A look at The PUREX plant at Hanford
The huge PUREX processing plant at Hanford is at risk of releasing radioactive contamination into the environment the longer it remains standing, according to a new Department of Energy report.
The plant built in 1956 is heavily contaminated after being used to chemically process irradiated fuel rods to remove plutonium for the nation’s nuclear weapons program.
But given other pressing environmental cleanup priorities at the 580-square-mile nuclear reservation, a decision on how to do final cleanup and likely tear down the plant is not expected until about 2032.
A new engineering evaluation of the plant looks at what can be done in the meantime, concluding that the best option is to spend about $218 million to remove hazards, prepare the main processing building for demolition and demolish two attached annexes.
However, when that could be done will depend on when money is available and how the work fits in with other cleanup priorities, the evaluation said.
The report included a risk evaluation that found contamination is spreading throughout the Plutonium Uranium Extraction, or PUREX, building as it degrades.
The amount of radiological contamination and asbestos-containing material in the building presents a threat of a release to the environment, it said.
The release could come because of a fire or a break in a utility pipe, containment wall or roof, the report said. Or the main building or its two attached annexes could collapse as they age and deteriorate.
In May 2017 a radioactive waste storage tunnel at the plant partially collapsed. Since then, both of the waste storage tunnels have been filled with concrete-grout to stabilize them, and the tunnels are not considered in the current risk evaluation.
The risk in the main plant — called a canyon because of its long, high interior — and two annexes is sufficient to consider taking action now to prevent a release of radioactive or chemical contamination to the environment, the evaluation said.
The main plant is 1,005 feet long, 30.5 feet wide and 104 feet high, with about 40 feet below ground. The roof is concrete with a metal roof installed over the top in 2002 because it was leaking.
The building has extensive plutonium contamination in its processing cells, which are beneath the floor, or deck, of the canyon. It is contaminated with other radionuclides.
The main building also has a contaminated product removal room and a cell used to process plutonium oxide.
The annexes on the north side of the building include one that is two stories high and one that is five stories high. They contain a control room, utility equipment, a laboratory and tanks, including a 405-gallon tank that held nitric acid.
The plant, one of five canyons built to process plutonium at Hanford, operated from 1956 to 1972 and then from 1983 to 1988.
By 1998 the plant had been deactivated, with work that included emptying tanks as much as possible and flushing them out, draining piping and removing materials such as chemicals and excess equipment. Utilities were shut off.
No one has worked in it since the mid-1990s.
Options for reducing risk
Options considered to further prevent a release of contamination included removing or stabilizing hazards in the main canyon building at a cost of $178 million. Modifications of the buildings ventilation system would be needed.
For another $12 million, work could be done to prepare the two annex buildings for demolition. That would include decontamination or stabilization of contamination; draining fluids from piping; removing overhead utilities and possibly tearing down some parts of the interior.
Then demolition preparation could be done above the floor deck in the main canyon and the two annexes could be demolished at an additional cost of $18 million
The engineering evaluation concluded that all of the steps should be done — at a total cost of $218 million — to best protect people and the environment.
The work also would have other advantages.
It could help reduce the increase in maintenance and surveillance costs and the complexity of future maintenance at the plant.
Other Hanford work a priority
It would help maintain the nuclear reservation’s workforce with experience in deactivating and decommissioning contaminated structures when more money becomes available for work to clean up central Hanford structures.
Currently, much of the focus at Hanford is on preparing to treat up to 56 million gallons of waste held in underground tanks to allow permanent disposal of the waste.
Other key cleanup work includes moving radioactive sludge out of underwater storage near the Columbia River, preparing to dig up a highly radioactive spill beneath the 324 Building near Richland and finishing demolition of the highly contaminated Plutonium Finishing Plant.
Although maintenance work has been done on Hanford’s defunct processing canyons, demolition has started on just one, U Plant.
U Plant was built to process plutonium but was never needed. Instead, it was used for training and to recover uranium from the waste left from chemically processing fuel at other plants.
In 2011 and 2012 the processing cells below the deck of the canyon were filled with concrete-like grout. A plan approved in 2005 calls for eventually collapsing the walls of the canyon and constructing an earthen barrier over the demolished building to keep out water.
Comment on PUREX plant proposal
No cleanup plan has been approved for the other four processing canyon buildings, but U Plant could serve as a model for it.
The public may comment on the plan to take steps now at the PUREX plant before a final cleanup is undertaken by email at PUREX_EECA@rl.gov or by mail at U.S. Department of Energy; PUREX EE/CA; P.O. Box 650, H1-20; Richland, WA 99352. The public comment period closes Aug. 2.
To learn more, go to hanford.gov and look on the events calendar under any date from July 3 to Aug. 2 to find the report and a fact sheet.
After considering public comments, DOE will confer with its regulator, the Washington state Department of Ecology, and then issue a decision.