ML19329B619

RO NP-32-77-06:on 770711,during Valve Lineup on Decay Heat Loop 1-2,flowpath Inadvertently Established Between RCS & Borated Water Storage Tank.Caused by Personnel Error in Valve Lineup.Pump 1-1 Started to re-establish Flow Rate

ML19329B619
Person / Time
Site:	Davis Besse
Issue date:	07/20/1977
From:	Batch S, Lingenfelter J TOLEDO EDISON CO.
To:
Shared Package
ML19329B542	List: ML19329B541 ML19329B619
References
NUDOCS 8002050736
Download: ML19329B619 (4)

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• evawr os scairtion r@sl,While a valve line,up was being performed on the Decay Heat Loop 1-2. a _j<o

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@l flowpath was inadvertently established htween the RCS and the iBWST. I ss g g Pressurizer level dropp'd,.and e the RC Pumps were tripped. From 1612 hour0.0187 days <br />0.448 hours <br />0.00267 weeks <br />6.13366e-4 months <br />.o s; o es e

[jgg t to 1619 hours0.0187 days <br />0.45 hours <br />0.00268 weeks <br />6.160295e-4 months <br />, a flow of 2 2800 GPM did not exist in violation of Techni- l 3 es ma 8 Leal Specification 3.4.1.

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l[,, The cause for this, occurrence has been determined to be due to personnel l ao g [ error in the performance of the valve lineup.

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TOLEDO EDISON COMPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION

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SUPPLEMENTAL INFORMATION FOR LER NP-32-77-6

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DATE OF EVENT: July 11, 1977

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FACILITY: Davis-Besse Unit 1 IDENTIFICATION OP OCCURRENCE: Loss of Reactor Coolant Flow Due to Error in Valve Lineup

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Conditions Prior to Occurrence: The plant was in Mode 4 - Power (MWT) = 0 and Load (MWE) = 0. RCS Tave 260 F - RCS Pressure 240 psig, Reactor Coolant Pumps 2-1 and 2-2 on Description of Occurrence: At 1606 hours0.0186 days <br />0.446 hours <br />0.00266 weeks <br />6.11083e-4 months <br /> on July 11, 1977, Decay Heat (DH) Pump 1-2 was shutdown at the completion of a Surveillance Test (ST 5011.01) which ran the pump in a recirculation flowpath of the Borated Water Storage Tank (BWST).

While changing the flowpath on DH Pump 1-2 to a recirculation flowpath of the Reactor Coolant System (RCS), the DH Pump 1-2 suction from the RCS valve DH 1518 was opened before the discharge to the BWST valves DH 65 and DH 68 were closed, which allowed water from the RCS to travel to the BWST.

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Pressurizer water level went from 85 inches to 50 inches before the Control Room Operator realized the mistake and cic-ed valve DH 1518. When pressurizer level went below the setpoint, MU 32 "M,ketp Valve to the RCS" went wide open. Since the makeup pumps also feed the  ;. Coolant Pump seals, seal flow decreased from approximately 8 GPM to be'. 3 GPM.

The component cooling water flow to the Recetor Coolant Pump (RCP) 2-1 seal cooler was at this time operating at 45-46 CPM which is below the setpoint for the FIS 4333 " Low Component Cooling Water Flow to RCP Seal Coolers". RCP 2-1 tripped due to both low component cooling water and seal injection flows.

The large flow rate of the Makeup (MU) Pump caused makeup tank pressure to decrease from 10 PSIG to 1 DSIG. At this time, the Control Room Operator tripped the MU Pump to protect it from loss of net positive suction head.

At 1612 hours0.0187 days <br />0.448 hours <br />0.00267 weeks <br />6.13366e-4 months <br />, the Control Room Operator shut down RCP 2-2 to protect the pump seals and to stay within our limit for single RCP operation. From 1612 hours0.0187 days <br />0.448 hours <br />0.00267 weeks <br />6.13366e-4 months <br /> until 1619 hours0.0187 days <br />0.45 hours <br />0.00268 weeks <br />6.160295e-4 months <br />, a flow of Jt 2800 GPM as required by Technical Specification (TS) 3.4.1 did not exist. At 1619 hours0.0187 days <br />0.45 hours <br />0.00268 weeks <br />6.160295e-4 months <br />, a flow 2:2800 GPM was obtained using DR Pump 1-1 which removed us from violation of TS 3.4.1. (See attached flow chart.)

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g TOLEDO EDISON COMPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLEMENTAL INFORMATION FOR LER NP-32-77-6 PAGE 2

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Designation of Apparent Cause of Occurrence: The cause for this occurrence has been determined to be a personnel error in the performance of the valve lineup.

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Analysis of Occurrence: There was no reactor coolant flow for less than six

• minutes after the RCP 2-2 cos.down. Since flow was not needed for decay heat removal and DH Pump 1-1 was :arted, no threat resulted to the health and safety of the public or station' personnel. ,

Corrective Action: DH Pump 1-1 was started to re-establich it2800 GPM flow race.

The operators will be instructed to be cognizant of all possibic flowpaths when performing valve lineups. Also to prevent recurrence, the Decay Heat Operat-ing Procedure will be modified to include a precaution to forewarn the operators.

Failure Data: No previous similar events have occurred.

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• 'TOLED'O EDISON COMPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION N, SUPPLEMENTAL INFORMATION FOR LER NP-32-77-6 PAGE 3 INITIAL VALVE LINEUP ERROR.

DH 1518 OPENED WITH DH 65 AND DH 68 NOT CLOSED.

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i TRANSFERRING OF WATER FROM THE REACTOR COOLANT SYSTEM TO THE BORATED WATER STORAGE TANK -

3r PRESSUhIZER WATER LEVEL DROPS FROM 85 TO 50 INCHES 3r l

MAKEUP VALVE MU 32 OPENS i  % AUTOMATICALLY TO RAISE PRESSURIZER LEVEL sr $r MARGINAL CCW LOW RCP SEAL MU TANK LOW FLOW TO RCP 2-1 FLOW PRESSURE

t t RCP 2-1 AUTO- OPERATOR SHUT-MATIC TRIP DOWN MU PUMP.

NO SEAL FLOW

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> 7 OPERATOR TRIPPED 7,P 2-2 t

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1 NO RCS FLOW.

VIOLATION OF TECH SPEC 3.4.1 t

OPERATOR STARTED DH PUMP

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l-1. PLANT REMOVED FROM VIOLATION OF T.S. 3.4.1

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