The last of hundreds of obsolete buildings surrounding seven of Hanford's nine production reactors have been demolished.
Work in the areas around those seven reactors is assigned to Washington Closure Hanford, which is close to finishing most environmental cleanup along the Columbia River in 2015.
The Department of Energy contractor recently completed tearing out the 183-B Clearwell, one of Hanford's oldest structures. It was built in 1943 to hold filtered cooling water for use at Hanford's B Reactor, the world's first production-scale reactor.
"With this last demolition we have finished demolition activities in the reactor areas under the River Corridor Closure Contract," said Doug Shoop, acting manager of the DOE Richland Operations Office. "This work shows the enormous progress made at Hanford reactor areas."
Hanford's reactors were surrounded by buildings and other facilities, such as tanks, when they were operating. Some reactor areas had more than 100 buildings, said Cameron Hardy, DOE spokesman.
Today, not many buildings remain along the Columbia River, where nine reactors once produced plutonium for the nation's nuclear weapons program.
About 15 support structures and seven major structures still stand near the K East and K West reactors, which are excluded from Washington Closure's contract. Final work cannot be done there until radioactive sludge is removed from underwater storage in the K West Reactor's basin.
But little stands around the other reactors except for some temporary offices and groundwater treatment systems that continue to operate. Six of the reactors have been torn down to little more than their reactor cores, which have been sealed up and left to let radiation decay to safer levels.
Scott Sax, president of Washington Closure, told workers to finish building demolition work strong, and they did, said Mike Douglas, who was Washington Closure's decommissioning and demolition manager for reactor areas.
The clearwell demolition "was a fun job to finish the project up with," he said. And work was completed ahead of schedule.
The above-ground structures at the clearwell, including the filter building, were demolished in the 1980s. But two 5 million-gallon, reinforced-concrete reservoirs with covers were left in place. The plan may have been to use them as needed for demolition debris in an era before the Environmental Restoration Disposal Facility, a lined landfill in central Hanford, was built.
Before Washington Closure could tear the clearwell out, the underground structure was checked to make sure it was not being used as a bat habitat.
Another Hanford clearwell, the one once used for F Reactor, has been saved because it is home to a maternity colony of Yuma bats from mid-March to mid-October. The colony, which originally had about 2,000 bats, has continued to grow and now numbers about 6,000 bats, according to DOE.
But the B Reactor clearwell was largely empty, containing neither disposed debris nor a bat colony.
Because clearwells were used to hold water before it went into the reactors, the water had no radiological contamination.
However, the B Reactor clearwell, which covered an area about three football fields long and two wide, did have some asbestos in the joints of the ground-level roof. It could not be removed before demolition, because the roof was unsafe to send workers onto, Douglas said.
Washington Closure is continuing some cleanup work around reactors, including digging up some remaining waste sites, backfilling soil and planting vegetation on disturbed areas.
It also is doing some additional demolition work at the 300 Area just north of Richland along the Columbia River, where reactor fuel was fabricated and research conducted.
Washington Closure finished tearing down all the remaining buildings under its contract in the 300 Area earlier this year. But then work to tear down the 300 Area Treated Effluent Disposal Facility and a power substation were added to its contract.
Several other buildings remain standing there, including a few used by Pacific Northwest National Laboratory and Mission Support Alliance. The 324 Building also is still standing because more time is needed to address a highly radioactive waste spill beneath it.
Washington Closure has torn down 301 facilities, with more buildings torn down near the Columbia River by other contractors.
-- Annette Cary: 509-582-1533; email@example.com; Twitter: @HanfordNews