ML20129F668

Provides Notification & Reporting Info Re LOCA Analysis for Units 1 & 2 Performed IAW 10CFR50.46.Proprietary Justification for SPC 1986 LBLOCA Evaluation Model W/ Interim... Encl.Proprietary Rept Withheld Per 10CFR2.790

ML20129F668
Person / Time
Site:	Comanche Peak
Issue date:	10/25/1996
From:	Terry C TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML19353D907	List: ML20129F668 ML20129F699
References
TXX-96497, NUDOCS 9610290189
Download: ML20129F668 (8)

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! Log # TXX-96497 7 File # 10010

- '. C 10CFR50.46 T

nlELECTRIC' 1

October 25, 1996 C. Lance Terry

, Gmup We Presiden j

U. S. Nuclear Regulatory Commission

Attn: Document Control Desk j Washington, DC 20555 a

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SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)

DOCKET NOS. 50 445 AND 50 446 10CFR50.46 NOTIFICATION AND REPORTING INFORMATION i REF: 1) Letter logged TXX 96398, Dated June 28, 1996, from +

i C.L. Terry to the NRC

2) Letter to C. Lance Terry, TU Electric, from  !

i Brian W. Sheron, Office of Nuclear Reactor Regulation, i October 11, 1996.

l Gentlemen: I l

The large break loss of coolant accident (LOCA) analyses for Units 1 and 2

- were performed by TU Electric in accordance with approved methodologies.

l These methodologies relied on the Siemens Power Corporation (SPC) 1986 evaluation model supplemented by the 1991 version of T00DEE 2.

, TU Electric committed to revise the Unit 1 analysis prior to Cycle 6 operation and the Unit 2 analysis within three months following the end of the IRF05 refueling outage (Reference 1). The revised analyses, based

! solely on the 1986 version of the SPC evaluation model, have been

! completed. A list of the resulting licensing basis peak clad temperatures l (PCT) for the LOCA analyses is provided in the Attachment to this letter.

j TU Electric continues to satisfy the requirements of 10CFR50.46. The small break LOCA PCTs are bounded by the large break LOCA PCTs.

Backaround:

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On October 11, 1996, TU Electric was informed (Reference 2) by the NRC of I

an unacceptable error in the large break LOCA evaluation model used in the  !

analysis of both CPSES Units 1 and 2. The NRC requested affected

licensees to assess the impact of the model error and take whatever h

j actions are required to assure compliance with 10CFR50.46.

9610290189 961025 I POR F

ADOCK 03000445

. PDR h \ '

ENCLOSURE CONTAINS PROPRIETARY INFORMATION 0,[

P. O. Box 1002 Glen Rose Texas 76043 J 4 k

-, .v., . - , .- - - . . . .

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TXX 96497 l Page 2 of 3

, Discussion:

j The error in the 1986 evaluation model has been characterized as non- i i physical behavior of the heat transfer coefficient for reflood rates j between 1.0 and 1.77 inches /second. In the current LOCA analyses for

CPSES Units 1 and 2, the minimum reflood rate prior to the time of PCT is computed to be 1.735 inches /sec.

l TU. Electric, SPC, the NRC, and other SPC fuel users met on October 16, i

1996, to discuss this issue. Based on the information summarized in

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i Enclosure 1 to this letter, the 1986 Large Break LOCA evaluation model  ;

incorporates heat transfer coefficients during the reflood which, when  !

! compared to measured data, demonstrate ample conservatism to justify its  !

t use to show compliance with the 10CFR50.46 criteria. Of particular j

! interest are the comparisons between the Fuel Cooling Test Facility (FCTF) l l measured and computed heat transfer coefficients at a reflood rate of 1.74

, inches /sec (similar to CPSES), .which show a significant amount of I conservatism in the computed heat transfer coefficients. For example, the time of occurrence of PCT for the limiting cases is approximately 40 l

seconds following the start of the reflood period. Through a review of Figures 3.3 and 3.4 of the enclosed SPC report, it is observed that the

, values of the heat transfer coefficient predicted at this time (- 40 sec)

with the FCTF correlation are in the conservative direction relative to

! the measured coefficients. In addition, relevant comparisons of the computed FCTF heat transfer coefficient with data points from the FCTF

! test are shown in Figures 3.7 and 3.8 of Enclosure 1. As can be i

observed, the computed heat transfer coefficient is clearly conservative

{ relative to the measured coefficient.

j Furthermore, the CPSES Unit 2, Cycle 2 large break LOCA analysis, with an i Fa limit of 2.32, was performed by Westinghouse based on their 1981 ECCS i- evaluation model. TU Electric informally applied the 1986 SPC methodology i to CPSES Unit 2. Cycle 2 and concluded that a similar degree of conservatism exists relative to the Westinghouse analysis.

