ML20003H631

Requests Util Perform Review to Determine What Design Changes or Operator Actions Would Be Necessary to Assure That High Energy Line Breaks Will Not Cause Control Sys Failures to Complicate Event Beyond FSAR Analysis

ML20003H631
Person / Time
Site:	Summer
Issue date:	04/30/1981
From:	Tedesco R Office of Nuclear Reactor Regulation
To:	Nichols T SOUTH CAROLINA ELECTRIC & GAS CO.
References
NUDOCS 8105060545
Download: ML20003H631 (3)

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UNITED STATES 8

NUCLEAR REGULATORY COMMISSION o

WASHINGTCN, D. C. 20G56

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APR 3 01981 Docket No.: 50-395

/q'gf Mr. T. C. Nichols, Jr.

Vice President & Group Executive.

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South Carolina Electric & Gas Company 4

'0 P. O. Box 764 Columbia, South Carolina 29281 "A

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Subject:

Control System Failures Operating reactor licensees were informed by IE Information Notice 79-22, issued September 19, 1979, that.certain non-safety grade or control equipment, if subjected to the adverse environment of a high energy line break, could.

impact the safety analyses and the adequacy of the protection functions perfonned by the safety grade equipment. Enclosed is a copy of IE Information Notice 79-22, and reprinted copies of an August 20, 1979 Westinghouse letter and a September 10, 1979 Public Service Electric and Gas Company letter which address this matter.

Operating Reactor licensees conducted reviews to determine whether such problems could exist at operating facilities.

The NRC is concerned that a similar potential may exist at light water facilities now under construction. You are, therefore, requested to perform a review to detennine what, if any, design changes'or operator actions would be necessary to assure that high energy line. breaks will not cause control system failures to complicate the event beyond the FSAR analysis. Provide us with the results of your review including all identified problems and the manner in which you have l

resolved them.

The specific " scenarios" discussed in the above referenced Westinghouse letter are to be considered as examples of the kinds of interactions which might occur, l

Your review should include those scenarios, where applicable, but should not necessarily be limited to them.

I The analyses reported in Chapter 15 of the FSAR are intended to demonstrate L

the adequacy of safety systems in mitigating anticipated operational occurrences and accidents.

Based on the conservative assumptions made in defining these " design bases" events and the detailed review of the analyses by the staff, it is likely that they adequately bound the consequences of single contml system failures, t

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Mr. T. C. Nichols, Jr. APR 3 01981 To provide assurance that the design basis event analyses adequately bound other more fundamental credible failures you are requested to provide the following information:

1.

Identify those control systems whose failure or malfunction could seriously impact plant safety.

2.

Indicate which, if any, of the control systems identified in (1) receive power from common power sources. The power sources considered l

should include all power sources whose failure or malfunction could lead to failure or malfunction of more than one control system and i

should extend to the effects.of cascading power losses due to the failure of higher level distribution panels and load centers.

3.

Indicate which, if any, of the control systems identifie:I in (1) receive input signals from comon sensors. The sensors considered should include, but should not necessarily be limited to, common hydraulic headers or impulse lines feeding pressure, temperature, level or other signals to two or more control systems.

simultaneous malfunctions of the control Provide justification that any(3) resulting from failures or malfunctions 4.

systems identified in (2) and of the applicable comon power source or sensor are bounded by the analyses in Chapter 15 and would not require ection or response beyond the capability of operators or safety systems.

You should provide your schedule for responding to the requests contained herein within two weeks of receipt of this letter.

Sincerely, dur a

t Robpt. Ted co, Assi t Director

.for icensing Division of Licensing

Enclosures:

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Mr. T. C. Nichols, Jr.

Vice President & Group Executive Nuclear Operations-South Carolina Electric & Gas Company P. O. Box 764 Columbia, South Carolina 29218

. cc: Mr. Henry Cyrus.

Senior Vice. President South Carolina Public Service Authority 223 North Live Oak Orive Moncks Corner, South Carolina 29461 J. B. Knotts, Jr., Esq.

Debevoise & Liberran 1200 17th Street, N. W.

Washington, D. C.

20036 Mr. Mark B. Whitaker, Jr.

i Group Manager - Nuclear Engineering & Licensing South Carolina Electric & Gas Company P. O. Box 764 Columbia,-South Carolina 29218 Mr. Brett Allen Bursey Route 1, Box 93C t

Little Ho ntain, South Carolina 29076 u

Resident Inspector /Sumner NPS c/o U. S. NRC Route 1, Box 64 L

Jenkinsville, South Carolina 29065

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P00R OREL

l ENCLOSURE 1 UF ED STATES.

