Liberation of the Chernobyl power plant: IRSN takes stock

In Ukraine, on March 31 and April 1, 2022, Putin’s army finally withdrew from the Chernobyl nuclear power plant, which had been taken by Russian forces. This retreat allowed the Ukrainians to regain control of the administration of the site. Currently, the situation of the infrastructures, such as that of the operators responsible for their maintenance, is not precisely known, an inspection of the site by the Ukrainian authorities is underway to ensure the security of the premises and, in particular, to check the possible presence of mines. Karine Herviou, IRSN Deputy Director General in charge of Nuclear Facilities and Systems Safety, answers questions from science and future.

Sciences et Avenir: Did the Russians really abandon the Chernobyl power plant?

Karine Herviou: IRSN has no information on this matter, we have no warnings about the state of infrastructure and staff. However, we recently received data from a beacon (full of sensors, editor’s note), located at the Chernobyl site, and it shows no unusual increase in radioactivity compared to the last signal seen in mid-March, shortly after the Russians invaded the area.

Power was restored to the plant, which had been shut down during the Russian occupation. What were the risks associated with this cut?

The case of Chernobyl differs from other power plants. As it is in the process of being dismantled, it does not pose the same threat as a traditional facility that requires daily actions such as B. Maintenance to replace certain parts necessary for their operation. Decommissioning a power plant, even a classic one, can take several years, and the Chernobyl situation means that this delay is even longer.
Here the current is mainly used to power monitoring instruments, e.g. B. to measure radioactivity indoors and outdoors, to measure the water level and temperature of the water in the spent fuel pool or to ventilate the protective dome of reactor 4 caused the accident of 1986. The loss of these monitoring means would primarily require the intervention of the Operators delay in the event of a fault, but this is not synonymous with a radioactive release. 20,000 spent fuel elements used in the 4 reactors between 1977 and 2000, when the plant was shut down, are stored in a dedicated pool. Even turning off the cooling system would cause the water to warm up by a few tens of degrees: this is totally insufficient to consider drainage (Emptying the pool after boiling the water, d. editorial) and/or radioactive release.

According to several media, the Russians left the area because of the radiation. Is this plausible and how are Ukrainian operators usually equipped?

It’s hard to say, but it’s unlikely her departure was motivated by radiation issues. Although the environment around Chernobyl remains heavily contaminated, radiation levels are not high enough to cause any immediate health effects. Precautions still need to be taken in certain locations that remain heavily contaminated from the 1986 accident. Ukrainian workers are all equipped with dosimeters to measure nearby radiation levels. They follow a number of regulations to limit their exposure and wear protective equipment where appropriate.

What about the state of health of those responsible for the system?

Chernobyl does not require urgent actions on the facilities, it is a more static facility than an operational power plant, so its management should be less problematic in case of failure. Dismantling work stopped at the beginning of the Russian invasion and workers evacuated, leaving only the operators responsible for safety. These teams must be able to carry out their monitoring mission to the fullest extent of their capacities for optimal management of the facility. But given the pressure exerted by the Russian soldiers on the ground and the constant threats her family was under, it’s understandable that her mind wasn’t entirely on her work. The last replacement took place between March 20 and 21, during the Russian occupation. Since then there seems to have been no other.

On the side of Zaporizhia
The fire at the Zaporizhia power plant on the night of March 3rd, 2022 shaped the international community. Since then, the industrial site in southern Ukraine has been under Russian rule. And the messages that reach us are very fragmented. “The plant faced partial interruptions to its power supply, which has since been restored. explains Karine Herviou. The operators are visibly relieved, but the operating crews need composure to carry out their tasks with constant communication and we do not know if these conditions are met at the plant.“The situation remains tense as Russian troops are still present at the factory.A certain number of long-term measures are necessary and may be affected by the Russian presence, the specialist continues. For example, it is not known whether access to the Zaporijia power plant will allow certain specialized subcontractors to intervene if they are still available. IRSN also wonders about the implications for mid- and long-term management, which are difficult to measure but need to be carefully considered. The IRSN Crisis Center is still active and vigils are being maintained at the international level.”

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