By FRANK JORDANS, Associated Press
BERLIN (AP) — A Ukrainian nuclear power plant that was surrounded by Russian forces lost power Wednesday morning when a Russian missile damaged a remote electrical substation, raising the risk of a radioactive disaster, the operator said. of the central.
Power at the Zaporizhzhia nuclear power plant was restored about eight hours later, the International Atomic Energy Agency said. But experts say the outage – the second in five days – shows just how precarious the situation at Europe’s biggest nuclear power station is. They say repeated power cuts over short periods of time only make the problem worse.
Here is an overview of the risks:
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Fears of a nuclear disaster have been at the fore since Russian troops occupied the plant at the start of the war. Continued fighting between Russian and Ukrainian forces – as well as the tense supply situation for the plant – raised the specter of disaster.
Ukrainian authorities decided several weeks ago to shut down the last reactor to reduce the risk of a disaster like Chernobyl in 1986, where a reactor exploded and emitted deadly radiation over a large area.
But the reactor core and the spent nuclear fuel still need to be cooled for long periods of time to prevent them from overheating and triggering dangerous meltdowns like those that occurred in 2011 when a tsunami hit the Fukushima plant in Japan. Japan.
Some European countries are trying to prepare for the worst and have started stockpiling iodine tablets to help protect their populations from possible radioactive fallout.
In others, such as Germany, authorities have calculated that there is a low risk of radiation levels harmful to human health reaching their territory.
In the event of a disaster, the biggest risk outside Ukraine could be Russia, “depending on which direction the wind is blowing”, said Paul Dorfman, a nuclear expert at the University of Sussex in England.
“The main deposit will probably be in Ukraine and/or Russia, but there could be significant radioactive pollution in Central Europe, which is why countries around Ukraine are now very seriously considering releasing iodide tablets stable potassium,” he said.
The Zaporizhzhia power plant has received external power to ensure the continuation of the important task of cooling the reactor and spent nuclear fuel, but the connections are constantly at risk of being interrupted due to the conflict.
As power lines and substations were damaged in the fighting, Ukrainian nuclear operator Energoatom was forced to repeatedly rely on diesel generators. These generators, which have enough fuel for at least 10 days, came into action when the external power supply failed, but experts say their repeated use over a short period of time increases the risk of disaster.
“There are several redundancies and the facilities are now repeatedly on the last one,” said Mareike Rueffer, head of the nuclear safety department at the German Office for the Safety of Nuclear Waste Management.
“Having to repeatedly fall back on diesel generators also limits room for manoeuvre,” she added. “At that time, there is no more backup and it is a high-risk technology.”
Diesel generators started immediately on Wednesday when power to the missile-damaged substation was cut off. External power to the transmission line was restored a few hours later.
The shutdown of the plant’s last reactor several weeks ago greatly reduced the risk of a radioactive disaster by gradually increasing the time it would take for a meltdown to occur. But if the cooling fails due to a total loss of power, meltdowns would still eventually occur, Rueffer said.
Dorfman said that in the worst case, Ukraine could see a situation similar to what happened in Fukushima.
“You would see a warming of the spent fuel ponds at high level. You would see a hydrogen explosion, like we saw in Fukushima,” he told The Associated Press. “And then you would see a significant radiation release.”
Associated Press writer David Keyton contributed from Stockholm.
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