[en] The maximum temperature rises above ambient to which blocks of vitrified waste will heat if disposed singly in large volumes of granite, are predicted to be 77⁰C and 770⁰C for blocks with 1kW and 10kW respectively of initial fission product heating. The minimum dimensions, if these maxima are not to be appreciably exceeded, are calculated for dispersed cubic, cuboidal and planar arrays of such blocks to accommodate a total of 7MW initial fission product heating and are found to lie in the range of 0.2 to 1.3 km. The minimum depth of depositories is found to be 500 m if the rise in surface temperatures is to be less than 0.3⁰C. (author)