ML19338D002
| ML19338D002 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 12/23/1974 |
| From: | Stephenson B COMMONWEALTH EDISON CO. |
| To: | |
| References | |
| 919-74, NUDOCS 8009150582 | |
| Download: ML19338D002 (2) | |
Text
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D Commonwea. Edison
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Reg!ajory &:,a,w BBS Ltr. #919-74 Dresden Nuclear Power Station 5s Illinois 60450 O@'
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Mr. James G. Kappler, Regional Director
- ._3 Directorate of Regulatory Operations-Region III M-
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U. S. Atomic Energy Coimission s';
799 Roosevelt Road Is hel$$
4 Glen Ellyn, Illinois 60137 N
SUBJ11CT: REPORT OP ABNORMAL OCCURRENCE PER SECTION 6.6.A OF THE TECHNICAL SPECIFICATIWS REACTOR HIGH PRESSURE INST.SETPOINP DRIPT
References:
- 1) Regulatory Guide 1.16 Rev.1 Appendir A
- 2) Notification of Region III of AEC Regulatory Operations Telephone:
P. Johnson at 1335 hours0.0155 days <br />0.371 hours <br />0.00221 weeks <br />5.079675e-4 months <br /> on December 15, 1974 Telegram J. Keppler at 1545 hours0.0179 days <br />0.429 hours <br />0.00255 weeks <br />5.878725e-4 months <br /> on December 16, 1974
- 3) Drawing N aber GE 7368E84 Report Number 50-10/1974-20 Oh Report Date: December 23, 1974 M:E kW 9
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Occurrence Date: December 14, 1974 JE e /4 Facility: DresdenNuclearPowerStation, Morris,T114nnia]
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IDE2TfIFICATIN OP OCCURRENCE Dresden Unit 1 Reactor high pressure switch setpoint violation CONDITION PRIOR TO OCCURRENCE l
Dresden Unit-1 war in the run mode with a steady load of 144 lefe.
DESCRIPTION OP OCC'JRR8MCE During routine instrument surveillance of Reactor high pressure switch PSE-4, it was observed that its setpoint was 1076 pai, which is 3 psi above the j
1073 psi limit. The W4 was i=xatdiately reset to 1063 psi. The Technical l
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.Mr. James G. K:ppler $._ Dec-wr 23, 1974 Specification defines the =mHwwn setpoint of this switch to be 1050 psi.
The switch is located at elevation 490'-3".
The pressure sensing line is tapped into the reactor at 547'-6" elevation. This arrangement sets up a head correction of 25 p.1 which saast be added to the switch setpoint at the time of calibration. The point of pre ~ssure measurement is approximately the top of the active fuel.
(See attached letter from R. J. Smith to H. K. Hoyt).
DESIGNATION OF APPARENT CAUSE OP OCCURRENCE Unknown at this time, apparently a unique setpoint drift situation.
ANALYSIS OP OCCURRENCE Reactor pressure switch PSE-4 is one of four switches that monitor reactor pressure and provide a scram. The ewitches are arranged in a "one-out-of-two-twice" logic array. The other three switches were found to be set below the Technical Specification Limit, and would have initiated a scram at 1072 psi. It is therefore concluded that this occurrence is no way jeopardized the safety of plant personnel or the general public.
CORRECTIVE ACTION The switch was immediately reset to 1063 pai. In addition, a graph will be maintained plotting the "as found" setpoint for all subsequent instrument calibrations. This graph will be utilized to determine if the instrument exhibits a drift potential. No further corrective action is deemed necessary at this time.
PAILURE DATA Pressure switch PS!!-4 is a Foxboro Model 41E. No incidences of setpoint drift have been observed since the Dresden Unit One. Technical Specifications have been in effect. The switch is calibrated routinely once every 3 months.
Sincere
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