ML051190301

Attachment 2 - Regulatory Guide 1.1 - Net Positive Suction Head for Emergency Core Cooling and Containment Heat Removal System Pumps

ML051190301
Person / Time
Issue date:	05/24/2005
From:	Black S Division of Systems Safety and Analysis
To:
Lobel R, NRR/DSSA/SPSB 415-2865
Shared Package
ML051860237	List: ML051190292 ML051190301
References
+sispmjr200506, Y020050076/RG 1.082 RG-1.001
Download: ML051190301 (1)

Text

SAFETY GUIDE 1 REGULATORY GUIDE 1.1 NET POSITIVE SUCTION HEAD FOR EMERGENCY CORE COOLING AND CONTAINMENT HEAT REMOVAL SYSTEM PUMPS*

A. Introduction possible accident conditions. For example, if Proposed General Design Criterion 41 re- proper operation of the emergency core cooling quires that the emergency cooling and contain- system depends upon maintaining the contain-ment heat removal systems be capable of ac- ment pressure above a specified minimum complishing their required safety functions as- amount, then too low an internal pressure (re-suming partial loss of installed capacity. In cur- sulting from impaired containment integrity rent designs the ability to accomplish these or operation of the containment heat removal safety functions reliably depends in part on the systems at too high a rate) could significantly proper performance of system pumps which, affect the ability of this system to accomplish in turn, depends on the conditions under which its safety functions by causing pump cavita-the pumps must operate. One of these condi- tion. In addition, the deliberate continuation of tions is suction pressure. This guide describes a high containment pressure to maintain an a suitable relationship between increases in adequate pump NPSH would result in greater containment pressure caused by postulated loss leakage of fission products from the contain-of coolant accidents and the net positive suc- ment and higher potential offsite doses under tion head (NPSH) of emergency core cooling accident conditions than would.otherwise result.

and containment heat removal system pumps Changes in NPSH for emergency core cool-which may be used to implement General De- ing and containment heat removal system sign Criterion 41. pumps caused by increases in temperature of the pumped fluid under loss of coolant accident B. Discussion conditions can be accommodated without reli-A significant consideration related to emer- ance on the calculated increase in containment gency core cooling and containment heat re- pressure. Adequate NPSH can be assured by moval systems is the potential for degraded locating pumps at-suitable elevations with re-pump performance which could be caused by a spect to the storage volumes connected to their number of factors, including inadequate NPSH. suction sides, by using multistage or booster If the NPSH available to a pump is not suffi- pumps, by a combination of these methods, or cient, cavitation of the pumped fluid can occur. by other techniques.

This cavitation may reduce significantly the capability of the system to accomplish its safety C. Regulatory Position functions. Emergency core cooling and containment heat removal systems should be designed so It is important that the proper performance that adequate net positive suction head (NPSH) of emergency core cooling and containment is provided to system pumps assuming maxi heat removal systems be independent of calcu- mum expected temperatures of pumped fluids lated increases in containment pressure caused and no increase in containment pressure from by postulated loss of coolant accidents in order that present prior to postulated loss of coolant to assure reliable operation under a variety of accidents.

1.1

• This regulatory guide has been superseded by Regulatory Guide 1.82 Revision 4. However, this regulatory guide may continue to be used if it is part of a plants licensing basis on the date of issuance of Regulatory Guide 1.82 Revision 4.

ATTACHMENT 2