Ukraine's Zaporizhzhya Nuclear Power Plant (ZNPP) has for several days depended on a single power line for the off-site electricity it needs to cool its six reactors and for other essential nuclear safety and security functions, leaving it highly vulnerable to any further grid disruptions during the military conflict, Director General Rafael Mariano Grossi of the International Atomic Energy Agency (IAEA) said today.
The site's fragile power supplies continue to be at the centre of concern regarding nuclear safety and security at Europe's largest nuclear power plant (NPP), underlined by the site's eighth complete loss of external electricity last Saturday after the separate connections to both of its remaining power lines were cut, apparently caused by external grid events outside the ZNPP. As a result, the plant temporarily relied on emergency diesel generators for power.
It regained the connection to its main 750 kilovolt (kV) line after nearly five hours, but its last 330 kV back-up power line is still disconnected. The IAEA experts at the ZNPP have been informed that the repairs are expected to be completed by early next week. Before the conflict, the ZNPP had four 750 kV lines as well as several back-up options available.
The IAEA team also reported that reactor unit 4 - whose main cooling pumps briefly stopped running during last week's external power loss - is once again in hot shutdown mode producing heating and steam for the site and the nearby town of Enerhodar, where most plant staff live. The other five reactors remain in cold shutdown.
"The IAEA remains fully focused on doing everything it can to help prevent a nuclear accident during this devastating war. The repeated loss of off-site power at the Zaporizhzhya Nuclear Power Plant, sometimes from causes at a considerable distance from the plant, remains one of our main challenges in this context, especially during the winter months. No one would gain from a nuclear accident and it must be avoided," Director General Grossi said.
The ZNPP has also previously relied on one sole external power line, but it is clearly not a sustainable situation, Director General Grossi added.
Two days ago, a new team of IAEA experts crossed the frontline to replace their colleagues who had been monitoring nuclear safety and security at the ZNPP for the past several weeks. It is the fourteenth IAEA team at the site since the IAEA Support and Assistance Mission to the ZNPP was established by the Director General in September 2022.
The new team of IAEA experts will continue to pay close attention to the staffing situation at the ZNPP, the status of the external power supply as well as maintenance activities at the site, including any actions the plant may take following last month's detection of boron in the secondary circuit of a steam generator of unit 5. Borated water is used in the primary coolant to help maintain nuclear safety functions.
In a continuous reminder of the physical proximity of the conflict to the ZNPP, the IAEA experts continue to hear explosions in the distance, likely from heavy artillery and rockets. Today, the new team reported that they heard nine explosions closer to the site.
Also today, the IAEA team conducted a walkdown of the turbine halls of all six reactor units. The experts did not observe any mines, explosives, military equipment or vehicles in the areas they visited. Not all parts of the turbine halls were accessed so additional access would be required to fully assess whether there were any items present that could potentially impact nuclear safety.
Elsewhere in Ukraine, the IAEA experts present at the Khmelnitsky, Rivne and South Ukraine NPPs as well as at the Chornobyl site have reported that nuclear safety and security is being maintained despite the challenging war-time circumstances, including the frequent sound of air raid alarms at some of the facilities.
The IAEA is continuing to support nuclear safety and security in Ukraine with the delivery of much-needed equipment and other technical assistance. Last week, the South Ukraine NPP received the third and final delivery of spare parts and rubber products for the site's emergency diesel generators, ensuring their operational readiness if the site were to lose external power. The provision of this assistance was organized under a tripartite agreement between the IAEA, France and Ukraine's nuclear operator Energoatom signed in May this year.
