Ukraine’s nuclear operator warns of critical safety risks at Zaporizhzhia plant

Ukraine’s state nuclear company Energoatom has warned that the Zaporizhzhia Nuclear Power Plant faces a critical safety situation after operating on diesel generators for more than two weeks.

The plant lost its external power supply on Aug. 20, according to Energoatom, which said this marked the 27th disconnection from the grid since the beginning of Russia’s full-scale invasion. The facility then switched to emergency diesel generators.

On Sept. 5, International Atomic Energy Agency Director General Rafael Grossi announced a localized ceasefire intended to restore the plant’s external power supply. Energoatom said the generators had been used as the primary power source for an extended period and under non-design operating conditions.

The company warned that prolonged, continuous operation increases the risk of a common-cause failure, one of the most serious threats to nuclear plant safety. “Constant cyclical starts and load switching significantly increase the probability of start-up automation failure,” Energoatom said.

Although all reactor units remain in cold shutdown, Energoatom said a power outage could threaten control of primary safety systems, spent nuclear fuel storage pools and technological parameters. The company previously warned that every blackout further damages equipment, including the diesel generators intended to provide backup power.

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Constant cyclical starts and load switching significantly increase the probability of start-up automation failure. Even though all units are in cold shutdown mode, a power outage threatens the loss of control over primary safety systems, spent nuclear fuel storage pools and technological parameters.