Dose Assessment Following a 238 Pu Inhalation Incident at Los Alamos National Laboratory.

ABSTRACT: A glovebox breach at the plutonium facility at Los Alamos National Laboratory potentially exposed 15 individuals to 238 Pu aerosols. One of the individuals (P0) received two 1-g intravenous DTPA treatments, one on the day of the intake and another the following day. Several urine samples were collected from the individuals involved in the incident. Particle size analysis on the PPE and solubility analysis of the particles on a filter sample were conducted in vitro. The applicability of the results from the in vitro studies for dose assessment was questionable because of the effect of the cloth mask the workers were wearing for COVID-related protection. Based on several considerations, including the effect of cloth masks on the "effective" particle size inhaled and the analysis of fecal-to-urine ratio, the default Type M 1 µm AMAD model was used to estimate intakes and doses. Using the urinary excretion data collected after 100 d post last chelation treatment, the committed effective dose, E(50), for P0 was calculated to be 5.2 mSv. For all others, the bioassay data were consistent with no intakes or very small intakes [corresponding to E(50) less than 0.1 mSv].

Accuracy and precision of (238)Pu determination at fg level by alpha spectrometry using (239)Pu and (240)Pu amount analyzed by ICP-MS.

The accuracy and precision of the determination of (238)Pu amount at the fg (mBq) level by a combination of alpha spectrometry and inductively coupled plasma mass spectrometry (ICP-MS) were studied using a standard reference material (CRM 137-Plutonium [corrected] Isotopic Standard, National Bureau of Standards, Washington, D.C., USA). The activity of (238)Pu was calculated from the amount of (239)Pu and (240)Pu obtained by isotope dilution method and ICP-MS combined with the intensity ratio of (238)Pu/(239,240)Pu obtained by alpha spectrometry without adding spike. The results show that approximately 130 fg of (238)Pu can be analyzed within an accuracy of 7% bias and with 5-12% of total uncertainty. The examined analytical procedure was applied to the quantitative analysis of (238)Pu in water samples representing Safeguards inspection samples. The combination of alpha spectrometry and ICP-MS is useful for quantitative and isotopic analysis in low-level Pu samples. Also the method leads to improving the accuracy of (238)Pu determination because efficiency calibration is not necessary for alpha spectrometry.