ML20084K198
| ML20084K198 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 08/02/1974 |
| From: | Kalivianakis N COMMONWEALTH EDISON CO. |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20084K201 | List: |
| References | |
| 50-254-74-25, AO-50-254-74-25, NJK-74-194, NUDOCS 8305190205 | |
| Download: ML20084K198 (3) | |
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k,,O+ g {6 NJK-74-194 E/ y (V N AM August 2, 1974 N' . Mr. John F. O ' Leary, Di rector Directorate of Licensing Regulation U. S. Atomic Energy Commission Washington, D. C. 20545
Reference:
Quad-Ci ties Nuclear Power Station Docket No. 50-254, DPR-29, Appendix A Sections 1.0.A.2, 3.2.B, and 6.6.B.I.a
Dear Mr. O '. Leary:
Enclosed please find Abnormal Occurrence Report No. A0-50-254/74-25 for Quad-Cities Nuclear Power Station. This occurrence was previously reported to Region sei, n a ro, t n r :. t. n + won..inenry nnorme.nne sy .i.nknn. .... y if, ip m ann en nn you and Region 111, Directorate of Regulatory Operations by telecopy on July 23, 1974. This report is submitted to you in accordance with the requirements of Technical Specification 6.6.B.I.a. Very truly yours, COMMONWEALTH EDISON COMPANY QUAD-CITIES NUCLEAR POWER STATION V. !/ we <.s
- 4. J. Kalivianakis Station Superinten ent NJK/RAR/j eh cc: Rcgion li t, Directorate of Regulatory O perations j
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N.J n%.) O ,1 ~ ' REPORT NUMBER: A0 254/74-25 REPORT DATE: August 2,1974 OCCURRENCE DATE: July 23, 1974' FACILITY: Quad-Cities Nuclear Power Station Cordova, Illinois 61242 IDENTIFICATION OF OCCURRENCE: Reactor low pressure instrument PS-1-263-52B setpoint drif t. CONDITIONS PRIOR TO OCCURRENCE: Unit I in cold shutdown. DESCRIPTION OF OCCURRENCE: At 1100 hours on July 23, 1974, while doing routine instrument department surveil-lance on Unit One, the lef t hand switch of PS-1-263-528 was found to trip at a setpoint which exceeded the limiting condition for operation as given in section 3.2.B of the Technical Specifications. The switch tripped at 355 psig; the limit is 300 5 P ?350 psig. DESIGNATION OF APPARENT CAUSE OF OCCURRENCE: The cause of this occurrence is attributed to instrument dritt. ANALYSIS OF OCCURRENCE: Auto start of the low pressure ECCS pumps was not impaired by this occurrence. Both the Core Spray and RiiR Systems would have performed properly in the event of an accident with this switch at the as found setpoint. The injection valves for those pumps would have opened at 355 psig instead of between 350 psig and 300 psig. This means that injection to the vessel would have started slightly sooner than l I the analyzed case. Since the pressure was only 5 psig above the limit, the in-tegrity of the low pressure piping for the system was not threatened. Consequently, the setpoint drif t experienced by this switch did not compromise the safe operation i of the plant, and thus had no adverse effects on the health and safety of the public. CORRECTIVE ACTION: The switch was immediately recalibrated and functionally tested according to the instrument department procedure. Since this is the first time this switch has drif ted beyond its limiting setpoint, an addit ional calibration c' heck will be made ~ within 30 days of this occurrence, if contino:ng drift of this switch is experi-enced, forther action will be taken as is necessary to prevent further occurrences of this problem. I
r-AO-50-254/74-25 0 2.- o The pressure switch discussed in this report ~ is a Barksdale Model No. 02T-M1255. Since this is the first failure of this. switch, there is no cumulative experier.ce on which to base any safety implications. Studies are in progress by various .9roups to try to resolve the continuing problem of instrument setpoint drift. o 0 e e h O 6 9 9 l l l t - -... -.}}