ML18039A621

Forwards Rev 0 to Calculation MD-Q0999-970046, NPSH Evaluation of BFN RHR & CS Pumps & Proprietary Rev 0 to GENE-E12-00138-01, ECCS Suction Strainer Hydraulic Sizing Rept, in Response to Verbal Rai.Proprietary Encl Withheld

ML18039A621
Person / Time
Site:	Browns Ferry
Issue date:	11/25/1998
From:	Abney T TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML18039A622	List: ML18039A621 ML18039A623
References
NUDOCS 9812080127
Download: ML18039A621 (30)

Text

CATEGORY~ j.

A REGULA'1 RY INFORMATION DISTRIBUTIO 'SYSTEM (RIDS)

ACCESSION NBR:9812080127 DOC.DATE: 98/11/25 NOTARIZED: YES FACIL:50-260 Browns Ferry Nuclear Power Station, Unit 2, Tennessee DOCKET 05000260 I

50-296 Browns Ferry Nuclear Power Station, Unit 3, Tennessee .05000296 AUTH. NAME AUTHOR AFFILIATION ABNEY,T.E. Tennessee Valley Authority 5~>~

RECIP.NAME RECIPIENT AFFILIATION Records Management Branch (Document Control Desk)

SUBJECT:

Forwards rev 0 to calculation MD-Q0999-970046, "NPSH C Evaluation of BFN RHR & CS Pumps" E proprietary rev 0 to A GENE-E12-00138-01, "ECCS Suction Strainer Hydraulic Sizing Rept," in response to verbal RAI.Proprietary encl withheld.

DISTRIBUTION CODE: D030D COPIES RECEIVED:LTR ENCL SIZE: E TITLE: TVA Facilities Routine Correspondence NOTES:

RECIPIENT COPIES RECIPIENT COPIES

ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-3 1 1 PD2-3-PD 1 1 DEAGAZIO,A 1 1 INTERNAL: ACRS 1 1 LE CE 1 1 OGC/HDS3 1 0 RES/DE/SSEB/SES 1 1 EXTERNAL: NOAC 1 1 hit NRC PDR -. 6P D

.N NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE. TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DISTRIBUTION LISTS OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR ORGANIZATION, CONTACT THE DOCUMENT CONTROL DESK (DCD) ON EXTENSION 415-2083 TOTAL NUMBER OF COPIES REQUIRED: LTTR 9 ENCL 8

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Tennessee Valley Authority, Post Office Box 2000, Decatur, Alabama 35609-2000 November 25, 1998 U.S. Nuclear Regulatory Commission ATTN; Document Control Desk Washington, D.C. 20555 Gentlemen:

In the Matter of Docket Nos. 50-260 Tennessee Valley Authority 50-296 BROWNS FERRY NUCLEAR PLANT (BFN) RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION (RAI) RELATING TO UNITS 2 AND 3 LICENSE AMENDMENT REGARDING USE OF CONTAINMENT OVERPRESSURE FOR EMERGENCY CORE COOLING SYSTEM (ECCS) PUMP NET POSITIVE SUCTION HEAD (NPSH) ANALYSES This letter is in response to NRC's verbal request for additional information concerning TVA's proposed September 4, 1998, amendment to Operating Licenses DPR-52 and DPR-68 to allow the use of available containment overpressure for ECCS NPSH analysis. By letter dated July 25, 1997 (Reference 1),

TVA provided a proposed resolution for NRC Bulletin 96-03, "Potential Plugging of Emergency Core Cooling Suction Strainers by Debris in Boiling-Water Reactors". In part, TVA's methodology for resolution of the bulletin requires the use of containment pressure in excess of atmospheric pressure (containment overpressure) to maintain adequate ECCS pump NPSH: Because credit for containment overpressure is not taken in BFN's current licensing basis, on September 4, 1998, (Reference 2), TVA submitted a proposed change to the BFN Units 2 and 3 operating licenses to permit the use of the available containment overpressure to meet ECCS NPSH requirements.

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U.S. Nuclear Regulatory Commission Page 2 November 25, 1998 In a teleconference on November 4, 1998, NRC requested additional information to aid in the review of the subject amendment request submittal. Specifically, NRC requested the following:.

