Imperiled Ukrainian nuclear power plant has the world on edge – a safety expert explains what could go wrong

Russian forces occupy Europe’s largest nuclear power plant, the Zaporizhzhia Nuclear Power Station in the Ukrainian city of Enerhodar. Russian and Ukrainian forces are fighting nearby, and shelling has damaged power and communication lines to the plant, prompting fears for the plant’s safety and evoking painful memories in a country still scarred by the world’s worst nuclear accident, at Chernobyl in 1986.

In addition, Russian authorities have developed plans to disconnect the plant from Ukraine’s power grid – in the event of damage to the plant, according to the Russians, as a prelude to switching the plant to the grid in Russian-occupied territory, according to the Ukrainians. Disconnecting the plant from the grid is a risky operation.

The Conversation asked Najmedin Meshkati, a professor and nuclear safety expert at the University of Southern California, to explain the risks of warfare taking place in and around nuclear power plants.

How safe was the Zaporizhzhia power plant before the Russian attack?

The facility at Zaporizhzhia is the largest nuclear plant in Europe and one of the largest in the world. It has six pressurized water reactors, which use water to both sustain the fission reaction and cool the reactor. These differ from the RBMK reactors at Chernobyl, which used graphite instead of water to sustain the fission reaction. RBMK reactors are not seen as very safe, and there are only eight remaining in use in the world, all in Russia.

The reactors at Zaporizhzhia are of moderately good design, and the plant has a decent safety record, with a good operating background.