Results: l 1

TU Electric has assigned a temporary assessment, with a reduced value of -

the total peaking factor (Fo) limit, pending the resolution of the issue with the heat transfer model in the 1986 evaluation model. As described at the October 16, 1996, meeting, this assessment was performed using a reflood heat transfer coefficient no greater than that corresponding to a reflood rate of 1.77 inches /sec up th:ough the time of PCT. This i

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TXX-96497 Page 3 of 3 adjustment is conservative and consistent with the methodologies approved I by the NRC for use at CPSES. The additional conservatism in the heat transfer coefficient with this approach is identified in Figures 3.7 and 3.8. Based on this assessment, the results of which are summarized in the Attachment, the requirements of 10CFR50.46 continue to be satisfied.

Siemens Power Corporation (SPC) considers information contained in the l to be proprietary. In accordance with the requirements of 10CFR2.790(b) for withholding of proprietary information from public disclosure, an Affidavit is provided as part of Enclosure 1.

Correspondence with respect to the proprietary aspects of the supporting i SPC Affidavit should be addressed to Siemens Power Corporation, Attention l H. D. Hunt, 2101 Horn Rapids Road, P.O. Box 130, Richland WA, 99352-0130. , provides a non propriety version of the SPC report, ) . l Please contact Dr. W. G. Choe at (214) 812-4371 or Mr. J. D. Seawright at l (817) 897 0140 if you have any questions in this regard. .

I Sincerely, b, d g C. L. Terry l

By: M be a Rogeri. Walker Regulatory Affairs Manager l JDS/grp i Attachment Enclosures c- .Hr. L. J. Callan, Region IV Hr. T. J. Polich, NRR Hr. J. I. Tapia, Region IV Resident Inspector, CPSES

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Attachment to TXX 96497 Page 1 of 1 i

i CPSES Units 1 and 2 Limiting Peak Clad Temperatures i

.J Analysis / Evaluation CPSES Unit 1 CPSES Unit 2 Total Total I

Peakino Peakina

{ PCT (*F) Factor (F 31 PCT (*F) Factor (F 31 Limiting LOCA PCT ('F) 2055 2.42 2048 2.42 l [Large Break]

f i Temporary Assessment 2112 2.40 2036 2.40 4 pending resolution of SPC issues with 1986

version of T00DEE 2 l

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1 AFFID AVIT l

STATE OF WASHINGTON )

i ) ss COUNTY OF BENTON )

i 1, H. D. Curet, being duly sworn, hereby say and depose:

1. I am the Manager, Product Licensing, for Siemens Power- Corporation

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("SPC"), and as such I am authorized to execute this Affidavit. )

i j 2. I am familiar with SPC's detailed document control system and policies which govern the protection and control of information. j

3. I am familiar with the Siemens Power Corporation information in I

SEJ:96:021, " Justification for SPC 1986 LBLOCA Evaluation Model with Interim Adjustment

! for Non-Physical Behavior," referred to as " Document." Information contained in this Document has been classified by SPC as proprietary in accordance with the control system i

and policies established by SPC.for the control and protection of information.

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4. The Document contains information of a proprietary and confidential nature i l and is of the type customarily held in confidence by SPC and not made available to the public. Based on my experience, I am aware that other companies regard information of the i

kind contained in the Document as proprietary and confidential.

I i 5. The Document has been made available to the U.S. Nuclear Regulatory Commission in confidence, with the request that the information contained in the Document will not be disclosed or divulged.

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) 6. The Document contains information which is vital to a competitive advantage of SPC and would be helpful to competitors of SPC when competing with SPC.

l 7. The information contained in the Document is considered to be proprietary l by SPC because it reveals certain distinguishing aspects of SPC licensing methodology which

. secure competitive advantage to SPC for fuel design optimization and marketability, and includes information utilized by SPC in its business which affords SPC an opportunity to i

) obtain a competitive advantage over its competitors who do not or may not know or use the j information contained in the Document.

l 8. The disclosure of the proprietary information r:ontained in the Document to 4

i a competitor would permit the competitor to reduce its expenditure of money and manpower i

and to improve its competitive position by giving it valuable insights into SPC licensing a

{ methodology and would result in substantial harm to the competitive position of SPC.

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9. The Document contains proprietary information which is held in confidence l 1 by SPC and is not available in public sources, i

10. In accordance with SPC's policies governing the protection and control of l information, proprietary information contained in the Document has been made available, on a limited basis, to others outside SPC only as required and under suitable agreement providing  ;

i for nondisclosure and limited use of the information. l l

11. SPC policy requires that proprietary information be kept in a secured file or l

area and distributed on a need-to-know basis.

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12. Information in this Document provides insight into SPC licensing ,

methodology developed by SPC. SPC has invested significant resources in developing the )

methodology as well as the strategy for this application. Assuming a competitor had available the same background data and incentives as SPC, the competitor might, at a minimum, develop the iMormation for the same expenditure of manpower and money as SPC.

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l THAT the statements made hereinabove are, to the best of my knowledge, l

l information, and belief, truthful and complete.

FURTHER AFFIANT SAYETH NOT. l l

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1 SUBSCRIBED before me this M3 -

day of C ,1996. g s M 4/4 gOT Apr p )

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l Sue M. Galpin F WAS NOTARY PUBLIC,- STATE OF WASHINGTON MY COMMISSION EXPlRES: 2/27/00 l

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Enclosure 2 to TXX 96497 l

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