Quintessa

Geological Disposal of LILW

AMBER has been used to assess the post-closure safety of geological repositories for low and intermediate level radioactive waste (LILW), for example the Canadian Deep Geological Repository, the final repository for LILW at Forsmark (SFR) in Sweden and the Baita Bihor repository in Romania.

The Deep Geologic Repository (DGR) in Canada is being developed by the Nuclear Waste Management Organisation (NWMO). The total system model developed in AMBER includes the release of radioactive, heavy metal and organic contaminants in gaseous and liquid phases, and their potential migration via the host rock and shaft seal system. The model also represents advection in the shallow groundwater system, subsequent well abstraction and discharge to Lake Huron with associated biosphere and foodchain modelling. The modelling demonstrates the robustness of the site and disposal concept.

The Swedish Radiation Safety Authority (SSM) has contracted a number of external experts to support its review of SKB’s assessment (SR-PSU) of the long-term safety for the expansion of the final repository for low and intermediate level waste at Forsmark (SFR). Quintessa is supporting SSM in a number of areas, including radionuclide transport modelling and biosphere modelling. As part of the review, Quintessa has re-implemented key aspects of SKB’s radionuclide transport and biosphere models using AMBER, in support of both the initial phase and main phase of the review.

The Baita Bihor repository is located in a disused uranium mine in the Carpathian Mountains in Romania. AMBER was used as part of a Preliminary Safety Analysis Report (PSAR) for the operational and post-closure radiological safety of the repository, including the identification and quantification of the uncertainties underlying the assessed doses. The repository has accepted low- and some intermediate-level radioactive waste from industry, medical establishments and research activities since 1985 and the current estimate is that disposals might continue for around another 20 to 35 years. Impacts were evaluated for the maximum potential inventory that might be available for disposal to Baita Bihor for a number of operational and post-closure scenarios and associated conceptual models. The results showed that calculated impacts were below the relevant regulatory criteria for both the operational and post-closure assessments. An AMBER training course was held as part of this project with the aims of demonstrating its functionality and applicability to the post-closure safety assessment of the Baita Bihor repository.  This involved a series of lectures followed by hands-on sessions in which the participants had the opportunity to explore the software through a series of tutorials.  Also, an initial model was developed by participants to represent the near-field, geosphere and biosphere components of the Baita Bihor system.