Regulatory Guide 1.1
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| ML052440069 | |
| Person / Time | |
|---|---|
| Issue date: | 09/06/2005 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Lobel R, NRR/DSSA/SPSB 415-2865 | |
| Shared Package | |
| ML052440303 | List: |
| References | |
| Reg Guide 1.1, RG-1.001 | |
| Download: ML052440069 (1) | |
ATTACHMENT 2
3:SAFETY GUIDE 1 REGULATORY GUIDE 1.1NET POSITIVE SUCTION HEAD FOREMERGENCY CORE COOLING AND CONTAINMENT HEAT REMOVAL SYSTEM PUMPS
- A. Introductionpossible accident conditions. For example, ifProposed General Design Criterion 41 re-proper operation of the emergency core coolingquires 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 minimumcomplishing 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 integrityrent designs the ability to accomplish theseor operation of the containment heat removalsafety functions reliably depends in part on thesystems at too high a rate) could significantlyproper performance of system pumps which,affect the ability of this system to accomplishin turn, depends on the conditions under whichits safety functions by causing pump cavita-the pumps must operate. One of these condi-tion. In addition, the deliberate continuation oftions is suction pressure. This guide describesa high containment pressure to maintain ana suitable relationship between increases in adequate pump NPSH would result in greatercontainment pressure caused by postulated lossleakage of fission products from the contain-of coolant accidents and the net positive suc-ment and higher potential offsite doses undertion head (NPSH) of emergency core coolingaccident conditions than would.otherwise result.and containment heat removal system pumpsChanges in NPSH for emergency core cool-which may be used to implement General De-ing and containment heat removal systemsign Criterion 41.pumps caused by increases in temperature ofthe pumped fluid under loss of coolant accidentB. Discussionconditions can be accommodated without reli-A significant consideration related to emer-ance on the calculated increase in containmentgency core cooling and containment heat re-pressure. Adequate NPSH can be assured bymoval systems is the potential for degradedlocating pumps at-suitable elevations with re-pump performance which could be caused by aspect to the storage volumes connected to theirnumber of factors, including inadequate NPSH.suction sides, by using multistage or boosterIf the NPSH available to a pump is not suffi-pumps, by a combination of these methods, orcient, cavitation of the pumped fluid can occur.by other techniques.This cavitation may reduce significantly the capability of the system to accomplish its safetyC. Regulatory Positionfunctions.Emergency core cooling and containment heat removal systems should be designed soIt is important that the proper performancethat adequate net positive suction head (NPSH)of emergency core cooling and containmentis provided to system pumps assuming maxiheat removal systems be independent of calcu-mum expected temperatures of pumped fluidslated increases in containment pressure causedand no increase in containment pressure fromby postulated loss of coolant accidents in orderthat present prior to postulated loss of coolantto assure reliable operation under a variety ofaccidents.1.1*This regulatory guide has been superseded by Regulatory Guide 1.82 Revision 4. However, this regulatory guide may continue tobe used if it is part of a plant's licensing basis on the date of issuance of Regulatory Guide 1.82 Revision 4.