ML20084A945
| ML20084A945 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 08/03/1972 |
| From: | Stephenson B COMMONWEALTH EDISON CO. |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20084A946 | List: |
| References | |
| BBS-72-5, NUDOCS 8304060031 | |
| Download: ML20084A945 (2) | |
Text
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. Commonwealth Edison Company O U A D.CITIE S N U C L E A R POWER ST ATIO N w..
POST OfflCE SOX 216
- CORDOVA, ILilNOl$ C1242 1
50-265 August 3, 1972 BBS-72-5
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Mr. J. F. O' Leary PT a
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Director, Directorate of Licensing
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-j i U. S. Atomic Energy Commission
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Dear Mr. O' Leary:
_y REF:
Quad-Cities Nuclear Power Station Unit II DPR-30 Appendix A Sections 1. 0. A. 2. and 6. 6.B. 3 The purpose of this letter is to inform you of the details regarding the failure of the inboard primary containment isolation valve in the Reactor Core Isolation Cooling System (RCIC).
The incident occurred at 4:00 P. M. on July 27, 1972 on Quad-Cities Unit II.
DESCRIPTION OF INCIDEN'I' & IMMEDIATE ACTIONS 3
,During a r @ ly valveQ up on Quad-Cities Unit II the RCIC inboard steam supp (1301-16) failed in the open position, reactor pressure at the time was 200 psi.
Sev-eral attempts were made unsuccessfully to close the valve from the control room.
The heatup was terminated while a drywell entry was made by the General Electric Shift Super-i visor and Station Maintenance Department personnel to de-termine the nature of the problem.
Investigation of the valve revealed that the malfunction was not mechanical s
but electrical and that an immediate repair was not possible, fshutdownanddepressurizationoftheunitpursued.he situation was re The outboard steam supply valve (1301-17) was manually closed to isolate the RCIC system.
INVESTIGATION AND REPAIR An investigation performed by Station Electrical Maintenance revealed that the torque switch for the valve was faulty.
An internal spring in the switch which normally resets the contacts after actuation had failed.
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CONCLUSION fTheinvestigationindicatedthatthevalvefailurere-i
/ sulted from a defective torque switch.
Once the torque switch was replaced the valve operated correctly.
The system was still capable of isolating on a line break signal since the outboard valve was openable at all times.
Also with the valve failed in the open position the sys-tem could have performed its intended safety function.
Very truly yours, COMMONWEALTH EDISON COMPANY QUAD-CITIES 1 LEAR OWER STATION i
5 f' 14G/S
. B.
hy son Assistant perintendent
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