抄録
Since the passive safety system turns out to be a desirable method to achieve simplification and increase the reliability of the performance of essential safety functions, passive technology has been generally applied to the design of advanced nuclear power plant. The traditional generation II+ nuclearpower plant is proposed to be improved with some passive systems to enhance safety performance. There are two series of passive safety systems for this kind of nuclear power plant in this paper, one of them contains: (1) the RMT (reactor makeup tank); (2) the A-ACC (advanced accumulators); (3) the IRWST (in-containment refueling water storage tank); (4) the PDS (passive depressurization system); and (5) the PRHRS (passive residual heat removal system), which is installed on the reactor coolant system (RCS) loop;the other contains:(1) the RMT (reactor makeup tank); (2) the A-ACC (advanced accumulators); (3) the IRWST (in-containment refueling water storage tank); (4) the PDS (passive depressurization system); (5) the PEFS(passive emergency feed water system), which is installed on the secondary side of SGs. In this research, the transient characteristics of SGTR accident with the two different passive residual heat removal systems which are PRHRS and PEFS is investigated using the best-estimate transient simulation code Relap5/MOD3.3. The calculation results show that both of PRHRS and PEFS could remove the decay heat from the primary loop efficiently to ensure the reactor safety and reduce the radioactive leakage to mitigate the accident impact during the SGTR accident. Due to the significant cooling effect of PRHRS and PEFS, the water level of broken SG would not be overfilled in both conditions, which is different with the SGTR accident of traditionalgeneration II+nuclear power plant. Compared with the PEFS, the PRHRS performed better in cooling efficiency, long-term cooling performance, reducing radioactive leakage capacity and mitigating accident effect.
