ML20207G292

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Provides Status on Wits Item 9600184, Clarity & Intent of NRC Safety Guide 1, as It Related to Isat Insp of Maine Yankee Atomic Power Station
ML20207G292
Person / Time
Site: Maine Yankee
Issue date: 03/04/1999
From: Collins S
NRC (Affiliation Not Assigned)
To: Travers W
NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO)
References
GL-97-04, GL-97-4, NUDOCS 9903120043
Download: ML20207G292 (4)


Text

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9 March 4, 1999 f:

- MEMORANDUM TO: ' William D. Travers

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Executive Director for Operations f

FROM: Samus! J. Collins, Director Office of Nuclear Reactor Re n i

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SUBJECT:

STATUS REPORT ON WITS ITEM 9600184, "Cl.ARITY AND INTENT

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OF NRC SAFETY GUIDE 1" l l

. 1 One of the issues identified by the NRC independent Safety Assessment Team (ISAT)

! . inspection at the Maine Yankee Atomic Power Station (in a report dated October 7,1996) was 3

[ the inclusion of containment accident pressure (containment overpressure) in determining

. whether adequate net positive suction head (NPSH) exists for the emergency core cooling l i

! system and the containment heat removal pumps following a design-basis loss-of-coolant accident (LOCA). As a result of the review of this issue during and following the ISAT 2

inspection, tne NRC staff questioned the guidance in NRC Safety Guide 1. " Net Positive Suction

' Head for Emergency Core Cooling and Containment Heat Removal System Pumps," dated

November 2,1970, related to reliance on containment overpressure for ensuring adequate
NPSH for these pumps. This issue became WITS Item 9600184. The time period for responding to this issue was extended as a result of the issuance of Generic Letter (GL) 97-04,

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" Assurance of Adequate Net Positive Suction Head for Emergency Core Cooling and 1 Containment Heat Removal Pumps," dated October 7,1997, so as to provide time for staff p revi6w of the industry responses since these were directly related to the question raised by the I l i WITE item. l i

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- WITS 9600184 requests that the staff Review and clarify the staff's criteria relative to relying on containment overpressure for )

ensuring appropriate NPSH for emergency core cooling and containment heat removal pumps. The staff is already conducting a separate program to determine if and how all plants, including Maine Yankee, meet these criteria. Upon review of this information, the staff will determine the measures to be taken for thoss plants not in compliance with the  ;

cnteria.

l We are continuing our review of licensee responses to GL 97-04. As of February 19,1999, the staff has completed the review of 88 of 103 plants for GL 97-04. The remaining reviews requia further staff discussion with licensees. The major issue has been the need to clarify the licensing basis with respect to the use of containment overpressure in NPSH calculations. The need for containment overpressure comes from several different factors, in general, the older plants have more of a need for containment ovaerpressore. Only a few pressurized water CONTACT: R. Lobel, SCSB:DSSA  ;

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- William D. Travers ,

i reactors (PWRs) need containment overpressure to ensure adequate NPSH. The staff i ' considers credit for containment overpressure that has not been previously reviewed and 1 . approved by the staff to be an unreviewed safety question as defined in 10 CFR 50.59.

Licensees have submitted revised analyses and licensing amendments, as appropriate, to resolve this issue. The staff has discussed this issue with the Advisory Committee on Reactor

. Safeguards (ACRS), and the ACRS agrees with the staff approach to this issue (see letter from

,' R. L. Seale, Chairman, ACRS, to NRC Chairman Jackson, dated December 12,1997). Some j enforcement actions have also been taken.

l The staff anticipates'that the remaining reviews will be closed by October 1,1999.

i The Office of Nuclear Regulatory Research is currently working on a related issue, Generic

] Safety issue (GSI) 191, " Assessment of Debris Accumulation on Pressurized Water Reactor  :

j Sump Performance." GSI 191 deals with the adequacy of the design of PWR containment

emergency sumps with respect to LO% generated debris, an issue with a direct impact on NPSH, (This issue was resolved for boiling water reactors with the issuance of NRC j Bu'!etin 96-03. " Potential Plugging of Emergency Core Cooling Suction Strainers ty Debris in i
Boiling Water Reactors.") GSI 191 is not scheduled to be completed until 2001. When this

. issue is resolved, the staff will assess the need to revise the present regulatory guidance related .

to NPSH.

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William DcTravers 1

. - reactors (PWRs) need containment overpressure to ensure adequate NPSH. The staff considers credit for containment overpressure that has not been previously reviewed and '

approved by the staff to be an unreviewed safety question as defined in 10 CFR 50.59.

Licensees have submitted revised analyses and licensing amendments, as appropriate, to l resolve this issue. The staff has discussed this issue with the Advisory Committee on Reactor .

