Document: NUREG-0800
Document ID: 2cd63ebf-9196-42c0-880d-a80500b202a4
Document Type: srp
Title: - 15.1.4
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550005.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.1.1
CFR Part: 
CFR Title: 

Content:
system may be caused by operator action or a false actuation signal that opens the valves that normally isolate the PRHR heat exchanger from the RCS. This moderate-frequency event causes an injection of relatively cold water into the RCS and results in the addition of positive reactivity in the presence of a negative MTC. B. Boiling Water Reactors (BWRs) i. Loss-of a Feedwater Heater ii. Shutdown Cooling (RHR) Malfunction iii. Steam pressure regulator malfunctions or failures that result in increased steam flow. iv. For ESBWR, inadvertent actuation of isolation condenser. The topics covered in the primary review include: postulated initial core and reactor conditions which are pertinent to feedwater system malfunctions, pressure regulator or pressure relief valve malfunctions, methods of thermal and hydraulic analysis, postulated sequence of events including time delays prior to and after protective system actuation, assumed reactions of reactor system components, functional and operational characteristics of the reactor protection system in terms of how it affects the sequence of events, and all operator actions required to secure and maintain the reactor in a safe condition. The results of the transient analysis are reviewed to ensure that the values of pertinent system parameters are within the ranges expected for the type and class of reactor under review. The parameters include: core flow and flow distribution, channel heat flux (average and hot), minimum critical power ratio (MCPR), departure from nucleate boiling ratio (DNBR), vessel water level (for BWRs), thermal power, vessel pressure, steam line pressure (for BWRs), steam line flow (for BWRs), feedwater flow (for BWRs), and reactivity. The staff reviews the sequence of events described in the SAR for these transients. The reviewer concentrates on the need for the reactor protection system, the engineered safety systems, and operator action to secure and maintain the reactor in a 15.1.1-15.1.4-3 Revision