Occupation History

• Russian forces seized the Zaporizhzhia NPP on 4 March 2022, the fifth day of the Kyiv-directional invasion when Russian forces advancing north from Crimea into Zaporizhzhia oblast reached the plant; the seizure involved direct military assault on the plant — with video footage showing fires near reactor buildings during the assault, creating the first-ever instance of live-fire military operations at an operating nuclear power station; no major radiological release resulted from the assault itself, primarily because the reactors' containment structures were not directly struck; but the nature of the seizure established from the outset that Russian military commands were willing to conduct operations at the site in ways contrary to every norm of nuclear safety
• Operational transition: after seizing the plant, Russian forces installed a military command structure at the site that placed Russian Rosatom personnel and Russian military commanders above the Ukrainian civilian operating staff — who continued (and continue) to operate the plant under these conditions; Ukrainian Energoatom (the state nuclear operator) maintains formal operational responsibility in Ukrainian law and considers its staff at Zaporizhzhia to be operating under duress and coercion; Russian authorities have issued conflicting claims about the eventual transfer of the plant to Rosatom management or to a newly constituted Russian legal entity
• Military presence at the plant: Russian forces have used the plant's campus for military purposes that violate all nuclear safety conventions — military vehicles are parked in and around reactor buildings (identified on multiple IAEA inspection walks); IAEA inspectors have observed military equipment that appeared to include weapons and explosive material in proximity to reactor and spent fuel storage areas; turrets were reported placed on reactor building roofs in initial phases of occupation; the military use of the plant creates detonation risks near nuclear material that are not present in any other peacetime nuclear safety scenario and cannot be adequately risk-managed

Reactor Status 2026

• All six VVER-1000 reactors at Zaporizhzhia have been shut down since September 2022, when the last operating reactor was taken to cold shutdown due to the inability to maintain reliable external power supply for cooling systems; the reactors remain in cold shutdown as of February 2026 — they are not generating electricity and are not in an active self-sustaining fission state; however, "cold shutdown" does not mean "no risk" — the spent nuclear fuel in the reactors and in the on-site spent fuel storage facility (a wet storage pond and a dry cask storage facility) continues to generate decay heat that requires active cooling; failure of cooling for extended periods would lead to fuel damage and potential release of radioactive material even without reactor restart
• Spent fuel storage: the Zaporizhzhia site contains approximately 2,200 spent fuel assemblies in wet (pond) storage and a large inventory in dry cask storage; the wet storage pond requires continuous cooling water circulation; loss of cooling pump power for more than a few hours begins the process of pool temperature rise that, if uncorrected over days, could lead to fuel damage; the dry cask storage is more robust — the casks are passive cooling systems that do not require external power to maintain safe temperatures under normal conditions — but the casks themselves could be damaged by direct military strike or explosion in their vicinity
• Decommissioning risks: prolonged shutdown under conditions that cannot meet normal maintenance standards introduces risks of equipment degradation that would need to be resolved before any reactor restart — or before full decommissioning can be safely accomplished; qualified maintenance personnel operating under occupation conditions cannot perform all the procedures that peacetime standards require; the IAEA has repeatedly expressed concern that the absence of maintenance to standard is degrading the safety systems that would be needed if any restart were attempted, and that correcting this degradation will require significant investment and time after any return to Ukrainian control

External Power Supply Crises

• The most acute nuclear safety crises at Zaporizhzhia have been caused by loss of external electrical power supply to the plant; paradoxically, an operating nuclear plant is a massive power producer but requires external power input for safety systems — cooling pumps, instrumentation, control systems — when it is shut down; the plant has five high-voltage transmission lines connecting it to the Ukrainian electricity grid; these lines have been severed by military action (attacks on pylons, cables, and substations) on multiple occasions, with the plant forced to rely on diesel backup generators; the diesel generators have finite fuel and limited run time, creating a countdown clock to fuel exhaustion each time power was lost
• IAEA-documented near-misses: the IAEA has documented multiple occasions — at least 7 separate events confirmed in IAEA reporting through 2025 — when the plant lost all external power and was running solely on diesel generators; the most dangerous recorded event occurred in November 2022 when the last connection to the grid was severed and the plant was simultaneously on diesel backup for approximately 12 hours before partial external power was restored; at one point, less than 6 hours of diesel fuel remained; a complete loss of power to cooling systems for the durations involved in these events would begin the process of uncovering spent fuel and exposing it to air — the sequence that, at Fukushima, led to fuel damage and hydrogen explosions
• Current power connection: as of 2026, the plant maintains its connection to the Russian-controlled electricity grid through South Ukraine-direction transmission infrastructure that Russia has established across occupied territories; this connection is more geographically stable than the Ukrainian grid connection which required routing through active conflict zones, but it is also not fully reliable and the plant continues to maintain diesel backup capability as a last resort

