Nuclear accident at Zaporizhzhia plant highly unlikely after dam attack

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A nuclear accident following the rupture of Ukraine’s Kakhovka dam in Ukraine is highly unlikely, despite the loss of water supply used to cool nuclear fuel at the nearby Zaporizhzhia power plant, nuclear scientists and the international body overseeing the nuclear power plant said atomic energy.

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It’s not good in fact it’s bloody awful, but in terms of a power plant I don’t see an immediate risk of a nuclear accident, said Paddy Regan, professor of nuclear physics at the University of Surrey in the UK. The greatest risk to loss of life is probably flooding from a dam burst.

Kiev and Moscow blamed each other for Tuesday’s extensive damage to the dam, which crosses the Dnipro River and is located about 140km southwest of the Zaporizhzhia nuclear power plant. Since the plant in the southern province of Kherson is located upstream of the dam, it will not be flooded.

When in operation, nuclear plants require a constant supply of water to prevent melting of radioactive fuel in reactors and overheating of spent fuel in cooling ponds.

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The Zaporizhzhia plant, which is Europe’s largest by generating capacity and relies on a reservoir fed by the Kakhovka Dam for its water, is built similarly to Japan’s Fukushima nuclear power plant. In 2011, a tsunami knocked out the power generators used to pump water around four of Fukushima’s reactors, causing a nuclear disaster.

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Five of Zaporizhzhia’s six reactors were placed in cold shutdown last year while its sixth reactor is in hot shutdown, meaning neither require large supplies of fresh water to keep temperatures in check.

The temperatures in the cold-stopped reactors will be below 100°C; all they have to do is keep circulating the water they already have inside them, said Mark Wenman, a lecturer in nuclear materials at Imperial College London.

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Even the hot shutdown reactor generates only kilowatts of energy, thousandths of a fraction of the gigawatts it produces while in operation. I don’t see any real risk of an accident due to water leaking into the reactors, he added.

Further reducing the likelihood of a nuclear accident are the low temperatures in the giant cooling pools used to store spent fuel rods. There may be a release of radioactive material if the rods are still hot and exposed to air. But the rods are probably only about 50 degrees Celsius, Wenman said.

Also, the water levels in the ponds are deep. Energoatom, the state energy company of Ukraine, said: At 8 am, the water level is 16.6 meters, which is sufficient for the needs of the power plant.

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Rafael Grossi, head of the International Atomic Energy Agency, said in a statement that the IAEA’s assessment is also that there is no immediate safety risk to the facility.

Grossi added that the water level in the reservoir was falling at a rate of 5 cm per hour, but that it would still be able to supply the plant with water for a few more days and that a large cooling pond could then serve as an alternative water source.

Since the reactors have been shut down for several months, this pond is estimated to be sufficient to provide cooling water for several months, said Grossi, who will visit the plant next week.

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Western officials, military analysts and scientists have long warned of the possibility of a nuclear accident at the power plant, which has been occupied by Russian forces since last March.

Adding to the risks are the exhaustion and low morale of the Ukrainian staff who operate and maintain it.

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Staff morale and well-being issues pose a significant risk…[They] they must perform their tasks in an active war zone and in the presence of Russian military personnel, Darya Dolzikova and Jack Watling warned in a recent report on civilian nuclear infrastructure for the Royal United Services Institute think-tank in London.

Historically, dam bursts have caused far more deaths than nuclear accidents, Regan said. The collapse of the Banqiao, Machhu II and Hirakud dams and hydroelectric plants in China and India in the 1970s and 1980s claimed the lives of tens of thousands of people.

In contrast, deaths directly associated with radiation exposure from civilian nuclear accidents are estimated by the World Health Organization to be around 50, all stemming from the 1986 Chernobyl disaster in northern Ukraine.

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The situation clearly needs continuous and careful monitoring, but the first health problems are sure to arise as homes and farms are flooded by the destroyed dam, Regan added.

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