Document: NUREG-0800
Document ID: a650b8f2-b0fa-4f0f-bc8f-55bb3f6ec603
Document Type: srp
Title: INADVERTENT OPENING OF A PWR PRESSURIZER PRESSURE RELIEF VALVE
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0708/ML070820094.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.6.1
CFR Part: 
CFR Title: 

Content:
OR A BWR PRESSURE RELIEF VALVE REVIEW RESPONSIBILITIES Primary - Organization responsible for review of transient and accident analyses for PWRs/BWRs Secondary - None I. AREAS OF REVIEW An accidental depressurization of the reactor coolant system (RCS) could be caused by the inadvertent opening of a pressure relief valve, which in turn could be caused by a spurious electrical signal or by an operator error. As this event can occur one or more times during the plant’s lifetime, it is an anticipated operational occurrence (AOO), as defined in 10 CFR Part 50, Appendix A. The inadvertent opening of a pressure relief valve results in a decrease in reactor coolant inventory and RCS pressure. A pressure relief valve, as defined in American National Standards Institute (ANSI) B95.1-1972, is a device designed to reclose and prevent further fluid flow after normal conditions are restored. The effect of the decreased pressure is a decreased neutron flux (via moderator density feedback). In a pressurized-water reactor (PWR), a reactor trip occurs with low RCS pressure or low thermal margin. In a boiling water reactor (BWR), the pressure relief valve discharges into the suppression pool and normally there is no reactor trip. The pressure regulator senses the RCS pressure decrease and partially closes the turbine control valves to stabilize the reactor at a lower pressure. The reactor power settles out at nearly the initial power level. The coolant inventory is maintained by the feedwater control system with water from the condensate storage tank via the condenser hotwell. The specific areas of review are as follow: 15.6.1-2 Revision 2 - March 2007 1. The review of these transients should consider the sequence of events, the analytical model, the values of parameters in the analytical model, and the predicted consequences of the transient. A. The sequence of events described in the applicant's safety analysis report (SAR) is reviewed by the organization responsible for review