ML20084U523
| ML20084U523 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 01/24/1975 |
| From: | Kalivianakis N COMMONWEALTH EDISON CO. |
| To: | Oleary J Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20084U525 | List: |
| References | |
| AO-50-265-75-5, NJK-75-45, NUDOCS 8306290104 | |
| Download: ML20084U523 (3) | |
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Quad-Citie: Generating Station i
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January 24, 1975
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Mr. John F. O' Leary, Director Directorate of Licensing Regulation U. S. ATOMIC ENERGY COMMISSION Washington, D. C.
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REFERENCE:
QUAD-CITIES NUCLEAR POWER STATION Docket No. 50-265, DPR-30 Appendix A, Sections 1.0.A.2, 3.2.A., and 6.6.B.I.a.
Dear Mr. O' Leary:
Enclosed please find Abnormal Occurrence Report No. A0-50-265/75-5 for Quad-Cities Nuclear Power Station. This occurrence was pre-vlously reported to Region lit, Directorate of Regulatory Opera-tions by telephone on January 15, 1975 and to you and Region lil, Directorate of Regulatory Operations by telecopy on January 15, 1975 This report is submitted to you in accordance with the reautrements of Technical Specification 6.6.B.I.a.
Very truly yours,
. COMMONWEALTH EDISON COMPANY QUAD-CITIES NUCLEAR POWER STATION y
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f N. J. Kalivianakis Station Superintendent i
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Region Ill, Directorate of Regulatory Operations E
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c REPORT NUMBER: A0 50-265/75-5 REPORT DATE: January 24, 1975 OCCURRENCE DATE:
January 15, 1975 FACILITY:
Quad-Cities Nuclect P:wer Station Cordova, IL 61242 IDENTIFICATION OF OCCURRENCE:
Instrument drift of PS-2-261-308 beyond its limit.
CONDITIONS PRIOR TO OCCURRENCE:
Unit two was in cold shutdown for refueling.
DESCRIPTION OF OCCURRENCE:
On January 15, 1975 at 3:00 p.m., while doing routine REFUELING OUTAGE survell-lance calibration of the(Main Steam Line Low Pressure Isolation pressure switches,-
it was discovered that one switch, PS-2-261-308,' tripped at 846 psig7 Technical Specification 3.2. A. gives a limit of > 850 psig for this switch.
No operator actions were needed to bring the situation under control.
DESIGNATION'0F APPARENT CAUSE OF OCCURRENCE:
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instrument Drlft - The instrument history was reviewed.
It showed that all the Main Steam Line Low Pressure switches tend to drift in both the positive and negative directions. Normally, this drift is not enough to exceed the limit.
ANALYSIS OF OCCURRENCE:
i There are four Main Steam Line Low Pressure switches that are arranged in a one out of two taken twice logic system.
The other three switches had set i
points within limits.
These switches are provided mainly to protect against i
a pressure regulator malfunction which would cause a control or bypass valve to open.
Iflthis condition had occurred the system would have isolated before the pressure' reached the limit of 850 psig and no fuel would have been uncov-ered and the peak clad temperature would have been much less than 1500 F.
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'Therefore, no radioactive materials, other than what was contained initially in the water, would have been released ' " '
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JCORRECTIVE ACTION:
The switch was recalibrated and'left at 864 psig.. Since March 1973, when the setpoint was raised to 864 psig and the calibration frequency was increased from once a quarter to once a month, there have been no cases of instrument drif t beyond the Technical Specification limit. This regular routine surveil-
' lance will be continued.. There is no. plan at this time to initiate any further corrective ~ action.
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Since the setpoint was raised in March 1973 this is the first case of an in-strument drifting beyond the limit.
EQUIPMENT PIECE NUMBER PS-2-261-30B MANUFACTURER Barksdale MODEL B2T-A!2SS RANGE 50-1200 psig I
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