After the Zaporijia nuclear power plant, it is now Chernobyl’s turn to focus concerns in Ukraine. The Ukrainian operator Ukrenergo announced on Wednesday 9 March that the power supply “fully” cut on the spot as a result of Russian military actions. However, according to experts, the power cut does not “no major security risk”†
What happened ?
The plant, the cause of the worst civil nuclear disaster in 1986, “completely disconnected from the electricity grid due to military action by the Russian occupier”, the operator wrote on his Facebook page, without further details. With the offensive in full swing, “there is no possibility to restore the lines”he specified.
Emergency diesel generators took over andt “will be able to guarantee the vital activity of the site for a maximum of 48 hours”reports the supervisor. “After that, the stored fuel cooling systems stop”Ukrainian Foreign Minister Dmytro Kuleba warned.
The Chernobyl nuclear power plant, site of the worst civilian nuclear disaster in history in 1986, includes reactors that have been decommissioned, including No. 4 covered in a sarcophagus, and radioactive waste storage sites.
Telephone communications are also interrupted at the site, where more than 200 technicians and security guards have been blocked since February 24. They now operate under Russian command. The International Atomic Energy Agency (IAEA), the UN’s nuclear police officer, has asked Moscow to rotate them with other teams, as rest and fixed hours are essential for site safety.
What is the risk?
The damaged reactor itself is not a problem, said AFP Karine Herviou, deputy director general of the French Institute for Radiation Protection and Nuclear Safety (IRSN). Because “the molten heart does not need a cooling system”† And the fuels still stored in a pool on the site?
Given the time that has passed since the Chernobyl accident in 1986, “the thermal load of the spent fuel storage pool and the cooling water volume are sufficient to ensure efficient heat dissipation without electricity”guarantees the International Atomic Energy Agency (IAEA)† This interruption in the electrical supply therefore does not “no major impact on safety”.
The 20,000 fuel assemblies stored in the pool “are relatively cold”and even if the electricity is not restored after 48 hours, “there is no risk of radioactive discharges according to what we know about the installations”confirms Karine Herviou, Deputy Director General of the French Institute of Radiation Protection and Nuclear Safety (IRSN).
In such a case, investigations were conducted after the accident at the Fukushima nuclear power plant in Japan in March 2011 “shows a slow temperature rise in the order of magnitude up to 60°C but no dewatering of the assemblies”† “The water will gradually heat up but not boil”she says.
What about the operating power plants?
A power outage “would cause more problems” in the four power plants operating in the country“where it is absolutely necessary to ensure cooling of the fuel present in the reactor core or in the pool”says the head of the IRSN. “The heat to be removed is much greater there” than in Chernobyl.
Generators can “power cooling systems” for 7-10 days”† Out there, without electricity, “There would be a Fukushima-type scenario with a risk of reactor core collapse”†
Since the beginning of the Russian invasion, IAEA Director General Rafael Grossi has called for the utmost restraint. He has repeatedly offered to visit Ukraine to set up a framework to ensure site security during the conflict, the first to take place in a country with a major nuclear program.
“This time, if an accident happens, the cause is not a tsunami caused by Mother Nature, but the result of human failure to act when we knew we could and should.”he launched earlier this week.