PSCRP-BESA Reports No. 136 (June 24, 2025)
by Dmitry Kovchegin
The threat of Russia using tactical nuclear weapons largely fuels public “nuclear” fears associated with the war in Ukraine. However, the less visible “nuclear” dimension of the war—with a more tangible impact—is the effect of the conflict on nuclear sites in Ukraine.
The war in Ukraine has created an unprecedented global crisis with devastating humanitarian consequences. Against this backdrop of immense human suffering, the nuclear safety and security implications might seem secondary. Yet the conflict has introduced an entirely new challenge: the first war fought in a country with a major nuclear power program, with risks and long-term implications that extend far beyond Ukraine’s borders. Unlike conventional warfare damage, a nuclear accident could affect neighboring countries and persist for decades. The legacy of Chernobyl—still fresh in the collective memory—adds particular gravity to attacks on nuclear facilities in Ukraine.
Ukraine operates one of Europe’s most extensive nuclear power programs, comprising four active nuclear power plants with 15 operational reactors: Zaporizhzhia NPP (6 VVER-1000 reactors, Europe’s largest nuclear facility), Rivne NPP (2 VVER-440 and 2 VVER-1000 reactors), South Ukraine NPP (3 VVER-1000 reactors), and Khmelnytskyi NPP (2 VVER-1000 reactors). Additionally, the Chernobyl Nuclear Power Plant, site of the 1986 disaster, houses four decommissioned RBMK-1000 reactors that were permanently shut down between 1991 and 2000; the facility now serves as a decommissioning and waste management site. Before Russia’s invasion in February 2022, nuclear power generated approximately 50–55% of Ukraine’s total electricity, making Ukraine the country with the second-highest nuclear share globally after France. Beyond power generation, Ukraine hosts several nuclear research facilities, including the research reactor at the Institute for Nuclear Research of the Ukrainian Academy of Sciences in Kyiv, a subcritical assembly at the Kharkiv Institute of Physics and Technology, and a research and training reactor at the Sevastopol National University in Russian-occupied Crimea.
Attacks Against Nuclear Sites
The war went “nuclear” immediately. Russian forces captured the defunct Chernobyl Nuclear Power Plant (ChNPP) on the first day, within hours of Russia’s invasion on February 24, 2022. The most significant escalation occurred on March 4, 2022, when Russian forces attacked and captured the Zaporizhzhia Nuclear Power Plant (ZNPP), Europe’s largest nuclear facility. Shelling damaged the plant’s training building and set it ablaze. While the reactors themselves were not hit, the attack demonstrated that nuclear facilities were no longer off-limits in this conflict. Russian forces withdrew from Chernobyl in late March 2022, but the occupation of the ZNPP continues, creating an ongoing crisis that has fundamentally altered the plant’s operations and safety posture.
The Kharkiv Institute of Physics and Technology, which hosts a nuclear research facility, was heavily damaged by shelling in March and June 2022. An International Atomic Energy Agency (IAEA) mission in November 2022 reported that “the extent of damage to this nuclear research facility is dramatic and shocking, even worse than expected.” However, the mission found no indication of any radiological release or loss of nuclear material.
Multiple explosions occurred in the vicinity of other Ukrainian nuclear power plants—Khmelnytskyi, Rivne, and South Ukraine—without causing direct damage. However, they have experienced numerous issues due to war-related disruptions in the power supply.
Russia has also reported Ukrainian attempts to carry out drone attacks on the Kursk Nuclear Power Plant, located near the Russian-Ukrainian border. However, there is no evidence of damage or independent confirmation of these reports. During Ukraine’s summer 2024 incursion into the Kursk region, Ukrainian forces stopped several dozen kilometers from the Kursk NPP, forcing Russia to implement additional protection measures.
The pattern of attacks has evolved significantly throughout the conflict, with drones becoming the primary threat. In April 2024, drones attacked the ZNPP, hitting a reactor building in the worst such incident since November 2022. On January 28–29, 2025, Russia claimed that Ukrainian drones targeted the Smolensk Nuclear Power Plant during overnight attacks; however, Russian authorities reported that the facility continued to operate normally. On February 14, 2025, an unmanned aerial vehicle hit and severely damaged the New Safe Confinement structure at the ChNPP, marking a concerning escalation in direct attacks on nuclear infrastructure.
