SSM perspective
Background
The Swedish Radiation Safety Authority (SSM) examines the Swedish Nuclear Fuel Company’s (SKB) applications in a step-wise review and approval process according to the government’s licence conditions under the Act on Nuclear Activities (SFS 1984:3) for the construction and operation of a geological disposal facilities. As part of the review, SSM commissions consultants to carry out work in order to obtain information on specific issues. The results from the consultants’ tasks are reported in SSM’s Technical Note series.
Objectives of the project
The objective of this project was to provide a review and assessment of recent research activities undertaken by SKB that are relevant to hydrogeological aspects of the disposal of radioactive waste. The scope incorporates general developments of SKB’s hydrogeological modelling capabilities, as well as detailed updates of models relevant to planned facilities in the Forsmark area.
Summary by the author(s)
The review covers the following main topics:
- Advances in the treatment of multiple coupled processes relating to groundwater flow under glacial and periglacial conditions. It is noted that an ambitious development has been carried out, but that modelling challenges remain, for example as regards the representation of matrix diffusion. Furthermore, the overall significance of glacial and periglacial scenarios for disposal system safety may be declining against the background of the latest projections of future global climate on 100,000 year timescales.
- Development of the discrete-fracture network (DFN) modelling methods. Specific developments in the methodology include (1) demonstration of DFN conditioning methods, by modelling groups using two separate software tools, (2) incorporation of rock stress effects on the hydraulic properties of fractures, pointing towards development of an integrated DFN description of shallow and deep bedrock at Forsmark, and (3) examination of the influence of fracture inhomogeneity on network-scale transport.
- Modelling of near-field hydrology for the low- and intermediate-level radioactive waste disposal facility, SFR. It is noted that there has been a relatively minor update of previous calculations, reflecting modifications to the layout of the planned extension and assumptions regarding the properties of engineered barriers. The results are judged to be well-presented, in a way that generally allows for direct comparison with those of the previous model.