Chernobyl: A 108-Meter Arch Still Shields Reactor 4, But Only for a Century

It stands 108 meters tall, weighs 36,000 tons, and was designed to shield Reactor 4 for a century. Yet, less than a decade after its installation, a drone damaged the enormous arch. How can a nuclear disaster be safeguarded for generations to come?

The Chernobyl Arch Was Built Far From the Reactor Before an Incredible Rail Journey

It would have been impossible to calmly assemble a steel cathedral directly above a blown-out reactor. To limit workers’ exposure, engineers therefore built the new confinement for Chernobyl at a distance, on a cleaned-up area. Its dimensions are dizzying: 108 meters tall, 162 meters long, and 257 meters across.

In November 2016, the behemoth began its move toward Reactor 4. For this, a system of 224 hydraulic jacks pushed it forward in 60-centimeter steps. After covering 327 meters, the arch reached its final position. The EBRD still presents the whole ensemble as one of the largest mobile land structures ever built.

Under its 36,000 Tons of Steel, the 1986 Accident Is Far from Over

The arch does not erase Chernobyl. On the contrary, it encloses the remains of the destroyed reactor following the 26 April 1986 explosion, as well as the first Soviet sarcophagus hastily erected. According to the EBRD, the whole complex still houses about 200 tons of highly radioactive materials, including from molten fuel.

At the time, that first shelter was dangerously aging. Cracks, corrosion, and infiltrations were already complicating the situation. The new confinement was therefore meant to fulfill two missions: limit the dispersion of contaminated dust and allow teams to gradually dismantle the old sarcophagus using remotely operated equipment installed beneath the arch.

Moreover, even the air here is tightly controlled. A ventilation system keeps humidity low to slow down the rusting of steel. The century-long timeframe does not signify the disappearance of radioactivity; it primarily buys time for operations that several generations will need to carry on.

The Whole World Paid 1.5 Billion Euros for a Century of Safety

The construction of this metallic envelope cost roughly 1.5 billion euros. Additionally, the international program to secure the reactor exceeded two billion. Forty-five countries and institutions funded the confinement, under the coordination of the European Bank for Reconstruction and Development, which has become a key player in the project.

This mobilization tells another story of Chernobyl. Thirty years after the accident, the issue still crossed Ukrainian borders. Thus, in July 2019, authorities officially took charge of the confinement, its cranes, its monitoring systems, and its technical installations. The spectacular construction was nearing completion, but nuclear work was simply changing its form.

On 14 February 2025, however, a drone strike damaged the confinement envelope. Inspections revealed a roughly 15-square-meter through-and-through hole, damage to the cladding, and damage affecting several pieces of equipment. Despite the fire, available measurements showed no significant deterioration in the radiological situation around the site.

A Drone Strike in 2025 Brutally Reminded That Even This Giant Is Vulnerable

The issue is primarily about the long term. Indeed, the EBRD explained that the impact affected several systems essential to sustaining the planned lifespan. Teams launched emergency work, with costs potentially exceeding 100 million euros. In 2026, international partners also approved new studies and preparatory operations.

Now, the objective is to restore the arch’s functions in full by 2030. Yet this schedule changes the way people view the monument. Engineers had designed it to withstand cold, corrosion, and extreme natural phenomena. However, war has imposed a threat they had not placed at the center of their scenarios.

Even repaired, the arch remains only a pause point. During its century of operation, teams will need to dismantle, sort, monitor, and secure the materials resting beneath it. Tchernobyl is now measured in generations: when this immense vault eventually reaches the end of its life, what will be built to take over?