Break accident analysis of residual heat removal system of HPR1000

The residual heat removal system (RHR) is one of the most important fluid systems in the reactor Under shutdown condition, when RHR system is connected to the primary channel to cool the core, if there is a breach in the RHR pipeline, the core cannot be effectively cooled and the safety of the core will be seriously affected. This paper analyzes the accident that the RHR system of HPR1000 breaks during the access stage, especially the two typical accidents of unisolatable breach occurred in the line connecting the RHR system to the primary circuit and breach occurred on the line outside the containment for the RHR system. By calculating net positive suction head available (NPSHa) for the residual heat removal pump and assessing the effective isolation means for the break on the outside of containment, it is demonstrated that the design scheme of HPR1000 RHR system can deal with the rupture accident and ensure the effective cooling of the primary core. (authors)