrastructure for low- and intermediate-level radioactive waste generated by reprocessing. Public descriptions identify deep-well injection facilities at the site and report storage volumes exceeding 30 million cubic meters. SKhK is therefore both a historical weapons-production site and an active nuclear-fuel-cycle enterprise. Its public identity is less a consumer-facing brand than an institutional and industrial designation used within Russia's nuclear sector. The combine's significance rests on the scale and breadth of its infrastructure, its role in Soviet strategic production, and its continuing integration into Rosatom's uranium, fuel, isotope, and radioactive-waste activities.
History
The Siberian Chemical Combine was established in 1953 in the Soviet closed city of Tomsk-7, now Seversk, as an integrated nuclear-production complex. Its creation formed part of the Soviet Union's effort to expand and secure domestic capacity for nuclear weapons materials. Rather than operating as a single-purpose plant, the combine incorporated isotope-separation, uranium-processing, radiochemical, chemical-metallurgical, and reactor facilities within one restricted industrial site. The complex's early work focused on fissile materials. Its isotope-separation plant began operations in 1953 and initially used gaseous-diffusion technology to separate uranium isotopes. Centrifugal separation was introduced later, replacing the older process. The site's sublimation plant, launched during 1954–1955, handled uranium-bearing materials, including highly enriched uranium intended for fuel elements and uranium hexafluoride prepared for enrichment. These installations gave SKhK a central role in the Soviet uranium-enrichment system. Reactor and radiochemical operations expanded the combine's capabilities. The first reactor identified in historical descriptions, EI-1, began operating in 1955, followed by EI-2 in 1958, ADE-3 in 1961, and ADE-2 in 1963. The reactor group supported plutonium production and related nuclear-material activities. The ADE reactors also supplied heat and electricity, with the site's generating capacity reported to have reached approximately 600 megawatts electric. The radiochemical plant began in stages in 1961 and 1962, processing irradiated uranium blocks to recover uranium, plutonium, and other radionuclides. The chemical-metallurgical plant processed plutonium and manufactured components for nuclear weapons and other special applications. It also produced magnetic alloys and associated magnets, as well as ultrafine powders. Together, these operations made the combine an important component of the Soviet strategic-industrial complex. In 1962, the enterprise received the Order of Lenin for fulfilling a government assignment involving special defense products. In 1971, it received the Order of the October Revolution for production performance, equipment modernization, and the introduction of advanced technology. The strategic role of the site changed as the Cold War ended. Highly enriched uranium production ceased, while the plutonium-production mission was progressively wound down. The last plutonium-production reactor was shut down in 2008. Reactor decommissioning continued over subsequent years, and all five reactors associated with the combine were reported as decommissioned by 2023. The end of reactor production did not mean the end of nuclear activity at Seversk. The site retained inventories, storage systems, processing infrastructure, and expertise associated with weapon-usable materials and nuclear components. In the post-Soviet and contemporary period, SKhK was incorporated into Russia's nuclear-industrial corporate structure and operates as a subsidiary of TVEL within Rosatom. Its surviving and adapted facilities support civilian nuclear activities. The isotope-separation plant uses centrifugal technology for uranium enrichment and also produces selected stable isotopes, including isotopes of xenon, tin, and selenium. The former radiochemical infrastructure has been used for uranium refining and other nuclear-material processing. The combine supplies low-enriched uranium requirements for Russian nuclear fuel production and enriches reprocessed uranium for foreign customers. Radioactive-waste management remains another major part of the site's legacy and present profile. The complex is described as one of the largest locations for storage and handling of low- and intermediate-level waste from reprocessing. Public reference material associates the site with deep-well injection and reports more than 30 million cubic meters of stored material. This aspect, together with the site's history of plutonium and highly enriched uranium production, makes SKhK an important subject in discussions of nuclear safety, environmental management, arms-control legacies, and the long-term stewardship of Soviet nuclear facilities.
- 2023
Production-reactor decommissioning completed
[1]Reference material reports that all five production reactors associated with the combine had been decommissioned by this year.
