Immediate Response, Medical Decision Making, and Dose Assessment Following a Glovebox Window Change Incident at Los Alamos National Laboratory

A 238 Pu inhalation incident occurred during a glovebox window change operation at Los Alamos National Laboratory involving four workers wearing respiratory protection. A continuous air monitor alarmed shortly after the glovebox window seal was broken, and subsequent surveys identified skin contamination on two workers and a positive nasal swab on another worker, prompting medical evaluation and internal dose assessment. Process knowledge indicated that the glovebox contained “fine” 238 Pu oxide particles. Based on the expected limited efficacy of chelation therapy for insoluble plutonium compounds, the relatively low and uncertain initial dose estimates, the slow systemic uptake of insoluble material, and the potential adverse effects of treatment, internal dosimetry staff advised that immediate chelation could reasonably be deferred. After considering this advice in consultation with medical personnel, the worker elected not to initiate chelation, with the decision to be revisited if early bioassay results indicated a need for medical intervention. Urine bioassay data were subsequently evaluated using biokinetic models incorporating particle size and absorption behavior. The data favored submicron particle sizes and were broadly consistent with particle sizes expected from size-dependent respirator penetration, and with Type S absorption behavior generally expected for plutonium oxides.