Vector and parallel processing of the nuclear reactor transient analysis code RELAP5

An experiment on vector processing and multitasking of the nuclear reactor transient analysis code RELAPS has been carried out. Vector processing and multitasking were achieved by using the independency of the spatial meshes. The vectorization ratio is 83%. The performance ratio in the vector mode to that in the scalar mode is about three on the FACOM VP-100. For multitasking the spatial meshes are halved, and each group of meshes is processed on a different processor. The effect of multitasking was estimated from the CPU time on the FACOM VP-100, which is a single-processor system. The improvement of wall clock time will be about 1.6 for parallelized subroutines. The total improvement of wall clock time will be about 1.2 because of parallelization ratio 45%