ML20084S753
| ML20084S753 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 06/20/1975 |
| From: | Kalivianakis N COMMONWEALTH EDISON CO. |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20084S754 | List: |
| References | |
| AO-50-265-75-18, NJK-75-328, NUDOCS 8306170227 | |
| Download: ML20084S753 (2) | |
Text
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Ouad-Cres Nuclear Power Station i.
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June 20,_1975 9
Director of Office of Nuclear Reactor Regulation 1
U. S. Nuclear Regulatory Conmission Washington, D. C. 20555
Reference:
Quad-Ci ties Nuclear Power Station i'
Docket No.60-265, DPR-30, Unit 2 Appendix A, Sections 1.0.A.4, 3.7.B.1, 6.6.B.2.b Abnormal Occurrence Report No. 50-265/75-18 4
The purpose of this letter is to provide you with details concerning an un-3 usual event which occurred at quad-Cities Nuclear Power Station, Unit 2, on May 22, 1975 This report is being :,ubmi tted in accordance with the requi re-ments of Technical Specification 6.6.B.2.b.
Circumstances leading to the discovery of this event were reported to you on May 30, 1975 in Quad-Cities Nuclear Power Station Abnormai Occurrence Report No. 50-265/75-18.
Very truly yours, i
COMMONWEALTH EDISON COMPANY QUAD-ClTIES NUCLEAR POWER STATION f/}
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N. J. Kalivicnakis Station Superintendent i
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NJK/RAR/lk cc:. Region lII, Directorate of Regulatory Operations J. S. Abel 4
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,e' REPORT NUMBER: Unusual Event Letter REPORT DATE: June 21, 1975 EVENT DALE: May 22, 1975 FACILITY: Quad-Ci ties Nuclear Power Station Cordova, 111. 61242 IDENTI FI CATION OF EVENT:
A single valve failure made the Standby Gas Treatment system inoperable.
CONDITIONS PRIOR TO EVENT:
Unit one was at 670 MWe and increasing at the rate of 3 MWe per hour.
Unit two was at 495 MWe and increasing at the rate of 20 MWe per hour.
DESCRIPTION OF EVENT:
On May 22, 1975 a condition involving a single failure of a SBGT system inlet valve was discovered which could result in the loss of the capability of this system to perform i ts safety function.
As the logic for the system is presently designed, an auto initiation signal for one uni t automatically closes the inlet valve to the SBGT system f rom the other unit.
If a failure occurs on the inlet valve for the unit that auto initiates, the condition is such that no inlet valve at all is open to the system.
This is a vio-lation of the " single failure" criteria for the SBGT system.
DESIGNATION OF APPARENT CAUSE OF EVENT:
Design Deficiency Due to a design deficiency, the SBGT system will not remain operable under all conditions with a single component failure.
_ ANALYSIS OF EVENT :
There are no safety implications from the event.
Due to a previous abnormal occurrence both inlet valves have been taken out of service in the open direction and the conditions described above will not affect SBGT system operability.
CORRECTIVE ACTION:
A modifice-request has been initiated and routed to the Station Nuclear Engineerir separtment.
The modi fication request should result in a revision to the present logic scheme to preclude the possibility that a failure similar to that described above would render the system inoperable.
Until the time that the modification is implemented, the inlet valves will remain positioned as described above.