F Reactor has passed its five-year check-up, with Hanford workers finding nothing amiss after unsealing and entering what remains of the reactor.
Hanford workers have torn down six of the nuclear reservation’s plutonium-production reactors to little more than their radioactive core, sealed up all openings and reroofed them.
The plan is to leave them in a state of temporary storage, or cocooned, for 75 years to allow radioactivity to decay to more manageable levels.
This was the second time Hanford workers have ground away the welds from around the steel door of F Reactor to go inside since the reactor was cocooned in 2003.
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“This inspection gives us an opportunity to conduct radiological surveys, make any repairs to the roof and remove any hazardous substances,” said Rick Moren, director of long-term stewardship for Mission Support Alliance. “During the inspection, workers found the reactor to be in good shape and almost identical to the last time it was inspected.”
The workers who entered saw no wild creatures, but they did find a small amount of bat guano and a few spider webs, Moren said. There was no moisture, despite the recent rains.
The door to the reactor was unsealed a few days before the first entry to allow it to air out and for air samples to be collected to make sure it is clear of contaminants. Radon is a particular concern in closed-up Hanford reactors.
DOE is required to inspect cocooned reactors every five years to check for structural integrity and make sure any remaining hazardous materials remain confined. But F Reactor was sealed up a little longer than that before being reopened.
As a cost-savings measure, the Department of Energy has received permission from its regulators, the Washington State Department of Ecology and the Environmental Protection Agency, to adjust the schedule for inspecting reactors, said Keith Grindstaff, manager of the DOE long-term stewardship program.
It is moving toward inspecting the six Hanford reactors that have been cocooned so far in quick succession every five years. That should avoid the cost of repeatedly mobilizing entry crews.
This coming spring, the C, D, H and N Reactors will be inspected. Those reactors have been inspected from three to seven years ago. The other reactor cocooned so far, the DR Reactor, was last inspected in 2013.
Mission Support Alliance decided to start with an entry only into F Reactor because it had not opened up a cocooned reactor before.
The previous entries and inspections have been done by Washington Closure Hanford, which is responsible for environmental cleanup along the Columbia River. But with much of the cleanup along the Columbia River close to completion, the cocooned F Reactor has been moved to DOE’s Long-Term Stewardship Program, with inspections conducted by Mission Support Alliance.
“This entry marks a transition of sorts,” Grindstaff said. “As the river corridor cleanup work is completed and transitioned to long-term stewardship, our program will manage any ongoing requirements.”