Risk Assessment of Nuclear Facilities in Ukraine-Russia Armed Conflict

Armed conflict between two countries leading to a nuclear catastrophe is generally thought of in terms of the use of nuclear weapons. The ongoing Russia-Ukraine armed conflict has given this another meaning. On March 4, 2022, Russian forces took control of Enerhodar in the southeast region of Ukraine, where Europe’s largest nuclear power station exists 1. Zaporizhzhia nuclear power station has six units (or nuclear reactors), each with a 950 MW capacity and a net capacity of 5700 MW 2. During the battle between Russian and Ukrainian forces, projectiles hit the nuclear facility in Zaporizhzhia. This caused a localized fire in one of its buildings at the nuclear facility 3. The fire was extinguished swiftly, and there was no damage to any of the reactors or reactor buildings 4. Radiation levels remained in the normal range throughout this incident, as per the Ukrainian State Emergency Service 5. Attacks on nuclear facilities, especially those that contain large amounts of highly radioactive material, during an armed conflict raise fears of radioactive fallout that can have disastrous and long-term implications. This commentary assesses the significance of the Zaporizhzhia nuclear power station and the risk of attacks on nuclear facilities during an armed conflict.

The Soviet Union began construction of reactor units at the Zaporizhzhia nuclear power station in the 1980s. The first reactor began commercial operation in 1985 and the last unit in 1996 6. These reactors are pressurized water reactors (PWR) of the VVER-1000 type (a Russian abbreviation of the water-water energetic reactor), run on low enriched uranium (LEU) fuel, and use water as both the primary moderator and the primary coolant 7. Two of its units (Units 3 and 5) have undergone modernization work in the last five years, which is crucial for their life extension 8. According to Energoatom, Ukraine’s nuclear operator, Zaporizhzhia nuclear power station supplies one-fifth of the country’s total electricity 9. None of its reactor units has faced any major nuclear safety issues since the beginning of the commercial operation. There had been an attempted security breach in 2014 by an armed group to take control of the nuclear facility, but it was thwarted by the Ukrainian police 10. Incidents of nuclear safety and breaches in nuclear security are both considered worrisome eventualities, and all entities involved in running the nuclear operation take appropriate measures to guard against such occurrences.

The biggest risk associated with any kind of attack on nuclear facilities is the radiation exposure to workers, people, and the environment. States, nuclear suppliers, operators, and regulators, as well as international organizations like the International Atomic Energy Agency (IAEA), take all aspects of nuclear safety and emergency preparedness very seriously. Mitigating against any physical threat is a key feature of these measures. The Chernobyl nuclear disaster of 1986 (incidentally, the disaster site is also in Ukraine and is now controlled by Russian forces) and the terrorist attacks of 9/11 gave impetus to the nuclear industry to reinforce the nuclear safety practices and nuclear security regimes in nuclear-operating countries as well as in international law 11. Several measures for improving nuclear safety and security have been incorporated into the design and management of nuclear facilities, which also help in the event of emergency preparedness. These measures help in mitigating the consequences of a nuclear accident or in the case of a targeted attack. Ensuing paragraphs will assess how these nuclear safety and security measures helped in the attack on Zaporizhzhia nuclear power station. Nuclear reactors (e.g., the ones at the Zaporizhzhia nuclear power station) are fortified with steel and concrete containments over the reactor building 12. This means that even if an explosive projectile hits the containment structure, it will not cause sufficient damage and will not result in any radiation leak. However, a one-off hit may not cause damage to the reactor itself, but repeated attacks can result in more destruction. The events of March 4 may be collateral damage or a deliberate attack (there are conflicting versions from Russia and Ukraine) 13. But both fighting forces need to be extra careful to not target nuclear facilities in this armed conflict. Who knows the repercussions of radiation leakage better than Russia itself, which experienced it in 1986? Ukraine has 15 nuclear reactors all over the country 14. Some are far away from the main battlegrounds, but others have more proximity to the fire exchange. Any attack on nuclear reactors with radiation leakage will have far-reaching effects on not only Ukraine but also its neighboring states, including Russia. Spent fuel storage sites, in addition to nuclear reactors, are also equally, if not more vulnerable, to armed attacks.

Ukraine, like many other nuclear operators around the world, stores the spent fuel on-site at the nuclear facility 15. Ukraine stores spent fuel in two ways: cooling pools and dry storage 16. The spent fuel is contained in fuel rods and submerged in water pools. This arrangement helps in removing the decay heat of spent fuel so that the fuel becomes easier to handle and can be shifted to permanent storage as and when the operators and regulators decide to do so. At Zaporizhzhia, the nuclear power station’s spent fuel is stored in water pools for four to five years and then transferred to the Spent-Fuel Dry Storage Facility (SFDSF), which has been built on the site 17. Unlike the building containing the reactor vessel, spent fuel storage pools are not fortified with reinforced containments. This is where the danger lies in the case of an armed conflict. Any accidental or deliberate attack can damage the water pools, which can interrupt the cooling process and result in the exposure of fuel rods. Exposed fuel rods can heat up due to an increased fission process in the absence of water as a coolant and moderator. In extreme circumstances, exposed fuel rods can catch fire and result in radiation leakage into the atmosphere. Older fuel rods that have been in water pools for a long time pose less threat than newly stored fuel rods. It is important to point out that, according to the IAEA, the spent fuel storage site at the Zaporizhzhia nuclear power station is safe at the moment and no damage has been reported to the water pools 18.