1. Provide the NPSH calculations for short-term and long-term for the Residual Heat Removal (RHR) and Core Spray (CS) system pumps;

2. Provide the support information for the calculations;

3. Explain how the analysis at pre-power uprate conditions bounds uprated conditions as discussed on page E1-6 of the September 4, 1998, submittal;

4. In the July 25, 1997, submittal, one loop of CS is in runout. The current analysis assumes design flow for the CS pumps. Explain why this change in assumptions is appropriate and'onservative;

5. TVA requested a 1 pound per square inch gauge (psig) additional overpressure (3 psig versus 2 psig) based on uncertainties since the Utility Resolution Group (URG) was not approved at the time.. Since the URG is now approved, does TVA still need the 1 psig additional overpressure?

6. Provide a graph showing NPSH required for CS and RHR operation versus time,and containment .pressure available. provides TVA's response to the above NRC questions 3, 4, and 5. In response to item 1, Enclosure 2 provides TVA's NPSH calculation for the short-term and long-term analysis for RHR and CS pump operation. TVA's calculation, "NPSH Evaluation of Browns Ferry RHR and CS Pumps," is based on the "Boiling Water Owners'roup Utility Resolution Guidance for ECCS Suction Strainer Blockage,"

dated November 1996. provides the support information (item 2) for the calculation. A portion of the information provided in Enclosure 3 is proprietary and should be withheld

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U.S. Nuclear Regulatory Commission Page- 3 November 25, 1998 from public disclosure in accordance with 10 CFR 2.790(a)(4).

An affidavit,supporting the request in accordance with 1'0 CFR 2.790(b)(1) is included in Enclosure 3.

In response to item 6, Enclosure 4 provides graphs showing the required NPSH for the RHR pumps and CS pumps,. The first graph provides the long term NPSH analysis starting at 6 seconds after the event and the second graph provides the long term analysis starting at 100 seconds.

Additionally, as a resul't of the containment coating inspections performed during the recent Unit 3 Cycle 8 refueling outage, it was, determined that the quantity of degraded coatings in the drywell may have been greater .than the quantity of unqualified/degraded coatings assumed as a design basis, for the replacement ECCS suction strainers. TVA has since performed an evaluation to ensure that a larger amount of unqualified/degraded coating debris source term could'e accommodated by the strainers wi'thout impacting the NPSH of .the ECCS'umps. This evaluation is provided in Enclosure '5.

There are no commitments contained in this letter. If you have.-any questions about this information, please telephone me at (256) 729-.2636.

Sincerely,.

T. E. Abney Manager of Li ensi g and Indus y Af'f irs

>Enclosures cc: See page 5

0 Ck U.S. Nuclear Regulatory Commission Page 4 November 25, 1998

References:

1. TVA letter to NRC, dated July 25, 1997, Browns Ferry Nuclear Plant (BFN) NRC Bullets.'n 96-03, Potential Plugging Of Emergency Core Cooling Suction (ECCS) Strainers By Debris In Boiling-Water Reactors

2. TVA letter to NRC dated September 4, 1998, Browns Ferry

.Nuclear Plant (BFN) Units 2 and 3 License Amendment Regarding Use of Containment Overpressure for Emergency Core Cooling System (ECCS) Pump Net Positive Suction Head (NPSH) Analysis

It II U.S. Nuclear Regulatory Commission Page 5 November 25, 1998 Enclosures cc (Enclosures):

Mr. Harold 0. Christensen, Branch Chief

.U.S. Nuclear Regulatory Commission 61 Forsyth Street, S. W.

Suite 23T85.

Atlanta, Georgia 30303 NRC Resident Inspector Browns Ferry Nuclear Plant Route 12', Box 637 Athens, Alabama 35611 Mr. L. Raghavan, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852

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ENCLOSURE 1 TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)

UNITS 2 AND 3 BROWNS FERRY NUCLEAR PLANT (BFN) RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION (RAI) RELATING TO UNITS 2 AND 3 USE OF

'ONTAINMENT OVERPRESSURE FOR EMERGENCY CORE COOLING SYSTEM (ECCS)

PUMP NET POSITIVE SUCTION HEAD (NPSH) ANALYSES NRC Question 3 Explain how the analysis at pre-power uprate conditions bounds uprate conditions as discussed on Page E1-6 of the September 4, 1998, submittal.

