ML19329A812

RO NP-33-77-76:on 770901,reactor Coolant Pump 1-2-1 Tripped.Caused by Low Seal Injection & Component Cooling Water Flow,Due to Personnel Error.Instrument Air Valves Relabeled

ML19329A812
Person / Time
Site:	Davis Besse
Issue date:	10/04/1977
From:	Zell J TOLEDO EDISON CO.
To:
Shared Package
ML19329A805	List: ML19329A804 ML19329A812
References
NUDOCS 8001150707
Download: ML19329A812 (2)

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@ gat 1510 hours0.0175 days <br />0.419 hours <br />0.0025 weeks <br />5.74555e-4 months <br /> on September 1, 1977, Reactor Coolant Pump 1-2-1 tripped 7 83 "

gldue to low seal injection and component cooling water flow. In Action  ;

g l Statement of Technical Specification 3.4.1. Reactor Coolant Pump 1-2-1 ,

E DL,e-started r at 1524 hours0.0176 days <br />0.423 hours <br />0.00252 weeks <br />5.79882e-4 months <br /> on September 1, 1977. (NP-33-77-76) l 7 83 "

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT 0 ,

SUPPLEMENTAL INFORMATION FOR LER NP-31-77-76

. ,3 b DATE OF EVENT: September 1, 1977 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Reactor Coolant Pump (RCP) 1-2-1 tripped causing single pump operation in a Reactor Coolant Loop. -

Conditions Prior to Occurrence: The plant was in Mode 1, with Power (MWT) = 10%,

and Load (MWE) = 0. ,

Description of Occurrence: At 1510 hours0.0175 days <br />0.419 hours <br />0.0025 weeks <br />5.74555e-4 months <br /> on September 1, 1977, the component cool- ,

ing water flow to RCP l-2-1 was oscillating at its low flow setpoint. At the same 1 ti=e, seal injection flow to RCP l-2-1 dropped below its low flow setpoint due to Normal Makeup Flow Control Valve MU 32 failing full open. The control interlock which requires either seal injection or component cooling water flow was not satis-  ;

fled and, therefore, tripped RCP l-2-1.,,

This placed the station in the Action Statement of Technical Specification 3.4.1 l which requires all four reactor coolant pumps operatir.:;; while in Mode 1. 1 l

Designation of Apcarent Cause of Occurrence: This occurrence was due to personnel error. An operator mistakenly shut Instrument Air Valve IA 601.(instead,of SA 601) which supplies the pneumatic operator of Normal Makeup Flow Control valve MU 32, causing it to fail open with a resultant drop.in flow to RCP l-2-l' seal injection.

The wrong valve was shut due to the close proximity of valve IA 601 to SA 601.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. The three operating reactor coolant pumps provided nore than sufficient flow to remove the heat in the reactor core.

Corrective Action: Instrument Air Valve IA 601 which supplies control air for Normal Makeup Flow Control Valve MU 32 was found to be closed and was immediately re-opened. Seal injection flow was re-established and RCP l-2-1 restarted at 1524 l hours on September 1, 1977. Since the error was due to the unusual situation of two similarly labeled valves being in close proximity, IA 601 was relabeled as IA 603 and the appropriate procedure modifications have been made.

Failure Data: There has been one previous failure of a Reactor Co'olant Pump, l

.NP-33-77-64, but the cause was a capacitor failure.

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