Azimuthal temperature variation in the cladding of PWR fuel elements

Abstract

This paper is concerned with the prediction of the azimuthal temperature distribution in the cladding of the fuel elements of a pressurized water reactor (PWR), in the event of a loss of coolant accident (LOCA). It is assumed that ballooning of the fuel elements results in local restrictions of flow area as the cladding of adjacent rods contact each other to form singly connected passages of the 4-cusp shape. A “fin-type” analysis of the circumferential heat transfer in the walls (the cladding) of the channel is made, account being taken of the variation of convective heat transfer coefficient around the channel perimeter. Predicted results for the maximum azimuthal temperature difference in the cladding are presented for a range of variables and percentage blockage, and a comparison is made with the predictions of other workers in this field of study.