As of now, all six reactors at the ZNPP are in cold shutdown mode due to safety considerations. The three other NPPs operate relatively normally in power generation mode, though their operations are affected by the war, requiring additional protection measures and safety precautions.
Limited Direct Impact, High Risks From Off-Site Disruptions
Beyond attacks on nuclear sites themselves, the safety and security of nuclear facilities are affected by attacks on off-site infrastructure critical for their operation.
The destruction of the Kakhovka Dam in June 2023 created an additional nuclear safety crisis at the ZNPP. The dam’s reservoir provided cooling water for the nuclear plant’s emergency safety systems. When the dam was destroyed—with both sides blaming each other—water levels in the reservoir dropped dramatically, substantially increasing safety risks. If the ZNPP’s reactors needed emergency cooling during a crisis, the plant might lack a sufficient water supply. While the reactors were already in cold shutdown, the spent fuel pools still required cooling, and the plant’s emergency systems depend on reservoir water for various safety functions. Since then, additional measures have been implemented to compensate for the decreased reservoir levels and ensure a stable water supply. However, this issue remains a concern and is subject to continuous monitoring.
Perhaps the most insidious nuclear safety threat stems from intentional or unintended grid disruptions. Due to operational technicalities, even electricity-producing NPPs need access to an external power supply to ensure the operation of safety and security systems. Without an external power supply, NPPs rely on diesel generators for backup power. However, diesel generators can typically ensure only 7–10 days of operation. Ultimately, the prolonged absence of an external power supply requires the shutting down of reactors for safety purposes.
While the grid was regularly damaged throughout the conflict, recent months have seen Russia’s systematic campaign against Ukraine’s electrical grid. Rather than directly attacking nuclear plants, Russia has focused on destroying the power infrastructure that nuclear facilities depend on for safe operations. Disruptions in the external power supply were a key reason for the complete shutdown of all six reactors at the ZNPP and interruptions in the operation of other NPPs. Due to war-related damage to coal and gas power generation, nuclear power now accounts for over 70% of electricity generation in Ukrainian-controlled territory. Thus, interruptions in NPP operations create severe power shortages, exacerbating the humanitarian and economic crisis. Russia’s strategy effectively weaponizes Ukraine’s dependence on nuclear power generation by abstaining from direct attacks against NPPs while attacking power infrastructure, all while maintaining plausible deniability about directly targeting nuclear facilities.
Safety And Security Personnel Under Severe War-Related Pressure
The war has dramatically affected Ukrainian nuclear power plant (NPP) personnel. A sufficient number of qualified personnel is critical for the safe and secure operation of nuclear sites. When these human resources are compromised, the risk of accidents increases. War-related stress on nuclear site personnel further amplifies this risk.
The personnel crisis began when Russian forces occupied both the Chernobyl and Zaporizhzhia nuclear plants. At Chernobyl, 210 workers were trapped for over a month without shift rotations, working under extreme stress while armed soldiers controlled the facility. Normal shift rotations resumed after 35 days of occupation, and core nuclear safety and security functions have been sufficiently staffed. Still, operations are affected by additional war-related safety and security precautions, and psychological stress is exacerbated by the fact that several dozen National Guard soldiers abducted from the plant remained in Russian captivity as of November 2024.
At Zaporizhzhia, the situation has been even more dire, with documented cases of Ukrainian staff being tortured, kidnapped, and intimidated to force them to abandon their Ukrainian employment and sign contracts with Russian nuclear agencies. Before the war, the ZNPP employed approximately 11,500 qualified personnel. Today, that number has plummeted to around 5,000. Many experienced Ukrainian nuclear workers chose to flee rather than collaborate with the occupying forces.
Russia has had some success in maintaining operations. Russian personnel imported to ZNPP have relevant experience with VVER-type reactors, the same design used at the facility. Critically, some key Ukrainian personnel have remained, including the former deputy chief engineer, who now serves as the Russian-appointed director. Approximately 3,000 Ukrainian staff have signed contracts with a Russian operating organization.
