"Russian President Vladimir Putin has launched an illegal war on the people of Ukraine, and he is now risking a nuclear disaster. The only way to eliminate the risk of such a disaster is an immediate cease-fire at Zaporizhzhia, withdrawal of all Russian military forces to allow firefighters and the nuclear plant security to re-establish a security zone. This should be the last time we ever see the Russian military coming anywhere near Ukraine's nuclear plants, and is another reason, amongst so many, why Putin has to stop his war immediately."
On 2nd March Greenpeace International released a new analysis on the vulnerability of Ukraine's nuclear reactors during war. The analysis focussed on the Zaporizhzhia reactors. The risks from an armed attack at any nuclear plant are almost beyond comprehension. But, Zaporizhzhia is Europe's largest nuclear plant, with six reactors and perhaps more than 2200 tons of highly radioactive spent fuel.
In the worst-case scenario, the reactor containment could be destroyed by explosions and the cooling system would fail, the radioactivity of both the reactor and the fuel pool could then freely escape into the atmosphere. This risks making the entire plant inaccessible because of the high radiation levels, which could then lead to a further cascade of the other reactors and fuel pools, each spreading large quantities of radioactivity into different wind directions over several weeks. It could make a large part of Europe, including Russia, uninhabitable for at least many decades and over a distance of hundreds of kilometres, a nightmare scenario and potentially far worse than the Fukushima Daiichi disaster in 2011.
Even without a deliberate armed attack on the nuclear plant, the operation of the reactors and cooling of the nuclear fuel and spent fuel is dependent upon stable electrical supply from the grid. Loss of power from the grid would require the operation of Zaporizhzhia's emergency diesel generators which have limited fuel supply and are not considered reliable.
Greenpeace analsis of the vilnerability of Ukraine's nuclear reactors during war can be viewed here
