ML20198K249

Discusses RAI Re Response to NRC GL 97-04, Assurance of Sufficient Net Positive Suction Head for ECC & Containment Heat Removal Pumps

ML20198K249
Person / Time
Site:	Cooper
Issue date:	12/23/1998
From:	Swailes J NEBRASKA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-91-18, GL-97-04, GL-97-4, IEB-96-003, IEB-96-3, NLS980201, NUDOCS 9812300388
Download: ML20198K249 (5)

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N Nebraska Public Power District l

Nebraska's Energy Leader NLS980201 December 23,1998 U.S. Nuclear Regulatory Commission l

Attention: Document Control Desk Washington, D.C. 20555-0001

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Gentlemen- l

Subject:

Response to NRC Generic Letter 97-04 i Request for AdditionalInformation

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i Cooper Nuclear Station, NRC Docket 50-298, DPR-46

Reference:

1. NRC Generic Letter 97-04 dated October 7,1997," Assurance of Sufficient Net Positive Suction Head for Emergency Core Cooling and Containment l Heat Removal Pumps"

2. Letter to G. R. Horn from NRC dated August 14,1998, " Request for Additional Information Related to Generic Letter 97-04"

3. Letter NLS970226 to USNRC from G. R. Horn (NPPD) dated January 5, 1998, " Response to NRC Generic Letter 97-04"

4. Letter NLS980149 to USNRC from M. F. Peckham (NPPD) dated September 22,1998," Response to NRC Generic Letter 97-04, Request for Additional Information" j

5. Letter to G. R. Horn from NRC dated November 24,1998,"CNS Response to Request for Additional Information Related to Generic Letter 97-04" l i

On October 7,1997, the Nuclear Regulatory Commission (NRC) issued Generic Letter 97-04 (Reference 1) regarding an issue which may have generic implications for Emergency Core Cooling System (ECCS) and containment heat removal system pumps. The Nebraska Public Power District (District) provided a response to the Generic Letter 97-04 in Reference 3 which described the methods used to determine available Net Positive Suction Head (NPSH) for the

ECCS pumps and the results of those analyses. In Reference 2 the NRC indicated that there was a 9812300388 981223 i PDR ADOCK 05000298 -

. oper Nudear Station PO. Box 98/ Brownville. NE 68321M90 ]

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k Telephone: (402) 825 3811/ fax: (402) 825-5211 http //www.nppd.com

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! NLS980201 December 23,1998 Page 2 of f

l l concern with the District's response in that more containment overpressure is required to assure adequate NPSH than in the original analysis during plant initial licensing. The NRC indicated that this may have placed the Cooper Nuclear Station (CNS) outside ofits licensing basis with respect to the is. sue of NPSH to the ECCS pumps.

The District's response (Reference 4) was that by maintaining adequate margins between the ECCS pump NPSH requirements and the available NPSH, including a contribution from containment overpressure, CNS is operating within its licensing basis. The NRC (Reference 5) stated that the increased magnitude of the reliance on containment overpressure to ensure adequate NPSH for the ECCS pumps had not been reviewed and approved by the NRC staff.

Since the NRC believe that the magnitude of the containment overpressure contribution, as well l as the margins, are part of the CNS design basis, the NRC maintains its position that CNS is operating beyond the licensing basis for the facility, l District technical staff have reviewed the latest NRC letter (Reference 5) and its enclosure in detail and the District will prepare and submit for NRC approval, a License Amendment on this i

issue. During the interim period while the License Amendment is being reviewed by the NRC staff, safe plant operation is assured by two Operability Evaluations (OEs), one for the short term l Core Spray (CS) pump runout concern, and the other for the long term suppression pool heatup I

! concerr. These OEs demonstrate that the ECCS pumps are operable but nonconforming i i consistent with the guidelines of Generic Letter 91-18, Revision 1,"Information to Licensees I

l Regarding NRC Inspection Manual Section on Resolution of Degraded and Nonconforming l l Conditions", dated October 8,1997.

The License Amendment will address the following issues:

a) The use of a 90"F Service Water (SW) temperature and a 95 F torus water initial l temperature in determining the NPSH available for the ECCS pump following a large break l Loss of Coolant Accident (LOCAL). In addition the use of the ANSI 5.1 decay heat curve in I

this analysis will also be justified.

l b) Investigations on the NPSH for the CS pumps have recently determined that higher CS pump l flow during the first ten minutes of a large break LOCA may have an effect on the available J NPSH for the CS pumps. The CNS Engineering staff has determined that, as a result of the l l increased runout flow during the first 10 minutes of the event, the CS pumps will require a l contribution from containment overpressure to assure adequate NPSH. This is an increased i early reliance on containment overpressure to assure adequate CS NPSH, since previous l i

analysis did not require any containment overpressure contribution until some hours into the j LOCA event. After the first 10 minutes credit can be taken for operator action to reduce the CS flow so that the CS NPSH requirements revert to the present description in the CNS l

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NLS980201 December 23,1998 Page 3 of #

Updated Safety Analysis Report, Section VI-5.3.2 which would be addressed by item a) above.

c) The effect on ECCS pump NPSH of the final design basis ECCS strainer debris loadings.

These debris loadings are based on the guidance provided in the SER recently issued by the NRC on the Utility Resolution Guidance document developed by the Boiling Water Reactor Owners Group in response to the Inspection and Enforcement Bulletin 96-03.

i This License Amendment will be submitted by April 30,1999. As discuased above the OEs, I presently in effect, ensure that the ECCS pumps are operable, bu: nonconforming, and are therefore capable of fulfilling their safety function if required.

Should you have any questions concerning this matter, please contact me.

Sincerely, l

J.I Swailys

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Vice P nt of Nucle Energy

/dm cc: Regional Administrator USNRC - Region IV Senior Project Manager USNRC - NRR Project Directorate IV-1 Senior Resident inspector USNRC NPG Distribution

NLS980201 December 23,1998 Page 4 of '4'

STATE OF NEBRASKA )

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NEMAHA COUNTY )

J. H. Swailes, being first duly sworn, deposes and says that he is an authorized representative of the Nebraska Public Power District, a public corporation and political subdivision of the State of Nebraska; that he is duly authorized to submit this correspondence on behalf of Nebraska Public

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Power District; and that the statements contained herein are true to the best of his knowledge and '

belief.

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[ 67 %%. ivailes Subscribed in p ace and sworn to before me this b day of _ ,1998.

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.s. _.. ___.

/ Wilma M. Werner l General Notary ,"

,' State of Nebraska ,

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. My Commission Ernw na oc onno e

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j l ATTACHMENT 3 LIST OF NRC COMMITMENTS l Correspondence No: NLS980201 The f,ollcWing ,tpble identifies those actions committed to by the District in this i

document!

• Any bther actions discussed in the submittal represent intended or planned actions by the District. They are described to the NRC for the NRC's l information and are not regulatory commitments. Please notify the Licensing Manager at Cooper Nuclear Station of any questions regarding this document or any associated regulatory commitments.

COMMITTED DATE COMMITMENT OR OUTAGE The District will submit for NRC approval a License

! Amendment which details the ECCS pump NPSH requirements ^E# '

in a post LOCA condition.

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l PROCEDURE NUMBER 0.42 l REVISION NUMBER S l PAGE9OF13[~~)

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