A lapse in communication procedures likely contributed the spread of radioactive particles at the Department of Energy’s Hanford Site that contaminated 14 vehicles and led to checks at seven workers’ homes. As of midday Thursday, 240 workers at the Washington state facility had requested bioassays to determine whether they had inhaled radioactive particles.
The spread is believed to be linked to a significant accomplishment in demolition of Hanford’s Plutonium Finishing Plant: completion of teardown of its highly contaminated Plutonium Reclamation Facility. Demolition was suspended again this week in the wake of the incident.
Work stopped for about a day last week after several lapel air monitors worn by workers well away from demolition areas tested positive for airborne radioactive contamination. Specks of contamination also were found south of the reclamation facility, including just beyond the Plutonium Finishing Plant fence line.
The stop work order was lifted to allow demolition of the Plutonium Reclamation Facility to wrap up on Dec. 15 after the contamination control area around demolition sites at the plant was expanded. Routine radiological surveying was conducted that night after demolition work finished for the day. Surveyors found specks of contamination to the east of the reclamation facility, some of them too small to be seen.
Workers failed to follow procedures to notify the appropriate manager of the contamination spread Friday night and no work was done to contain the spread on Saturday, said Ty Blackford, president of demolition contractor CH2M Hill Plateau Remediation Co. Saturday had been scheduled as a day off for Plutonium Finishing Plant crew.
“It is unacceptable to us that we had contamination get away,” Blackford said. “It is also unacceptable to us that we didn’t follow our processes for notifications so that we could take timely action on this condition.”
The shift manager early Sunday learned of the contamination spread and demolition of the plant was stopped again. Demolition has yet to restart.
Workers spent Sunday stabilizing a rubble pile from demolition of the reclamation facility and surveying for radioactive particles beyond the demolition zone’s control area and containing contamination they found.
On Sunday night a wind storm swept across Hanford, and surveying Monday found areas that had been clean Sunday were now contaminated, including concrete outside a trailer serving as the project shift office. The office is a hub of worker activity. Workers were told to stay inside the plant’s office trailers until areas outside could be surveyed and any contaminants contained.
The Department of Energy said it was not a “take cover” order, because the concern was not airborne contamination and ventilation did not have to be deactivated inside the offices. The last of the workers were allowed to leave their offices at about 6:30 p.m. Monday, after radiation control technicians confirmed that pathways outside the offices were clean. No contamination was found within the offices and the only worker contamination was found on the boot of the radiological control technician who found the contamination outside the shift office.
Additional contamination was found early in the week. Seven worker vehicles and seven government or contractor vehicles were found to be contaminated with specks of radiation. Two of the cars might have been driven home after demolition Dec. 15 and then returned to the plant this week. The homes of the Hanford workers with contaminated vehicles were surveyed for radiation, with none found.
All but one of the contaminated vehicles had been parked at the Plutonium Finishing Plant. The remaining vehicle was being used for nearby waste tank farm work and had been driven near the Plutonium Finishing Plant several times. Contamination was found on the other side of Camden Avenue from the plant, but not on the roadway. Workers who have driven near the plant recently were advised to have their personal or project vehicles surveyed for contamination.
Air monitors at the plant have not detected airborne radioactive contamination since the start of the latest incident on Dec. 15. Hanford officials say contaminants likely were blown along the ground. However, they are offering bioassays to check for inhaled contamination to any workers who want them. Those requesting the bioassays include 62 CH2M employees, 96 Mission Support Alliance employees, and 82 tank farm employees. Some workers for other contractors were recruited to help with the surveying and containment of contamination at the Plutonium Finishing Plant, and others requesting the bioassays might have recently worked in central Hanford near the site.
“No spread of contamination on site — outside of posted radiation areas — or off site is acceptable,” said Doug Shoop, manager of DOE’s Richland Operations Office, in a message to all Hanford employees on Wednesday. “We expect that personnel on the Hanford Site are protected and that the public is not put at risk.”
Demolition of the remainder of the Plutonium Finishing Plant is on a “safety pause,” according to DOE. CH2M will not be allowed to resume demolition until the department approves its plan to complete the work safely. The contamination area around the demolition zone is being expanded again. CH2M also plans to delay loading out demolition rubble at the plant to prevent any interference as the remainder of the site is demolished. Workers will be moved to offices farther away from the rubble.
The expanded control area boundaries will affect some other Hanford projects and CH2M will coordinate its demolition schedule with those projects. The changes will delay completion of site stabilization, including ensuring the soil and remaining slab foundations have no contamination that could become airborne. DOE faced a Tri-Party Agreement deadline of September to have the Plutonium Finishing Plant down to slab on grade, but regulators have not pushed to accelerate work out of concern that remaining work is done safely.
The only part of the plant still standing is a portion of the main building. It housed two production lines where glove boxes were used to turn plutonium that arrived at the plant in a liquid solution into pucks and oxide powder to be shipped to the nation’s nuclear weapon production plants. Open-air demolition using heavy equipment was expected to be finished in a matter of weeks before the Sunday halt to teardown work.
The now-demolished Plutonium Reclamation Facility was added to one end of the plant in 1963 to meet Cold War demands for more plutonium. It recovered plutonium from scrap material that otherwise would have been waste. Work on the facility began 13 months ago, but stopped several times because of airborne contamination and an unusually cold and wet winter as demolition began.
The facility covered 22,000 square feet and was topped with a “penthouse” that stood six stories above the ground. At its center was a canyon hung with 52 long, skinny “pencil” tanks shaped to prevent a criticality from the plutonium they held. Removing the tanks took about four years as a crane that was original to the plant frequently broke down as it was used to move the tanks into a maintenance bay.
