The Reactor that Caused the World's Worst Nuclear Disaster Had to Be Enclosed; But Project Teams Had to Stay Safe and on the Same Page
BY NOVID PARSI
Construction of the first section of the shelter. Top right, the site in the aftermath of the reactor explosion in April 1986. Bottom right, the sarcophagus that sealed the reactor immediately after the accident.
Cleaning up the worst nuclear accident in history has taken more than 30 years—and a nonstop cluster of high-risk projects. But the final phases of remediation for the Chernobyl nuclear power plant in Ukraine couldn't proceed safely until the 10-year, US$1.6 billion New Safe Confinement project was completed.
French construction consortium Novarka and a Bechtel project management unit (PMU) led a global project team that assembled and installed a massive arch to entomb the Chernobyl reactor and any toxic residuals. Installation was completed in November 2016, and final tests on the arch's confinement system will be completed in November 2017.
The structure covers a hastily built sarcophagus that sealed the reactor in 1986. The reactor's explosion that year set off deadly radioactive contamination across Europe.
“The sarcophagus was considered unstable, and there was the fear that at some point, due to normal deterioration, it could collapse,” says Oscar McNeil, managing director, PMU, Bechtel, Chernobyl, Ukraine. “If that happened, there likely would be another radioactive release.”
Bechtel's PMU brought in 18 specialists, including project managers, engineers and safety personnel, all of whom worked closely with cleanup program sponsor European Bank for Reconstruction and Development (EBRD) to help the arch project team navigate technical and regulatory challenges to complete a unique design and assembly. For instance, to reduce radiation exposure to construction workers, the shelter was built in two halves and joined together at an assembly site 300 meters (984 feet) from the reactor. It was then elevated onto rails and slid into place over the reactor at a clip of 76 centimeters (30 inches) at a time, says Nicolas Caille, project director, Novarka, Chernobyl, Ukraine. The Novarka and Bechtel teams also had to collaborate with a global roster of top nuclear cleanup specialists while ensuring safety amid Chernobyl's radioactive ashes.
“The PMU worked with Novarka through all the very difficult issues,” Mr. McNeil says. “The contractors have to do the job correctly, but as the PMU, we have to make sure they're successful. We were all adapting as we went along because nobody had ever done this type of project before.”
Burying the Past
1986: The Chernobyl nuclear power plant accident spreads radioactive contamination across Europe.
1997: Project sponsor European Bank for Reconstruction and Development and the government of Ukraine enter into a framework agreement for the Shelter Implementation Plan, a program that includes the New Safe Confinement arch project.
2007: Design and construction contracts are awarded.
2011: French consortium Novarka begins construction of the arch.
2013: First section of arch is completed.
November 2016: The arch slides into place over the reactor.
November 2017: Testing of the arch's climate system and membrane is scheduled to be completed.
“We were all adapting as we went along because nobody had ever done this type of project before.”
—Oscar McNeil, Bechtel, Chernobyl, Ukraine
The teams had to cull knowledge from the world's top experts during all phases of the project, particularly during the six-year window to build and install the shelter. For example, the team consulted with specialists to work around one long-term risk: corrosion, which could negate the shelter's 100-year structural guarantee. To ensure the arch's metal is rust-resistant, the team gathered feedback from scientists who provided lessons learned from a previous project that involved a smaller shell. The Chernobyl arch's design ultimately included large desiccant dryers that generate up to 80,000 cubic meters (2.8 million cubic feet) of air per hour to ensure the humidity doesn't exceed 40 percent. “Instead of protecting the structure against corrosion, we control the air so corrosion can't start,” Mr. Caille says.
Mr. Caille's team also worked with French engineering consultants to develop an airtight membrane inside the shell that would seal off any contaminants. But the membrane had to be flexible enough to move with the shell if it were struck by tornadoes or other bad weather. The solution was to use a membrane similar to what the consultants developed for the missile doors inside French military submarines, he says.
But the primary project management challenge appeared in 2015, when Novarka realized the arch would need to be installed earlier than scheduled to allow enough time to complete all post-installation tasks, such as testing the arch's climate system and membrane. But when Novarka pushed up the installation date to November 2016 instead of July 2017, it created a domino effect for all construction tasks. The arch end walls, for instance, couldn't be installed until the arch was slid over the reactor.
“That the end walls were ready on time reflects tremendous effort and creativity on the part of both the Ukrainian contractor and the PMU,” Mr. McNeil says. “This was an accomplishment that many felt was unachievable.”
Bechtel helped the Ukrainian contractor find ways to save time. For example, instead of following a typical construction method that installs and then removes temporary forms to shape the poured concrete, the contractor purchased forms that could be left in place. This way the team didn't have to wait for each section of poured concrete to cure.
