NOC-AE-000038, Submits 90-day Response to GL 97-04, Assurance of Sufficient NPSH for ECC & Containment Heat Removal Pumps

Submits 90-day Response to GL 97-04, Assurance of Sufficient NPSH for ECC & Containment Heat Removal Pumps

ML20198B694
Person / Time
Site:	South Texas
Issue date:	12/30/1997
From:	Cloninger T HOUSTON LIGHTING & POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-97-04, GL-97-4, NOC-AE-000038, NOC-AE-38, STI:30498963, NUDOCS 9801070039
Download: ML20198B694 (7)

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' december 30, 1997 NOC-AE-000038 File No.: GO3.08 10CFR50.54(f)

STI:30498963 U.S. Nuclear Regu'.atory Commission Attention: Document Control Desk Washington, DC 20555-0001 South Texas Project Units 1 and 2 Docket Nos. STN 50-498, STN 50-499 90 Day Response to Generic 12tter 97-N,

" Assurance of Sufficient Net Positive Suction Head for Emergency Core Cooling and Containment Heat Removal Pumps" Pursuant to Generic Letter 97-N, " Assurance of Sufficient Net Positive Suction Head for Emergency Core Cooling and Containment Heat Removal Pumps," the South Texas Projcet hereby subm5 the requested information.

The South Texas Project has reviewed the current design-basis analysis nsed to determine the available net positive suction head for the emergency core cooling (including core spray and decay heat removal) and containment heat removal pumps that meet either one of the following criteria:

1) pumps that take suction from the containment sump or suppression pool fotowing a design-basis LOCA or secondary line break, or

2) pumps used in " piggyback" operation that are nececsary for recirculation cooling of the reactor core and containment (that is, pumps that are supplied by pumps which take auction directly from the sump or suppression pool).

9901070039 971230 PDR ADOCK 05000498 P PDR i

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File No.: G03 Ob Page 2 The South Texas Project utilizes emergency core cooling (including core spray and decay heat removal) and containment heat removal pumps that meet criterion one above, and does not utilize ,

emergency core cooling (including core spray and decay heat removal) and containment heat removal pumps that meet criterion two above.

The following five issues were reviewed and the details are summarized below.

I. Specify the general methodo*ogy used to calculate the head loss associated with the ECCS suction strainers Enginecting calculations determined the head loss associated with the ECCS suction strainers following a Design Basis Accident (DBA). The general methodology used to determine these losses was to calculate the head loss associated with individual components of the ECCS suction strainers. The individual components considered were:

4 e debris pile generated by the DBA e trash racks ahead of screens e screens 3 vonex breaker The general methodologies used for each of these components are summarized below:

Ikbris pile Head loss due to debris was determined in accordance with NUREG/CR-2791, S AND82-7067, Methodology for Evaluation Insulation Debris Effects, Containment Emergency Methodology for Sump Performance Unresolved Safety Issue A-43. Equation 27 in Section 5.3 of the NUREG is utilized for a debris pile composed of Type 1 fibers.

Trash racks ahead of screens The methodology used for the trash racks was to oetermine the effect on the fluid velocity and the resultant head loss based on the available flow aru which was l

adjusted to compensate for the debris pile effect on containment / emergency sump  !

water level. I l

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NOC-AE-000038 File No.: G03.08 Page 3 Sacentand Vortex Breaker Similarly, the methodology to determine head loss associated with the emergency sump screens and vortex breaker was to determine the s elocity head loss based on the available flow area.

2. Identify the required NPSH and the available NPSH for those pumps which may take suction from the Emergency Sumps Component Etquired Head Anilable Head Iow Ilead 16.5 ft. > 20 ft.

Sarcty injection Pumps High IIead 16.1 ft. > 20 ft.

Safety injection Pumps Containment Spray Pumps 16.4 ft. > 20 ft.

3. Specify whether the current design basis NPSH analysis difiers from the mesi recent analysis reviewed and approved by the NRC for which a safety <

evaluation was issued. 7 The current design-basis NPSH analysis for the South Texas Project differs from the most recent analysis reviewed and approved tv the NRC for which a safety evaluation was issued (SER NUREG 0781, Safety Evaluation Report Related to Operation of the South Texas Project, April 1986). The original engineering calculations have been refined which resulted in minor changes in calculated head loss; however, in all cases, the available NPSH is greater than the required NPSH.

