Work to tear down one of Hanford’s most radiologically contaminated buildings could restart in October under new plans to do the work more carefully and deliberately.
The plant could be torn down to the ground by June 2019, completing a lengthy and sometimes troubled project at the nuclear reservation.
Work at the Plutonium Finishing Plant was stopped in December when radioactive particles spread, leaving 11 workers with small amounts of contamination radioactively decaying inside their bodies from inhaling or ingesting the particles.
The 11 were in addition to 31 workers contaminated when radioactive particles became airborne in June 2017.
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In the December incident, private and government vehicles were contaminated with radiation, and some of them were driven into town.
Small amounts of radioactive contamination were found to have spread for miles in December and earlier, with contamination found near the Columbia River and at the site’s Rattlesnake Barricade just off public Highway 240.
Demolition of the plant was being done with heavy equipment in the open air, and the new plan stops short of requiring some sort of covering, such as tenting contaminated areas during demolition.
Work to design, purchase materials and build a tent or other covering could take a couple of years, said Karen Wiemelt, a senior vice president for Jacobs Engineering Group.
During those years, the partially demolished building would keep degrading, and stopping small animals from getting into contaminated areas and spreading material would be difficult.
Open air demolition to complete work more quickly was determined to be the less risky option.
“It makes far more sense to proceed very deliberately with enhanced controls,” she said
CH2M Hill Plateau Remediation, the Jacobs-owned company with the contract to demolish the plant, plans to improve controls as demolition and related work resumes at the nuclear reservation plant.
Monitors to detect radioactive material will be placed at more locations. Those monitors also will be checked more often, including during the day while demolition is being done rather than at night.
Demolition will be done at one place at the plant at a time. Dual demolition projects had been started as a catch-up measure as work fell behind schedule to meet legally enforceable deadlines.
Contamination might have spread earlier from rubble piles on the ground that grew larger as the speed of demolition increased.
When demolition restarts, no more than a day’s rubble will be allowed to accumulate, Wiemelt said.
CH2M will keep using a paint-like fixative to “glue” contaminated particles in place, but it will only be used to the manufacturer’s recommendations.
A review of problems that led to the spread of contamination in December found that fixative was being diluted to make it easier to apply.
The new demolition plan calls for doing work in two phases, starting with the least risky work.
As soon as September, work could begin to remove contaminated demolition debris left on the ground and unpackaged at the main part of the plant after the December stop.
The next month, demolition of much of the remainder of the main part of the building could resume, along with removing a vault used to store plutonium.
During the Cold War, the plant was used to process nearly two-thirds of the plutonium for the nation’s nuclear weapons program. Plutonium came into the plant in a liquid solution and was turned into a powder or hockey puck-sized buttons that could be sent to weapons production plants.
Much of the processing was done in two long lines of glove boxes, with workers reaching their hands through gloves attached to portals to do the work.
The higher risk demolition that would be done next, possibly starting in January, includes tearing down the two production lines.
Most of the glove boxes have already been removed, but contamination of the area during production years was sometimes painted over or covered with tiles.
Exhausters will be used to pull air through the area, helping to contain contamination.
The final demolition step will be to remove the demolition rubble left at the plant’s Plutonium Reclamation Facility.
In December, the facility, attached to one end of the main part of the Plutonium Finishing Plant, had just been torn down to only stub walls.
Then the contamination spread was discovered.
The rubble pile, which has been covered with several inches of soil, will be saturated with water to produce a muddy slurry to keep contamination from becoming airborne as the debris is removed, Wiemelt said.
The Plutonium Reclamation Facility was believed to be the most radioactlvely contaminated part of the plant.
Hanford officials said that 312 grams of plutonium or related radionuclides remain in the demolition project. The majority of that, 238 grams, is in the reclamation facility’s rubble pile, and 64 grams are in the part of the plant where the processing lines were.
The Washington Department of Ecology, a regulator on the project, issued a stop-work order after the contamination spread.
It agreed in June to lift the order for the low-risk work once improvements are made, including those identified in a management review planned for August before demolition work resumes.
Ecology will consider lifting the stop-work order for the high-risk work only after the initial work is completed and the effectiveness of the increased controls to stop the spread of contamination are assessed.
CH2M had the opportunity under terms of its 10-year-contract to earn a maximum of $51 million in incentive pay for timely demolition of the plant.
It earned $12 million by 2012, but is not expected to earn more.
Work began to prepare the plant for demolition about two decades ago, starting with the stabilization of plutonium left in the plant in a liquid solution at the end of the Cold War.
Demolition started in late 2016.
The deadline for tearing down the plant under the legally binding Tri-Party Agreement has come and gone.
It was the end of September 2017, which included a one-year extension for the work. But the focus has shifted since then from meeting a schedule to making sure the work can be completed safely.