Spray Cooling Heat Transfer for a BWR Fuel Bundle

Considerable experimental and analytical work has been done to evaluate the heat transfer phenomena in BWR fuel elements during spray cooling conditions. Two types of experimental studies have been performed. &asic separate-effect experiments have given some detailed information on the individual phenomena during BWR spray cooling conditions. Experiments with full scale BWR fuel element simulators have given extensive information on the integrated performance of the fuel element under representative spray cooling conditions. The experiments have been complemented with both semi-empirical models and detailed mechanistic models based on physical descriptions of the individual two-phase flow and heat transfer phenomena in the bundle. These methods are described herein and it is concluded that a comprehensive amount of information and phenomena understanding on BWR spray cooling heat transfer exists, and that it is presently possible to perform accurate and detailed calculations of core heat-up transients for a BWR-LOCA. (A)