ML20062B221

Requests Response to Question Re Facility Cold Overpressure Mitigation Sys Actuation During Accident Events.Response Requested by 901214

ML20062B221
Person / Time
Site:	Comanche Peak
Issue date:	10/09/1990
From:	Linville J Office of Nuclear Reactor Regulation
To:	William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
References
NUDOCS 9010240147
Download: ML20062B221 (3)

Text

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October 9, 1990' S 4

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/ Docket Nos. 50-445 DISTRIBUTION

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and 50.446 ADectet' N 1e # MFields s N NRC & Local PDRs OGC Mr. William J. Cahill, Jr.. PDIV-2 Reading ACRS (10)

! 1 Executive Vice President, Nuclear PDIV-2 Plant EJordan .

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. Texas Utilities Electric Company DCrutchfield DChamberlain .

400 North Olive Street, L.B. 81 MVirgilio Dallas, Texas 75201 JLinville EPeyton

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION UNITS 1&2'- COLD OVERPRESSURE MITIGATION SYSTEM (COMS) ACTUATION DURING ACCIDENT EVENTS (SDAR CP-88-30)

Your letter dated October 5,1988 (TXX-88688) to the staf f on this subject concluded that the postulated failure of the Cold Overpressure Mitigation System (COMS) during a Main Steam Line Break (MSLB) or Steam Generator Tube Rupture (fGTR) need not be considered because it would require a-random, simultaneous, independent failure of a wide range temperature channel. In order for the staff to conclude on the adequacy of this position, you are-requested to respond to the attached list of questions by December 14, 1990.

The staff does not consider this issue to be an immediate safety concern for C .:.o nche Peak Unit 1 because it has a relatively low probability of occurrence, and because it is expected that the licensing basis limits will still be met, even if the COMS is postulated to actuate during MSLB and SGTR events.-

T'.e reporting requirements contained in this letter affect fewer than ten respondents; therefore, OBM clearance is not required under Public Law 96-511.

f Should you have any questions regarding this request, please contact Mel Fields at (301) 492-1334.

Sincerely, bfIhIdbf5Idd'0%

James C. Linville, Acting Director Project Directorate IV 2 Division of Reactor Projects - III, IV, V and Special Prc.jects

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Mr. William;J. Cahill, Jr. , .-  !

! cc w/ enclosure:

Senior Resident Inspector Jack R. Newman, Esq.

U.S. Nuclear Regulatory Commission Newman & Holtzinger i

P. O. Box 1029 1615 L Street, N.W.

, Granbury, Texas 76048 Suite 1000 Washington, D.C. 20036 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission Chief, Texas Bureau of Radiation Control 611 Ryan Plaza Drive, Suite 1000 Texas Department of Health Arlington, Texas 76011 1100 West 49th Street Austin, Texas 78756 Ms. Billie Pirner Garde. Esq.

Robinson, Robinson, et al Honorable George Crump 103 East College Avenue County Judge Appleton, Wisconsin 54911 Glen Rose, Texas 76043 Mrs. Juanita Ellis, President Citizens Association for Sound Energy 1426 South Polk Dallas, Texas 75224 E.-F. Ottney P. O. Box 1777 Glen Rose, Texas 76043 Mr. Roger D. Walker Manager, Nuclear Licensing Texas Utilities Electric Company 400 North Olive Street, L.B. 81 Dallas, Texas. 75201 Texas Utilities Electric Company I c/o Bethesda Licensing l 3 Metro Center, Suite 610 l Bethesda, Maryland 20814 l William A. Burchette, Esq.  !

Counsel for Tex-La Electric i e

Cooperative of Texas Heron, Burchette, Ruckert & Rothwell i 1025 Thomas Jefferson Street, N.W. ,

Washington, D.C. 20007 1 i

GDS Associates, Inc.

Suite 720 j 1850 Parkway Place Marietta, Georgia 30067-8237  !

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1 4 \ I STAFF QUESTIONS ON COMANCHE PEAK STEAM ELECTRIC STATION, UNITS 1 AND 2 COMS ACTUATION DURING ACCIDENT EVENTS (SDAR CP-88-30)

I The October 5, 1988 letter (TXX-88688) provides the rationale for why the' actuation of the Cold Overpressure Mitigation System (COMS) during a Main Steam Line Break (MSLB) or Steam Generator Tube Rupture (SGTR) is not considered to be a credible event. The key to the staff's acceptance of this argument is assurance that the control room operators would be immediately aware of the existence of a failure in the COMS circuitry that would result in its actuation '

during a MSLB or SGTR event. To assist the staff in this regard, please '

provide the following information:

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1. Provide a detailed failure analysis of the COMS that lists each component whose failure would result in the actuation of the COMS during a MSLB or ,

SGTR, all possible failure modes of these components, and why each of n these failures would be immediately noticed by the control room operators. t 2.

Human errors such as calibration mistakes must be considered in the failure analysis. Show why.there cannot be any human errors that will go undetected by the control room operators during normal operating conditions that would result in COMS actuation during MSLB or SGTR events.

' 3. . .The possibility of wide range temperature instrument drift great enough -

to cause actuation of the COMS during:a MSLB or SGTR event (but not great enough.to arm the COMS during normal operating conditions; thereby L alerting the operators) was discounted by the licensee as not being a i credible failure mechanism. Provide a detailed justification for this L position, including-test data, if available, that demonstrates that these L types. of instruments will not drif t appreciably between calibratior, L intervals. Describe the calibration techniques used on these instruments and specify the time interval between calibration cherks.

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