The development comes two weeks after Russian forces took control of the site, the agency’s director general Rafael Mariano Grossi said. He expressed concern at the news, as the ‘secure off-site power supply from the grid for all nuclear sites’ was one of seven indispensable pillars of nuclear safety and security outlined by him at a meeting of the IAEA’s Board of Governors on 2 March.
However, the director general said the IAEA agreed with the Ukrainian regulator that the disconnection would not have a critical impact on essential safety functions at the site, where radioactive waste management facilities are located.
The IAEA said that regarding the site’s spent fuel storage facility, the volume of cooling water in the pool is sufficient to maintain effective heat removal from the spent fuel without an electricity supply. The site also has reserve emergency power supplies with diesel generators and batteries.
Nevertheless, lack of power is likely to lead to further deterioration of operational radiation safety at the site and create additional stress for technical experts and guards who have been effectively ‘living there around the clock’, director general Grossi added.
“From day to day, we are seeing a worsening situation at the Chernobyl NPP, especially for radiation safety, and for the staff managing the facility under extremely difficult and challenging circumstances,” he said.
“I repeat my urgent appeal to the forces in effective control of the plant to respect internal radiation protection procedures, to facilitate the safe rotation of staff and to take other important steps to ensure safety.”
Commenting on the IAEA’s statement, Professor Claire Corkhill, chair in Nuclear Material Degradation at Sheffield University, said that there are ‘several areas of concern’ regarding safety of nuclear material at Chernobyl, the first being the spent nuclear fuel from reactors 1 and 3 stored in the cooling pond.
“This material produces heat through radioactive decay and requires constant cooling, which is achieved by pumping fresh cool water into the ponds. With no power supply, this water could slowly evaporate, potentially resulting in contamination of the building by low levels of radioactive isotopes,” Corkhill said.
“It is essential that radiation monitoring systems are able to constantly monitor the situation inside reactor 4 so that we can be aware of any potential reasons for concern about the exposed nuclear fuel that resides there.
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“Another serious concern is the maintenance of the ventilation system in the New Safe Confinement structure. This prevents further degradation of Reactor number 4 and the hazardous exposed nuclear fuel within, and is essential to the future decommissioning of the site. If there is no power to this structure, we could see the complete failure of the 1.5 billion euro decommissioning programme to make the site safe once and for all.”
Director general Grossi said the IAEA had also recently lost remote data transmission from its safeguards systems installed to monitor nuclear material at the Chernobyl NPP and another Ukrainian nuclear power plant now controlled by Russian forces, the Zaporizhzhya NPP.
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He expressed concern about sudden interruption of data flows to the IAEA’s Vienna headquarters from the sites, where large amounts of nuclear material are present. The reason for the disruption wasn’t immediately clear, the IAEA said, adding that it continues to receive such data from other nuclear facilities in Ukraine including three other power plants.
Although technical features were in place to ensure data was stored locally, the storage capacity and operational status of the monitoring systems remained uncertain, Grossi said.
Through safeguards technical measures the IAEA verifies that countries are honouring their legal obligations to use nuclear material and technology only for peaceful purposes.
Materials professor Tom Scott, Bristol University, said that he agrees with the IAEA that the spent fuel in the storage ponds at Chernobyl doesn’t present a ‘substantial risk’.
“The fuel in these pools is decades old, and hence has very little residual heat being generated,” Prof. Scott said. “This low heat load added to the very large volume of water in the cooling pools means that the heat coming from the fuel can be dissipated safely even without power to circulate the water.”
He added that it is still important that the situation continues to be actively reported to the IAEA, and any communications break needs to be quickly re-established.
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