Document: NRC Regulatory Guide
Document ID: 4a6ff506-3e14-471e-90ad-8c6b7081650a
Document Type: regulatory_guide
Title: Net Positive Suction Head for Emergency Core Cooling and Containment Heat Removal System Pumps
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0037/ML003739925.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.1
CFR Part: 
CFR Title: 

Content:
ssure above a specified minimum amount, then too low an internal pressure (re sulting from impaired containment integrity or operation of the containment heat removal systems at too high a rate) could significantly affect the ability of this system to accomplish its safety functions by causing pump cavita tion. In addition, the deliberate continuation of a high containment pressure to maintain an adequate pump NPSH would result in greater leakage of fission products from the contain ment and higher potential offsite doses under accident conditions than would otherwise result. Changes in NPSH for emergency core cool ing and containment heat removal system pumps caused by increases in temperature of the pumped fluid under loss of coolant accident conditions can be accommodated without reli ance on the calculated increase in containment pressure. Adequate NPSH can be assured by locating pumps at- suitable elevations with re spect to the storage volumes connected to their suction sides, by using multistage or booster pumps, by a combination of these methods, or by other techniques. C. Regulatory Position Emergency core cooling and containment heat removal systems should be designed so that adequate net positive suction head (NPSH) is provided to system pumps assuming maxi mum expected temperatures of pumped fluids and no increase in containment pressure from that present prior to postulated loss of coolant accidents. 1.1