Analyses on Flow Instability of Secondary-Side Passive Residual Heat Removal System for Advanced Nuclear Heating Reactor

An advanced nuclear heating reactor model is provided to study the flow instability of secondary-side passive residual heat removal system. The RELAP5 program is used to simulate the transient process of PRHRS after accident. The results show that the origin for the condensate flow instability is the mismatch of vapor pressure and two phase length in the condensate tube of PRHRS. The condensate flow stability boundary calculated numerically by RELAP5 is satisfied with Bhatt's theoretical formula analysis results. By increasing the condensate tube inlet throttling, flow area and heat transfer area, the condensate flow instability can be avoided. (authors)