Safeguards (ACRS), and the ACRS agrees with the staff approach to this issue (see letter from

' R. L. Seale, Chairman, ACRS,% NRC Chairman Jackson, dated December 12, j997). Some ,

enforcement actions have also been taken.

t.

The staff anticipates that the remaining reviews will be closed by October 1,1999.

h The Office of Nucleaf Regulatory Research is currently working on a related issue, Generic j

Safety issue (GSI) 191, " Assessment of Debris Accumulation on Pressurized Water Reactor  !

- Sump Performance."' GSI 191 deals with the adequacy of the design of PWR containment ,

emergency' sumps with respect to LOCA-generated debris, an issue with a direct impact on  !

NPSH. (This issue was ;esolved for boiling water reactors with the issuance of NRC i

Bulletin 96-03, " Potential Plugging of Emergency Core Cooling Suction Strainers by Debris in .

1

' Boiling Water Reactors.") GSI 191 is not scheduled to be completed until 2001. When this issue is resolved, the staff will assess the need to revise the present regulatory guidance related to NPSH.

e

. DISTRIBUTION:

' R. Elliott . K.Kavanagh

. A. Serkiz M. Marshall .

T. Collins ~ . R. Zimmerman

~ J. Kudrick -PDR File Center .- SCSB R/F (2)

M. Bridgers A.Thadani W.- Kane F Miraglia l

P. Norry M.Knapp J. Blaha P. Magnanelli NRR Mailroom

  • See previous concurrences
DOCUMENT NAME: RG182 WIT.5

~ To receive e cor of this document, hdcate in the boa: "C" = Copy without ettachment/ enclosure 'E' = Copy with attachment / enclosure "N" = No copy j OFFICE - SCSB:DSSA:NRR- l BC:SCSB:DSSA -l TECH ED D:DSSA l '

NAME- RLobel:bw CBerlinger BCalure GHolahan DATE 1/06/99* - 1/07/99* 1/04/90* 1/20/99*

OFFICE - ADT:NRR - l D:NRR pn l - l l NAME <

BSheron L SCollins '

DATE 2/22/99* 'l 3/lf /99 2/ /99 2/ /99

. OFFICIAL RECORD COPY  !

1 l

O' s; ,

]: I William D. Travers reactors (PWRs) need containment overpressure to ensure adequate NPSH. The staff considers credit for containment overpressure that has not been previously reviewed and approved by the staff to be an unreviewed safety question as defined in 10 CFR 50.59.

Licensees have submitted revised analyses and licensing amendments, as appropriate, to resolve this issue. The staff has discussed this issue with the Advisory Committee on Reactor Safeguards (ACRS), and the ACRS agrees with the staff approach to this issue (see letter from R. L. Seale, Chairman, ACRS, to NRC Chairman Jackson, dated December 12,1997). Some enforcement actions have also been taken.

The staff anticipates that the remaining reviews will be closed by October 1,1999.

The Office of Nuclear Regulatory Research is currently working on a related issue, Generic Safety issue (GSI) 191, " Assessment of Debris Accumulation on Pressurized Water Reactor Sump _ Performance." GSI 191 deals with the adequacy of the design of PWR containment emergency sumps with respect to LOCA-generated debris, an iscue with a direct impact on i NPSH. (This issue was resolved for boiling water reactors with the issuance of NRC Bulletin 96-03, " Potential Plugging of Emergency Core Cooling Suc"on Strainers by Debris in Boiling Water Reactors.") GSI 191 is not scheduled to be completed until 2001. When this issue is resolved, the staff will assess the need to revise the present regulatory guidance related

. to NPSH.

DISTRIBUTION:

R. Elliott K.Kavanagh ~

A. Serkiz M. Marshall T. Collins - R. Zimmerman i J. Kudrick PDR l

^

File Center SCSB R/F (2)

M. Bridgers A. Thadani W. Kane F. Miraglia P. Norry M. Knapp J. Blaha P. Magnanelli -

NRR Mailroom

  • See previous concurrences DOCUMENT NAME: RG182 WIT.5 To receive e cop ' of this document indicats in the bos: 'C' = Copy without ettechment/ enclosure *E' = Copy with attachment / enclosure *N" = No copy OFFICE ' SCSB:DSSA:NRR l BC:SCSB:DSSA l TECH ED l D:DSSA l NAME '

RLobel:bw CBerlinnen BCalure GHolahan DATE 1/06/99*. 1/07/99* -

1/04/99* 1/20/99*

i OFFICE . ADT:NRR l D:NRR g(Q- l l l NAME BSheron L SCollins '

DATE 2/22/99*

3/4 /99 2/ /99 2/ /99 OFFICIAL RECORD COPY

.