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The Chernobyl nuclear power plant has ceased transmitting data to the UN's atomic watchdog, the agency said, nearly two weeks after Russian forces seized the site.
President Vladimir Putin’s troops captured the defunct site on February 24, the first day of the full-scale invasion of Ukraine.
The International Atomic Energy Agency expressed concern for staff — working under Russian guard — who have not been allowed to rotate shifts with their peers who were off duty on the day of the attack. The agency said Ukrainian authorities had informed it that power at the station had been switched off.
The agency’s chief, Rafael Grossi, “indicated that remote data transmission from safeguards monitoring systems installed at the Chernobyl NPP had been lost”, according to an agency statement on Tuesday.
“The agency is looking into the status of safeguards [and] monitoring systems in other locations in Ukraine and will provide further information soon,” it said.
Ukrainian grid operator Ukrenerho said that, according to the national nuclear regulator, all Chernobyl facilities are without power and the diesel generators have fuel for 48 hours. Without power the “parameters of nuclear and radiation safety” cannot be controlled, it said.
The IAEA said it saw “no critical impact on safety” from the power cut. The Vienna-based UN nuclear watchdog said Ukraine has informed it of the loss of electricity and that the development violates a “key safety pillar on ensuring uninterrupted power supply”.
The IAEA said there could be “effective heat removal without need for electrical supply” from spent nuclear fuel at the site.
Foreign Minister Dmytro Kuleba said the grid supplying electricity is damaged and called for a ceasefire to allow for repairs.
The plant is the site of the infamous 1986 disaster that killed hundreds and spread radioactive contamination west across Europe.
The IAEA uses the term “safeguards” to describe technical measures it applies to nuclear material and activities, with the objective of deterring the spread of nuclear weapons through early detection of the misuse of such material.
More than 200 technical staff and guards are trapped at Chernobyl, and have worked 13 consecutive days since the Russian takeover.
The situation for the staff “was worsening” at the site, the IAEA said, citing the Ukrainian nuclear regulator.
The station is located in an exclusion zone that houses decommissioned reactors as well as radioactive waste facilities. More than 2,000 staff still work at the plant because it requires constant management to prevent another nuclear disaster.
The UN agency called on Russia to allow workers to rotate because rest and regular shifts are crucial to safety at the site.
“I'm deeply concerned about the difficult and stressful situation facing staff at the Chernobyl nuclear power plant and the potential risks this entails for nuclear safety,” Mr Grossi said.
“I call on the forces in effective control of the site to urgently facilitate the safe rotation of personnel there.”
Just over a week after seizing Chernobyl, Russian soldiers attacked and took control of Europe's largest atomic power plant, Zaporizhzhia, last week, drawing accusations of “nuclear terror” from the Ukrainian government.
Zaporizhzhia alone has six reactors of a more modern, safer design than the one that melted down at Chernobyl.