A nuclear incident following the breach of Ukraine’s Kakhovka dam is “highly unlikely” despite the loss of water supplies used to cool nuclear fuel at the nearby Zaporizhzhia nuclear power plant, nuclear scientists and the international oversight body said. on atomic energy.
“It’s not good – in fact it’s bloody awful – but as far as the power plant is concerned I don’t see any immediate risk of a nuclear incident,” said Paddy Regan, a professor of nuclear physics at the University of Surrey in the UK. “The biggest risk of loss of life is probably flooding from the dam burst.”
Kiev and Moscow blamed each other for Tuesday’s extensive damage to the dam, which spans the Dnipro River and is located about 140 km southwest of the Zaporizhzhia nuclear power plant. Since the plant in the southern province of Kherson is upstream from the dam, it will not be flooded.
When nuclear power plants are operating, they require a constant supply of water to prevent radioactive fuel from melting in reactors and to prevent spent fuel from overheating in cooling ponds.
The Zaporizhzhia plant, the largest in Europe in terms of generating capacity and dependent for its water on a reservoir fed by the Kakhovka dam, was built in a similar way to Japan’s Fukushima nuclear power plant. In 2011, a tsunami knocked out power generators used to pump water around four of Fukushima’s reactors, causing a nuclear disaster.
Five of the six reactors at Zaporizhzhia were placed in “cold shutdown” last year, while the sixth reactor was placed in “hot shutdown”, meaning neither need large supplies of fresh water to keep their temperatures under control.
“Temperatures in the cold shutdown reactors will be below 100C; all they have to do is circulate the water they already have in them,” says Mark Wenman, reader in nuclear materials at Imperial College London.
“The warm shutdown reactor also generates only a kilowatt of energy, one-thousandth of a fraction of the gigawatts it produces when in operation. I don’t see any real risk of an incident due to loss of water to the reactors,” he added.
The chance of a nuclear incident is further minimized by low temperatures in the giant cooling pools used to store spent fuel rods. Radioactive material can be released if the rods are still hot and exposed to air. But the rods are probably only about 50C, Wenman said.
In addition, the water levels in the ponds are deep. Energoatom, the state energy company of Ukraine, said: “As of 8 am, the water level is 16.6 meters, which is sufficient for the needs of the power plant.”
Rafael Grossi, head of the International Atomic Energy Agency, said in a statement that the IAEA’s assessment was also “that there is no immediate risk to the plant’s safety”.
Grossi added that the water level in the reservoir was dropping at a rate of 5 cm per hour, but it could continue to supply water to the power plant for “a few more days” and a large cooling pond could then serve as an alternative source of water .
“Since the reactors have been shut down for many months, it is estimated that this pond will be sufficient to provide cooling water for several months,” said Grossi, who will visit the plant next week.
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 personnel who manage and maintain it.
“Staff morale and well-being are at significant risk. . . (They) must perform their duties in an active war zone and in the presence of Russian military personnel,” said 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, burst dams had led to far more deaths than nuclear incidents, Regan said. The collapse of the Banqiao, Machhu II and Hirakud dams and hydroelectric power plants in China and India in the 1970s and 1980s caused the deaths of tens of thousands of people.
In contrast, the number of deaths directly related to radiation exposure from civil nuclear accidents is estimated by the World Health Organization to be about 50 and all resulted from the Chernobyl disaster, in northern Ukraine, in 1986.
“The situation clearly requires ongoing and close monitoring, but the first health problems will certainly arise due to flooding of homes and farms from the destroyed dam,” added Regan.