Nuclear: tense situation but under control in Chernobyl

The specter of Chernobyl hasn’t finished terrifying the whole world yet. On Wednesday, Ukrainian operator Ukrenergo announced that the Chernobyl site, where the worst nuclear accident in history took place in 1986, has lost its electricity supply due to military actions nearby. The site has been occupied by Russian forces for several days and has also interrupted automatic communication of its data to the Ukrainian authorities and the International Atomic Energy Agency (IAEA).

“The factory’s sole power source has been damaged. I call on the international community to demand a ceasefire from Russia so that repairs can be made and food can be restored,” Ukrainian Foreign Minister Dmytro Kuleba asked. At this stage, the site only has emergency generators to provide the facilities with additional cooling, with 48 hours of diesel reserves to keep them running.

Swimming pools to cool off

However, the IAEA reassured, saying the risks of another disaster appear limited. This power outage will have “no major impact on safety,” the agency said because “the thermal load on the spent fuel storage basin and the volume of cooling water are sufficient to ensure efficient heat dissipation without electricity.”

“After the Fukushima accident, a study was conducted to assess the impact of a total loss of electricity on the site. It showed that the temperature of the pool responsible for cooling the nuclear fuel assemblies, historically used in the reactors at the Chernobyl site, would not exceed 60 degrees. If nothing else happens, there is therefore no risk that the water in this pool will evaporate,” says Karine Herviou.

The Chernobyl site still has four disused reactors, including the one that was damaged in 1986. The last reactor on the site was shut down in 2000 and the nuclear fuel has been unloaded ever since. There also remains – in addition to the famous basin responsible for cooling the spent fuel assemblies – “cold” storage of nuclear waste, that is, which does not require cooling.

A worrying situation

“A loss of external electricity would be more concerning in a working factory that must constantly run pumps to cool the nuclear fuel. In Chernobyl, the loss of electrical power mainly means a loss of information available to control the site. The sensors that measure the water level in the swimming pools, the water temperature and the level of radioactivity are no longer powered,” explains Karine Herviou.

This context makes the work of the employees responsible for the safety and security of the installations considerably more difficult. Especially since the latter have not been forwarded by their colleagues for ten days. “I am deeply concerned about the difficult and stressful situation for the Chernobyl nuclear power plant personnel and the risks it poses to nuclear safety,” said Atomic Energy Agency head Rafael Grossi.