ML20080G273

Discusses Feasibility & Benefits to Util of Eliminating Postulated Pipe Breaks in RCS Primary Loop from Structural Design Basis,Per NRC .Approx 200,000 Manhours of Installation Time Per Unit Will Be Saved

ML20080G273
Person / Time
Site:	Marble Hill
Issue date:	09/16/1983
From:	Shields S PSI ENERGY, INC. A/K/A PUBLIC SERVICE CO. OF INDIANA
To:	Harold Denton Office of Nuclear Reactor Regulation
References
SVP-0121-83, SVP-121-83, NUDOCS 8309200185
Download: ML20080G273 (4)

Text

PUBLIC SERVICE INDIANA S. W. Shields Septettber 16, 1983 SVP-0121-83 Senior Vice President.

Nuclear Division Mr. Harold R. Denton, Director Docket Nos.:

STN 50-546 Office of Nuclear Reactor Regulation STN 50-547 U.S. Nuclear Regulatory Commission Construction Permit Nos.:

Washington, D.C.

20555 CPPR - 170 CPPR - 171 Marble Hill Nuclear Generating Station - Units 1 and 2

Dear Mr. Denton:

Your letter of May 2, 1983 (Reference a) has prompted Public Service Company of Indiana, Inc. (PSI) to eval' tate the technical feasibility and potential benefits of eliminating postulated pipe braaks in the reacter coolant system (RCS) primary loop from the structural design basis of the Marble Hill Plant. In reviewing the technical feasibility of this concept, we have considered industry development work and NRC-sponsored research which has been completed. As a result of its develop-ment efforts, Westinghouse has requested from.the Staff (Reference b) generic approval to eliminate RCS primary loop pipe breaks from the structural design basis of all Westinghouse plants. NRC-sponsored research results also support the elimination of RCS primary loop pipe breaks in all Westinghouse plants east of the Rocky Mountains. The ACRS has reviewed both industry and NRC

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efforts in this area and concluded (Reference c) that such cn approach is feasible. Additionally, in Reference d, Mr. Dircks has indicated that i

the staff is continuing toward the implementation of this conept on j

a case-by-case basis.

t As a result of the Westinghouse and NRC efforts in this area, rSI has concluded that it is technically feasible to eliminate postulated pipe breaks in the RCS primary loop from the structural design basis of the Marble Hill plant. As such, PSI plans to implement the leak before break concept on the Marble Hill plant.

Implementation of this concept will have the following effects on the structural design for Marble Hill.

1.

Eliminate the need to postulate circumferential and longitudinal pipe breaks in the RCS primary loop.

2.

Eliminate the need to install pipe whip restraints and other provisions associated with previously postulated breaks in the RCS primary loop.

8 00I 8309200185 830916 PDR ADOCK 05000546

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P. O. Box 190, New Washington, Indiana 47162 812. 289.3000

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. SERVICE

. INGANA Letter:

H. R. Denton

- September 16, 1983 SVP-0121-83 3.

Eliminate the need to consider dynamic effects and loading conditions associatcd with previously postulated' pipe breaks in the RCS primary loop.

4

.In implementing this concept on th'e Marble Hill Plant no enanges to the RCS~

g sapport eystem will.be made. RCS supports are currently designed for the combination of LOCA and SSE loads. PSI will continue to ensure the high quality of the RCS piping and supports. Additionally, PSI will install a reactor coolant pressure boundary leak-detection system which satisfies the requirements of Regulatory Guide 1.45.

.In addition to the technical evaluation. performed by PSI the potential benefits from the elimination of RCS primary loop pipe breaks have been

. evaluated taking into consideration the current status of plant design and construction..These benefits. include a 7 million dollar savings in construction costs for Units 1 & 2 RCS piping whip restraints and provisiens, as well as other benefits during plant operation. A detailed evaluation of-the potential benefits is provided in Attach-

' ment A.-

In' order to' realize the potential benefits identified above, current

' construction schedules dictate the need for a regulatory decision on this ' issue by. November 4,.1983.

PSI is committed to implement this

' concept on Marble Hill to realize the perceived benefits. Staff guidance and concurrence are necessary, consistent with construction schedule constraints,--to ensure that _no future licensing delays are

-incurred.

In ' summary, ' PSI will implement these changes on the Marble Hill Plant

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based on the positive Staff position regarding the technical acceptability of the leak before break concept.. Your specific concurrence relative to the Marble Hill Plant-is requested. PSI suggests that a mutually agreeable date during the week of October 4,1983, be arranged to meet and discuss 4

this subject further. If you have any questions please contact me-at your

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- convenience.

Sincerely, 1

S. W. - Shields SWS/DAK/bak

. Attachments E

cc:

D.;G.-Eisenhut.

T. M. Novack B. J.-lYoungblood-P.'W. O'Connor; g

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REFERENCES a.

Letter form liarold Denton (NRC) to Murray Edelman (AIF) dated May 2,1983.

b.. Letter from E. P. Rahe (Westinghouse) to Richard Vollmer (NRC) dated May 11, 1983.

c. - Letter from J. J. Ray. (ACRS) to William Dircks (NRC) dat'ed June 14, 1983.

~d.

Letter from Pillica Dircks (NRC) to J.. J. Ray (ACRS) dated July-29, 1983.

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ATTACHMENT A The benefits to PSI of eliminating pipe whip restraints and other provisions associated with postulated breaks in the Reactor Coolant System include:

1.

Total estimated savings of $7.0 million installation costs for Units 1 and 2.

2.-

Savings of approximately 200,000 manhours installation time per Unit.

3.

Savings on rework costs anticipated for 95% of all pipe whip restraints.

4.

Improved accessability during in-service inspection.

5.

Lower worker radiation exposure during planned shutdown maintenance.

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