ML20083F254

Forwards Proprietary & Nonproprietary Technical Bases for Eliminating Large Primary Loop Pipe Ruptures as Structural Design Basis for Catawba Units 1 & 2, Per NRC 831017 & Util 830919 & 1118 Ltrs.Proprietary Rept Withheld

ML20083F254
Person / Time
Site:	Catawba
Issue date:	12/20/1983
From:	Tucker H DUKE POWER CO.
To:	Adensam E, Harold Denton Office of Nuclear Reactor Regulation
Shared Package
ML19268E619	List: ML20083F254 ML20083F263 ML20083F276
References
NUDOCS 8312300220
Download: ML20083F254 (3)

Text

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DUKE POWER GOMPANY P.O. IBOX 33189

. CHARLOTTE. N.c. 2E-242 HAL B. TUCKER . Trt.zessows

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December 20, 1983 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation

.U. S. Nuclear Regulatory Commission

~ Washington, D. C. 20555 Attention: Ms. E. G. Adensam, Chief Licensing Branch No. 4 Re: Catawba Nuclear Station Docket Nos. 50-413 and 50-414

References:

1) Letter from W. H. Owen (Duke Power Company) to W. J. Dircks (NRC), dated September 19, 1983

2) Letter from H. R. Denton (NRC) to W. H. Owen (Duke Power Company), dated October 17, 1983

3) Letter from H. B. Tucker (Duke Power Company) to H. R. Denton (NRC), dated November 18, 1983

Dear Mr. Denton:

References 1) and 3) infonned the NRC that Duke Power Company was evaluating the technical feasibility and potential benefits of eliminating postulated pipe breaks in the Reactor Coolant System (RCS) primary loop from the structural design basis of the Catawba Nuclear Station. As a result of efforts by Westinghouse, the NRC, and Duke Power, we have concluded that it is technically feasible to eliminate these postulated pipe breaks. In addition, Westinghouse has assured Duke Power Company that the generic information previously submitted to the NRC to justify the elimination of RCS primary loop pipe breaks is applicable to the' Catawba Nuclear Station.

As a result of the above developments, and in accordance with the statement in Reference 2) that applications related to the leak-before-break pipe failure concept will be permitted prior to the NRC completing all of the changes in regulatory requirements, this letter is submitted. Duke Power hereby requests NRC approval for application of the " leak-before-break" concept to the Catawba Nuclear Station to eliminate postulated pipe breaks in the RCS primary loop from the plant structural design basis. A specific plant applicability report is included as Enclosure A to this-letter. Because of the proprietary nature of this report, Enclosure A has been provided only to the addressee and Mr. James P. O'Reilly of the NRC. A non-proprietary version of the specific plant applicability report is included as Enclosure B and has been provided to others on the attached distribution list.

As Enclosure A contains inf0rmation proprietary to Westinghouse Electric Corporation, it is supported by the attached letter (Attachment 1) and affidavit signed by Westinghouse, the owner of the information. The affidavit sets forth the basis on which the information may be withheld from public disclosure by the Commission and addresses with specificity i 8312300220 831220 PDR ADOCK 05000413 PDR l A

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~Mrs Harold R..Denton', Director r

^ December 20,c1983: -

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theconsiderations, listed-inparagraph(b)(4)ofSection2.790ofthe, J Commission's regulations.1 Accordingly,~ it is respectfully requested' that-the ,infonnation which is proprietary to Westinghouse be withheld from1public disclosure in'accordance with 10 CFR Section 2.790 of the Commission's

regulations. Correspondence with respect to the proprietary aspects of the Application for Withholding or the supporting Westinghouse affidavit should Ereference CAW-83-106,'and should be addressed to R.' A. Wiesemann. Manager,-

' Regulatory and Legislative Affairs, Westinghouse' Electric Corporation, -

-P. 0. Box;355, Pittsburgh, Pennsylvania 15230.

/ Implementation of the leak-before-break concept will have the following effects on the structural design ~for _ Catawba Nuclear Station:

1)L ' Eliminate the need .to: postulate.circumferential and longitudinal

- pipe' breaks in 'the RCS primary loop-(hot leg, cold leg, and cross-over leg piping).

2) Eliminate the~ need for associated' pipe whip restraints in the RCS primary loop and eliminate the. requirement to design for the structural effects associated with RCS primary loop pipe breaks including jet impingement.

3)EEliminate the need to consider dynamic effects and loading conditions associated.with.previously postulated primary loop pipe breaks. These effects include blowdown loads, jet impingement loads,.'and reactor cavity and.subcompartment pressurization.

Employment of the leak-before-break concept would not eliminate pipe breaks in.the RCS primary loop as a design basis for the following:

1) Containment design

-2) Sizing of; Emergency Core Cooling System

3)

Environmental qualification of equipment:

~4) Supports for heavy components The crack sizesland' resultant flows from the leak-before-break analysis will' be used when reactor cavity and subcompartment pressurization data are revised.

sThe. impact on important design aspects of implementing leak-before-break on Catawba Nuclear Station has been evaluated by Duke Power and is summarized in Attachment 2. A detailed. list of affected pipe: whip' restraints is provided in Attachment 3. - Duke- Power has also evaluated the potential cost savings and operational-benefits that result from the elimination of postulated pipe breaks in the RCS primary loop. J A summary of the potential benefits which-can be: realized specifically from the elimination of these pipe breaks ~ for Catawba Unit 2-is provided in Attachment 4. Note that these benefits total at least$2 million and involve an estimated 600 man-rem dose reduction over the life of Unit 2. _ Implementation'of the ' leak-before-break concept will

. therefore be cost-effective.as- well' as technically justifiable while resulting infimproved overall plant. safety.

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.- ' Mr. Harold R. 0:nton, Director December 20, 1983

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' Enclosure C consists of the revised Catawba FSAR pages associated with the elimination of RCS primary loop breaks, and it will be included in Revision 9

-to the FSAR.' This current request is for implementation on Unit 2 only; Duke Power will ~ submit additional infonnation prior to implementation on Unit 1.

Construction completion of the RCS primary loop pipe whip restraints at Catawba Nuclear Station Unit 2 is on. hold:pending an NRC ruling on this proposal. In order to realize the maximum advantage from the elimination of RCS primary loop ruptures, we request a decision by February 15, 1984.

If I can be of further assistance, or if a meeting with the Staff is deemed beneficial for a final resolution of this _ matter, please contact me.

Very truly yours, g/s. s j~g/p Hal 8. Tucker

.ROS/php Attachment

'cc: Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303 NRC Resident Inspector Catawba Nuclear Station Mr._ Robert Guild,-Esq.

Attorney-at-Law P. O. Box 112097-Charleston, South Carolina 29412 Palmetto Alliance 21351 Devine Street Columbia, South Carolina 29205 Mr. Jesse L. Riley Carolina Environmental Study Group 854 Henley Place

' Charlotte, North Carolina 28207

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