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OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON. D.C. ' 20555 September 14.'1979 i

IE Information Notice No. 79-22 QUALIFICATION OF CONTROL SYSTEMS

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Public Service Electric and Gas Company notified the NRC of a potential unreviewed safety question at their Salem Unit 1 facility.

This notification was based on a continuing revie. by Westinghouse of the environmental qualificatiens of equipment Based on the present status that they supply for nuclear steam supply systemsj of this effert, Westinghouse has informed their customers that the performance of non-safety grade equipment subjected to an adverse envirensent could impact Thesa non-safetf the protective functions performed by safety grade equipment.

grade systems include:

Steam generator power operated relief valve control system I

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environment could al'soTgTve' erroneous info'riationi to-the plant operators.

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Wastinghouse states that..the' consequences"of'suchl an ' event could possibly be

.more limiting than res'ults presented in Safety-Analysis Reports, however, Westinghouse also states-that the. s.everity. of the! results can be limited by operator actions together with operating characterisitics of the safety

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Further. Westinghouse has recommended to their customers that they systems.

review their systems to determine whether'-ai$eenreviewed safety questions exist.

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This Information Notice is previded as an early notification of a possibly It is expected that recipients will review the information significant matter..

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No specific action or response for possible applicabiltty"to their facilities.:NRC4 evaluations-so indicate, further licens is requested at this time.

If:

a:tions may be requested or. required..If youthave questions > garding this matter, riate NAC Regional Office.

please contact.the Director;,pf_the_ap_p-4 3- '

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No written respon'se to IIiisiTNormation'.Not cais required.

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ENCLOSURE 2 4

1 REPRINT.

Westinghouse Electric Corporation-

. Water Reactor Division L

. Nuclear Service Division

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August 30, 1979 PSE-79-21 e.

Mr. F. P. Librizzi, General Manager i

Electric Production Public Service Electric and Gas Company 80 Park Place l

Newark, New Jersey 07101

Dear Mr. Librizzi:

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Salem Unit No.1 OUALIFICATION OF CONTROL SYSTEMS

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l Westinghouse supplied NSSS equipment Westinghouse has also found it necessary to consider the interaction with non-safety grade systems.

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environment could impact the protective-functions performed by NSSS-...-

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safety grade equipment. The NSSS control and protection systems were included in this review to' assess the adequacy of the present environ-mental _ qual.ificat_ionsequirements m

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system operation which may impact protective functions. These systems

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i Each of the above mentioned systems could potentially malfunction if

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s impacted by adverse environments due to a high energy line break inside or: outside containment. In each case, a limited set of breaks, coupled with possible consequential control malfunction in an adverse direction, ofj the abovir events pould yield results which are more limiting than those In all cases, however, the pr,esentc.d 11 the plant Safety Analysis Reports. severity of the results ca r.

operating characteristics of the safety systems.-

We believe these systems identified do not constitute a substantial safety However, Westinghouse recaimmends you review them to determine if hazard.

any unreviewed safety questions or significant deficiencies exist in your l

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pl, ant ( s ).

To assist you in understanding these concerns. Westinghouse will hold a I

seminar in Pittsburgh on Thursday, September 6 at Westinghouse R&O Center, The seminar will Building 701, with all our operating plant customers.

address tht potential impact of these concerns for various plant designs and various licensing bases.

Please contact your WNSD Regional Service office to confirm your attendance at the seminar. We will' provi.de additional details concerning the agenda

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~t ENCLOSURE 3 i

REPRINT PUBLIC SERVICE ELECTRIC AND GAS' COMPANY

-c Salem Nuclear Generating Station P..D. Box 56 Nancocks Bridge, New-Jersey 08038 September 10, 1979 Mr. Boyce H. Gri[r*

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Director of USKtC Office of Inspection and Enforcement Region 1 631 Park Avenue King of Prussia, Pennsylvania 19406

Dear Sir:

REPORTABLE OCCURRENCE 79-58/OlP l

SALEM NO. 1 UNIT LER t

This letter will se ve to confint our telephone report to Mr. Gary Schneider of the Regional NRC office on Friday, September 6,1979, advising of a potential reportable occurrence in accordance with Technical Specification 6.9.1.8.

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We have been notified by our Engineering Department thatTWesting '? -;~

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associated with high energy line breaks inside or outside containment

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operated relief. valve' control, main feedwater control and 'automatici.D;4p m-

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