The basis for assessing the potential postclosure radiological impacts of a deep geological repository on non-human biota has been evolving, particularly with the development of new data. The Nuclear Waste Management Organization (NWMO) has developed an updated model and dataset consistent with current international practice (Ref. 1). This paper describes the application of the updated non-human biota dose model, using as a basis the calculated environmental media concentration outputs from recent NWMO postclosure safety assessments for hypothetical crystalline and sedimentary rock sites (Ref. 2).

Two analysis cases were selected from each of the postclosure safety assessments - a Normal Evolution Scenario and a Disruptive Event Scenario. Results are generated using two methods of modelling the partitioning behavior of radionuclides - Concentration Ratios and Transfer Factors. The results are compared with two sets of criteria - Screening Criteria and Acceptance Criteria.

Conclusions are drawn for both hypothetical sites and these would need to be repeated for any real candidate site. However, the results illustrate the methodology, provide information on the nature and importance of the various pathways, and are consistent with prior conclusions that an appropriately sited deep geologic repository should have no long-term detrimental impact on biota populations around the site.