Analysis of the oscillation in the system of parallel narrow channels

Abstract

In this paper, the RELAP5/MOD3.4 code is used to study the instability of the parallel narrow flow channel system in detail. First, the rationality of the RELAP5 code is verified with experimental data. By extracting the pressure drop in the channel under different node numbers, the importance of reasonable node model in pressure drop calculation using RELAP5 program is illustrated. Thus, the deep reason of the influence of the node number on the instability boundary is revealed. After that, the influences of various factors on the instability were investigated. The results show that: The more channels, the more unstable the system is, and the flow instability boundary tends to a fixed value; The fuel module separation has a significant effect on the instability in multi-channel system, and the single side heating channel has a stabilizing effect on the system; The flow instability of the system mainly depends on the hottest channel.