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Situation at Ukrainian nuclear plants worrying as shelling and power cuts threaten containment

Ukraine’s four operational nuclear power plants all have access to the national grid again following a complete loss of off-site power last week. It was the first time that all the plants suffered a loss of external power at the same time since the conflict began nine months ago. They relied on diesel generators for back-up electricity

‘The complete and simultaneous loss of off-site power for Ukraine’s nuclear power plants shows that the situation for nuclear safety and security in the country [has] become increasingly precarious, challenging and potentially dangerous,’ said Rafael Mariano Grossi, director general of the International Atomic Energy Agency (IAEA). ‘It is extremely concerning. The situation further underlines the need for stepped-up action to protect the plants and prevent the danger of a serious nuclear accident.’

The recent shelling at the site of Ukraine’s Zaporizhzhia Nuclear Power Plant (ZNPP) has been one of the most intense episodes in recent months, according to the IAEA, which has a team on site. The ZNPP, Europe’s largest nuclear power plant, has lost power from the grid several times in recent months. Russia captured the plant early in the war.

The facility remains in shutdown mode but still needs electricity to maintain essential safety and security functions. Reactors need power for cooling even when they are in shutdown. Four of its six reactor units are in ‘cold shutdown’, while the two other units have been returned to ‘hot shutdown’ again – enabling them to provide steam to the plant and heat to the nearby city of Enerhodar.

The ZNPP has 20 diesel generators which start operating automatically when connection to the grid is lost. Typically, plants hold 10 days’ worth of fuel. In this latest episode, eight generators were needed over a day or so. The IAEA team reported that the plant’s six reactors were safe, and confirmed the integrity of the spent fuel, the fresh fuel and radioactive waste storage facilities. However, there was widespread minor damage across the site.

Matthew Bunn
, professor of the practice of energy, national security, and foreign policy at the Harvard Kennedy School, agrees that nuclear reactors in a war zone pose potentially deadly dangers. ‘Operating a reactor on the backup diesel generators is something that should be done rarely and briefly,’ he says. ‘In Ukraine, they are being forced to do it again and again. Every time off-site power gets cut off, you’re operating with no backup to the diesel generators. If they fail, within hours the water will boil off, the reactor core will be exposed, and the fuel in the core will begin to melt and a catastrophic radiation release is likely. This is true even if a reactor is not operating: when the reactor shuts down, it stops releasing energy from splitting atoms, but the intensely radioactive material in the core continues to generate a lot of heat from radioactive decay. However, some of the reactors at Zaporizhzhia have been shut for months and have cooled somewhat. Now, if there were a total loss of power at those reactors, there would be significantly more time to try to restore power before melting would begin.’……………………………………..more


November 30, 2022 - Posted by | safety, Ukraine

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