The U.S. National Nuclear Security Administration (NNSA) this week removed a breached cesium-137 source from a University of Washington medical research building in Seattle, clearing the way to begin remediation of the facility following its May 3 contamination.
The semiautonomous Department of Energy agency on Tuesday trucked the cesium-137 source to the Pacific Northwest National Laboratory in Richland Wash., from the Research and Training Building near the university’s Harborview Medical Center, a spokesperson wrote in an email.
“Now that the source has been removed, all contaminated areas in the Research and Training Building will be remediated by the U.S. Department of Energy and its contractors to a level that meets the ‘free release’ standard the Washington State Department of Health sets for allowing the general public — including building occupants and laboratory personnel and facilities and maintenance personnel — to be in the building,” the NNSA spokesperson wrote.
“A timeline for reoccupation is pending,” the spokesperson said, without saying where exactly the NNSA would ultimately dispose of the breached cesium-137 source.
Workers with International Isotopes, of Idaho Falls, Idaho, breached the cesium-137 source on the irradiator, manufactured by J. L. Shepherd and Associates, while they were removing the device as part of the NNSA-funded Cesium Irradiator Replacement Project.
International Isotopes performed the removal under a subcontract to Los Alamos National Laboratory manager Triad National Security. International Isotopes will handle remediation of the building under the same contract, which is worth about $190,000, according to the NNSA spokesperson.
“However, we will not know the full and final cost of remediating the Research and Training Building until the operation is completed,” the spokesperson wrote in an email.
The University of Washington used the irradiator to research the interaction between bone marrow cells and immune response.
The NNSA wants to eliminate potentially vulnerable cesium-137 sources. The non-fissile, gamma-ray-emitting, nuclear-fission byproduct could be used to build a population-sickening radioactive dispersal device — sometimes called a dirty bomb.