TVA Re 1 ECCS NPSH requirements were evaluated as part of BFN's power uprate licensing analysis. It was concluded that the overpressure requirement under uprate conditions is less limiting. This is because more containment overpressure is available under power uprate than for the pre-power uprate conditions. Therefore, the evaluation of NPSH performed at pre-uprated condition (with lower initial operating dome pressure and lower containment overpressure characteristics) conservatively bounds the evaluation performed for the power uprate conditions.

A previous NRC Staff review of the effects of power uprate on ECCS performance is documented in Section 4.5 of the September 8, 1998, (See Reference) NRC Safety Evaluation for the Power Uprate amendment which agreed that there is adequate NPSH margin for the Residual Heat Removal (RHR) and Core Spray (CS) pumps at uprated conditions. The uprate peak suppression pool temperature is approximately the same as the pre-uprate condition and suppression chamber airspace pressure is increased for power uprate. Therefore, the conditions presented by power uprate do not adversely affect compliance to ECCS pump NPSH requirements.

NRC Question 4 In the July 25, 1997, submittal, one loop of CS is in runout.

The current analysis assumes design flow for the CS pumps.

Explain why this change in assumptions is appropriate and conservative.

TVA Re 1 The BFN low pressure ECCS systems are comprised of four RHR pumps and four CS pumps. In both systems, the pumps are divided into two independent loops with two pumps supplying each loop. Their suction path includes a common ring header connected to the suppression pool (torus) via four passive strainers. These strainers have been replaced with strainers with approximately 60 times the flow area of the originally installed strainers.

The design basis assumptions for ECCS available NPSH includes the consideration of one RHR loop (if aligned to the postulated pipe break pathway) at maximum off-normal flow conditions (which is less than runout. flow). The RHR pump discharge lines are orificed such that they cannot go to a true full runout condition, but rather are limited to a maximum flow condition by the throttling effects of discharge orifices.

The CS system, which is not orificed, can only go to runout under one of the following two conditions. Otherwise, CS will be operating at design flow as assumed in the worst case NPSH analysis for the recirculation line break.

1. The loss of one CS pump at system initiation, or;

2. The postulated pipe failure is in one of the CS loops.

Respectively, these two conditions are not considered the worst case NPSH condition for NRC Bulletin 96-03 concerns due to the following reasons:

1. In a loop of CS with one pump in runout, approximately 1600 gallons per minute (GPM) less net ECCS flow is produced than used in the worst case NPSH evaluation.

2. The worst case design basis accident break considers a recirculation system pipe failure. A CS line failure results in RHR flow requirements that are significantly reduced as compared to the design bases accident. Thus, this condition is bounded by worst case NPSH requirements.

For these reasons, conservative to it istheconsidered assume to are be adequate and at design flow in the CS pumps limiting NPSH evaluations.

0 NRC Question 5 TVA requested a 1 pound per square inch gauge (psig) additional overpressure (3 psig versus 2 psig) based on uncertainties since the Utility Resolution Group (URG) was not approved at the time.

Since, the URG is now approved, does TVA still need the 1 psig additional overpressure?

TVA Re 1 BFN requests that a minimum of 3 psig overpressure be considered as a design basis for NPSH requirements. While the URG has been approved, restrictions and provisions for head loss assumptions and other assumptions were added. Also, future issues such as those described in NRC Generic Letter 98-04, "Potential For Degradation of The Emergency Core Cooling System and the Containment Spray System After a Loss of Coolant Accident Because of Construction and Protective Coating Deficiencies", or other types of future potential debris issues make it prudent for BFN internal to retain a small overpressure margin to allow assessments of future issues up to the 3 psig limit. The BFN long-term NPSH analysis supports up to 4 psig overpressure under most conditions, thus ensuring that the 3 psig requested is conservative and appropriate.

Reference:

NRC letter to TVA dated September 8, 1998, issuance of Amendments RE: Power Uprate Browns Ferry Plant, Units 2 and 3 (TAC Nos.

