Repeated shelling at the Zaporizhzhya nuclear power plant complex over the past seven days has raised concerns about a nuclear accident.
The Ukrainians have accused the Russians of leading strikes there to cut off energy supplies to other cities and to try to discredit the Ukrainian military in the eyes of the world. The Russians say Ukraine is carrying out the shelling.
Both sides would suffer if a meltdown occurred and radioactive material was dispersed.
While they’re designed to withstand a range of risks — from a plane crashing into the facility to natural disasters — no working nuclear power plant has ever been in the midst of active combat, and it wasn’t designed with the threat of cruise missiles in mind.
There are a number of important concerns.
The concrete shell of the site’s six reactors provides strong protection, as was the case when reactor No. 1 was hit in March, officials say. More troubling is the chance of a transformer being hit by shelling, increasing the risk of fire.
Ukrainian officials have accused Russia of hiding dozens of military vehicles with an unknown amount of ammunition on the grounds of at least two reactors. If a fire broke out at the current transformers and the grid was taken offline, it could cause a failure in the plant’s cooling system and lead to a catastrophic meltdown, said Edwin Lyman, a nuclear energy expert with the Union of Concerned Scientists. , a private group in Cambridge, Mass.
He noted that the loss of coolant during the Fukushima accident in Japan in 2011 resulted in three reactors undergoing some degree of meltdown.
If the cooling is interrupted, said Dr. Lyman, the nuclear fuel can become hot enough to melt in a matter of hours. Eventually, it could melt through the steel reactor vessel and even the outer containment structure, releasing radioactive material.
According to Ukrainian officials, a grenade hit a current transformer in reactor No. 6 at the same time that reactor No. 1 was hit. According to Ukrainian officials, it did not explode.
dr. Lyman said the threat would diminish in the event of a military attack on the dry spent fuel deposit next to the Zaporizhzhya reactors. While spent fuel can still be dangerously hot for years, it quickly loses much of its radioactivity, making any breakthrough less threatening — though the radioactive particles would spread into the air if hit by a grenade or missile.
