ML20084H446

AO BFAO-50-260/744W:on 740810,HPCI Isolated Due to Excessive Steam Flow During Manual Start of Hpci.Caused by Spurious Spiking of Pdis Switches Monitoring HPCI Steamflow.Snubbers Added to Instrument Lines & 3 Delay Relays Added

ML20084H446
Person / Time
Site:	Browns Ferry
Issue date:	08/20/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084H447	List: ML20084H446 ML20084H448
References
NUDOCS 8305040232
Download: ML20084H446 (2)

Text

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• TENNESSEE CHATTANOOGA,VALLEY AUTHORITY TENNESSEE 11 MT1 ff^ fav 37401 L1 -

//A August 20, 1974 7 g hr I[e

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Mr. John F. O' Leary, Director Directorate of Licensing { p

' Office of Regulation Q.l-Qlp U.S. Atomic Energy Co-ission

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Washington, DC 20545 N

Dear Mr. O' Leary:

THINESSEE VALLEY AUTHORITY - BROWS FERRY NUCLEAR PLANT UNIT 2 -

DOCKET HO. 50-260 - FACILITY OPERATING LICCTSE DPR ABHOPl4AL OCCURRETCE REPORT BFAO-50-260/744U The enclosed report is to provide details concerning HPCI steanline auto isolation and is submitted in accordance with Appendix A to

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Regula' tory Guide 1.16, Revision 1, October 1973. This event occurred on Browns Ferry nuclear Plant unit 2 on Au6ust 10, 1974.

Very truly yours, THINESSEE VALLEY AUTHORITY

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51' rector of Power Production Enclosure CC (Enclosure):

Mr. Norman C. Moseley, Director Region II Regulatory ~ Operations Office, USAEC 230 Peachtree Street, UW., Suite 818 Atlanta, Geor6 ia 30303 O

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ABNORMAL OCCURRECE REPORT

. i Report No.: BFAO-50-260/744W -

Report Date: August 20, 1974 Occurrence Date: August 10, 1974 Facility: Browns Ferry Nuclear Plant unit 2 ,

Identification of Occurrence HPCI steamline auto isolation.

Conditions Prior to Occurrence The reactor was operating at 800 psig in the hot functional phase of the startup test progren at approxi=ately 4-percent power.

Description of Occurrence While performing a manual start of HPCI as called for in Startup Test Instruction 15, HPCI isolated due to excessive steamflow. HPCI was initiated a second time and isolated again due to excessive steemflow. A third manual start was successful. An auto =atic initiation followed this and met all surveillance and STI criteria.

Designation of Annarent Cause of Occurrence The isolation was caused by spurious suiking of the PdIS switches monitoring.

HPCI steamflow during a cold start of the HPCI turbine.

Analysis of Occurrence The isolation of HPCI presented no danger to the safe shutdown of the reactor since other engineered safeguard systems were available at this time. HFCI did operate following the isolation end met all SI and STI criteria. An isolation during auto initiation of HPCI would remove the system from service at a time it might be badly needed. .

Corrective Action Snubbers were added to the instru=ent lines and 3-second time delay relays were added to each logie channel to prevent these spurious flow spikes from causing an isolation during a cold turbine start.

- Failure Data

. - This is similar to a prob 1cm experienced on unit 1 and reported in BFAO-7h35W.

The same modifications discussed above were made on unit 1 at that time.

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