ML20238A040

Responds to Requesting Exemption from GDC 4 by Using leak-before-break Concept to Eliminate Postulated Pipe Breaks in RCS Primary Loop from Plant Structural Design Basis.Exemption Unnecessary

ML20238A040
Person / Time
Site:	Washington Public Power Supply System
Issue date:	09/02/1987
From:	Rubenstein L Office of Nuclear Reactor Regulation
To:	Mazur D WASHINGTON PUBLIC POWER SUPPLY SYSTEM
References
NUDOCS 8709090107
Download: ML20238A040 (3)

Text

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. September 2, 1987~

Docket No.:STN 50-460-E

.Mr.' D. W. Mazur, Managing Director'

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Washington Public Power Supply System i

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3000 George l Washington.Way 1

Post Office Box 968 Richland Washington' 99352f

Dear Mr. Mazur:

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Subject:

. Request for exemption from the requirements' of.GDC-4 for WNP.-l.

- By letter dated January 30, 1987; you requested an exemption from the requirements of General Design Criterion 4 by applying the " Leak-Before-Break" concept to WNP-1 to eliminate postulated pipe' breaks in the reactor coolant system primary loop from the plant structural design basis.. At the time of

>your. request, the change to'the regulation, 10 CFR 50, Appendix A, General Design Criterio.n 4 (51 FR 12502,l April 11,1986) was'in effect.

The rule change allows the. dynamics effects: associated with postulated pipe' ruptures of primary coolant loop piping in pressurized. water reactors to be

. excluded from the design basis when analyses demonstrate the probability of rupturing such piping. is extremely low under design basis conditions'.

We have' determined that your exemption request is not necessary since the rule-

. does allow the elimination of postulated ~ pipe breaks in the reactor, coolant:

system' primary. loop from the plant structural design basis. Also we have determined,that'your-analyses, which show.s that the; probability of rupturing such piping is extremely low under design basis conditions, is acceptable.

Sincerely, original signed by tester S. Rubenstein, Director Standardization and Non-Power Reactor Project Directorate Division of Reactor Projects III, IV, V and Special Projects-Office of Nuclear Reacto* Regulation

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September 2, 1987 Docket No. STN 50-460 Mr. D. W. Mazur, Managing Director Washington Public Power Supoly System 3000 George Washington Way Post Office Box 968 Richland, Washington 99352

Subject:

Request for exemption from the requirements of GDC-4 for WNP-1 By letu. dated January 30, 1987, you requested an exemption from the i

requirements of General Design Criterion 4 by applying the " Leak-Before-Break" f

concept to WNP-1 to eliminate postulated pipe breaks in the reactor coolant system primary loop from the plant structural design basis. At the time of your. request, the change to the regulation, 10 CFR 50, Appendix A, General-Design Criterion 4 (51-FR 12502, April 11, 1986) was in effect.

The rule change allows the dynamics effects associated with postulated pipe ruptures of primary coolant loop piping in pressurized water reactors to be excluded from the design. basis when analyses demonstrate the probability of rupturing such piping is extremely low under design basis conditions.

-We have determined that your exemption request is not necessary since the rule does allow the elimination of postulated pipe breaks in the reactor coolant system primary loop from the plant structural design basis. Also, we have determined that your analyses, which shows that the probability of rupturing such piping is extremely low under design basis conditions, is acceptable.

Sincerely, y

Lester S *' R enstein, Director Standardization and Non-Power Reactor Project Directorate Division of Reactor Projects III, IV, Y and Special Projects Office of Nuclear Reactor Regulation cc: See next page

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'Mr. D. 'W.i azur WPPSS Nuclear Project No.1 M

Washington Public Power Supply System (WNP-1) cc:.

Mr. Charles B. Brinkman '

Mr. G. C. Sorensen, Manager Washington Nuclear Operations Regulatory Programs

Combustion Engineering, Inc..

Washington Public Power Supply 7010 Woodmont Avenue, Suite 1310 System Bethesda, Maryland 20814 Post Office Box 968 Richland, Washington 99352 Nicholas S. Reynolds, Esq.

DeBevoise & Liberman 1200 Seventeenth Street Washington, DC 20036 G. E.'Doupe, Esq.

' Washington Public Power Supply System 3000 George Washington Way Richland,-Washington 99352 Mr. Curtis. Eschels, Chairman Energy Facility Sfte Evaluation Council Mail Stop PY-11 Olympia, Washington 98505 Mr. Douglas Coleman-Washington Public Power Supply System

.P. 0. box 1223 Elma, Washington. 98541 Mr. William Ang Region Inspector /WPPSS 3/5 U.S. Nuclear Regulatory Commission 1450 Maria Lane - Suite 210 Walnut Creek, California 94596 Mr. Eugene Rosolie, Director Coalition for. Safe Power 408 Southwest Second Avenue Portland, Oregon 97204 l

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