ML20244D855

Requests Review of Results of Suppression Pool Temp Limits. Local Temps Near Safety Relief Valve Discharge Points Could Cause Loss of NPSH & Endanger ECCS Pumps.Completion of Evaluation/Prioritization Requested by 861231

ML20244D855
Person / Time
Site:	Oyster Creek, 05000000
Issue date:	04/30/1986
From:	Bernero R Office of Nuclear Reactor Regulation
To:	Speis T Office of Nuclear Reactor Regulation
Shared Package
ML20195F761	List: ML20235J954 ML20236D162 ML20236D237 ML20236X312 ML20236X348 ML20236X386 ML20236X537 ML20236X577 ML20236X629 ML20236X654 ML20236X673 ML20236X694 ML20236X703 ML20236X732 ML20236X738 ML20236X746 ML20236X939 ML20236X959 ML20236X967 ML20236X988 ML20236X996 ML20236Y022 ML20236Y063 ML20236Y094 ML20244B981 ML20244D524 ML20244D615 ML20244D618 ML20244D726 ML20244D855 ML20244D938 ML20244D943 ML20244E090 ML20244E142 ML20244E158
References
FOIA-87-714, RTR-REGGD-01.100, RTR-REGGD-1.100 NUDOCS 8605160525
Download: ML20244D855 (1)

Text

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MEMORANDUM FOR: Themis P. Speis, Director Division of Safety Review and Oversight FROM: Robert M. Bernero, Director Division of BWR Licensing

SUBJECT:

REQUEST FOR PRIORITIZATION OF GENERIC SAFETY ISSUE - NPSH FOR ECCS PUMPS During a recent review of suppression pool temperature limits at Oyster Creek, it was determined that available NPSH for ECCS pumps may be a limiting consideration. This arises from tha fact that NPSH calculations do not generally take into account temperature gradients in the suppression pool, but rather assume a bulk pool temperature. However, at locations near safety relief valve discharge points local temperatures can be significantly higher and may result in inadequate available NPSH if ECCS suction points are nearby. Loss of NPSH can lead to pump damage and loss cf ECCS injection capability.

We have reviewed Regulatory Guide 1.1 " Net Positive Suction Head for Emergency Core Cooling and Containment Heat Renoval System Pumps" (November 1970) and note that there is no guidance regarding local temperature considerations. We expect that all plants have assumed a uniform pool temperature in their NPSH calculations. Plants reviewed after 1970 (Hatch and later) include a Regulatory Guide 1.1 conservatism wherein no NPSH credit is taken for wetwell pressurization during a LOCA. Plants befora 1970 (before Hatch) do not include this conservatism and are therefore of greater concern.  :

I request that the issue be evaluated by DSR0 and a priority assigned for the investigation. Because of the importance of NPSH considerations for ECCS operation, I request that the evaluation /prioritization be completed by December 31, 1986. -

OristmalgigreeBf!h nobert & B* m e w l Robert M. Bernero, Director Division of BWR Licensing cc: H. Denton DISTRIBUTION D. Eisenhut W. Minners Central FiTes RSB R/F / ')' 3 c

F. Congel T. Collins R/F -

BWR/PDs RSD Members G. Lainas R. M. Berners n()

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Contact:

T. Collins, RSB, x29463  ;

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