[en] Flexible methods and codes have been developed to calculate thermal responses in a spent nuclear fuel repository located in granitic bedrock. The thermal resistance of the backfill material makes an essential contribution to the temperature at the canister surface. The backfill is however so thin compared to the rock masses of the repository that a stationary solution for the temperature drop across the backfill can be used. Combining analytical solutions of thermal diffusion in the rock and the stationary temperature following the released heat power across the backfill gives a very good description of the thermal behaviour of a repository. Temperatures at different points in a repository were calculated for encapsuled spent fuel with different cooling times (10, 20, 30 and 40 years) and having different burn-up values (33, 35 and 45 MWd/kgU). The amount of spent fuel in each canister was supposed to originate from 1.4 tons of fresh Uranium in the calculated examples. A more crucial variable in a thermal analysis of a repository configuration is however the heat power of canisters as a function of time and not the content of canisters. The study shows that the largest temperature rise at the boundary of a centrally located canister and buffer mass will be at most 85 K with assumed thermal data, when the heat power of 900 canisters does not exceed 1200-1400 W each at the time of emplacement depending on burn-up and cooling time. Assuming a higher value for the heat conductivity of the buffer material corresponding to that of the water saturated bentonite gives 15% higher limits respectively. The canisters were supposed to be placed in 15 rows 25 m apart from each other and 60 canisters in each row. The distance between canisters was taken to be 6 m