[en] In assessing the feasibility of a potential site for underground storage of nuclear waste, one has to consider whether thermal loading imposed on host rock by the heat released from radioactive decay can lead to crack opening. Since there is little experience in the effects of temperature on rock mass behaviour, a series of in situ experiments are being conducted. In the present work, 3-D finite element analysis of thermal model of the multi-heater experiment is described. Temperature and stress field around the heaters have been calculated in advance to guide the design and operation of the experiment and to provide predicted data. Separate analysis has been done for triangular and square pitch heaters. Rock anisotropy in the direction of seistosity and perpendicular to it has been considered in the analysis. The results, however, show that the effect of anisotropy is negligible. (author). 2 refs., 21 figs., 10 tabs., 10 photographs