A stop work order was issued at the Hanford Site’s Plutonium Finishing Plant after workers learned that plutonium and americium were found in high-volume air samples collected at the Energy Department facility’s Rattlesnake Barricade.
The samples were collected by the Washington state Department of Health on June 8, the day workers were ordered to take cover about 3 miles away at the Plutonium Finishing Plant after alarms for airborne contamination sounded during demolition of the plant’s Plutonium Reclamation Facility. The Health Department received results of the analysis late on Aug. 7 and Hanford workers received a memo the next day telling them low levels of contamination had been detected.
The lead Hanford Atomic Metal Trades Council (HAMTC) safety representative at Hanford cleanup contractor CH2M Hill Plateau Remediation Co. issued the stop work order on Aug. 10 to prevent further open-air demolition of the plant until safety measures were increased. CH2M leadership, managers from the Plutonium Finishing Plant, and HAMTC officials met to discuss options. They mutually agreed later that day to expand contamination control zones at the plant by another 150 feet beyond the current boundary before construction resumes.
The expanded safety boundaries were expected to require work over several weeks to move some equipment and worker trailers farther from the plant. Work has been allowed to continue in the meantime inside the plant to prepare it for demolition. Demolition has started from the outside in at the plant as preparations for demolition of some areas of the plant continue.
“I believe these changes as suggested by HAMTC leadership and worked through the project leadership are sound and worthwhile to assure improved safety and better isolation from hazards during demolition as we come into the final phases of this important project,” said Ty Blackford, president of CH2M at Hanford, in a message to employees. He also emphasized CH2M’s support of the right of any employee to issue a stop work order to ensure the safety of the workforce.
The detection of airborne contamination at the Rattlesnake Barricade — where workers enter the secure area of Hanford from public Highway 240 — was not expected by state or Department of Energy officials, they said at a Hanford Advisory Board committee meeting on Aug. 8. The wind was not blowing toward the barricade from the Plutonium Finishing Plant on June 8. The Health Department found no contamination in air samples collected that day downwind of the plant at the Columbia River, state officials said.
Health Department officials emphasized that low levels of contamination had been detected at the Rattlesnake Barricade. “The level is interesting from a regulatory point of view, but is not a health risk,” said Mike Priddy, manager of the Environmental Sciences Section of the Health Department Office of Radiation Protection.
The Health Department and DOE are investigating the findings at the Rattlesnake Barricade, and officials for both agencies said they could not definitively say the contamination came from the Plutonium Finishing Plant. “We are taking it seriously,” said Tom Teynor, federal project director for the plant.
When airborne contamination was detected June 8, no contamination was found on the skin or clothing of Hanford workers at the Plutonium Finishing Plant. However, employees were offered bioassay kits to check for internal contamination as a precaution. A small number of the first 65 bioassay tests analyzed have been positive for worker internal contamination, according to DOE and CH2M Hill Plateau Remediation.
CH2M characterized the positive results as showing a dose of 1 millirem or less over 50 years, calling the amount significantly less than a typical chest X-Ray. CH2M distributed 301 bioassay kits, but Teynor told the advisory board that more information about the results would not be released for four to six weeks when all results should be available.
