Radioactive plutonium and americium have been found in air samples collected at the Rattlesnake Barricade just off public Highway 240, where workers enter the secure area of the Hanford nuclear reservation, according to the state Department of Health.
Air samples were collected by the Department of Health on June 8, the day that workers at the Plutonium Finishing Plant were ordered to take cover indoors because of an airborne release of radioactive particles during demolition of the highly contaminated facility.
Analysis results for the air samples were received Monday, Department of Health officials said at a Hanford Advisory Board committee meeting Tuesday in Richland.
The levels of contamination in the samples were “very, very low,” said John Martell, manager of the Radioactive Air Emissions Section of the Department of Health Office of Radiation Protection.
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“The level is interesting from a regulatory point of view, but is not a health risk” to the public, said Mike Priddy, manager of the Environmental Sciences Section of the Department of Health Office of Radiation Protection.
Hanford employees were told in a memo early Tuesday afternoon that the Department of Health considers “that the amount detected is below levels that would be of concern for human health.”
The amount of americium detected is about three times the limit allowed by state air quality standards, but the standard is based on an average amount over 365 days for someone living there and growing food there, according to Department of Health officials.
We are taking it seriously and we will be working with the Department of Health.
Tom Teynor, Department of Energy project director for the Plutonium Finishing Plant
No one lives in the area, with land on both sides of Highway 240 closed to the public where it crosses Hanford.
The amount of plutonium found was too small to exceed air quality standards, according to the Department of Health.
The departments of Energy and Health are beginning an investigation and have not conclusively linked the airborne contamination to the Plutonium Finishing Plant incident, officials at the meeting said.
“We are taking it seriously and we will be working with the Department of Health,” said Tom Teynor, Department of Energy project director for the Plutonium Finishing Plant.
The samples were collected in an area where officials were not expecting to find airborne contamination.
The Rattlesnake Barricade is at least three miles from the Plutonium Finishing Plant and the wind was not blowing in that direction, Martell said.
However, there may have been eddies and swirls of air currents, health officials said.
Air samples collected downwind of the Plutonium Finishing Plant at the Columbia River, where the public has access, found no contamination.
The Plutonium Finishing Plant was used in the plutonium production process during the Cold War. About two-thirds of the plutonium for the nation’s nuclear weapons program was produced at Hanford.
On June 8, workers were using a shear at the end of an excavator arm to peel off the outer face of a large glove box running the length of the plant’s Plutonium Reclamation Facility.
Doors of the plant were open to air out radon from the intact portion of the building. An airborne radiation monitor inside the plant and another outside the plant alarmed.
Within 15 to 30 seconds about 350 workers at the plant were ordered to take cover indoors, Teynor said at the advisory board meeting.
No contamination was found on the skin or clothing of workers, but the next day workers were offered tests to determine if they might have inhaled any radioactive particles.
At the time, Hanford officials said data collected so far did not suggest that workers were in enough danger to require testing for exposure.
However, some of the first bioassay tests — checks of a workers’ bodily waste — analyzed have come back positive for contamination lodged within the body from inhaling or ingesting contaminated particles.
“The results received show a very low internal contamination dose that is significantly less than a typical chest x-ray,” said Destry Henderson, spokesman for CH2M Hill Plateau Remediation Co. at Hanford.
All the tests will not be completed for four to six weeks, Henderson said.
At the advisory board meeting, Teynor declined to discuss the number of positive results until all tests are completed. The day after the take-cover order, 65 bioassay kits were available to give to workers immediately, and eventually a total of 301 kits were distributed.
It’s a pretty sobering thing that people ingested plutonium. I’m heartsick for those folks.
Shelley Cimon, Hanford Advisory Board member
Workers were told when the first results came back in July that a small number of tests had found that workers had inhaled radioactive particles.
Because the particles would remain within a worker’s body for a lifetime, the exposure was calculated as a dose, or the amount of radiation a worker’s body would be exposed to internally over 50 years.
The test results that were found were calculated at 1 millirem or less of radiation over 50 years. In comparison, a standard chest x-ray would expose a person to about 10 millirem all at once, according to CH2M.
The legal limit for workers is 5,000 millirem per year, and CH2M sets a limit of 500 millirem per year.
“It’s a pretty sobering thing that people ingested plutonium,” said Shelley Cimon, who represents the environmental group Columbia Riverkeeper on the advisory board. “I’m heartsick for those folks.”
The take cover order June 8 did not include central Hanford workers outside the Plutonium Finishing Plant campus. Hanford officials on Tuesday were discussing whether other central Hanford workers should be given bioassay tests after contamination was found miles away at the Rattlesnake Barricade.
Demolition work has shifted to other parts of the Plutonium Finishing Plant and changes to procedures will be made before work resumes on demolition of the plant’s Plutonium Reclamation Facility.
Temporary ventilation exhausters with filters will be used to draw a negative pressure on the remaining Plutonium Reclamation Facility glove boxes and the highly contaminated central area of the facility to limit the spread of contamination when demolition resumes there.
DOE faces a legal deadline to have the plant torn down to the ground by the end of September.
It continues to work to meet that deadline, but has notified regulators that it is at risk of missing it.