Russia puts Zaporizhzhia NPP unit on hot shutdown, which Ukraine says violates law
Photo: Zaporizhzhia NPP

Russia on Monday put power unit 4 of the Zaporizhzhia nuclear power plant into hot shutdown, Ukrainian state nuclear operator Energoatom said in a statement.

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The Ukrainian state nuclear regulatory inspectorate has previously warned that would run significant additional risks to nuclear and radiation safety.

It is due to the prolonged downtime of unit 4 equipment; the lack of proper routine maintenance and repair of safety-critical equipment; and the insufficient number of qualified personnel at the Zaporizhzhia NPP.

The operating licence for unit 4, as well as for other ZNPP units, only allows operation in cold shutdown state.

The Ukrainian nuclear inspectorate believes cold shutdown is the optimal mode to reduce nuclear risks as the blowing up of the Nova Kakhovka dam has deprived the nuclear plant of a reliable source of water supply.

Cold shutdown is a safe state of a nuclear reactor when it is shut down at low pressure and low temperature of cooling water. During a cold shutdown, a nuclear reactor does not generate electricity. The reactor can remain in this state indefinitely if it is connected to the power supply.

Hot shutdown is a mode in which water is heated from a reactor that is not in operation, and is distilled by pumps powered by an external power source.

Energoatom president Petro Kotin says the change in the power unit’s mode is a violation of the rules for handling radioactive materials, nuclear safety rules, and might be a preparation for a terrorist attack.

"This is a deliberate and intentional violation of Ukrainian and international law," he was quoted as saying.

Russia’s Rosatom, in turn, said the change in the operating mode of unit 4 of the Zaporizhzhia NPP was "to provide steam for the plant's own needs".

Last month, Ukraine warned Russia has mined the Zaporizhzhia nuclear power station in southeastern Ukraine, which is the largest in Europe and among the 10 largest in the world.

Kyiv has also repeatedly warned that Moscow might stage provocations on the plant.