Nuclear safety risk grows: Russian-occupied nuclear plant’s cooling pond keeps sinking, Russia runs short of diesel and staff, Ukraine says

The Russian-occupied Zaporizhzhia Nuclear Power Plant is short of cooling water, diesel, and qualified staff, Ukraine’s Defense Intelligence (HUR) said on 20 October, warning of rising risks to nuclear safety. The water level in the plant’s cooling pond fell to 12.27 meters on 12 October, down from 12.86 meters in July, while the plant needs at least 15 meters to fully meet its needs, according to HUR. Russian managers are also considering cutting the number of backup generators kept on automatic standby, which would inevitably raise the risk of emergencies, the intelligence agency said.

Europe’s largest nuclear plant has been under Russian control since March 2022. Its six reactors have been in cold shutdown since April 2024, but they and their spent fuel still need constant cooling, which depends on water, on a single remaining external power line, and on diesel generators as the last resort. The International Atomic Energy Agency (IAEA) warned on 16 October that depleted diesel reserves increase the risk that nuclear safety is challenged if the plant loses power again, and that the situation may become acute in winter.

A pond with no source to refill it

The cooling pond has been sinking since Russia destroyed the Kakhovka dam in June 2023, cutting off the reservoir that fed it. Energoatom, Ukraine’s state nuclear operator, recorded 15.70 meters in October 2023. By June 2025, the level had fallen below 14 meters against a norm of above 16, Oleh Korikov, head of Ukraine’s State Nuclear Regulatory Inspectorate, said.

HUR’s figures show the decline continuing this year, from 12.86 meters in July to 12.63 in early August, 12.55 at the end of August, and 12.34 at the start of October. In 2025, the IAEA said groundwater wells on site were supplying cooling water for the safety systems. Its team had not been allowed to inspect a new dam in the cooling channel, access IAEA Director General Rafael Grossi called essential to assess the cooling water situation.

Diesel for a blackout that Russia cannot supply

If the plant loses external power, its diesel generators would burn about 150 metric tons of fuel a day in a prolonged blackout, HUR said. The occupation administration cannot deliver enough, so reserves stay minimal. Russian managers are also looking for covert fuel supplies, including low-quality fuel, without informing the IAEA mission, according to HUR.

The IAEA has already reported fewer generators on automatic standby. Since late September, only four of the plant’s 20 emergency generators would start automatically in a blackout, with the rest needing manual connection, which Grossi said deviates from normal practice. No diesel deliveries have reached the plant since March, the agency said on 16 October.

The plant spent nearly three weeks on generators after losing its last external line on 20 August, EP reported, until the Ferosplavna-1 line was restored under an IAEA-brokered ceasefire. The main 750 kV Dniprovska line remains out. HUR said the Kremlin rejected Ukraine’s proposal to supply power through it, which raises the nuclear safety risks.

Explore further

Russia blacked out Europe’s largest nuclear plant 15 times since occupying it in 2022

A plant short of the people who know it

About 5,000 people now work at the plant, against roughly 11,000 before the full-scale invasion, and only 1,450 were on site, HUR said. The plant lacks specialists who know its equipment, as well as the experts needed for repairs and for reconnecting it to external power. Russian managers plan training courses for applicants from Russian regions to replace Ukrainian staff, according to HUR.

In Enerhodar, the city where the plant’s staff live, mobile, internet, electricity, and water supplies keep failing, HUR said.