Fire broke out at a training building at Ukraine's Zaporizhzhia Nuclear Power Plant overnight, thought to have been triggered by shelling by Russian forces, but recent reports suggest it was contained before spreading to the reactors themselves. However, Russian forces have subsequently captured the plant, leading to fears about future operations and radiation monitoring there.
Nuclear scientists note a fire will not necessarily trigger a meltdown, with radiation levels currently stable and safety mechanisms having improved dramatically in the 36 years since Chernobyl. Ukrainian Foreign Minister Dmytro Kuleba warned if safety procedures are not maintained a meltdown would be “10 times worse than Chernobyl”, although this probably represents hyperbole brought on by the stress of war.
The Zaporizhzhia plant is the largest in Europe and supplies more than a fifth of Ukraine's electricity. Cutting off supply would be a major win in Russian efforts to force the Ukrainian people into submission, with temperatures in Kyiv predicted to hover around 0º C (32º F) for the next 48 hours.
Yesterday, Russia informed the International Atomic Energy Agency they had seized territory around the plant. The easiest way to cripple the Ukrainian electricity supply might have been to cut the transmission lines from Zaporizhzhia but either deliberately or by accident the attacking forces appear to have started a fire instead.
However, the Ukrainian state emergency service has posted on Facebook the fire has been put out with “no victims”.
Inevitably, panic started about a nuclear explosion, but the risk of this is low. Nuclear weapons require uranium-235 to make up at least 85 percent of their nuclear material. Power plants like Zaporizhzhia, on the other hand, use fuel with only a few percent U-235 composition – enriched from the 0.7 percent that occurs naturally, but incapable of becoming a bomb without extensive further processing.
A more realistic threat is of nuclear meltdown, similar to the one that occurred at Chernobyl, also in Ukraine, in 1986, which led to radioactivity spreading over most of Europe. However, Dr Tony Irwin of the Australian National University said in a statement that the risk is low: “The six nuclear power reactors at Zaporizhzhia are not Chernobyl type reactors....Unlike Chernobyl, they have a containment around the reactor to stop any radioactive release. Unlike Fukushima, these VVER reactors have separate water circuits to cool the reactor and to produce steam.
In addition to the normal cooling systems, these reactors have emergency core cooling systems consisting of four hyroaccumulators which will passively inject cooling water into the reactor in the event of a problem. They also have multiple train high pressure and low pressure injection systems to prevent a core melt.”
Professor Tom Scott of the University of Bristol echoed these sentiments: “The good news is that radiation levels around the plant are reportedly normal and 5 of the 6 reactors are now turned off, with one still operating."
"I am not overly concerned that inadvertent damage could cause a major nuclear incident."
Others pointed out the spent nuclear fuel stored nearby might be more at risk, although the scale of disaster it would produce would be smaller.
In the fog of war, the truth is currently difficult to confirm. Some reports say the fire was restricted to a training facility and that emergency services quickly gained access to put it out. Others reported rescuers were prevented from reaching the station.
Dr Maria Rost Rublee of Monash University said: “We also need to understand if the plant has been shut down, and where external power is coming from. If the connection to the grid is broken we're relying on back-up diesel generators which are a massive fire hazard."