M99711 and M99712)

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~I ENCLOSURE 2 TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)

UNITS 2 AND 3 BROWNS FERRY NUCLEAR PLANT (BFN) RESPONSE'O REQUEST FOR ADDITIONAL INFORMATION (RAI) RELATING TO UNITS .2 AND 3 USE OF CONTAINMENT OVERPRESSURE FOR EMERGENCY CORE COOLING SYSTEM (ECCS)

PUMP NET POSITIVE SUCTION HEAD (NPSH) ANALYSES

~ TVA Calculation, "NPSH Evaluation of Browns Ferry RHR and CS Pumps", MD-Q0999-970046, dated November ll, 1998. This calculation is current as of the submittal date. Future revisions as may be required will be available for review on site.

ik 0 ENCLOSURE VALLEY AUTHORITY 3'ENNESSEE BROWNS FERRY NUCLEAR PLANT (BFN)

UNITS 2 AND 3 BROWNS FERRY NUCLEAR PLANT (BFN) RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION (RAI) RELATING TO UNITS 2 AND 3 USE OF CONTAINMENT OVERPRESSURE FOR EMERGENCY CORE COOLING SYSTEM (ECCS)

I PUMP NE T POS TIVE SUCTION HEAD (NPSH) ANALYSES

1. General Electric Affidavit for GENE-E12-00148-01, S

GENE-E12-00148-02, and GENE-E12-00148-04.

2. ECCS Suction Strainer Hydraulic Report, GENE-E12-00148-01 Revision 0, dated July 1997

3. Debris Loading Report for Sizing of Browns Ferry ECCS Pump Suction Strainers, GENE-E12-00148-02, Revision 0, dated July 1997

4. Net Positive Suction Head (NPSH) Evaluation For Browns Ferry Nuclear Plant ECCS Strainer Design, GENE-E12-00148-04 Revision 0, dated June 1997

5. Browns Ferry Nuclear Power Plant LOCA Containment Analyses for Use in Evaluation of NPSH for RHR and Core Spray Pumps, GENE-E12-00148-06 Revision 0, dated July 1997

0 General Electric Company AFFIDAVIT I, George B. Stramback, being duly sworn, depose and state as follows:

(1) I am Project Manager, Regulatory Services, General Electric Company ("GE") and have been delegated the function of reviewing the information described in paragraph (2) which is sought to be withheld, and have been authorized to.apply for its withholding.

(2) The information sought to be withheld is contained in the GE proprietary reports GE-NE E12-00148-01, ECCS Suction Strainer Hydraulic Sizing Report, Revision 0, GE Proprietary Information, dated July 1997, GENE E12-00148-02, Debris Loads Report for Sizing of Browns Ferry ECCS Pump Suction Strainers, Revision 0, GE Proprietary Information, dated July 1997, and GENE E12-00148-04, Net Positive Suction Head (NPSH) Evaluation for Browns Ferry Nuclear Plant ECCS Strainer Design, Revision 0, GE Proprietary Information, dated June 1997. The proprietary information is delineated by bars marked in the margin adjacent to the specific material.

(3) In making this application for withholding of proprietary information of which it is the owner, GE relies upon the exemption from disclosure set forth in the Freedom of Information Act ("FOIA"), 5 USC Sec. 552(b)(4), and the Trade Secrets Act, 18 USC Sec. 1905, and NRC regulations 10 CFR 9.17(a)(4), 2.790(a)(4), and 2.790(d)(1) for "trade secrets and commercial or financial information obtained from a person and privileged or confidential" (Exemption 4). The material for which exemption from disclosure is here sought is all "confidential commercial information", and some portions also qualify under the narrower definition of "trade secret", within the meanings assigned to those terms for purposes of FOIA Exemption 4 in, respectively, Critical Mass Ener Pro'ect v. Nuclear Re ulato Commission 975F2d871 (DC Cir. 1992), and Public Citizen Health Research Grou

v. FDA, 704F2d1280 (DC Cir. 1983).

(4) Some examples of categories of information which fit into the definition of proprietary information are:

a. Information that discloses a process, method, or apparatus, including supporting data and analyses, where prevention of its use by General Electric's competitors without license from General Electric constitutes a competitive economic advantage over other companies; GBS-98-8-af suction strainer Hydraulic & NPSH BF2&3 14.doc AffidavitPage 1

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b. Information which, if.used by a competitor, would reduce his expenditure of resources or improve his competitive position in the design, manufacture, shipment, installation, assurance of quality, or licensing of a similar. product;

c. Information which reveals cost or price information, production capacities, budget levels, or commercial strategies of General Electric, its customers, or its suppliers;

d. Information which reveals aspects of past, present, or future General Electric customer-funded development plans and programs, of potential commercial value to General Electric;

e. Information which discloses patentable subject matter for which it may be desirable to obtain patent protection.

