In parallel to studies of disposal of vitrified high-level waste from
reprocessing, projects have been initiated to examine options for direct
disposal of spent fuel in Switzerland. The basic concept involves in-tunnel
emplacement of encapsulated spent fuel in a deep repository which is
backfilled with compacted bentonite. Two possible host rocks are considered
- crystalline basement and Opalinus Clay. This paper reports the results of
a thermal analysis which was carried out to evaluate constraints on
repository layout set by the desire to limit temperatures experienced by the
bentonite backfill.