Zaporizhzhia Nuclear Power Plant Relies on Emergency Diesel Generators to Maintain Operations

The International Atomic Energy Agency (IAEA) recently stated that the Zaporizhzhia Nuclear Power Plant (ZNPP) has been relying on emergency diesel generators to maintain critical safety systems for over a week following the interruption of its external power supply. After inspections by the agency's on-site expert team, it was confirmed that as of the 23rd local time, the plant's diesel reserves could support approximately 10 days of operation, approaching the minimum regulatory requirement.

According to the IAEA, the Zaporizhzhia Nuclear Power Plant lost its connection to the only remaining 330 kV Peresopravna-1 external transmission line starting on the 20th. Subsequently, the plant activated multiple emergency diesel generators to power critical equipment, including the six reactors and pumps related to spent fuel cooling and storage.

IAEA Director General Rafael Grossi stated that ensuring the nuclear power plant has sufficient diesel fuel is of paramount importance. If external power cannot be restored in the near term and additional diesel fuel cannot be delivered in time, the plant may face more severe power supply risks in approximately 10 days.

Regarding fuel replenishment, the IAEA stated that the external fuel storage facility at the Zaporizhzhia Nuclear Power Plant last received fuel in March of last year, and the subsequent replenishment originally planned for May was not completed on schedule due to delays in transportation arrangements. Since March 2025, for safety reasons, IAEA on-site expert teams have also been unable to access the relevant fuel storage facilities to conduct inspections.

In addition to power supply issues, the security situation around the plant continues to affect nuclear safety and security efforts. The IAEA on-site expert team reported that explosions have been heard near the plant on multiple occasions recently. This week, three drone-related incidents also occurred within the Zaporizhzhia Nuclear Power Plant site, one of which took place near the cooling pond and injured two plant employees, while another occurred near the dry spent fuel storage facility. There were also reports of a drone striking the plant's unit spray system. Radiation levels at the plant currently remain within normal range.

The IAEA stated that it continues to communicate on the on-site security arrangements required to restore the external transmission line and is advancing its support plan for Ukrainian nuclear facilities. The plan includes delivering portable power generation equipment to the Chernobyl Nuclear Power Plant and providing equipment such as dosimeters, batteries, and inverters to Ukraine's nuclear regulatory authority.