Consequently, the design basis is maintained.

4. Specify whether containment overpressure (i.e., containment pressure above the vapor pressure of the sump or suppression pool fluid) was credited in the calculation of available NPSH. Specify the amount of overpressure n.eded and the minimum overpressure available, As stated in Section 6.3.2.2 of the South Texas Project's UFSAR:

In addition to considering the static head and suction line pressure drop, the calculation ofavailable NPSH in the recirculation mode assumes that the vapor pressure of the liquid in the rump is equal to the Containment ambientpressure. This assures that the act al available NPSH is always greater than the calculated NPSH.

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NOC.AE-000038 File No.: G03.08 -

Page 4 Containment overpressure was no_t credited in the calculation of available NPSH and therefore is not part of the South Texas Project design basis.

5. Wisen containment overpressure is credited in the calculation of available

' NPSH, confirm that an appropriate containment pressure analysis was done to establish the minimum containment pressure.

Per Response to Question .4, containment overpressure was not credited in the calculation to determine available NPSH for the South Texas Project.

. We belic.ve the response provided above addresses the issues identified in this Generic Letter. This letter contains no new commitments to the NRC. Should you nave any <1uestions in regard to this response, please contact Mr. K. D. House at (512) 972-8922 or me at (512) 972-8787 T. H lonin ,

Vi P ent, Nucle Enginee ng KAW/

Attachment:

Affidavit 4

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NOC-AE-000038

'. File No.: G03.08 Page 5 Ellis W. MerschoiT- Jon C. Wood Regional Administrator. Region IV Matthews & Branscomb U. S. Nuclear Regulatory Commission One Alamo Center 611 Ryan Plaza Drive, Suite 400 106 S. St. Mary's Street, Suite 700 Arlington, TX 76011-8064 San Antonio, TX 78205-3692 Thomas W. Alexion Institute of Nuclear Power Project Manager, Mail Code 13H3 Operations - Records Center U. S. Nuclear Regulatory Commission 700 Galleria Parkway Washington, DC 20555-0001 Atlanta, GA 30.139-5957 David P. Loveless Richard A. Ratliff Sr. Resident inspector Bureau of Radiation Control c/o U. S. Nucler.r Regulatory Comm. Texas Department of Health P. O. Box 910 1100 West 49th Street Bay City, TX 77404-0910 Austin, TX 78756-3189 J. R. Newman, Esquire C. R. Crisp /R. L.Balcom Morgan, Lewis & Bockius Houstoa Lighting & Power Co.

1800 M Street, N.W. P. O. Box 1700 Washington, DC 20036-5869 Houston, TX 77251 M. T. Hardt/W. C. Gunst Central Power end Light Company City Public Service ATTN: G. E. Vaughn/C. A. Johnson P. O. Box 1771 P. O. Box 289, Mail Code: N5012 San Antonio,TX 78296 Wadsworth,TX 77483 J. C. Lanier/A. Ramirez U. S. Nuclear Regulatory Commission City of Austin Attent on: Document Control Desk Electric Utility : epartment Washington, D.C. 20555-0001 721 Barton Springs Road Austin,TX 78704 l

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i ATTACHMENT 1 AFFIDAVIT L

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..n:. . UNITED STATES OF AMERICA ' f NUCLEAR REGULATORY COMMISSION

. In the Matter of - )

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-South Texas Project Nuclear _ ) Docket Nos. 50-498

_ Operating Company - ) 50-499 South Texas Project )

-Units 1 and 2 )

AFFIDAVIT

- 1 T. H. Cloninger, being duly sworn, hereby depose and say that I am Vice President, Nuclear Engineering, of the South Texas Proje:t Nuclear Operating Company; that I am duly authorized to sign and file with the Nuclear Regulatory Commission the attached information

- regarding NRC Generic Letter 97-04; that I ara familiar with the content thereof; and that the -

.- matters set forth therein are true and correct to the best of my knowledge and beli ,

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.i.Clo'ger

. Vice P iden ,

- Nucle Engin STATE OF TEXAS - )

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COUNTY OF MATAGORDA )

. Subscribed and swom to befcre me, a Notcry Publ .and for the State of Texas, thisdo* day of 3ecemhv ,1997.

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