In March of 2022 Russian troops took control of the 6-reactor site of Ukraine’s nuclear energy plant at Zaporizhzhia. They caused minor damage in the battle but raised fears of a wider catastrophe. In the following paragraphs I will explain why that is highly unlikely.
While the Russians have blamed Ukraine for launching attacks against their forces at the reactor site endangering the reactors; the Ukrainians have accused the Russians of deliberately putting the reactors at risk by stationing troops on the grounds. Russia has told the Ukrainian operators that the reactors now belong to Russia, the International Atomic Energy Agency (IAEA) has asked to visit the reactors to confirm they remain safe. The news media is filled with speculation about what might happen to the reactors and how that might affect Ukraine, Europe, and the world. Here are the facts.
The reactors at Zaporizhzhia provide as much as 20% of Ukraine’s electrical energy –5700 MW when all reactors operate at full power. Electrical energy powers most of the nation and is also vital to fight a war which is one of the reasons Russia wanted to seize these plants – to deny this power to Ukraine and possibly to take it for themselves. At present, only two of the six reactors are operating online.
Do we need to worry about a stray shell hitting a reactor and causing a meltdown? It is quite doubtful. A direct hit on a reactor building with a large high-explosive shell will be blunted by the reactor containment structure which absorbs most of the shell’s energy.
The reactor has multiple layers of protection; the containment, a few meters of reinforced concrete, is only the outermost layer. Within the containment is the reactor pressure vessel that holds the fuel – this is made of tough steel designed to hold in the high-pressure reactor coolant. Unfortunately, holding in a high-pressure liquid isn’t quite the same as standing up to high-pressure gas (i.e., an explosion) on the outside, so we don’t know exactly how much of an external shock the reactor vessel or pipes can take. On the other hand, the force from an explosion drops off relatively quickly with distance from the site of the blast, meaning that a miss won’t have nearly the power of a direct hit.
The third barrier is the fuel construction itself. Uranium fuel is formed into small pellets encased inside metal capsules and placed into a tube made of an alloy of zirconium (a tough metal with a high melting temperature). If the reactor loses cooling, the fuel can still suffer thermal damage or melt – but it provides additional protection against damage from the physical shock from any shells that might penetrate through the containment structure.
The Zaporizhzhia site currently has two operating nuclear reactors and is located just under 300 miles from the nearest NATO nation – Romania – and about 400 miles from Turkey and Bulgaria; were any radioactivity to be released, it would disperse considerably before reaching the borders of any NATO members. What might reach one of our allies would almost certainly not cause any deaths. This is not speculation – this is our experience following the Chernobyl reactor accident and the aftermath of Fukushima. Ironically, the nearest nation to this reactor site and the most likely to receive the highest radiation exposure is Russia, which is only about 160 miles away.
In 2006 the World Health Organization and the International Atomic Energy Agency conducted a careful examination of health records in Ukraine, Belarus, Russia, and other, more-distant nations, concluding that fewer than 100 deaths (as of 2006) had been caused by radiation exposure from Chernobyl. Calculations of future cancer deaths showed that several thousand people might die of cancer over a period of 50 years (1986 – 2036), but the cancers that appear soonest after exposure and most likely to be caused by radiation (leukemia and other blood cancers) had not increased in the nations hardest-hit by fallout from this accident.
Considering the different reactor and containment designs (in particular, Chernobyl lacked any containment whatsoever), this suggests that the meltdown of newer, better-designed reactors with containment is similarly unlikely to cause health issues to anybody a few to several hundred miles away.
But a better example would be the Fukushima meltdowns, which occurred in reactors with containment structures. The reactor accidents were not initiated by an explosion in the reactor core (as happened at Chernobyl). In the case of Fukushima, the WHO and the IAEA concluded that there will likely not be a single death due to radiation exposure, either in the short term or over the next several decades. A meltdown at the Zaporizhzhia site is much more likely to resemble what happened at Fukushima; the fact that even the Japanese in the vicinity of the Fukushima reactor site are expected to be unaffected suggests that our NATO allies are almost certainly safe as well.
It is hoped the IAEA is granted access to the site to confirm that the reactors are still being operated safely. We can hope that the Russians and Ukrainians find it in their best interests to demilitarize the area and withdraw all troops from the reactor site.
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