Ukraine's Zaporizhzhia nuclear plant shuts down last reactor in face of flooding threat

Ukraine's nuclear energy agency says it has put the last operating reactor at Europe's largest nuclear power plant into a "cold shutdown" — a safety precaution as catastrophic flooding from the collapse of a nearby dam threatens the facility's water supply.

Five out of six reactors at the Zaporizhzhia Nuclear Power Plant, which is occupied by Russian forces, are already in cold shutdown, in which all control rods are inserted into the reactor core to stop the nuclear fission reaction and generation of heat and pressure.

Energoatom, the Ukrainian nuclear power agency, said in a statement late Friday that there was "no direct threat" to the Zaporizhzhia plant due to the breach of the Kakhovka dam further down the Dnipro River, which has forced thousands of people to flee flooding and also sharply reduced water levels in a reservoir used to help cool the facility.

The last reactor was put into cold shutdown on Thursday, Energoatom said, adding that other factors in the decision included shelling near the site which has damaged overhead lines connecting the plant to Ukraine's energy system.

With all nuclear reactions stopped, temperatures and pressure inside reactors gradually decline, reducing the required intensity of water cooling of the radioactive fuel. This is a nuclear power plant's safest operating mode. Energoatom employees are still working at the power plant, although it remains controlled by the Russians.

The site's power units have not operated since September last year. The head of the International Atomic Energy Agency, Rafael Mariano Grossi, is due to visit Kyiv next week, when he will present President Volodymyr Zelensky with details of a new programme to help the country avoid a nuclear disaster.

Both