World’s worst nuclear disaster site faces 'catastrophic' collapse, 36,000-ton arch damaged

 A Greenpeace report released Tuesday, April 14, 2026, states that the internal radiation shell at the defunct Chernobyl nuclear power station is at risk of an uncontrolled collapse. 

Damage to the facility’s outer protective structure has compromised safety functions designed to prevent the release of radioactivity into the environment.

This warning comes days before the 40th anniversary of the 1986 reactor explosion. The report indicates that recent military actions have created technical failures that threaten the containment of the site.

The Chernobyl site utilizes a dual-layer containment system to manage the remains of reactor unit 4. The inner layer, known as the Sarcophagus or Shelter Object, is a steel-and-concrete shell built hastily in 1986.

This structure contains approximately 200 tons of highly radioactive nuclear fuel, dust, and debris. According to the report, the Sarcophagus is at an increased risk of a catastrophic collapse due to decades of structural fatigue and recent external shocks.

“That would be catastrophic because … there’s four tons of dust, highly radioactive dust, fuel pellets, enormous amounts of radioactivity inside the sarcophagus,” Shaun Burnie, a senior nuclear specialist for Greenpeace Ukraine, said earlier this month, as reported by The Japan Times.

Structural risks with the confinement system

An uncontrolled failure of this internal shell would release large quantities of radioactive particles. While the Sarcophagus requires urgent dismantling to mitigate this risk, current conditions at the plant prevent this engineering process from moving forward.

The stability of the internal ruins is now dependent on the integrity of the secondary shield, which has also sustained damage. A collapse would loft radioactive dust into the atmosphere, which can create a hazard for the surrounding region and potentially reach across international borders.

The New Safe Confinement (NSC) is a modern technological structure built to enclose the Sarcophagus and facilitate its eventual decommissioning. It is a 36,000-tonne steel arch designed to provide an airtight seal and allow for the robotic dismantling of the internal ruins.

“The NSC is an arch structure with a span of 257m, 162m long and 108m high. Its final skidded weight is 36,000 Tons,” as mentioned in a study by IABSE Symposium Report.

Investigations following a Russian drone strike in 2025 indicate that the NSC’s specialized confinement functions are now compromised.

A strike pierced the exterior of the NSC, which has impacted the complex systems required to maintain internal environmental controls.

“The Russian drone strike has now increased the risk that the Sarcophagus will collapse before it can be carefully dismantled,” highlighted Greenpeace.

Active war conditions hinder restoring the facility

Despite attempted repairs, the report finds that the facility’s ability to fully contain radiation has not been restored.

Engineer Eric Schmieman, who worked on the design and construction of the NSC, stated that the damage prevents the safe dismantling of the Sarcophagus using the facility’s internal cranes and robotic systems.

The NSC relies on ventilation and pressure management to ensure that no radioactive material escapes through the structure.

Constant missile and drone activity, along with frequent losses of electrical power, hinder the operation of these essential safety systems and the monitoring equipment used to track the state of the reactor core.

Ukraine and international donor nations previously agreed on a four-year timetable to investigate and repair the NSC. However, the report notes that performing major engineering works is nearly impossible under active war conditions.