ML13316B769
| ML13316B769 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 09/05/1980 |
| From: | Haynes J Southern California Edison Co |
| To: | Engelken R NRC Office of Inspection & Enforcement (IE Region V) |
| References | |
| IEB-80-20, NUDOCS 8010080274 | |
| Download: ML13316B769 (3) | |
Text
Southern California Edison Company P 0.
BQx 800 2244 WALNUT GROVE AVENUE ROSEMEAD.
CALIFORNIA 91770 September 5, 1980 U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region V 1990 North California Boulevard Suite 202, Walnut Creek Plaza Walnut Creek, California 94596 Attention:
Mr. R. H. Engelken, Director DOCKET NO. 50-206 SAN ONDFRE -
UNIT 1
Dear Sir:
IE BULLETIN 80-20 FAILURES OF WESTINGHOUSE TYPE W-2 SPRING RETURN TO NEUTRAL CONTROL SWITCHES Reference is made to your correspondence of July 31, 1980 which forwarded the subject IE Bulletin. This bulletin identified potential deficiencies in Westinghouse Type W-2 spring return to neutral control switches.
The following is our response to each item in the Bulletin:
ITEM 1:
Determine whether Westinghouse Type W-2 control switches with spring return to neutral position are used in safety-related applications at your facility. If so, identify the safety-related systems using these switches and the total number of switches so used. If no such switches are usea in your facility, you should indicate that this is the case and ignore the remaining questions.
Response
We have determined that a total of eleven (11) Westinghouse Type W-2 control switches with spring return to neutral are in use in safety-relateo applications.. All eleven switches are in the safety injection system. Three control the three loop safety injection isolation valves (MOV's 850A, B and C).
The remaining eight control the feedwater pump 8 01008o 27'
U. S. Nuclear Reculatory Commission September 5, 1980 suction/discharce valves (HV-851A, B, HV-852A, B, HV-853A, B ano HV-854A, B), but are installed in the circuit in such a fashion that failure of the neutral contacts would not prevent operation of the valves for their automatic safety related function.
ITEM 2:
Licensees of operating plants using Type W-2 spring return to neutral control switches in safety-related applications shall perform continuity tests on all such switches. These tests shall be performed with the switch operator in the neutral position and completed within ten (10) days of the date of this bulletin. In addition, this continuity test shall be repeated at least every thirty-one (31) days after the initial test and after each manipulation of the switch from its neutral position. These continuity tests may be discontinued subsequent to implementing the longer term corrective measures described below.
Response
The plant has been in a cola shutdown condition since April, 1980. Theisafety injection system and the three switches in question are not required to be operable in cold shutdown. Consequently, failure of the switches under existing plant.conditions woulo not result in disabling of a safety-related function.
Continuity of the.,neutral contacts for these three switches was verified on August 15, 1980. Since the.switches are not required to be operable under the existing plant conditions, we intend to defer follow-up checks (31 days) pending return of the plant to a condition which would require that the safety injection system be operable.
Prior to placing.the plant in a condition which would require that the safety injection system be OPERABLE, the continuity of the neutral contacts will be verified and re-verified every 31 days thereafter whenever the safety injection system is required to be OPERABLE and until completion of any necessary long-term actions which may be inoitified as discussed in our response to Item 3, below.
ITEM 3:
Licensees of operating plants and holders of construction permits shall Describe the longer term corrective measures planned and the cate by which such measures will be implemented by actual installation or by design change, as appropriate. As a minimum, the longer term corrective measures should include rewiring the indicating light as shown in Figure 1 provideo the light is readily visible to the control room operator. If not, failures of the neutral position contacts should be annunciatec in the control room.
U. S. Nuclear Regulatory Commission September 5, 1980
Response
The specific circuit desion of the three switches in question does not allow the simple modification proposed in the Bulletin to be made. Further, we have been informed by Westinghouse that a preliminary cesign review has located no inherent defects in the Type W-2 switch neutral contacts ano that they regard the failure at Zion to be ranoom in nature ano non-ceneric. Consequehtly, we are deferring any long term corrective action pending completion of the Westinghouse desidn review which-is currently scheduled to be completed by November 1, 1980. If the final results of the Westinghouse review indicate a potential deficiency, the subject switches shall be modifieo, rewired or replaced to preclude failures of the neutral contacts from preventing actuation of the safety-relateo components. We will inform you in writing of our planned corrective action, if any is necessary, ano a schedule for same.
In accordance with your request in the cover letter to the subject bulletin, we have estimated that 48 man-hours of work were required to complete the report required by the subject bulletin. No man-hours have yet been required for corrective action.
If you have any questions or require additional information concerning this response, please contact me.
Sincerely, J. G. Haynes Manager of Nuclear Operations cc:
Division of Reactor Operations Inspection c/o Distribution Services Branch Division of Document Control, Administration Washington, D.C.
20555