ML19329B630
| ML19329B630 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 06/11/1977 |
| From: | Batch S, Lingenfetter J TOLEDO EDISON CO. |
| To: | |
| Shared Package | |
| ML19329B551 | List: |
| References | |
| NUDOCS 8002050746 | |
| Download: ML19329B630 (2) | |
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[jg[ Pump. HV-DHil was re-opened. Decay Heat Pump restarted and 3000 gpa fle r s ee a
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TOLEDO EDISON COMPA!N DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLEMENTAL INFORMATION FOR LER NP-32-77-3 DATE OF EVENT: May 28, 1977 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: 'While recalibrating SFAS Channel 4, a simulated
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pressure signal rose above setpoint 433 psig; HV-DHil stroked closed and Decay Heat Punp 1-2 tripped causing a situation in violation of Technical Specifica-tion 3.4.1.
I Conditions Prior to Occurrence: The plant was in Mode 5.
Power (MRI)0 - Power (MWE)D. RCS Pressure less than 200 psig.
Description of Occurrence: At 0045 Hours, May 28, 1977, an I&C mechanic was i
workfag on SFAS Channel 4, recalibrating the RCS pressure bistables. As the simulated pressure rose, KV-DH11 stroked closed at its setpoint of 433 psig.
Oper.stions immediately tripped decay heat pump.
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Designation of Anoarent Cause of Occurrence: This event has been determined to have been caused by'a procedural inadequacy in Maintenance Instruction I 1-1701 Analysis of 'ccurrence: The closing of DH 11 and subsequent de-energi:ation of O
Decay Heat Pump 1-2 caused decay heat flow to be less than 2800 gpm for three minutes.
Since flow was not needed for decay heat removal and Decay Heat Pump l-2 was re-started, no threat resulted to the health and safety of the public or station personnel.
Corrective Action: I&C mechanic i= mediately reset the bistable, operator re-opened HV-DH11, restarted Decay Heat Fump and re-established 3000 gpm flow to RCS. Maintenance Instruction I l-1701 was modified to defeat the DH 11 valve logic by utilizing a jumper across the ' interlock.
Failure Deta: DH 11 was inadvertently closed on May 27,1977 (LER NP-32-77-2),
but the cause was a wiring installation error, not a procedure error as caused this occurrence.
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