The reactor coolant system (RCS) pressure transients under ATWS for Maanshan PWR with MUR conditions were analyzed in this study. The main concern was to observe whether the peak RCS pressure still maintained within 3200 psig limit (defined by ASME Code Level C service limit criterion under 100% rated power). The Maanshan RETRAN model, which had been developed for PWR transients, was used for ATWS safety analysis and related sensitivity analysis under MUR conditions. In document SECY-83-293, all initializing events were classified as either turbine trip or non-turbine trip events and their ATWS risks were also evaluated according to these two events. Loss of condenser vacuum (LOCV) and Loss of normal feedwater (LONF) ATWS were identified as limiting transients of turbine trip and non-turbine trip events in this study. In order to analyze the RCS pressure variations, a moderator density coefficient (MDC) model was included to observe the influences of moderator temperature and system pressure to the reactor reactivity, and the possibility of the peak RCS pressure reaching its limit. In addition, this report also covers the following sensitivity studies, (1) different MTC settings, and (2) different initial conditions of steam generator outlet pressure. The peak RCS pressure was found to stay within the criterion of 3200 psig even at a conservative MTC setting of −4 pcm/°F. Furthermore, a lower steam generator outlet pressure also resulted in a lower peak RCS pressure.

This content is only available via PDF.
You do not currently have access to this content.