IR 05000446/1992049

Discusses Concern That Postulated Fire in CR Could Create Single Hot Short in Control Circuitry of MOVs Resulting in Spurious Operation.Required Hardware Mods Implemented to Control Circuits of Affected Mov,Per Insp Rept 50-446/92-49

ML20205B195
Person / Time
Site:	Comanche Peak
Issue date:	03/24/1999
From:	Polich T NRC (Affiliation Not Assigned)
To:	Terry C TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
References
50-446-92-49, GL-89-10, TAC-M86000, NUDOCS 9903310170
Download: ML20205B195 (3)

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Mr. C. Lancs Terry March 24, 1999

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TU Electric Senior Vice President & Principal Nuclear Officer Attn: Regulatory Affairs Department P. O. Box 1002 Glen Rose, TX 76043 1

_ SUBJECT: RESOLUTION OF MOTOR-OPERATED VALVE HOT SHORT ISSUE AT COMANCHE PEAK STEAM ELECTRIC STATION, UNIT 2 (TAC NO. M86000)

Dear Mr. Terry:

' During a review of plant schematic drawings and control circuit wiring diagrams in NRC Inspection Report 50-446/92-49, the. staff noted that a postulated fire in the control room could create a single hot short in the control circuitry of various motor-operated valves (MOVs),

resulting in spurious operation. The postulated fault could cause the position limit and torque switches to be bypassed. As a consequence, mechanical damage of the valve due to overtorque may occur. This condition could render the affected MOV inoperable (manually or

. automatically). This concern was previously described in detail by the NRC in Information Notice (IN) 92-18, " Potential for Loss of Remote Shutdown Capability During a Control Room Fire," dated February 28,1992.

By letter dated December 23,1992 (TXX-92640), Texas Utilities Electric' committed to

implement hardware modifications to the control circuits of the affected MOVs (as required)

similar to Figures 5 and 6 of IN 92-18. By letter dated February 27,1995 (TXX-95055), you certified that the required hardware modifications were implemented during the third refueling

outage on Unit 1 and the first refueling outage on Unit 2. The implementation of the hardware 4-modifications were reviewed as part of the Generic Letter 89-10 closeout inspection. This

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completes our review of this matter. TAC number M86000 is closed.

Sincerely, ORIGINAL SIGNED BY:

Timothy J. Polich, Project Manager h-Project Directorate IV-1 /O j Division of Licensing Project Management ,

Office of Nuclear Reactor Regulation j l

' Docket No. 50-446 >

cc: See next page ,

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p* *<*** / March 24, 1999 Mr. C. Lance Terry TU Electric Senior Vice President & Principal Nuclear Officer Attn: Regulatory Affairs Department P. O. Box 1002 i Glen Rose,TX 76043 l SUBJECT: RESOLUTION OF MOTOR OPERATED VALVE HOT SHORT ISSUE AT COMANCHE PEAK STEAM ELECTRIC STATION, UNIT 2 (TAC NO. M86000)

Dear Mr. Terry:

I During a review of plant schematic drawings and control circuit wiring diagrams in NRC Inspection Report 50-446/92-49, the staff noted that a postulated fire in the control room could create a single hot short in the control circuitry of various motor-operated valves (MOVs),

resulting in spurious operation. The postulated fault could cause the position limit and torque I switches to be bypassed. As a consequence, mechanical damage of the valve due to overtorque may occur. This condition could render the affected MOV inoperable (manually or automatically). This concern was previously described in detail by the NRC in information Notice (IN) 92-18, ' Potential for Loss of Remote Shutdown Capability During a Control Room Fire," dated February 28,1992.

By letter dated December 23,1992 (TXX-92640), Texas Utilities Electric committed to implement hardware modifications to the control circuits of the affected MOVs (as required)

similar to Figures 5 and 6 of IN 92-18. By letter dated February 27,1995 (TXX-95055), you certified that the required hardware modifications were implemented during the third refueling outage on Unit 1 and the first refueling outage on Unit 2. The implementation of the hardware modifications were reviewed as part of the Generic Letter 89-10 closecut inspection. This completes our review of this matter. TAC number M86000 is closed.

Sincerely, Timothy J. Polich, Project Manager Project Directorate IV-1 Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-446 cc: See next page

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i Mr. C. Lance Terry l TU Electric Company Comanche Peak, Units 1 and 2 cc:

Senior Resident inspector Honorable Dale McPherson l

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U.S. Nuclear Regulatory Commission County Judge P. O. Box 2159 P. O. Box 851 Glen Rose, TX 76403-2159 Glen Rose, TX 76043 Regional Administrator, Region IV Office of the Govemor U.S. Nuclear Regulatory Commission ATTN: John Howard, Director 611 Ryan Plaza Drive, Suite 400 Environmental and Natural Arlington,TX 76011 Resources Policy P. O. Box 12428 Mrs. Juanita Ellis, President Austin, TX 78711 Citizens Association for Sound Energy 1426 South Polk Arthur C. Tate, Director Dallas,TX 75224 Division of Compliance & Inspection Bureau of Radiation Control

- Mr. Roger D. Walker Texas Department of Health TU Electric 1100 West 49th Street Regulatory Affairs Manager '

Austin, TX 78756-3189 P. O. Box 1002 Glen Rose,TX 76043 Jim Calloway Public Utility Commission of Texas George L. Edgar, Esq. Electric industry Analysis Morgan, Lewis & Bocklus P. O. Box 13326 j 1800 M Street, N.W. Austin, TX 78711-3326 Washington, DC 20036-5869 l

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