ML20084K016
| ML20084K016 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 09/24/1974 |
| From: | Kalivianakis N COMMONWEALTH EDISON CO. |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| AO-50-245-74-28, NJK-74-296, NUDOCS 8305190118 | |
| Download: ML20084K016 (3) | |
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Commc lth Edison Ouad-Cit.__ J:nerating Station
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.ar h<C /d Cordova.lilinois 61242
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Telephone 309/654-2241
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SEP201974 -
September 24, 1974
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tir. John F. O ' Leary, Di rector
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Directorate of Licensing Regulation U. S. Atomic Energy Commission Washington, D. C.
20545
Reference:
Quad-Cities Nuclear Power Station, Unit i Docket No. 50-254, DPR 29, Appendix A Sections 1.0.A.2, 3.1 Table 3.1.1.c, 6.6.B. I.a
Dear Mr. O' Leary:
Enclosed please find Abnormal Occurrence Report No. A0 50-254/74-28 for Quad-Cities Nuclear Power Station. This occurrence was previously reported to Region 111, Directorate of Regulatory Operations by telephone on September 16, 1974, and to you and Region til, Directorate of Regulatory Operations by tele-copy on September 16, 1974.
This report is submitted to you in accordance with the requirements of Technical Specification 6.6.B.I.a.
Very truly yours, COMM0fMEALTH EDISON COMPANY QUAD-CITIES NUCLEAR POWER STATION
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H. J. Kallvianakis' Station Superintendent NJK/RAR/Jeh cc: Region t il, Directorate of Regulatory Operations J.S. Abel
Enclosure:
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REPORT NUMBER: A0 50-254/74-28 REPORT DATE: September 23, 1974 OCCURRENCE DATE: September 14, 1974 FACILITY:- Quad-Cities Nuclear Power Station Cordova, I llinois 61242 IDENTIFICATION OF OCCURRENCE:
PS-I-5600-PS-4, EHC Fluid Pressure, instrument setpoint drif t.
I CONDITIONS PRIOR TO OCCURRENCE:
Mode switch in RUN. Reactor power steady state at 23'19 HWt and 781 iMe.
DESCRIPTION OF OCCURRENCE:
At 1400 hours0.0162 days <br />0.389 hours <br />0.00231 weeks <br />5.327e-4 months <br /> on September 14, 1974, while doing routine monthly surveillance testing of the."EHC Low Pressure" scram switches, one of the switches was found to trip at 890 psig. This as found setting was outside the limits of 2900 psig as required by S'ection 3.1 Table 3.1.1.c of the Technical Specifications. The other~ three sini tar switches that monitor the EHC Fluid Pressure were found to have their setpoints within ligilts.
DESIGNATION OF APPARENT CAUSE OF OCCURRENCE:
il Other - Instrument Drift:
The instrument was checked for any apparent physical damage, the instrument's history was reviewed, and the instrument mechanic who performed the calibration was' interviewed. Nothing was discovered that could have caused the abnormal occurrence. Thus, the apparent cause of this occurrence is designated as in-strument setpoint drift.
ANALYSIS OF OCCURRENCE:
Ther'e are no safety implications associated with this occurrence. The three remaining instruments for this Reactor Protection System input were operable at the time of the occurrence. Thus, had there been an EHC low pressure signal at the time.of this occurrence, the remaining sensors would have sensed the event and placed the reactor in a safe condition by initiating a reactor scram. The health and safety of the public were not affected, and there were no exce.ssive
,. personnel exposures related to this occurrence.
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.cie CORRECTIVE ACTION:
The switch was immediately recalibrated; its setpoint was adjusted to 940 psig.
This switch'nas had a history of stability with no adjustm:nts being required for the past fifteen months. Since a setpoint drift such as this may be an indication that the piston assemblies of the switches are starting to wear, new assemblies are bcIng ordered. The switches will be inspected and overhauled when the replacement parts are received.
FAILURE DATA:
The switch involved in this occurrence is a Barksdale piston type pressure switch, Model C9512-2 with an adjustable range of 125-1500 psig. These switches were installed in September,1972, as replacements for Model C9622-3, switches with an adjustable range of 250-3000 psig. Since that time, on a total of eight switches, there has been only one case of an instrument drift beyond the Techni-cal Specification Limits.
MONTH / YEAR EQUIPMENT PIECE NUMBER "AS FOUND" SETPOINT Nov./1972 1-5600-PS,4 885 psig Sept./1974 1 -5600-PS -4 890 psig Since there has only been one previous occurrence of this type with these switches, there are no safety implications related to cumulative experience for these switches.
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