The Second Internal Dosimetry Intercomparison Study of the US Department of Energy

The findings are presented of the second internal dosimetry intercomparison study for the US Department of Energy (DOE), performed in 1995. As in the first intercomparison study, participants were asked to respond to five test exposure scenarios, assess the data provided, and calculate the resulting internal dose. The main difference between this study and the previous one is that test cases in the present study are more closely related to work performed either previously, or currently, at DOE facilities. The test cases cover both tritium and plutonium exposures, including single and multiple intakes, and some also involved chelation treatment. In addition to using test cases based on real exposure data, an artificial case was created using the new lung model described in ICRP Report 66. Six DOE facilities participated in the present study. The results of this study are similar to those found in the previous intercomparison, since they show that the main factors contributing to the variations in the numerical answers are: interpretation of bioassay and statistical treatment of bioassay data, the biokinetic models applied, and the computational method used. This study, however, further identifies areas that need to be improved to facilitate participation in future intercomparisons, such as improved management commitment for participants' involvement, increasing the response time, better presentation of the exposure data, more involvement of the participants in case preparation, and improved instructions to the participants on the amount of information that should be included in the response.