Chernobyl, the risk of another permanent nuclear incident

The risk of a nuclear accident at Chernobyl is now very low: the reactors have been shut down since 2000 and the spent fuel is safe. Reactor 4 is confined under an arch that was completed in 2017, and the other reactors are being dismantled. On February 14, 2025, a drone damaged the arch without causing radioactive releases. Currently, the site is being stabilized to reduce risks by 2060.

The risk of a major nuclear accident is extremely low. The reactors have been permanently shut down since 2000, making any core fusion accident related to a nuclear chain reaction impossible. Spent fuel has been removed and is stored in dedicated facilities, where it is kept in safe conditions. The main issues are no longer the risk of a nuclear accident in the traditional sense, but rather the long-term management of decommissioning, radioactive material from the damaged core, and contaminated structures [1].

Reactor No.4, destroyed during the accident, was first covered with an sarcophagus built under emergency conditions, whose long-term stability was uncertain. A containment arch was built between 2008 and 2017. This structure aims to sustainably contain radioactive material, protect the environment, and allow for dismantling of the damaged reactor.

The other three reactors on the site have been definitively shut down and are subject to delayed decommissioning. This strategy consists of first performing certain operations (removal of equipment, securing), then placing the facilities under surveillance for several decades before their complete dismantling, initially planned starting from 2045.

A major issue concerns the management of spent fuel. Initially stored in a pool (ISF-1), it is gradually being transferred to a new dry storage facility (ISF-2), designed for a period of 100 years. This solution improves long-term safety by reducing active cooling requirements and associated risks.

On February 14, 2025, a drone hit the arch, causing a perforation in its wall and a fire. This impact resulted in no casualties or measurable increases in radioactivity in the environment, confirming the overall effectiveness of containment. Nevertheless, it damaged some elements of the structure and its equipment, partially compromising safety functions, including its containment capacity. The dispersion of radioactive materials out of the arch could only occur under very extreme conditions, involving a significant resuspension of the materials present inside the destroyed reactor, under the first sarcophagus, and under the arch itself [2] [3].

Finally, the strategy for the site is based on decommissioning spread over several decades, with an initial target around 2060. This approach took into account technical, radiological, and economic constraints. The long-term objective remains stabilizing the site and gradually reducing risks, while considering a possible future industrial use despite the current war in Ukraine.