Document: NUREG-0800
Document ID: 16650158-402d-4897-850a-bc9e2cce7648
Document Type: srp
Title: INADVERTENT OPENING OF A PWR PRESSURIZER PRESSURE RELIEF
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070726.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.6.1
CFR Part: 
CFR Title: 

Content:
VALVE OR A BWR PRESSURE RELIEF VALVE REVIEW RESPONSIBILITIES Primary - Reactor Systems Branch (RSB)SRXB1 Secondary - None I. AREAS OF REVIEW The inadvertent opening of a pressure relief valve results in a reactor coolant inventory decrease and a decrease in reactor coolant system pressure. A pressure relief valve, as defined in ANSI B95.1-1972 (Ref. 1), is a pressure relief device which is designed to reclose and prevent further 2 fluid flow after normal conditions have been restored. The effect of the pressure decrease is to decrease the neutron flux (via moderator density feedback). In a pressurized water reactor (PWR), a reactor trip occurs due to low reactor coolant system (RCS) pressure. In a boiling water reactor (BWR), the pressure relief valve discharges into the suppression pool. Normally there is no reactor trip in a BWR. The pressure regulator senses the RCS pressure decrease and partially closes the turbine control valves (TCVs) 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 using water from the condensate storage tank via the condenser hotwell. The review of these transients should consider the sequence of events, the analytical model, the values of parameters used in the analytical model, and the predicted consequences of the transient. DRAFT Rev. 2 - April 1996 15.6.1-2 The sequence of events described in the applicant's safety analysis report (SAR) is reviewed by RSBSRXB. The RSBSRXB reviewer concentrates on the need for the reactor protection 3 4 system, the engineered safety systems, and operator action to secure and maintain the reactor in a safe condition. The analytical methods are reviewed by RSBSRXB to ascertain whether the mathematical 5 modeling and computer codes have been previously reviewed and accepted by the staff. If a referenced method has not been previously reviewed, the reviewer initiates a generic