Pressure pulse on a subassembly wall due to gas release from a failed fuel pin

Abstract This paper presents a mathematical model to predict the pressure pulse on a subassembly of fuel pins due to rapid release of gas from a failed pin into liquid coolant between the pins. The subassembly is simulated by a rigid circular tube, and liquid flow inside the tube is assumed incompressible, inviscid, and irrotational. A gas bubble along the centerline of the subassembly is considered to be formed as a result of the gas release from the plenum, and a pressure pulse on the subassembly wall is a consequence of the liquid being accelerated by the gas bubble. It is assumed that the gas bubble grows spherically until it touches the subassembly wall, and then expands as a cylinder with hemispherical ends. This analysis is particularly applicable to the EBR-II reactor.