In addition to the safety of spent fuel, another challenge is to ensure the safety of reactors that are not operating at this point. At the time of the writing of this article (March 5), two reactors (Unit 2 and Unit 4) out of six at the Zaporizhzhia nuclear power station were in operation, and the other four units have been safely shut down 19. The reactors must remain in cool shutdown, which means that the temperature in the reactor core is constantly regulated to acceptable levels and does not rise to the point where structural damage or radiation leaks occur 20. When a reactor is shut down, the fission process is reduced to low levels by inserting control rods, but heat is constantly being generated in the reactor core and needs to be removed. Water is circulated in the core through electric pumps to ensure temperature regulation 21. Pumps require electricity, which implies that even if the reactor itself is not producing electricity, its cooling systems require an alternative power source to do their job. To have redundancy and as an added safety measure, nuclear reactor sites also install backup diesel generators. Back-up diesel generators can be utilized in case the alternate electricity source is not available or is destroyed. Modern nuclear reactors have another added layer of passive safety measures that kick in to keep the reactor core cool. In an extremely remote possibility in which each layer of safety measures and emergency preparedness fails and the reactor core starts to heat up, there is still time for the core to heat up enough to start a fire and result in a radiation leak. Let me reiterate that this is an extremely far-fetched scenario. This situation is nothing like Chernobyl, where the reactor exploded, and the containment was breached. The VVER-1000 type reactors at Zaporizhzhia nuclear power station are more modern than the graphite-cooled RMBK-type reactors of Chernobyl and include several active and passive safety measures. Technology for mitigation in the case of nuclear accidents has improved, and emergency preparedness practices and protocols have also evolved since the Chernobyl nuclear disaster. The fear of nuclear accidents in the minds of people is greater than the probability of risk. These fears are so ingrained in the minds of people that when the news reports of the fire at Zaporizhzhia nuclear power station began circulating, stock exchanges across Asia went tumbling down and oil prices soared 22. People draw parallels between an imagined nuclear accident and those of a mushroom cloud in the case of a nuclear explosion. Nuclear energy has always had an image problem, and incidents like these require better information and perception management to assuage the fears of the public.

In the context of assuaging fears, it is still not clear who is in control of and monitoring the Zaporizhzhia nuclear power station following the takeover by Russian forces. It is of the utmost importance that Units 2 and 4 keep on operating safely and the rest of the four units remain in a cool shutdown. Despite automated systems, human control and intervention are required in this situation. So, who is in the control rooms of these six units? Is it the Ukrainian staff, scientists, and engineers, or are they working in shifts? Are Ukraine’s nuclear operator and regulator in constant communication with the staff and management at Zaporizhzhia nuclear power station? The IAEA’s latest update answers some of these questions. According to the IAEA, Ukraine’s nuclear regulator “was able to maintain communication with staff” at both Zaporizhzhia nuclear power plants 23. It further added, “One telephone communication line had been lost, but another was still functioning, as was mobile phone communication 24.” An interesting paragraph at the end of this update states

Director-General Grossi has repeatedly stressed the importance of staff operating Ukraine’s nuclear facilities being allowed to rest and rotate to be able to carry out their jobs safely and securely. He has also said that a “tense” situation with Russian forces controlling the Zaporizhzhya NPP site and Ukrainian staff operating it “certainly cannot last for too long”. The head of the national operator Energoatom, Petro Kotin, informed the Director-General on Friday that the plant was now allowed to change work shifts 25.

The IAEA will need to give more details because the above statement raises more questions than it answers. There were initial reports that first responders were not allowed inside the facility to extinguish the fire 26. What if another attack or fire happens at either Zaporizhzhia nuclear power station or any other nuclear facility? Who will be in charge of managing that crisis? The IAEA has activated its IAEA Incident and Emergency Centre (IEC) to “continuously receive, assess, and disseminate information” about any developments regarding Ukraine’s nuclear facilities 27. While the IAEA is in direct contact with the Ukrainian state nuclear operator and regulator, who will be in contact with the IAEA if Russian forces take control of the nuclear reactors? As argued before, it is in Russia’s interests too that those Ukrainian nuclear facilities are protected against any damage and either remain in safe operation or cool shutdown. Russia has an added responsibility to address these nuclear fears of the international community. Can the IAEA arrange with Russia and Ukraine and have its nuclear safety experts work alongside Ukrainian and Russian experts to ensure the safety of these nuclear facilities? These are all important questions that need to be addressed to assuage international fears about a nuclear catastrophe. The situation remains fluid and is changing rapidly. Ukraine, as the operator of these nuclear facilities, has the primary responsibility to ensure nuclear safety, nuclear security, and emergency preparedness, but its ability to carry out these responsibilities becomes questionable as its survival is at stake. Russia, as the invader, has a responsibility to ensure non-attacks on nuclear facilities. As a proponent of nuclear energy and a responsible agency for mitigating nuclear risks, the IAEA must take proactive measures. The IAEA has never faced a situation like this before, but it must act quickly and decisively in Ukraine. While staying within its mandate, IAEA leadership needs to reach out to both Russia and Ukraine and put measures in place to prevent any nuclear accident or radiation leak.

About the Author

Haleema Saadia

Haleema Saadia is a Doctoral Candidate at the National University of Sciences and Technology and is a Lecturer at the National University of Modern Languages, Islamabad.