Saskia Mordijck
Saskia Mordijck

On March 4, Russia attacked and eventually took control of the Zaporizhzhia nuclear power plant in southeast Ukraine. It is the largest nuclear power plant in Europe. The United Nations’ nuclear watchdog, the International Atomic Energy Agency, stated that none of the safety systems at the plant were affected and there was no release of radioactive material in the attack, but the event underscores the possible dangers of warfare around nuclear sites. To understand more about the science and the risk, W&M News spoke with Saskia Mordijck, assistant professor of physics at William & Mary and an internationally recognized fusion energy scientist. – Ed.

Q: You are currently at the headquarters for the International Atomic Energy Agency in Vienna. What is the feeling there about what is happening in Ukraine?

A: They are watchful and concerned. There are regular press conferences and all the representatives are here. From my IAEA colleague, I know that since the conflict started in Ukraine all his colleagues involved with safety and security have had to drop other things they were working on. Those working on nuclear power have also been busy. So the IAEA started monitoring the situation from the moment Russia invaded Ukraine. 

Q: Can you explain the science behind how these reactors work and what the major safety concerns are?

A: In a fission reactor, neutrons interact with uranium and produce more fast neutrons, a chain reaction. The water in these reactors slows the neutrons down and thus heats up. This water exchanges heat with a second water cycle, which is used to power a turbine, to generate electricity. This is very different from the Chernobyl reactor. This first water cycle and the nuclear reactor itself are housed in a strong concrete structure, which for example are predicted to withstand aircraft impacts, but bombing is another matter. There are six reactors at the facility and at the time of the attack only two were operating. The fire was not at any of the reactors where the nuclear materials are located. At this point, once all the reactors are shut down, the biggest risk is cooling. The nuclear material continues to split and generate heat. Even the spent fuel, from the other reactors, must be in a pool constantly submerged in enough water. 

Q: You work in fusion energy – and this is a fission facility, what is the difference between the two?

A: The main difference is in the safety. Fusion does not create a chain reaction, which means that if we lose control, the reaction shuts itself down. Fusion requires a lot of heat, which it can generate, but if there is a loss of confinement, then everything cools down. We also don’t require to store spend fuel and the radioactive waste isn’t long-lived, so we don’t need a storage solution.

Q: What do you think are possible repercussions for nuclear energy science should there be a nuclear disaster in Ukraine? I’m thinking of Chernobyl and the unintended consequences of relying on fossil fuels instead of nuclear energy. 

A: The type of accident at Chernobyl is not possible at this type of power plant. If in the worst case they lose all potential to cool the fuel, this will be more like Fukushima. However, as we have seen, the personnel of the plant were able to safely shut down the operation during a very stressful time. Since the annexation of Crimea by Russia, Ukraine decided to invest in nuclear power to depend less on fossil fuels. Europe, after a winter of suffering under high prices for gas set by Russia and now in the Ukraine crisis, is also looking into nuclear energy. 

Q: What should people in Ukraine, and maybe more specifically those near the Zaporizhzhia nuclear power complex, be doing to keep themselves safe from potential nuclear fallout right now? 

A: At this point, as the Russians have the powerplant, there will be no more shelling. The last reactor is being shut down, from what I’ve seen on the news. For there to be a fallout, it would require the active cooling systems to fail. There is no reason to believe this will happen and if it does, there will be time to leave. This is very similar to what we would have to do living in Williamsburg if we are required to evacuate because of a problem with the Surry nuclear power plant.

, Assistant Director for Research, News & Analytics