ML18039A895

LER 99-008-00:on 990905,HPCI Was Inoperable Due to Failed Flow Controller.Caused by Premature Failure of Capacitor 2C3.Replaced Controller & HPCI Sys Was Run IAW Sys Operating Instructions

ML18039A895
Person / Time
Site:	Browns Ferry
Issue date:	10/08/1999
From:	Moody G TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML18039A894	List: ML18039A893 ML18039A895
References
LER-99-008, NUDOCS 9910200172
Download: ML18039A895 (10)

Text

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB No. 3150-0104 ExPLREs i.) '6-19961 oerdoraoo t Estimated burden per response to comply with thrs rnandatNY inronnauon codecten reouest: 50 hrs. RepNted lessons learned are KKKxporatcd into LICENSEE EVENT REPORT (LER) thrl tccnsing pfoccss ahd rcd bacK to IAdustry, FCNfald comments fcgafdlng burden estimate to the Records Management Bmnch (TW F33), U.S, Nudesr Regulatory Comnussan. Washingtorl DC 205554001. and to'the (See reverse for required number of papenaorx Reduction protect (31500104k OSce cr Management.and digits/characters for each block) Budget. washington. Oc 20503. It an information codectxm does Aot, res pray a currently vabd OM8 control number, the NRC may not oonduct or.

sponsof. SAd a pclsNl is Act fecpllfcd lo fcspoAd to, the lnrNmabon l codccterL FACIUTYNAME ii) 4 DOCKET NUMSER (21 PAOE 13I Browns Ferry Nuclear Plant Unit 2 05000260 1of5 TITLE 14)

High Pressure Coolant Injection (HPCII Inoperable due to a Failed Flow-Controller EVENT DATE (5) LER NUMBER (6) REPORT DATE l7) OTHER ACIL TIES I VOL D IBI MONTH DAY , YEAR, SEOUENTIAL REVISION lu DOCKET NVMSER NUMSER NUMSER NA 09 OPERATING 05 99 1999 008 00 10 08 THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF

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'lo CFR  %: (Chock ona or mora DOCKET NVMSER I MODE (9) 20.2201 l b) 20.2203(a) (2) l v) 50.73(a) (2)(i) (B) 50.73(s) (2) (viii)

POWER 20.2203(s) (1) 20.2203(s) (3) (i) 50.73(a)(2) (ii) 50.73(s) (2) (x)

LEVEL (10) 100 20.2203(s) (2)(i) 20.2203(a) (3) (ii) 50.73(s) (2) liii) 73.71 20.2203(a) (2)(ii) 20.2203(s) (4) 50.73(a) (2)(iv) OTHER 20.2203(a) (2) (iii) 50.36(c)(1) 50.73(s) (2)(v) SpecBY in Abstract below or In NRC Form 366A 20.2203(a)(2) (iv) 50.36(cn2) 50.73(s)(2) (vii)

UCENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER (lndude Area Codel Gerald F. Moody, 4censing Project Manager (256) 729-7534 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE TO CAUSE SYSTEM COMPONENT MANUFACTURER REPORTASLE NPRDS TO NPRDS BJ CAP GAO SUPPLEMENTAL REPORT EXPECTED l14) EXPECTED MONTH 0AY YEAR YES No SUBMISSION DATE l15)

(It Yas, compiato EXPECTED SUBMISSION DATE).

AssTRACT (Limit to 1400 spaces, i.a., approximately l5 single-spaced typewritten lines) (16)

On September 8, 1999, at approximately 0610 hours0.00706 days <br />0.169 hours <br />0.00101 weeks <br />2.32105e-4 months <br /> Central Daylight Time (CDT) during a routine control room board-walkdown, the Unit 2 Operator observed that the HPCI flow controller output signal indication was downscale. The HPCI system was immediately declared inoperable. The HPCI controller was replaced, HPCI operability testing was completed satisfactorily, and the system was returned to an operable status at approximately.1520 hours0.0176 days <br />0.422 hours <br />0.00251 weeks <br />5.7836e-4 months <br /> CDT on September 8, 1999. Upon investigation of data taken from the plant's Integrated Computer. System history, it was determined that the controller began experiencing an erratic signal at approximately 1248 hours0.0144 days <br />0.347 hours <br />0.00206 weeks <br />4.74864e-4 months <br /> CDT on September 5, 1999. At approximately 1320 hours0.0153 days <br />0.367 hours <br />0.00218 weeks <br />5.0226e-4 months <br /> CDT on September 5, 1999, the controller lost power. During this event, HPCI was inoperable for a period of approximately three days out of the fourteen days allowed by the Technical Specifications Limiting Condition, for Operation. During the period of time that HPCI was inoperable, all other required safety systems were operable and would have performed their design function if called upon. Accordingly, there was no significant reduction in the degree of protection provided to public health and safety.

