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 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 support SSM in its consideration of issues linked to the design, construction and long-term structural integrity of the 2BMA disposal vault in the planned expansion of the SFR facility for the final disposal of short-lived low- and intermediate-level waste. The review covers SKB’s choice of methods and materials as well as the results of large-scale tests carried out by SKB regarding the feasibility of building the concrete caissons. The assignment also includes an assessment of the suitability of the models and data used by SKB to represent long-term degradation of concrete.
Summary by the author(s)
An in-depth review of the work carried out by SKB on the 2BMA disposal vault design has been carried out. Whereas the range of work undertaken is judged to be impressive, and its reporting logically structured, the development of concrete composition and caisson design from that presented as a basis for SKB’s license application could be more clearly presented. It is noted that SKB acknowledges some practical challenges associated with caisson construction using the proposed methods and materials, which indicate that there is scope for further optimisation prior to installation, in order to ensure that the required consistency of quality is achieved. Suggestions are made for potential improvements regarding the concrete mix design and construction methods. It is important that SKB demonstrates understanding of the impact of any changes in concrete composition in the final design on future evolution of the 2BMA caissons and their possible degradation, from the perspective of fulfilling barrier safety functions.