A three-dimensional finite element analysis of the HAW test field with two heated holes

A finite element study has been performed on a model of the HAW test field, which is an underground experimental facility used for the investigation of the effects of storage of nuclear waste in salt formations. The HAW test field consists of 2 parallel galleries situated in the Asse salt mine in Remlingen near Braunschweig in Germany. From each gallery 4 vertical boreholes have been drilled at equal distance in which electrical heaters of heat producing nuclear sources will be installed. Due to the delay in the availability of the nuclear sources, the field is operating with electrical heaters in 2 of the 8 holes for considerable time now. The temperature distribution in the course of time, the resulting stress and creep deformation for this situation where only 2 holes are generating heat have been analysed with the aid of the finite element analysis system ANSYS. From the analysis it appears that the maximum of the compressive stress on the borehole liner is of the same magnitude as that from the analysis with 8 heat producing boreholes. The decrease of the compressive stress after the occurrence of the maximum is significantly slower than in the case where all 8 holes of the field have been filled with heat sources. (author). 6 refs.; 44 figs.; 2 tabs