Destruction of Ukrainian dam threatens Zaporizhzhia

June 6, 2023, 3:00PMNuclear News

A Soviet-era dam downstream from the Zaporizhzhia nuclear power plant in southeastern Ukraine collapsed last evening, causing the water level of the Kakhovka Reservoir north of the dam to drop and raising new concerns over the already jeopardized safety of the Russian-occupied nuclear facility, Europe’s largest. The reservoir supplies water for, among other things, Zaporizhzhia’s cooling systems.

According to Ukrainian military intelligence, Russian forces blew up the Nova Kakhovka dam—which lies across the Dnieper River at the Kakhovka hydroelectric power plant—at 2:50 a.m. Tuesday (local time) in an attempt to derail an anticipated Ukrainian counteroffensive. Russia denies responsibility for the action and is instead pointing the finger back at Ukraine. (The hydroelectric plant was captured by Russia in the early days of its invasion of Ukraine. Strategically important, it supplies water to the Crimean Peninsula, annexed by Russia in 2014.)

Five of the six Zaporizhzhia reactors are currently in cold shutdown, with one in hot shutdown. The plant has lost external power seven times since the invasion due to shelling in the area, which has prompted the plant’s emergency diesel generators to kick in to cool the reactors and spent fuel pools. Zaporizhzhia currently relies on only one of its four external power lines for operation.

Reactions: In comments on the social media platform Telegram, Ukraine’s nuclear operator Energoatom noted that while the reservoir’s water level “is rapidly decreasing, which is an additional threat to the temporarily occupied Zaporizhzhia NPP,” the beleaguered facility’s cooling pond is full. “Currently, the situation at the ZNPP is under control, Ukrainian personnel are monitoring all indicators. In the event of a change in the situation, Energoatom will promptly inform about the state of affairs.”

International Atomic Energy Agency director general Rafael Mariano Grossi provided a similar message to his board of directors this morning: “Absence of cooling water in the essential cooling water systems for an extended period of time would cause fuel melt and inoperability of the emergency diesel generators,” Grossi said. “However, our current assessment is that there is no immediate risk to the safety of the plant. The IAEA staff on the site have been informed that the damage to the Nova Kakhovka dam is currently leading to about 5 cm/hour reduction in the height of the reservoir. The team continues to monitor this rate and all other matters on the site. The main line of cooling water is fed from the reservoir and pumped up through channels near the thermal power plant to the site. It is estimated that the water through this route should last for a few days. Water in the reservoir was at around 16.4 meters at 8 a.m. If drops below 12.7 meters, then it can no longer be pumped. ISAMZ [the IAEA Support and Assistance Mission to Zaporizhzhia] reported that ZNPP is making all efforts to pump as much water into its cooling channels and related systems as possible. In addition, nonessential consumers of water are being stopped at ZNPP to reduce the consumption of water. ZNPP management is discussing further measures to be implemented.”

Grossi also noted a number of alternative sources of water available to the plant in the event the reservoir is drained—first and foremost the cooling pond, which by design is kept above reservoir height. “As the reactors have been shut down for many months, it is estimated that this pond will be sufficient to provide water for cooling for some months,” he said. “The agency will confirm this very shortly. It is therefore vital that this cooling pond remains intact. Nothing must be done to potentially undermine its integrity. I call on all sides to ensure nothing is done to undermine that. My trip to ZNPP next week was planned, and now it is essential. I will go. I will keep the board informed as developments unfold.”

Related Articles

The arrow is pointing up

March 13, 2024, 7:10AMNuclear News

There have been significant changes in the outlook for the existing U.S. nuclear fleet in the last few years. In 2021, we were looking at the early closure of units and could not even think of...