Relevance of biotic pathways to the long-term regulation of nuclear waste disposal. Phase I. Final report. Vol. 4

Abstract

Licensing and regulation of commercial low-level waste (CLLW) burial facilities require that anticipated risks associated with burial sites be evaluated for the life of the facility. This work reviewed the existing capability to evaluate dose to man resulting from the potential redistribution of buried radionuclides by plants and animals that we have termed biotic transport. Through biotic transport, radionuclides can be moved to locations where they can enter exposure pathways to man. We found that predictive models currently in use did not address the long-term risks resulting from the cumulative transport of radionuclides. Although reports in the literature confirm that biotic transport phenomena are common, assessments routinely ignore the associated risks or dismiss them as insignificant without quantitative evaluation. To determine the potential impacts of biotic transport, we made order-of-magnitude estimates of the dose to man for biotic transport processes at reference arid and humid CLLW disposal sites. Estimated doses to site residents after assumed loss of institutional control were comparable to dose estimates for the intruder-agricultural scenario defined in the DEIS for 10 CFR 61 (NRC). The reported lack of potential importance of biotic transport at low-level waste sites in earlier assessment studies is not confirmed by order of magnitude estimates presented in this study. 17 references, 10 figures, 8 tables.