Problems can arise if the operating reactor shuts down, with risks ranging from melting spent fuel to exploding the reactor core. Meanwhile, the Russian forces send us a message: they can attack the plant at any time
Following the recent news about the bombing of the Zaporizhia nuclear power plant in southern Ukraine, which is the largest in Europe, there is great concern about the possibility of a Chernobyl-like release of radioactive material. Several members of the plant’s security personnel were injured in the attack.
With six large nuclear power reactors, there is a significant amount of nuclear material on site. Although they are not the same type of reactors as those at the Chernobyl plant, and are much safer in design, this does not make them any less vulnerable to weapons of war.
The building that suffered the attack and the subsequent fire is located about 500 meters from a group of six reactors. It contained no nuclear material, as it was used solely for training and administration purposes. No increase in radiation levels has been detected.
While Ukrainian personnel continue to control the reactors, Russian forces have taken control of the entire plant. Judging from the security camera footage, it does not appear to be an accidental attack, but rather a deliberate attack. Russian forces are sending a message: they can attack the plant at any time, but for now they are choosing not to. The fire may have been quickly extinguished, but not the threat of what might come next.
The situation is almost unprecedented. Nuclear materials have been targeted in times of armed conflict, such as Israel’s bombing of a secret Syrian reactor. However, considering that the Syrian reactor was still under construction at the time and the nuclear fuel had not yet been loaded, we are swimming in uncharted waters.
This is a threat that I myself, only a few days ago, considered highly unlikely. Attacking a nuclear power plant, especially one so close to the aggressor’s own territory, is a very risky strategy. The negative consequences are likely to far outweigh any potential benefits. Yet pundits like me have been consistently wrong in assessing what Vladimir Putin will or won’t do.
At the time of the attack, only one of the six reactors was operational: unit 4 at 60% power. All other units were already shut down for maintenance or in low power standby. Therefore, the plant continues to function somewhat normally, although under abnormal circumstances.
Maintain site security
Unfortunately, Ukraine’s nuclear power plants remain in danger. Even shutting down a nuclear reactor does not make it immediately safe. Once nuclear fuel has been placed in a reactor, it will continue to generate its own heat long after shutdown. Older reactors, like those in the Ukraine, require active measures to keep the fuel in a safe state. The water must circulate through the storage pools and the reactor even after shutdown, which means a source of electricity is needed, as well as staff to monitor and manage the plant.
Although Unit 4 can provide the power for this, trained operators will still need quick access to the site to secure it, as well as access to cooling water taken from the Dnieper River. Without this cooling, various accident scenarios can occur, from a nuclear fuel meltdown to a reactor core explosion.
If Unit 4 were to be closed, the necessary electricity would have to be brought in from off-site. However, in the current situation, external power may not be reliable or even available. Furthermore, once a nuclear power plant is shut down, it cannot be restarted for several days. Therefore, shutting down the plant would make it dependent on a potentially unreliable power source to maintain safety functions. As it is, keeping Unit 4 operational in a low-power state may be the best option.
Any attack on a nuclear facility is a major violation of international norms. However, this attack could have been much worse. For example, a direct attack on a fueled and operating reactor could be disastrous, releasing large amounts of nuclear material into the air.
This cloud of nuclear material could be carried by the wind, contaminating vast areas of land and water supplies. This scenario is also not limited to a nuclear reactor. If a used fuel storage pool were to be damaged and the fuel could not be cooled, a similar scenario could occur, albeit on a smaller scale.
However, the above is an unlikely worst-case scenario. If Russia’s decision to target an administrative building was indeed deliberate, we can expect this to mean that they will not target the reactors. It seems likely, at least at present, that Russia’s “special military operation” planners will seek to capture the plant as a piece of critical national infrastructure. However, if the conflict drags on beyond Moscow’s original expectation of three or four days, more extreme measures may be taken.
At a press conference the morning after the attack, the director general of the International Atomic Energy Agency, Rafael Mariano Grossi, declared that his organization will not sit idly by and monitor the situation from Vienna.
Grossi expressed his intention to travel for talks with both Ukraine and Russia. Let us hope that he can reach an agreement that minimizes the danger to the plant and allows the Ukrainian nuclear reactors to operate safely until the crisis is resolved.
This article has been published in The Conversation