This report is submitted pursuant to 10CFR50.73 (a)(2)(v) as a condition that alone could have prevented the fulfillment of the safety function of a structure or a system needed to mitigate the consequences of an accident.

't)qi0200i72 99i008 05000260 PDR ADQCK 8 PDR

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NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION I6.1998I LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITYNAME 1 DOCKET LER NUMBER 6 PAGE YEAR SEQUENTIAL REViSION NUMBER 2 of 5 Browns Ferry Nuclear Plant - Unit 2 . 05000260 1999 - 008 " 00 TEXT li/more space is required, use additional copies o1 NRC Form 366Ai I17)

I. PLANT CONDITIONS At the time of the discovery of this condition, Unit 2 was in Mode 1 at 100 percent power, approximately 3458 megawatts thermal. Unit 3 was in Mode 1 at 100 percent power, approximately 3456 megawatts thermal. Unit 1 was shutdown and defueled.

II. DESCRIPTION OF EVENT A. Event:

On September 8, 1999, at approximately 0610 hours0.00706 days <br />0.169 hours <br />0.00101 weeks <br />2.32105e-4 months <br /> Central Daylight Time (CDT) during a routine control room boardwalk down, the Unit 2 Operator observed that the High Pressure Coolant Injection (HPCI) [BJ) flow controller, 2-FIC-73-33, output signal indication was downscale. Upon discovery of the failed controller, HPCI was immediately declared inoperable. As required by Technical Specifications, Browns Ferry Unit 2 entered a fourteen day Limiting Condition for Operation (LCO) for an inoperable HPCI system. The HPCI controller was replaced,.HPCI operability testing was completed satisfactorily, and the system was returned to an operable status at approximately 1520 hours0.0176 days <br />0.422 hours <br />0.00251 weeks <br />5.7836e-4 months <br /> CDT on September 8, 1999.

A review of the plant's Integrated Computer System history showed that the controller began to experience an erratic signal at 1248 hours0.0144 days <br />0.347 hours <br />0.00206 weeks <br />4.74864e-4 months <br /> on September 5, 1999, and apparently failed at 1320 hours0.0153 days <br />0.367 hours <br />0.00218 weeks <br />5.0226e-4 months <br />.

This report is submitted pursuant to 10CFR50.73 (a)(2)(v) as a condition that alone could have prevented the fulfillment of the safety function of a structure or a system needed to mitigate the consequences of an accident.

B. Ino erable Structures Com onents orS stems that Contributed to the Event:

Capacitor 2C3 in the power supply internal to the HPCI flow controller.

C. Dates and A roximate Times of Ma or Occurrences:

September 5, 1999 1248 hours0.0144 days <br />0.347 hours <br />0.00206 weeks <br />4.74864e-4 months <br /> CDT- HPCI flow controller began to experience an erratic signal.

September 5, 1999 1320 hours0.0153 days <br />0.367 hours <br />0.00218 weeks <br />5.0226e-4 months <br /> CDT HPCI flow controller lost power.

'V September 8, 1999 0610 hours0.00706 days <br />0.169 hours <br />0.00101 weeks <br />2.32105e-4 months <br /> CDT During a routine control room board walkdown, an Operator observed the HPCI flow controller output signal indication was downscale. HPCI was declared inoperable and a fourteen day Technical Specifications LCO was entered.

September 8, 1999 0952 hours0.011 days <br />0.264 hours <br />0.00157 weeks <br />3.62236e-4 months <br /> CDT HPCI system flow controller was replaced.

NRc FDRM 366 {6-1998)

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NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION

' I6.1998)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME 1 DOCKET LER NUMBER 6 PAGE 3 YEAR SEOUENTIAL REVISION NUMBER 3 of 5 Browns Ferry Nuclear Plant - Unit 2 05000260 1999 008 - 00 TEXT llfmore spece is required, use addi rionel copies of ftfRC Form 366AI l ill C. DatesandA roximate Timesof Ma orOccurrences continued:

September 8, 1999 1520 hours0.0176 days <br />0.422 hours <br />0.00251 weeks <br />5.7836e-4 months <br /> CDT HPCI system operability testing was completed, the system was declared operable and the Technical Specifications LCO was exited.

D. Other S stems or Seconda Functions Affected:

None.

E. Method of Discove This condition was discovered during a routine waikdown of the Unit 2 control room panels.

F. 0 erator Actions None.

G. Safe S stem Res onses None.

,III. CAUSE OF THE EVENT A. Immediate Cause HPCI was declared inoperable due to a downscale indication on the system flow controller.

