A generation after the nuclear explosion at Chernobyl spewed radioactive material over more than 60,000 square miles, construction has begun on a new steel confinement shelter to enclose the ruined reactor.
Coatings and corrosion control will play important roles in the multinational construction project to cover the crumbling concrete reactor shelter—called the “sarcophagus”—hastily erected after the disaster at the Chernobyl Nuclear Power Plant on April 26, 1986.
|Soviet government authorities took this photo of the Chernobyl Nuclear Power Plant immediately after the explosion of Reactor No. 4 on April 26, 1986. Radioactive material was spewed six miles into the atmosphere and across more than 60,000 square miles.|
Construction of the new shelter, called the New Safe Confinement (NSC), began April 26, 2012—26 years to the day after the disaster.
The work is underway about 30 miles outside Chernobyl, in Slavutich, Ukraine—a town built after the disaster to house clean-up workers and displaced families
The NSC construction is the largest of 22 tasks outlined in the €1.5 billion ($1.87 billion US) Chernobyl Shelter Implementation Plan (SIP), developed in 1996 to transform the shelter to an environmentally safe condition.
The goal is to mitigate atmospheric radioactivity for the next century, while the interior is dismantled and cleaned.
The SIP is funded by donations from more than 30 nations to the Chernobyl Shelter Fund, which is administered by the European Bank for Reconstruction and Development.
SIP project management is being led jointly by Battelle, the world’s largest independent research and development organization; and Bechtel International Systems Inc. (Electricité de France, an original member of the consortium, withdrew in 2010.)
Site preparation has been underway since 2008 to ready the area for the approximately 1,000 workers now at work there. The site was cleaned, and contaminated soil was replaced and covered by concrete.
Battelle employees from corporate headquarters in Columbus, OH, are working on the NSC construction with staff from Pacific Northwest National Laboratory in Richland, WA.
Creative Commons / Carl Montgomery (right); Trulystand700 (left)
|The New Safe Confinement structure (left) will completely cover the old metal-framed concrete containment shelter (right) hastily erected over the ruined reactor in 1986. Inside lies 740,000 square meters (885,000 square yards) of radioactive debris.|
Built from one-meter diameter tubular steel, the 20,000-ton, arch-shaped confinement structure will weigh as much as three Eiffel Towers. At 250 meters (820 feet) wide, 150 meters (492 feet) long, and 100 meters (328 feet) tall, it will be large enough to enclose the Statue of Liberty.
Once construction of the structure is complete, the team will slide it into place over the old Object Shelter. The project should be complete in 2015.
Ukraine’s Cabinet of Ministers approved the conceptual design (created by the Battelle-Bechtel-EDF consortium) in 2004. A contract for final design and construction was awarded in 2007 to Novarka, a joint venture of two French construction companies. The arch’s steel is being fabricated in Italy.
The New Safe Confinement has been designed for a 100-year lifespan.
Initially, the steel structural components of the arch are being coated with inorganic zinc and then given an epoxy overcoat, primarily to avoid corrosion during shipping and assembly, according to Battelle engineer Eric Schmieman, who is working on site in Ukraine.
Battelle / Dan Kelly
|The new confinement shelter is being built about 300 meters west of Chernobyl. Extensive site preparation work began in 2008 to reduce the radiation risk to workers.|
Typically, such a structure would be periodically repainted with protective coatings throughout its life to protect against corrosion. However, because of radiation levels, repainting will not be possible, Battelle spokesman T.R. Massey explained in an email.
(The current sarcophagus covers 200 tons of radioactive corium, 30 tons of highly contaminated dust, and 16 tons of uranium and plutonium.)
Therefore, engineers have devised a different corrosion control solution, Massey said.
“The arch has an outer ‘skin’ and inner skin, such that the steel structural elements are enclosed in a 12m wide annular space,” Massey wrote. “There is a special ventilation system designed to maintain the annular space relative humidity less than 40%.
“Steel corrosion is negligible at humidity levels below this amount. So, in this unique structure, the steel is protected by environmental controls rather than coatings.”
‘The Whole World Came to Our Rescue’
At the kickoff ceremony for the new construction last month at the ruined plant, Ukrainian President Viktor Yanukovych thanked international donors for their support.
“It feels good to note that Ukraine wasn’t left alone with its pain,” Yanukovych said. “We felt that the whole world came to our rescue.”
In turn, Vince Novak, the European Bank’s director of Nuclear Safety, praised Ukraine’s commitment to the cleanup.
“It is definitely important for the bank and for the donors to know that there is a strong commitment in Ukraine to do everything necessary to ensure that the Chernobyl project progresses well,” Novak told The Associated Press. “We have no room or margins for delay, for errors or for poor performance.”