Break spectrum analysis and transient analysis of limited condition for CAP1400 MSLB

CAP1400 reactor is quite different from traditional Gen. II nuclear power plants worldwide. The primary system of CAP1400 is modeled using RELAP5/MOD 3.3 code, and the transient thermal hydraulic characteristics are analyzed under the accident sequence of main steam line break (MSLB). DNBR of core is calculated by VIPRE code. Through summarizing the break spectrum, the results show that when the break size is less than 0.058 m' 2 , the reactor will not shut down;when the break size is between 0.059 m' 2 and 0.105 m' 2 , the reactor will shut down by overpower ΔT triggering reactor trip; and when the break size is between 0.106 m' 2 and 0.15 m' 2 , the reactor will shut down by the steam pipe low pressure injection signal. And the limited condition is 0.105 m' 2. The results of the limited condition show that the core heat flux and reactor coolant system temperature and pressure fluctuate with time. The minimum value of the DNBR is 1.914, greater than limited value 1.45. It indicates that CAP1400 reactor is very safe and reliable under the MSLB condition. (authors)