The Department of Energy is scheduled next week to send a cesium-137 source that contaminated a University of Washington building in May to the Pacific Northwest National Laboratory (PNNL) for “forensic analysis,” an agency spokesperson said Tuesday.
Until then, the damaged irradiator’s cesium-137 source remains in the Research and Training Building near the university’s Harborview Medical Center, ensconced in a lead-lined cask provided by contractor International Isotopes and “monitored by health and safety professionals,” according to the spokesperson for DOE’s National Nuclear Security Administration (NNSA).
The agency decided to ship the cesium-137 source to PNNL, in Richland, Wash., about 200 miles southeast of Seattle, because the lab has “specialized facilities and staff to do a thorough analysis of the damaged source,” the spokesperson said.
It is “uncertain” how long the source will remain at the lab, the spokesperson said. “Once the forensic analysis is complete, it [the cesium-137] will be repackaged and shipped to a permanent waste disposal facility out of state.”
The spokesperson did not say which disposal facility might eventually get the sample.
The incident occurred as the University of Washington was throwing out its cesium irradiator, which was used to research the interaction between bone marrow cells and immune response. The NNSA funded the removal with a grant from its Cesium Irradiator Replacement Project, contracted to source-recovery specialist International Isotopes, of Idaho Falls, Idaho.
Personnel with the contractor inadvertently broke open the irradiator’s cesium-137 source while removing the device from the Research and Training Building. The release contaminated 13 people and parts of all seven floors of the building. International Isoptopes and Chase Environmental, of Louisville, Ky., will finish cleaning up the cesium, which was contained after the spill, after the source goes to PNNL. The building is still closed.
The cesium-137 source will travel to the Pacific Northwest National Laboratory in an RH-TRU 72-B container designed for remote-handled transuranic waste — something the isotope legally is not.
Nuclear Waste Partnership, the prime contractor for DOE’s Waste Isolation Pilot Plant deep-underground transuranic waste disposal site near Carlsbad, N.M., had to receive special permission from the Nuclear Regulatory Commission to ship the cesium-137 source in a RH-TRU 72-B container.
According to DOE’s safety analysis report for the hardware, RH-TRU 72-B casks may contain only about half of the 2,942 curies of cesium-137 found in the cesium chloride sample from the broken irradiator.
Nuclear Waste Partnership designed the packing assembly in which the container will travel, but the NNSA will actually transport the material, the agency spokesperson said this week.
The NNSA wants to eliminate unguarded or lightly guarded sources of cesium-137. In the wrong hands, the non-fissile, gamma-ray-emitting nuclear-fission byproduct could become fodder for a population-sickening radioactive dispersal device.