IAEA Monitoring and Findings

• The IAEA has maintained a continuous monitoring presence at Zaporizhzhia since September 2022, with a rotating team of 3–4 IAEA nuclear safety experts resident at the site; this is unprecedented in the IAEA's history — no prior conflict or emergency has required continuous resident IAEA monitoring — and reflects the international community's assessment that the Zaporizhzhia situation poses a nuclear safety risk that requires direct international surveillance; the IAEA team has reporting access to the IAEA Director General, who provides regular public updates on Plant Safety Indicators
• IAEA limitations and constraints: the IAEA monitoring presence is limited by the conditions Russia imposes on inspectors' access — the team can observe what it is shown but cannot move freely through all areas of the plant; IAEA inspectors have reported instances where they were prevented from accessing specific areas, where they observed evidence indicating military use of zones they entered, and where the information provided to them by the plant's Russian-appointed management appeared inconsistent with physical evidence; the IAEA cannot enforce compliance — it can only report, and Russia has the veto in the UN Security Council to prevent enforcement action
• Seven nuclear safety pillars: the IAEA's formal assessment framework identifies seven key nuclear safety pillars that must be maintained: physical integrity of the facility, off-site power supply, on-site backup power, cooling functions, radiation monitoring, emergency preparedness, and reliable communications; as of IAEA reporting through early 2026, none of the seven pillars is being maintained at the level IAEA standards require; each pillar shows specific deviations from standards that individually would be concerning and collectively represent a safety deficit of unprecedented scale; the IAEA has described this as a situation that "should have serious consequences" while stopping short of issuing a formal emergency declaration

Staff Conditions Under Occupation

• The Ukrainian operating staff at Zaporizhzhia — approximately 5,000–7,000 workers of the original pre-war complement of approximately 11,000 — have remained at the plant and continued operating under Russian military occupation; their situation is one of the most difficult human stories of the war: nuclear specialists who are obligated by professional duty and safety responsibility to maintain the plant's systems operating under constant stress, with limited freedom of movement, under coercion from armed Russian soldiers, isolated from normal information channels, and uncertain about their legal status under an occupying power that has attempted to force them to accept Russian employment contracts
• Captured and expelled staff: Russia has detained several plant directors and senior technical staff in circumstances that the IAEA and international organisations have characterised as arbitrary detention; Ihor Murashov, the plant's director, was detained by Russian forces in October 2022 and released only after intense IAEA and diplomatic pressure; other technical staff have been detained, expelled from the plant for refusing Russian employment, or reported coerced; the pattern of coercive management of the technical workforce has raised concerns that the most experienced and safety-conscious operators have been systematically removed, potentially reducing the skill level of the operating team at the most complex nuclear facility in Europe

Nuclear Accident Scenarios

• Extended loss of cooling: the most probable accident pathway at Zaporizhzhia is an extended loss of all cooling — external power lost, diesel backup exhausted, no alternative cooling water supply — leading to spent fuel pool temperature rise, potential fuel uncovering, and radioactive material release; this scenario does not require a reactor restart or a direct hit on a reactor building; it requires only a sustained loss of power in combination with inability to deliver diesel fuel to the site; the probability of this scenario in any given week is low but not negligible, and the cumulative probability over years of occupation is substantially higher
• Direct military strike: a direct strike by artillery, missile, or drone on the spent fuel storage building, a cooling pond, or an individual cask could cause radioactive material release without any cooling failure; Russian military equipment at the site creates detonation risks in proximity to fuel storage areas; the consequences of a direct strike releasing radioactive material from the spent fuel pond would depend on the scale of damage — a small breach would be logistically manageable with evacuation; a catastrophic structural failure releasing the full inventory into the atmosphere under unfavourable meteorological conditions would be the largest radiological event in European history, exceeding Chernobyl in released material mass
• Worst-case comparison: worst-case radiological release scenarios for Zaporizhzhia modelled by European nuclear safety authorities estimate a potential contamination zone extending hundreds of km depending on wind direction, potentially affecting Moldova, Romania, and southern Ukraine's farming and water resources; the modelling is precautionary and the probability of catastrophic release remains low, but the consequences at the tail of the distribution are severe enough to justify the extraordinary international attention the plant has received

Diplomatic Efforts for Protection

• Ukraine and the IAEA have consistently called for the establishment of a nuclear safety protection zone around Zaporizhzhia — a demilitarised area that would prohibit military operations and the presence of heavy weapons within a defined radius of the plant; Russia has not accepted this proposal and the UN Security Council's Russian veto has prevented any binding resolution; the proposal has been adopted in resolutions of the UN General Assembly with large majority support that cannot compel Russian compliance; the absence of a protection zone means that the current safety risks will persist for the duration of Russian occupation regardless of the war's broader course
• Post-war restoration: any ceasefire or peace agreement will need to address the return of Zaporizhzhia to Ukrainian operational control and conduct an IAEA-supervised assessment of the plant's safety systems before any decisions about restart or decommissioning can be made; the cost of repairing degraded systems, replacing compromised equipment, and restoring the trained workforce will be substantial; the alternative — full decommissioning of six reactors — is also expensive and technically complex; the war's outcome at Zaporizhzhia represents a major element of the reconstruction and security challenge that Ukraine will face regardless of how the conflict ends

Frequently Asked Questions