ML19329A807

RO NP-33-77-75:on 770829,RCS Have Less than 525 F in Mode 2,startup.Caused by Procedure Error in Shutdown Procedure & Fact That Only Three Reactor Coolant Pumps Were in Operation.Reactor Shut Down

ML19329A807
Person / Time
Site:	Davis Besse
Issue date:	09/28/1977
From:	Miller D TOLEDO EDISON CO.
To:
Shared Package
ML19329A801	List: ML19329A800 ML19329A807
References
NUDOCS 8001150703
Download: ML19329A807 (3)

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LICENSEE EVENT REPORT

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g , Reactor Coolant System Tave was less than 525 F in Mode 2, Startup. This; g' placed the unit in the Action Statement of Technical Specification  ;

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@l.s 3.1.1.4. The reactor was shutdown within twelve miautes as required by 'I u

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DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLEMENTAL INFORMATION FOR LER NP-33-77-75 DATE OF EVENT: August 29, 1977 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Reactor Coolant System Tave less than 525 F.

.:onditions Prior to Occurrence: The plant was in Mode 2, with Power (MWI) = 0 and Load (MWE) = 0. Reactor Coolant System pressure was 2155 psig and tempera-'

ture was 5320F. Reactor power was being decreased from approximately 10-6 amps to approximately 10-8 amps. Preparations were being made to allow maintenance to inspect the Reactor Coolant Pump 1-1-2 Surge Capacitors.

Description of Occurrence: At 0117 hours0.00135 days <br />0.0325 hours <br />1.934524e-4 weeks <br />4.45185e-5 months <br /> on August 29, 1977, the Main Feed Pump was removed from service. The Startup Feed Pump was on to provide minimum feed-  !

water flow to the steam generators. At 0120 hours0.00139 days <br />0.0333 hours <br />1.984127e-4 weeks <br />4.566e-5 months <br />, average Reactor Coolant Sys-tem temperature decreased to 5250F, and continued to decrease. This placed the station into the Action Statement of Technical Specification 3,1.4. The Techni-

! j cal Specification requires average reactor coolant temperature (Tavg) to be main-

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' tained at / 52507 while the reactor is critical. If Tavg decreases to less than i 5250F, the station must be in Hot Standby within 15 minutes. l When Tavg decreased to 5250F, the turbine bypass valves were shut momentarily to )

maintain system pressure. Gland Steam was transferred to the Auxiliary Boiler  !

and the Main Steam Line Warm-up Valves MS 1299A and MS 1299B were closed, to reduce stesa consumption.

The Shift Foreman ordered the ree.ctor shutdown. At 0129 hours0.00149 days <br />0.0358 hours <br />2.132936e-4 weeks <br />4.90845e-5 months <br />, the reactor re- )

gulating rods were fully inserted. A shutdown margin calculation was performed and the reactor was verified to have a shutdown margin of 4.73% delta K/K. The

~minimum Tavg temperature reached was 5120 F. The Operations Enginaar was informed of the occurrence.

Designation of Apparent Cause of Occurrence: A procedural error was one cause of this incident. The Shutdown and Cooldown Procedure, PP 1102.10.1, did not address i putting the Auxiliary Boiler on and switching steam loads to the Auxiliary Boiler until after reactnr power had been decreased to 10-8 amps.

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j Contributing factors include the decay heat production of the new core was minimmi

. and only three Reactor Coolant Pumps (RCP) were runnf*1g at the time. RCP l-1-2 l was out of service due to the failure of the surge capacitor at 1740 hours0.0201 days <br />0.483 hours <br />0.00288 weeks <br />6.6207e-4 months <br /> on

! August 27, 1977.

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. TOLEDO EDISON COMPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION i

SUPPLEMENTAL INFORMATION FOR LER NP-33-77-75 PAGE 2 i

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Analysis of Occurrence: The health'and safety of the public and station employees 3

was not endangered. As a result of this occurrence, no abnormal instrumentation

? upsets were observed. Pressure was maintained in the Reactor Coolant System. No ether abnormal incidents occurred.

I Corrective Action: As stated in the Description of Occurrence, the reactor was i==adiately shutdown to remove the station from the Action Statement.

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! To prevent further recurrences, the Plant Shutdown and Cooldown Procedure, j PP 1102.10.1, is being revised. Revision is being made to have the Auxiliary i Boiler in service and the major steam loads transferred to the Auxiliary Boiler

! prior to decreasing reactor power to 10-8 amps.

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Failure Data: No previous similar events have occurred.

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