The current operational state of ZNPP somewhat mitigates personnel-related concerns. With all six reactors in shutdown mode rather than generating electricity, the plant requires significantly fewer personnel than during normal power operations. The IAEA has confirmed that essential positions remain filled and that there are sufficient certified personnel for the plant’s current reduced operational level. However, the IAEA was unable to confirm personnel qualifications due to Russian administrative restrictions on communications between operating personnel and IAEA monitors.
The population of Enerhodar, ZNPP’s satellite city where most plant personnel live, decreased from its pre-war level of 53,000 to 15,000. The Russian administration has invested in Enerhodar’s social and economic development to maintain its attractiveness for Russian and Ukrainian personnel. This process is part of a broader effort to develop occupied territories, managed by Sergey Kirienko, the Deputy Head of the Russian President’s staff, who has strong connections to Rosatom.
Ukraine has not passively accepted the occupation of its nuclear facilities. In late 2022, Ukrainian special forces reportedly attempted an unsuccessful commando operation to retake ZNPP. Ukraine has also engaged in psychological operations against ZNPP personnel working under Russian control, including broadcasting messages warning workers that collaboration with occupying forces could result in prosecution for treason after Ukraine regains control. One ZNPP security service employee was killed in a car explosion in October 2024, with circumstances hinting at Ukrainian military intelligence involvement. While these tactics aim to maintain Ukrainian loyalty among plant workers, they create additional stress for personnel already working under difficult conditions. This case highlights the complex loyalties at nuclear facilities during occupation. Workers face choices between personal safety, professional duty, and national loyalty—all while maintaining safety at a facility that could affect millions of people if something goes wrong.
The Iaea’s Mission
The International Atomic Energy Agency (IAEA), the United Nations nuclear watchdog responsible for promoting the peaceful use of nuclear energy and preventing nuclear weapons proliferation, plays a unique role in monitoring safety and security at nuclear sites in a war zone.
The IAEA’s first statement addressing the war in Ukraine was issued on the evening of February 24, 2022. Upon Ukraine’s request for assistance in April 2022, the IAEA developed a technical plan for safety and security assistance. The mission at the ZNPP was first established in September 2022, later expanding to all five Ukrainian nuclear sites by January 2023.
The IAEA’s functions across Ukrainian nuclear facilities encompass comprehensive monitoring, equipment delivery, and expert missions. At all five sites, Agency teams observe conditions against safety and security criteria derived from existing IAEA safety standards and nuclear security guidance, adjusted to wartime conditions. According to IAEA monitoring results as of 2025, these criteria are not being met for the ZNPP and the ChNPP. At Ukraine’s three operating nuclear power plants—Khmelnytskyi, Rivne, and South Ukraine—nuclear safety and security are being maintained despite ongoing challenges. Based on monitoring results, IAEA inspectors identify priority needs and provide suggestions for technical assistance. The IAEA reports the results of its work in Ukraine through regular Director General Updates (296 updates published as of June 12, 2025) and Director General Reports to the IAEA Board of Governors.
Both sides blame the IAEA for inaction. While not an official Ukrainian position, many Ukrainian experts blame the IAEA for its inability to regain control over the ZNPP from Russia. Russia blames the Agency for its unwillingness to attribute drone attacks on the ZNPP to Ukraine. However, the IAEA’s mandate as a United Nations organization is limited and allows for monitoring and factual reporting, but does not permit enforcement actions. The IAEA’s work is a diplomatic balancing act, navigating competing claims from Ukrainian and Russian authorities. Defending the IAEA’s neutrality and objectivity, Rafael Grossi explained: “We are not commentators. We are not political speculators or analysts, we are an international agency of inspectors. And in order to say something like that, we must have proof, indisputable evidence,” emphasizing that the Agency’s credibility requires measured words and concrete evidence before making any attributions.
While the IAEA’s mandate and capabilities are limited, its presence at the ZNPP likely deters both sides from the most dangerous actions against the plant and prevents a “nuclear Kakhovka” that could be triggered by the negligence of occupying forces.
