Natural Elemental Fluxes as Licensing Criteria: A Methodology

A study has been performed to assess the viability of using fluxes of natural elements and radionuclides from the geosphere into the biosphere as a basis for defining allowable releases from a radioactive waste repository into the biosphere. The mass and radioactive fluxes of elements and radionuclides due to groundwater transport, glacial erosion and non-glacial weathering in the vicinity of the Aespoe Hard Rock Laboratory, Sweden, were quantified and compared to proposed Swedish limits for biosphere releases from a high-level waste repository. This work demonstrates that it is possible to calculate fluxes of naturally-occurring radionuclides that are directly comparable to performance assessment predictions of repository fluxes to the biosphere. Since the radiological impact of natural fluxes of radionuclides is broadly understood and since natural and repository fluxes can be assessed on a comparable basis, this suggests that natural fluxes can be used as a basis for defining indicators of repository safety.