Poor design of local exhaust hood leads to radioactive release in the work area

At a U.S. Department of Energy (DOE) waste handling facility, transuranic waste contained in standard 208-L (55-gallon) drums was being prepared to meet the DOE's Waste Isolation Pilot Project Waste Acceptance Criteria. During a particular waste handling operation, it was necessary for the workers to open several 208-L drums with TRU waste and prepare the waste to meet the WIPP Waste Acceptance Criteria. This operation was performed while the waste drums where positioned adjacent to a drum ventilator, which was designed to capture emissions generated from the drums during waste handling activities. During this activity, the continuous air monitor alarmed and reached an instantaneous air concentration of 0.1 Bq m(-3), or a factor of 300 times higher than the derived air concentration for inhalation class W 239Pu. The DOE conducted an investigation to determine why the drum ventilator did not control the transuranic emissions and to evaluate possible improvements to the drum ventilator and exposure controls. By adding upper and lower flanges to the drum ventilator, the capture velocity was increased by 88% without increasing the fan's speed. Adding flanges is a simple and inexpensive modification that enhances the performance of the drum ventilator. In addition to a poor design, the drum ventilator's capture velocity was compromised by competing air velocities that were generated by waste handling activities.