Abstract: Taking the heat spectrum supercritical water cooled reactor design model SCLWRH proposed by Japanese as research object, the relevant thermal physical calculation modules were established. Under the assumptive stuck shaft accident of the reactor coolant pump, the variation trends of the main coolant flow rate, the flow rate in fuel channel inlet, the maximum cladding temperature of the internal fuel assembly, the core pressure and the reactor power in the beginning of the lifecycle of the reactor were analyzed, and the maximum values of the cladding temperature of the internal fuel assembly in the beginning, the mediumterm and the end of the reactor lifecycle were compared. The obtained conclusion is as below, when the stuck shaft accident occurs during the beginning of the lifecycle of the reactor, the reactor power will reduce quickly，the core pressure will reduce gradually, the cladding temperature of the internal fuel assembly will rise quickly first, and then will reduce quickly， the maximum cladding temperature rise is 132℃, which is still meet the accident safety design criteria; the hazard of the stuck shaft accident occurred in beginning of lifecycle is largest, and the accident occurs in end of the lifecycle will has smallest hazard. The computational analysis in this paper can provide basic reference for qualitative analysis of safety characteristics of supercritical water cooled reactor.

Key words: supercritical water cooled reactor, transient state, stuck shaft, maximum cladding temperature, safety