French LMFBR core thermo-hydraulic studies for nominal and accident conditions

Abstract This paper summarizes the present status of the analytical methods used by the CEA for the study of the thermal behaviour of subassemblies in a LMFBR core during normal operation. Particular emphasis is devoted to the effects related to irradiation induced distortions. The methods used for the determination of the coolant flow pattern in the interstitial space between the subassemblies are presented, and the formation and the thermo-hydraulic consequences of local blockages are analysed. Sodium boiling phenomena related to loss of coolant accidents are presented and methods are outlined for the estimation of dry-out occurrence in following situations: • - Loss of flow without scram, • - Natural convection boiling, • - Complete inlet blockage with cooling through the wrapper. Some observations and results from the SCARABEE in-pile experiments are discussed. A list of pertinent reference is provided.