Comparison of ICRP2 and ICRP30 for estimating the dose and adverse health effects from potential radionuclide releases from a geologic waste repository

This paper presents a comparison of the calculated risk of adverse health effects from the radionuclides considered in the inventory of a high-level waste repository using the ICRP2 and ICRP30 internal dosimetry models. A CRPC (cancer risk per curie) index was calculated to compare the two models. The CRPC indices for the ICRP30 model are approximately 2 to 20 times higher than the ICRP2 indices for most radionuclides for ingestion intakes. However, the 237Np index is approximately 200 times greater for the ICRP30 model and the 228Ra and 226Ra indices are approximately 30 to 90 times greater for the ICRP2 model. Generally, there is closer agreement of the CRPC indices for the inhalation intakes. A scenario that considers a U-tube effect and withdrawal of water from wells downdip from the repository was analyzed. This analysis, based on a hypothetical waste disposal site, considered groundwater transport and environmental transport with subsequent uptake by the human via ingestion and inhalation. The ICRP30 risks are higher by approximately 20 at 10,000 years post closure for the ingestion pathway. However, the ICRP2 risks are higher by factors of approximately 2 to 10 at times greater than 50,000 years. Differences in the mathematical modeling assumptions, gut uptakes and other metabolic parameters between the two models account for most of the variability in the risk estimates