What is the situation at Ukraine’s Chernobyl nuclear power plant?

• Does the takeover of Chernobyl by the Russian army lead to a new nuclear risk?

Since the entry of the Russian army into the Chernobyl zone on February 25, the former damaged power station has been cut off from the world. Reactor number 4, which exploded in 1986, rests under a protective enclosure. But the area still houses many waste deposits, as well as a building where radioactive fuel is stored, extracted from the three other reactors of the plant which operated until 2000 and which are in the process of being dismantled. Several hundred employees continue to work on this site.

On Wednesday March 9, the Ukrainian operator Ukrenergo reported that the plant “has been completely disconnected from the electricity grid due to the military actions of the Russian occupier”. According to the Ukrainian Foreign Minister, the plant has “backup generators with a capacity of 48 hours”. Beyond this period, the fuel stored in pools can no longer be cooled.

Nuclear: “People must be informed regarding the potential risks”

The International Atomic Energy Agency (AEIA), however, is reassuring. Even if the fuel cooling systems no longer work, “the thermal load of the swimming pool and the volume of the cooling water are sufficient to ensure efficient heat removal without electricity”. The French Institute for Radiation Protection and Nuclear Safety (IRSN) confirms that such a cut “would be serious for a plant in operation, much less in Chernobyl where the fuel has been removed for a long time”.

• Why is the IAEA concerned regarding staff?

“Chernobyl is shut down, but remains a nuclear facility, with fuel, waste, and risks, confides an expert of the file. This is not an abandoned site, far from it. We have to take care of it. » Hence the staff on site. Except that, since February 25, it can no longer be raised. The management of the plant estimates that 210 people are stranded. According to one staff member: “A shift lasts in principle twelve hours, during which the personnel remain constantly at their post, day and night. There, they are retained and chain the quarters. »

→ ANALYSIS. War in Ukraine: what threats to nuclear power plants?

All employees live in Slavutych, a town on the edge of the contaminated area. But since February 25, communications have been cut off. Only a plant supervisor was able to inform the families that the employees are alive, but that staff rotations are no longer authorized.

The Director General of the AEIA says to himself “deeply concerned regarding the difficult situation in which the personnel of the plant find themselves” and ask “the forces that actually control the site to immediately ensure that the personnel on site can be relayed in complete safety”.

• Is the IAEA’s loss of contact with Chernobyl worrying?

The IAEA is also concerned, in its latest press release, regarding the fact that “the remote transmission of data from the safeguards control systems installed at the Chernobyl nuclear power plant had been cut off”. In the jargon, “safeguards control” refers to the non-proliferation of nuclear weapons. Specifically, the agency monitors fissile materials that can be used to make bombs. Sensors on the stocks, the seals, or even on certain access doors make it possible to follow the movements of these materials.

With the power cut and the shutdown of communications, no more information filters through, whether on these stocks of fissile materials, on the waste or even on the state of the sarcophagus around reactor number 4. “Normally, data is transmitted by sensors in the installations, to measure, for example, an increase in heat or radioactivity, and beacons measure the radioactivity near the plant, indicates the IRSN. Today, the Ukrainian nuclear safety authority is blind to what is happening at the site. »

On March 6, President Emmanuel Macron spoke by telephone with Vladimir Putin to discuss the security of Ukrainian nuclear sites, while another plant, in Zaporijjia, was taken over by the Russian army during a assault that caused a fire. The Director General of the IAEA has also offered to go to Ukraine to negotiate a framework to guarantee the security of nuclear sites. But this proposal was not followed up.