Experiences with Nontraditional Bioassay Methods in a Plutonium Processing Line (U)
T. R. La Bone, W. M. Findley
An incident in an SRS plutonium processing line (FB-Line) in 1999 highlighted the fact that insoluble forms of plutonium exist at SRS that may not be readily monitored with the routine bioassay programs traditionally used at this site. To address this issue, a study was conducted in FB Line with 21 participants for a year ending in July 2002. The purpose of the study was to examine the use of three nontraditional monitoring methods and, based on this experience, recommend a routine bioassay program that is capable of monitoring workers potentially exposed to insoluble plutonium. These nontraditional monitoring methods are personal air sampling (PAS), thermal ionization mass spectrometry (TIMS) of urine samples, and routine fecal bioassay. Five main conclusions and recommendations of the study resulted. First, a routine TIMS urine bioassay program, which is called the enhanced bioassay program (EBP), is recommended for workers in SRS facilities that have a reasonable potential for exposure to insoluble forms of plutonium. Second, under certain conditions the EBP could result in onerous work restrictions. A contingency plan involving the use of PAS is recommended in this case. PAS is also recommended for workers who have had historic intakes of plutonium that interfere with the detection and interpretation of future intakes of insoluble plutonium. Third, for the EBP to be successful it must be used only for those workers who have a reasonable potential for exposure to insoluble plutonium, and these workers must take all necessary precautions to avoid cross-contamination of the urine (and follow-up fecal) samples. Fourth, fecal bioassay is an important tool for follow-up to abnormal events, but routine fecal bioassay is not recommended. Finally, the PAS data clearly show that workers are exposed to low levels of airborne plutonium, but the participants appear to be unlikely to exceed a committed effective dose equivalent of 100 mrem from these exposures.
This abstract was presented at the 37th Annual Midyear Meeting, "Air Monitoring and Internal Dosimetry", Personal Air Sampling, Part 1 Session, 2/8/2004 - 2/11/2004, held in Augusta, GA.