Piramid, a loop for European PAHR irradiations according to a Mol integrated device

On behalf of the Commission of the European Communities, the Nuclear Research Centre of Mol, S.C.K./C.E.N., is in charge of the execution in the BR2 reactor of three in-pile experiments aiming at the study of the post-accident heat removal (PAHR) phenomenology. The purpose of these experiments is to validate the physical models and the computer codes used to predict the temperature fields in a sodium saturated bed and in debris retention devices. From the large experience gained with in-pile Na-loops, the S.C.K./C.E.N. has followed the approach of an integrated design, which presents numerous advantages. The paper describes the lay-out of the first experiment, PIRAMID 1, which is foreseen for temperatures up to 1400 deg C in an UO2 debris bed with a bed loading of 1000 kg UO2/m2. It emphasizes also the importance of the back-up programme related to the in-pile PAHR programme. (Auth.)