The information sought to be withheld is considered to be proprietary for the reasons set forth in both paragraphs (4)a. and (4)b., above.

(5) The information sought to be withheld is being submitted to NRC in confidence.

The information is of a sort customarily held in confidence by GE, and is in fact so held. The information sought to.be withheld has, to the best of my knowledge and belief, consistently been held in confidence by GE, no public disclosure has been made, and it is not available in public sources. All disclosures to third parties including any required transmittals to NRC, have been made, or must be made, pursuant to regulatory provisions or proprietary agreements which provide for maintenance of the information in confidence. Its initial designation as proprietary information, and the subsequent steps taken to prevent its unauthorized disclosure, are as set forth in paragraphs (6) and (7) following.

(6) Initial approval of proprietary treatment of a document is made by the manager of the originating component, the person most likely to be acquainted with the value and sensitivity of the information in relation to industry knowledge. Access to such documents within GE is limited on a "need to know" basis.

(7) The procedure for approval of external release of such a document typically requires review by the staff manager, project manager, principal scientist or other equivalent authority, by the manager of the cognizant marketing function (or his delegate), and by the Legal Operation, for technical content, competitive effect, and determination of the accuracy of the proprietary designation. Disclosures outside GE are limited.to regulatory bodies, customers, and potential'ustomers, and their agents, suppliers, and-licensees, and others with a legitimate need for the information, and then only in accordance with appropriate regulatory provisions or proprietary agreements.

(8) The information identified in paragraph (2), above, is classified as proprietary because it contains detailed application methodology including 1) hydraulic GBS-98-8-af suction strainer Hydraulic & NPSH BF2&3 14.doc AffidavitPage 2

0 performance design-methods and 2) unique procedures for calculation of hydraulic sizing for the optimized ECCS suction, strainer, which GE has developed.

The development of this information and the methods was achieved at a significant cost, on the order of several hundred thousand dollars, to GE.

The development of the evaluation process along with the interpretation and application of the results is derived from the extensive experience database that constitutes a major GE asset.

(9) Public disclosure of the information sought to be withheld is likely to cause substantial harm to GE's.competitive position and foreclose or reduce the availability of profit-making opportunities. The information is part of GE's comprehensive

.BWR safety and technology base, and its commercial value extends beyond the original development cost. The value of the technology base.goes beyond the extensive physical database and analytical methodology and includes development of the expertise to determine and apply the appropriate evaluation process. In addition, the technology base includes the value derived from providing analyses done with NRC-approved methods.

The research, development, engineering, analytical and NRC review costs comprise a substantial investment of time and money by GE.

The precise value of the expertise to devise an evaluation process and apply the correct analytical methodology is difficultto quantify, but it clearly is substantial.

GE's competitive advantage will be lost if its competitors are able to use the results if of the GE experience to normalize or verify their own process or they are able to claim an equivalent understanding by demonstrating that they can arrive at the same or similar, conclusions.

The value of, this information to GE would be lost ifthe information were disclosed to the public. Making such informati'on available to competitors without their having been required to.undertake a similar expenditure of resources would unfairly provide competitors with a windfall, and deprive GE of the opportunity to exercise its competitive advantage to seek an adequate return on its large investment in developing these very valuable analytical tools.

GBS-98-8-af suction strainer Hydraulic & NPSH BF2&3 14.doc AffidavitPage 3

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STATE OF CALIFORNIA )

) ss:

COUNTY OF SANTA CLARA )

George B. Stramback, being duly sworn, deposes and says:

That he has read the foregoing affidavit and the matters stated therein are true and correct to the best of.his knowledge, information, and belief.

Executed at San Jose, California, this ck 3 day of 1998.

G rge B. tramback General Electric Company Subscribed and sworn before me this chic)

~ 2W day of Ov<~~rr 1998.

PAULA F. HUSSEY COMM. 41046120 Notary Public CaHfornla Notary Public, State of Cali rnia SANTA CtAPA COUNty My Comm. Exptres DEC 1.1998 GBS-98-8-af suction strainer Hydraulic & NPSH BF28r3 14.doc AffidavitPage 4

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