A Russian Drone Has Pierced One of the World’s Greatest Engineering Works. The Problem: It’s the Sarcophagus of Chernobyl’s Fourth Reactor

Saturday, April 26, 1986 will forever be remembered for the catastrophic events at Chernobyl, a nuclear power plant in Northern Ukraine, then part of the Soviet Union. The explosion of reactor number four resulted in the worst nuclear accident in history. In response, the Soviets hastily constructed a sarcophagus to mitigate the impact. Over time, an impenetrable shield was erected to contain radiation, but no one expected that a war would pass through that area.

An unexpected drone. On Feb. 14, Russia launched an Iranian-made Shahed 136 explosive drone that smashed a hole in the steel dome of Chernobyl’s fourth reactor, known as the New Safe Confinement. It’s considered one of modern engineering’s greatest feats and was designed to contain the aftermath of the worst nuclear disaster in history.

The confinement structure was completed in 2016 at a cost of $1.7 billion and involved the efforts of more than 45 countries. Although it was designed to withstand natural disasters, the structure wasn’t built to withstand acts of war. The Russian drone, which is estimated to have cost around $20,000, started a fire that lasted nearly three weeks. According to Ukrainian authorities and the International Atomic Energy Agency, the attack severely damaged the northern part of the structure and affected the southern section as well.

Immediate consequences. While the initial fire was quickly extinguished, a waterproof membrane inside the insulation continued to burn and smolder for days. To extinguish the fire, emergency teams had to make holes in the outer layer of the dome and introduce pressurized water. This action is technically prohibited because it contradicts the goal of keeping the interior dry to prevent corrosion.

What’s the issue? This intervention significantly increased humidity levels inside the enclosure, which now poses a serious risk to the structure’s stability and insulation capacity. On March 7, Ukraine officially declared the fire extinguished. However, extensive damage had already been done, seriously compromising the dome’s original functionality.

Although external measurements indicate normal radiation levels, the integrity of the system is now in question. This situation necessitates reconsidering the reactor’s decommissioning plan and the management of radioactive waste, which is scheduled to begin within the next five years.

Implications for nuclear security. Experts told The New York Times that the recent attack’s impact was both physical and symbolic. It highlighted the vulnerability of a structure designed to endure for a century and protect Europe and the world from the reactor’s radioactive contents. Experts and Ukrainian authorities point out that the structure no longer effectively serves its confinement purpose and may need to be completely dismantled and replaced. This operation would cost millions and involve significant technical challenges.

Eric Schmieman, one of the original project’s lead engineers, suggests implementing temporary measures to reduce moisture and prevent corrosion. These could include the use of temporary seals and reactivating the ventilation system. However, repairing or rebuilding the structure in its current location is nearly impossible due to high radiation levels. Additionally, moving it poses severe risks, especially considering the deteriorated condition of the original Soviet sarcophagus that remains inside.

The features of the perforated New Safe Confinement.

Historical context. The damaged shield is the result of decades of efforts to contain a catastrophe that led to the evacuation of a 1,000-square-mile exclusion zone in 1986. The nuclear accident also left an official death toll of 31 immediate fatalities and caused a sustained increase in cancers, particularly thyroid cancer.

The original sarcophagus was constructed as an emergency measure by the Soviet Union, but it eventually started to collapse. Planning and executing its replacement took years. The current structure was built 1,600 feet away to minimize exposure before being slid over the reactor. It’s made up of two layers of steel and features moisture control systems to prevent rust and collapse. Its purpose is clear. It aims to contain radioactive dust and facilitate the controlled dismantling of the reactor using cranes installed within. Unfortunately, this entire process is currently on hold indefinitely.

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Drones, warfare, and vulnerability. The recent attack highlights a significant milestone in the vulnerability of critical infrastructures to inexpensive and hard-to-intercept weapons like drones. So far, both Ukraine and Russia have refrained from directly targeting active nuclear power plants. However, the increasing use of drones for strategic attacks on energy facilities has raised global concerns.

In this context, as part of ceasefire negotiations, President Donald Trump even proposed that the U.S. assume control of Ukrainian nuclear and power facilities to mitigate threats. According to Artem Siryi, who oversees the structure operations, several drones fly over Chernobyl almost every night, primarily heading toward Kyiv. This situation underscores the necessity of reevaluating the protection of nuclear sites in light of this new, persistent, and accessible aerial threat.

Future. Predicting the outcome is challenging. The New York Times reported that fully restoring the damaged structures may prove nearly impossible. Experts recommend implementing urgent mitigation solutions while assessing the feasibility of reconstruction.

Ironically, the same type of device that damaged the dome could now serve as an ally. Small drones developed by Ukraine could assess internal damage and support remote repairs, minimizing human exposure to radiation.

The costs, extent of the damage, and associated risks create a technical and financial dilemma for the international community. The pressing question now is whether to embark on a new massive project or risk a future catastrophe due to inadequate protection.

Image | Romain Chollet

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