In addition to the obvious risks and challenges of working in a war zone, IAEA inspectors’ work at the ZNPP is complicated by restrictions imposed by Russian authorities on access to ZNPP personnel and certain plant areas. These restrictions raise suspicions, supported by multiple pieces of evidence, of illegitimate use of the ZNPP facilities for military purposes.
Uniquely among international leaders, IAEA Director General Rafael Grossi regularly meets with Russian leadership, including multiple meetings with President Vladimir Putin. These discussions address nuclear safety and security concerns, but Grossi’s direct access to the Kremlin amid the conflict could potentially be used for communications on other issues beyond his immediate authority as the IAEA Director General.
Challenges To International Regime Protecting Nuclear Sites
Russian military actions against Ukrainian nuclear facilities, particularly at the Chernobyl and the ZNPP, have exposed critical vulnerabilities in the international regime designed to protect nuclear sites during armed conflict. These events reveal that current legal frameworks are inadequate when faced with state-level military aggression, highlighting inherent weaknesses and the urgent need for comprehensive reform of both international humanitarian law and nuclear security arrangements.
The current protection regime consists of two main components: international humanitarian law, treating nuclear facilities as protected civilian objects under Additional Protocol I to the Geneva Conventions, and a nuclear security regime designed to counter non-state threats based on the “design basis threat”—a realistic adversary model used to develop requirements for the protection of nuclear sites. However, both pillars have proven fundamentally inadequate in the Ukrainian context.
International humanitarian law suffers from two critical deficiencies: ambiguous language that allows for broad interpretation and contains applicability gaps, and enforcement mechanisms that are ineffective against Russia, a nuclear weapons state with a UN Security Council veto power.
The nuclear security regime, based on the design basis threat, leaves facilities vulnerable to state military forces operating with heavy weapons and large personnel numbers—threats far beyond any feasible design basis threat that can be addressed by standard nuclear security means.
The occupation of the ZNPP and the ChNPP showcases these systemic failures.
Addressing these challenges requires comprehensive reform but faces substantial obstacles, including great power resistance to strengthened restrictions, sovereignty concerns over international oversight, and technical difficulties in expanding protection definitions while maintaining enforceability and feasibility of implementation.
Conclusion
The war in Ukraine has introduced a new dimension to the understanding of nuclear risks in modern warfare, revealing critical gaps in international protections for nuclear facilities during armed conflict. This unprecedented situation—the first major war fought in a country with extensive nuclear infrastructure—has exposed the inadequacy of existing legal and security frameworks designed primarily for peacetime operations or non-state threats. The nuclear safety and security impacts of this war represent uncharted territory in international relations, challenging existing legal frameworks and creating precedents that could influence future conflicts worldwide. The most immediate lesson is that nuclear facilities, despite their critical importance, are not immune to military targeting when states prioritize strategic objectives over international norms.
The human dimension of this crisis—from trapped workers at Chernobyl to the coercion and intimidation of ZNPP personnel—underscores how nuclear safety ultimately depends on qualified, willing staff operating under normal conditions. The psychological and physical pressures on nuclear workers during occupation create additional accident risks that existing safety and security protocols could not have anticipated.
The IAEA’s role, while valuable for monitoring and deterrence, highlights the limitations of international institutions when confronting state-level aggression. The Agency’s technical expertise and diplomatic neutrality provide essential oversight, but its lack of enforcement authority reveals a gap between monitoring capabilities and its preventive power.
The international community must urgently address the legal, technical, and institutional gaps this war has revealed. This includes strengthening international humanitarian law protections for nuclear facilities, developing new security frameworks that account for state-level threats, and enhancing international response mechanisms that can prevent nuclear facilities from becoming pawns in military conflicts.
Dmitry Kovchegin is an expert in nuclear security and nonproliferation. Dmitry works on the intersection of nuclear technology, international relations, and program management issues. For 20 years he has worked as a consultant for the US National Nuclear Security Administration, supporting its effort to improve nuclear security in Russia, Ukraine, and Belarus. He has also contributed to multiple research projects with leading American research and non-profit institutions, such as the Nuclear Threat Initiative, Harvard University, Princeton University, and many others, on the issues of nuclear security, nonproliferation, and nuclear energy.