[en] The Assessment Studies published so far [1], [2] are mainly concerned with the engineering aspects of a large High Temperature Reactor, whereas the actual power producing part of the plant, the core, has been the subject of detailed investigations to a much lesser degree. Early calculations by Brinkworth, U.K.A.E.A., Winfrith, [1], dealt with complete core replacement and continuous charge/discharge operation for a number of different core compositions, assuming fuel being reprocessed. The results have been re-evaluated by the author [3] to bring them into line with more recent calculations of the Dragon Project-itself, so that a direct comparison is possible. The new calculations refer to complete or part core replacement operations on a once-through basis and will be published soon.