ML20084K125
| ML20084K125 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 09/10/1974 |
| From: | Kalivianakis N COMMONWEALTH EDISON CO. |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20084K129 | List: |
| References | |
| AO-50-265-74-21, NJK-74-273, NUDOCS 8305190159 | |
| Download: ML20084K125 (3) | |
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Reference:
Quad-Cities Nuclear Power Station, Unit 2 Docket flo. 50-265, DPR-30, Appendix A Sections 1.0.A.2, 3.7.A.3, and 6.6,0.1.a
Dear ile. O'!.eary:
Enclosed alease find Abnormal Occurrence Rer, ort No. /0 50-265/74-21 for Quad-Ci ties tiucle r Ecuer 5tation. T ni s occurr ence wa:; prev ious ly reported to Region li t, Directorate of Regulatory Oncretions by.telepnene en Au'Jas t 31, 1974, and to you cnd Region li t, Directorate of Resulstory Operations by telecopy on liugust 31, 1974.
This report is submitted to you in accordance with the requirements of Technica l S peci f i cat ion 6.6.B. l.a.
Very t ruly yturc,
COMP.ONWEALTH EDISON C0!iPANY QUAD-CITI ES NUCLEAR POWER STAT 10!1
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N. J. Kalivianakis Station Superintendent 14JK/EAS /j eh cc: Region 111, Director of Regulatory Operations J. S. Abel o L.[
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REPORT NUMBER: A0 50-265/74-21 R_E_ PORT DATE: September 9, 1974 OCCURRENCE DATE: August 31, 1974 FAC I L I TY_: Quad-Citics Nuclear Power Station Cordova, Illinois 61242 IDENTIFICATION OF OCCURRENCE:
Reactor Building to suppression chainber vacuum breaker valve AO 1601-2GA failed to open during routine quarterly surveillance testing.
i CONDITIONS PRIOR TO OCCURRENCE:
Unit 2 reactor in startup mode withdrawing control rods towards cri ticality, surveillance tests in progress.
DESCRIPTICU OF OCCURRENCE:
During the uni t start un, quarterly operability surveillance was being per-formed on the Unit 2 heactor Building - to - Pressure Suppression Chc..ser V acuum Breaker valves A0 1601 -20A and <30 1601 -203.
Valve 20A failed to The control room operator then terminated con-open frcm the control room.
trol rod withdrawal and the Shif t Foreman and Equipment Operator procccded to examine the valve locally to determine the reason for the failure. Since the valve is a fail-open type valve, the control fuse was removed and the valve did open with some assistance. Therefore, an electrical problem was ruled out.
The fuse was replaced and the valve did close; yet it still cond u9c' that th-v ould o n omn fre
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was probably a faulty valve operator.
The 2CA valve was taken out-of-scevi;c, and a work request was issued to repair the valve.
ANALYSIS OF OCCURRENCE:
The purpose of the vacuum relief valves is to equalize the pressure between the pressure suppression chamber and the reactor building so that the struc-tural integrity of the suopression chamber is maintained. The system conteins two 100 per cent capacity flow paths. Although "A"
line was inoperable due to the 1601-20A failure, the "B" line was still operable. Va lve A0 1601 -205 had been demonstrated to be satisfactorily onerable during the surveillance test. Thus, the "B" flow path was capable of nerforming its intended functio, at all times.
fhe structural integrity of the suppression chamber was thus, not compromised due to this occurrence.
10 50-265/74-21, September 9, 197h
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DE; 1 G;;AT I C;4 CF in<Ai1El:T ClUSE OF OCCUdhE!.CE:
COMPONENT FAILURE:
The apparent cause of this occurrence is designated as component failure.
'Upon removal and inspection of the pilot solenoid valve assembly, a damaged rubber seat was found in the solenoid cap assembly. This apparently resulted in the failure of the solenoid mechanism to give an air signal to the four-way Versa pilot valve. Therefore, the main valve could not be opened.
The pilot valve was thus designated as the f ailed component due to excessive wear of the rubber seat.
t CORRECTIVE ACTION:
The pilot valve section was replaced, but the old solenoid coil was retcined.
The valve was satisfactorily orcrated from the control room three times.
Local operation was confirned and no sluggish operation was observed.
FAILURF DATA:
The 1601 -20A valve is a Henry Pratt 20 inch air operated butterfly valve. On February 17, 1972, the valve position and indicating light were adjusted.
Local leak rete tests were run on the sect ion of nine between A0-2-1601-20A and CV -1601 -3 i A on Ap'i l 16, 1973, and October 17, 1973. The rceasured leakages were 0.637 SCFH and 0 SCFil, respectively. The valve seating surf aces were in no way to blame for the valve failing to operate on August 31, 1974. The pi!ot solenoid 50 1601-50A has not had any previous naintenance history. Therefore, there is no cumulative experience with regsrds to this failure.
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