Nuclear, Waste Management & Decommissioning

Bechtel-led confinement arch completed over Chernobyl Unit 4 site

Thirty-three years after the horrific 1986 accident that killed 28 people at the time and more later, the massive containment arch is now complete and in place over reactor unit 4 at the Chernobyl nuclear site in the Ukraine.

Bechtel Corp., which is project leader, congratulated the international team for concluding a critical test to complete work last Friday. The arch, known as New Safe Confinement, will protect the environment from additional releases of radioactive materials, as well as protect the damaged reactor from weather and seismic events.

Bechtel led the consortium that designed the sports-stadium-sized arch that was slid over the reactor in 2016. Today, Bechtel is the project management unit, ensuring that engineering and construction meet the plant owner’s strict quality requirements.

 Since 2016, crews have added walls to both ends of the arch and installed equipment to allow future dismantling of the damaged building and reactor with remote-operated cranes and tools. 

The arch is the largest movable land structure ever built – massive enough to cover several Statues of Liberty, according to Bechtel.

“This is the day we’ve been working toward” said Oscar “Mac” McNeil, Bechtel’s project manager at the Chernobyl site. “With construction and testing complete, we will soon turn over the facility and all systems to the plant operators. It’s an accomplishment that required international cooperation and ingenuity to overcome the challenges presented by radiation and the environment around the plant, not the mention the Ukrainian winters.”

Chernobyl’s reactor No. 4 melted down in 1986. A concrete covering, hastily built over the reactor, developed cracks and became unstable, prompting the need for a longer-term solution.

Bechtel is under contract to the State Specialized Enterprise – Chernobyl Nuclear Power Plant. Also playing key roles on the team are the French consortium NOVARKA, who constructed the arch, and the European Bank for Reconstruction and Development, which has financed the project along with more than 40 donor nations.

The arch weighs 40,000 tons, measures 345 feet tall, 540 feet long, and spans 840 feet. It has 80 elements fastened together with some 600,000 bolts.

VINCI Construction Grands Projets and Bouygues Travaux Publics partnered to build the container for the confinement vessel.