Quintessa

Near Field Radionuclide Release and Transport

AMBER has been used to model the post-closure release of radionuclides from waste packages and their subsequent transport through surrounding engineered barriers in several geological disposal facilities.

When modelling release of radionuclides from a waste package as part of as safety assessment, it is typically necessary to take into account the 'availability' of radionuclides for release from the wastes; and how the waste package might evolve over time, for example due to corrosion of the container, or degradation of cementitious encapsulant. AMBER can be used to model releases of radionuclides from waste packages taking into account these process, and their subsequent transport through the surrounding engineered barriers, also taking into account evolution of the barriers.

Scenarios for the potential evolution of a waste package and the surrounding engineered barriers, that take explicit account of waste package heterogeneity and the time-dependence of the physical and chemical characteristics of the system, which will affect the release and transport of radionuclides in the near field, can be developed and implemented in AMBER. The use of NameSet Options enables a single file to be generated that covers all of the different evolution scenarios, such as early package failure times or enhanced engineered barrier degradation rates. The probabilistic capability within AMBER facilitates sensitivity studies around these different scenarios.

As examples, AMBER has been used to model the evolution of LILW packages and the engineered barriers in the Canadian Deep Geological Repository, the Baita Bihor repository in Romania, and the SFR repository in Sweden for LILW. AMBER has been used to model package and engineered barrier evolution in repositories for HLW and SF in support of the regulatory reviews by both SSM and STUK of the proposed SF disposal facilities at Forsmark, Sweden, and Olkiluoto, Finland, respectively.

Examples of recent publications using AMBER to model such systems include:

Penfold J (2014). Further Reproduction of SKB’s Calculation Cases and Independent Calculations of Additional “What If?” Cases. A report published by the Swedish Radiation Safety Authority: Technical Note 2014:55.

Walke R, Little R, Ramlakan A and Towler G (2011). Postclosure Safety Assessment: Analysis of Normal Evolution Scenario. A report published by Nuclear Waste Management Organisation, Report NWMO DGR-TR-2011-26.

Image courtesy of NDA RWM.