Mechanical perturbation of bentonite components of a KBS-3 repository
Project SSI P 1596.07 “IRSN support of the SR-Can review”, September 2007, Report DSU/SSIAD n°2, F. Deleruyelle and C. Serres, IRSN/DSU/SSIAD.
Elements of the SR-Can project relative to piping and erosion phenomena of bentonite components of a KBS-3 repository are analysed with regard to the experience feedback available at IRSN and consisting in experimental results obtained on samples at the UJF-Grenoble between 2000 and 2004. A synthesis of these tests is presented, with a closer attention to the Argillite/Bentonite tests during which phenomena of erosion occurred. The reference evolution of a KBS-3 repository, the resaturation and swelling kinetics of backfills and buffers and the possibility for a buffer to swell upwards the backfill have been considered. According to the reviewed documents, IRSN notes that the SR-Can project tackles the piping and erosion phenomena with local modellings and “rough estimates”, the latter being based on 3 “key” parameters: the water inflow in an underground opening, the concentration of bentonite in pipe water and the duration of the phenomena. IRSN considers that the reviewed elements do not evidence enough the conservatism of the parameters value, especially for the duration of the phenomena. Additional experimental results, at small and large scale, may be necessary.