Tri-Cities firm awarded $9.5M to build steel cage over plutonium reactor at Hanford

A Richland company has been awarded $9.5 million in subcontracts to build an enclosure over one of the Hanford nuclear reservation’s nine former reactors that produced plutonium.

Six of the nine reactors at the Hanford site along the Columbia River have been cocooned, or torn down to little more than their radioactive cores, reroofed and sealed up.

They are planned to be left for up to 75 years to allow their radiation to decay to more manageable levels and then a decision on how to dispose of the reactors will be made.

But for the K East Reactor the Department of Energy plans to try something new.

Its contractor Central Plateau Cleanup Co. has subcontracted with DGR Grant Construction to build a steel enclosure over the the reactor.

DGR Grant is scheduled to break ground on the foundation for the storage enclosure next month and complete construction of the enclosure in 2023.

When enclosing the reactor rather than cocooning it was proposed in 2012, DOE officials said the new way of putting the reactor into storage would be safer for workers.

In cocooning, workers install concrete forms and pour grout to seal piping and other parts at 80 to 100 feet off the ground. With the enclosure, the openings are sealed off with steel plates.

Reroofing the reactor, as has been done at previous reactors during cocooning, might have required extensive wall and ceiling bracing from inside the reactor, where workers would face industrial hazards and the potential for radiation exposure.

Because the roof of the enclosure will not be attached to the reactor, no structural changes to the building will be required.

Work already has been done inside the reactor to remove lead, oils and other hazardous substances. Ancillary structures, including the reactor basin, have been torn down.

The planned enclosure will be built of steel sheeting and have an angled roof to direct rain water runoff away from adjacent waste sites, according to DOE.

Building an enclosure also could be less expensive. In 2012, DOE estimated that cocooning the reactor would cost about $20 million, including the engineering and construction for structural bracing.

“Awarding this contract is a major step toward the completion of work in Hanford’s K Reactor Area,” said Bob Krebs, Central Plateau Cleanup Co. project manager.

K Reactors left for last

The K East and K West reactors are the last two Hanford reactors that need to be put into storage with cocooning or an enclosure.

The other reactor not cocooned or enclosed is B Reactor, which is now part of the Manhattan Project National Historical Park. The world’s first production scale nuclear reactor, it will remain as is to tell the story of the start of the atomic age.

The Hanford site in Eastern Washington was used from World War II through the Cold War to produce two-thirds of the plutonium for the nation’s nuclear weapons program.

The K reactors were left until last to cocoon or enclose because their reactor basins were used to store irradiated fuel under water after processing of irradiated fuel to remove plutonium ended at Hanford without all fuel processed.

Before the fuel was removed in 2004, it corroded underwater and fuel corrosion particles, metal fragments and dirt combined to form sludge.

About 950 cubic feet of highly radioactive sludge accumulated in the basins, with work completed to remove the sludge about two years ago. All of the sludge had earlier been consolidated from both reactor basins into underwater containers at the K West Reactor.

More work remains to be done at the K West Reactor before it also can be put into storage.

About 15,000 pounds of radioactive debris needs to be stabilized and removed from the basin, the water emptied from the 1.2-million-gallon basin and the basin removed.

This story was originally published August 11, 2021 at 5:00 AM.