- 2008
Final plutonium-production reactor shut down
[1]The last reactor used for plutonium production was taken offline, ending the site's reactor-based plutonium-production phase.
- 1971
Order of the October Revolution awarded
[1]The combine was recognized for production achievements, equipment introduction, and technological development.
- 1963
ADE-2 reactor begins operation
[1]The ADE-2 reactor entered service, expanding the site's reactor fleet.
- 1962
Order of Lenin awarded
[1]The enterprise received the Order of Lenin for fulfilling a government assignment involving special defense products.
- 1961
ADE-3 reactor and first radiochemical stage
[1]The ADE-3 reactor began operating, while the first stage of the radiochemical plant started processing irradiated uranium.
- 1958
EI-2 reactor begins operation
[1]A second reactor was added to the site's production and energy system.
- 1955
First production reactor begins operation
[1]The EI-1 reactor entered service as part of the combine's early nuclear-production infrastructure.
- 1953
Siberian Chemical Combine established
[1]The integrated nuclear complex was founded in Tomsk-7, now Seversk, to support production of fissile materials and nuclear-weapons components.
Products and positioning
A strategic Russian nuclear-fuel-cycle complex combining legacy weapons-program infrastructure with civilian uranium enrichment, fuel-material production, isotope separation, radiochemical processing, and radioactive-waste management.
Nuclear fuel cycle · 1953
Uranium isotope separation
The isotope-separation plant separates uranium isotopes for enrichment and nuclear-fuel-cycle applications. It operated with gaseous-diffusion technology in its earlier period and later transitioned to centrifugal separation. The facility also has capabilities for producing selected stable isotopes.
Nuclear fuel
Low-enriched uranium materials
SKhK supplies low-enriched uranium requirements associated with Russian nuclear-fuel production. Its enrichment and uranium-processing infrastructure represents the principal civilian continuation of the site's historical fissile-material expertise.
Nuclear fuel cycle
Reprocessed-uranium enrichment
The combine enriches uranium recovered through reprocessing for foreign customers. This activity uses the site's isotope-separation and uranium-handling infrastructure while serving commercial nuclear-fuel-cycle requirements.
Isotopes
Stable isotopes
In addition to uranium work, the isotope-separation plant produces a range of stable isotopes. Public descriptions specifically identify xenon, tin, and selenium isotopes among the site's outputs.
Radiochemical processing
Refined uranium compounds
The radiochemical plant's contemporary activities include the production of purified natural-uranium compounds. This represents a civilian and materials-processing continuation of facilities originally designed to recover uranium and plutonium from irradiated material.
Nuclear waste management
Radioactive-waste management
The site stores and handles low- and intermediate-level radioactive waste associated with nuclear-material reprocessing. Reference material describes deep-well injection infrastructure and very large accumulated storage volumes.
Brand decisions
2023
Completion of production-reactor decommissioningStrategyBackground
The combine's historical reactor fleet had become redundant after the end of production-oriented plutonium operations.
Action taken
All five production reactors associated with the complex were reported as decommissioned by 2023.
Aftermath
The site continued as a non-reactor nuclear-fuel-cycle and nuclear-materials complex within the Rosatom and TVEL structure.
2008
End of reactor-based plutonium productionStrategyBackground
The end of the Cold War and the decline of the Soviet weapons-production mission reduced the need for dedicated plutonium-production reactors at the complex.
Action taken
The final plutonium-production reactor at the site was shut down.
Aftermath
SKhK retained nuclear-material storage and processing functions while increasingly supporting civilian enrichment, fuel-cycle, isotope, and waste-management activities.
Recent events
- 2023
Siberian Chemical Combine reactor fleet fully decommissioned[1]
Other
Historical accounts report that all five production reactors associated with the combine had been decommissioned by 2023.
- 2008
Last plutonium-production reactor shuts down[1]
Other
The final reactor at the complex used for plutonium production was shut down, marking the end of the site's reactor-based plutonium-production era.
Sources1 sources
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