B. Root Cause The root cause of the failure was most likely premature failure of capacitor 2C3.

IV. ANALYSIS OF THE EVENT The HPCI flow controller, 2-FIC-73-33, is a GE model 540 series. On September 8, 1999, the malfunctioning controller was removed and examined in the shop. It has been concluded that the root cause of the failure was most likely the premature failure of capacitor 2C3. The capacitor in this circuit is a wet tantalum type capacitor which is an improved replacement for the aluminum electrolytic type which was originally. used in this application. The capacitor had been installed in this controller less than sixty days prior to its failure..lt had been replaced during a recent calibration of the controller.

V.- ASSESSMENT OF SAFETY CONSEQUENCES The HPCI system is designed to ensure that the reactor is adequately cooled to limit fuel cladding temperature in the event of a small pipe break in the nuclear system and a resulting loss of coolant which does not rapidly depressurize the reactor vessel. The HPCI system permits the nuclear plant to'be shut down, while maintaining sufficient reactor vessel water inventory until the reactor vessel is depressurized.

The HPCI s stem continues to o crate until the reactor vessel is below the ressure at which Low Pressure IRC FORM 366 l6 1998)

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NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (6- 'I 9 9 8 I LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION, FACILITY NAME 1 DOCKET LER NUMBER 6 PAGE 3 YEAR SEOUENTIAL REVISiON NUMBER 4 of 5 Browns Ferry Nuclear Plant - Unit 2 .05000260 1999 008 00 TEXT Ilfmore space is required, Ilse eddirionel copies of NRC Form 366Al (17)

Coolant Injection (LPCI) [BO] operation or Core Spray (CS) [BM] operation maintains core cooling. In the event HPCI is not available or not sufficient to maintain reactor water level, the Automatic Depressurization system (ADS) [SB] functions to reduce reactor pressure so that flow from the LPCI and CS enters the reactor vessel in time'to cool the core and'limit fuel cladding temperature.

BFN Technical Specifications allow continued reactor operation for up to fourteen days if HPCI is inoperable,, provided the ADS, CS,, LPCI and Reactor Core Isolation Cooling (RCIC) [BN] systems are operable. RCIC provides an alternate supply of high 'pressure reactor coolant makeup while ADS would depressurize the reactor to allow CS and LPCI to provide adequate low pressure ECCS makeup to the reactor. The availability of these redundant and diversified systems provides adequate assurance of core cooling while the HPCI system is inoperable. During this event HPCI was inoperable approximately three days, two and one half hours out of the fourteen days allowed by the Technical Specifications LCO. These above required systems were operable and would have performed their design function if called upon.

Accordingly, there was no significant reduction in the degree of protection provided to public health and safety.

VI. CORRECTIVE ACTIONS A. Immediate Corrective Actions.

Troubleshooting was initiated. The HPCI system flow controller was found to have failed. The controller was replaced and the HPCI system was run in accordance with the system operating instructions to verify proper operation of the new controller. Upon successful completion of the system run, HPCI was declared operable.

B. Corrective Actions to Prevent Recurrence A review of datalfrom the plant Integrated Computer System revealed that the failure of this controller had gone undetected for 5 shifts. The following corrective actions are intended to address this issue.

Integrated Computer System'(ICS) [ID] data points which monitor this condition were added to the Unit 2 and Unit 3 Main Control Room alarm printer which is closely and frequently reviewed by Operations personnel. Additionally, training will be provided to Operations personnel to enhance their ability to more rapidly identify failures of this nature.

'II.

ADDITIONALINFORMATION A. Failed Com onents The wet tantalum type capacitor 2C3 internal to the power supply in the HPCI flow controller (GE Model 540).

'VAdoes not consider these corrective actions regulatory. commitments. The completion of these items will be tracked in TVA's Corrective Action Program.

CRC FORM 366 {6-1996)

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NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (6-1998(

LICENSEE EVENT REPORT (L'ER)

TEXT CONTINUATION FACILITYNAME 1 DOCKET LER NUMBER (6 PAGE SI YEAR SEQUENTIAL REVISION NUMBER 5 of 5 Browns Ferry Nuclear'Plant - Unit'2 .05000260 1999 '008 00 TEXT llfmore space is required, use'addirional copies, of NRC Form 366Al (17)

B. Previous L'ERs on Similar Events A review of previous events for the past three years revealed no LERs that were the result of failed flow controllers.

C. Additional Information None.

D. Safe S stem Functional Failure:

This'event resulted in a safety system functional failure in accordance with draft NEI 99-02 Revision C.

VIII. COMMITMENTS None.

NRc FoRM 366 (6-1998(

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