“It cost a little more, but in the long term it kept the costs below what they would have been if we had delayed Novarka,” Mr. McNeil says. “About a third of the contract modification's value was tied up in incentives, so the end-walls contractor had to make the accelerated date in order to get those incentives.”
The metal dome that covers the Chernobyl reactor is the world's largest movable structure on land.
Height: 108 meters (354 feet)
Length: 162 meters (531 feet)
Width: 257 meters (843 feet)
Weight: 40,000 tons
By comparison, the arch is:
■ Taller than the Statue of Liberty
■ Big enough to enclose the entire Notre Dame cathedral of Paris
“There was a healthy amount of give and take throughout the project. … [W]e try to understand each other's opinions and make the best decisions.”
Oscar McNeil, managing director, Bechtel
Location: Chernobyl, Ukraine
Experience: 42 years
Other notable projects:
1. U.S. Embassy renovation to improve security and safety, Moscow, Russia. Mr. McNeil served as project manager.
2. Biological Threat Reduction Program, a U.S. government initiative to reduce the threat of biological weapons in the Republic of Georgia, Kazakhstan, Uzbekistan and Azerbaijan. Mr. McNeil served as program manager.
Lesson learned: “When you're doing a project that's unprecedented, all parties have to know we're all in this thing together and we all have to help each other out.”
Workers atop the shelter's roof. Top right, the sarcophagus and turbine hall section. Bottom right, the shelter in place.
WORLD OF HELP
The project team went well beyond Ukraine's borders to find contractors and other valuable specialists. In all, Novarka managed team members from 26 nations. “We have gone where the specialists are,” Mr. Caille says.
For instance, Novarka worked with scaffolding experts from Portugal, crane specialists from the United States, ventilation experts from England and a German university that helped design the arch. Novarka also tapped 20 team members from Azerbaijan to help lift the arch into place, because of the country's oil industry's lifting expertise. The organization had up to 2,500 team members on the project at any one time—about 10,000 people throughout the entire life cycle.
With so many team members in the mix, Mr. Caille made an adjustment early on to make sure everyone would work together toward the same goal. At the project's start, Novarka's team had office locations in several countries. But Mr. Caille quickly realized a dispersed team made collaboration harder, so he co-located them in Ukraine. Financial incentives and the delivered promise of frequent relaxation breaks helped to lure workers—and maintain high performance. “Even though we all had telephones and videoconferencing, it was better to have everyone in the same place,” he says.
Having a global team also led to regulatory flare-ups. EBRD stipulated that the project be built according to North American and European regulatory standards. But those standards can differ from the standards most familiar to the Ukrainian regulators in charge of ensuring EBRD's requirements were met. “So we had to show the local regulators that what Novarka proposed actually meets a Western standard,” Mr. McNeil says.
For example, Novarka's fire protection system for the arch included thermal-imaging cameras that detect flames. Yet the cameras aren't recognized as acceptable for fire detection by Ukrainian standards. Bechtel team members helped communicate to the regulators that the cameras met EBRD's demands—and the Novarka team added standard flame-detection sensors to satisfy the local regulators.
“There was a healthy amount of give and take throughout the project,” Mr. McNeil says. “But we have worked well together and work hard to maintain cohesiveness. We sometimes have our differences, and in those cases we try to understand each other's opinions and make the best decisions.”
PRESERVE AND PROTECT
Keeping all team members safe from radiation was a constant priority. The team strictly followed protocols based on Ukrainian regulations and the power plant's requirements to ensure workers’ exposure didn't exceed standards agreed upon as part of the project planning.
This was particularly crucial for the Ukrainian end-wall contractors who, unlike other team members, had to complete their work both inside and atop the sarcophagus. Each worker at that site wore protective gear, air filters and a radiation-measuring dosimeter that an electronic system checked twice a day. Bechtel received daily reports on the monitoring.
“If someone reached the dose limit, they had to leave the job and couldn't come back to work,” Mr. McNeil says.
Bechtel's team also contracted a consortium of four Ukrainian organizations that provided medical services needed for keeping team members safe from too much radiation. For instance, the medical teams tested workers’ fecal samples for radionuclides and provided a machine that tested for radionuclides in workers’ lungs.
But the project team's safety concerns extended into the future. The new shell will contain the reactor for at least 100 years—protecting the public and shielding the reactor against tornadoes, earthquakes and temperature extremes that could release new contamination. It also will ensure other final stages of cleanup can continue—including dismantling the reactor through a remotely operated crane system inside the arch—with no threat of radiation leaks.
“Even though we all had telephones and videoconferencing, it was better to have everyone in the same place.”
—Nicolas Caille, Novarka, Chernobyl, Ukraine
“The project has averted a potentially significant environmental catastrophe,” Mr. McNeil says. “A wide region surrounding Chernobyl will be protected from a second release of radiation from the Chernobyl reactor.” PM