ML17352A843

LER 94-005-00:on 940924,Unit 4 Manually Tripped.Caused by Manual Actuation.Light Bulb & Socket replaced.W/941020 Ltr

ML17352A843
Person / Time
Site:	Turkey Point
Issue date:	10/20/1994
From:	Knorr J, Plunkett T FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-94-252, LER-94-005-02, LER-94-5-2, NUDOCS 9411010225
Download: ML17352A843 (10)

Text

I a.IOa.XWV tACCELERATED RIDS PROCI'.SSIiG)

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION. NBR:9411010225 DOC.DATE: 94/10/20 FACIL:50-251 Turkey Point Plant, Unit 4, Florida Power and Light NOTARIZED: NO C

DOCKET 05000251 I

,AUTH.NAME 'UTHOR AFFILIATION KNORR,J.E. Florida -Power & Light Co.

PLUNKETT,T.F. Florida Power & Li.ght Co.

RECIP.NAME RECIPIENT AFFILIATION

~

R

SUBJECT:

LER 94-005-00:on 940924,.Unit 4 manually tripped. Caused by manual actuation. Light bulb & socket replaced.W/941020 ltr.

DISTRIBUTION CODE'E22T COPIES RECEIVED'LTR TITLE: 50.73/50.9 Licensee Event Report (LER), ZncidenWRpt, et L ENCL U SIZE 0 NOTES RECIPIENT COPIES RECIPIENT COPIES ZD CODE/NAME LTTR ENCL ZD CODE/NAME LTTR ENCL PD2-2 PD 1 1 CROTEAU,R 1 1 INTERNAL: AEOD/ROAB/DS~ 2 2 AEOD/SPD/RRAB 1 1

~'~CEITER~O'2 1 1 NRR/DE/EELB 1 1 NRR/DE/EMEB 1 1 NRR/DORS/OEAB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HZCB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRSS/PRPB 2 2 NRR/DSSA/S PLB 1 1 NRR/DSSA/SRXB 1 1 NRR/PMAS/IRCB-E 1 1 RES/DSIR/EIB 1 1 RGN2 FILE 01 1 1 EXTERNAL: L ST LOBBY WARD 1 1 LITCO BRYCE,J H 2 2 D

NOAC MURPHY,G.A 1 1 NOAC POORE,W. 1 1 NRC PDR 1 1 ~

NUDOCS FULL TXT 1 1 C

U N

EMOTE TO ALL "RIDS RECIPIENTS:

i P LE:KSE HEI.P I 'S TO RF Dl:CE iVKSTE! COiTA(:T'I I IE DOC I.'ifI'. I: CONTROL DESk. ROOXf Pf-37 (EXT. 304- OS9 ) TO I'.LIXIINATE5'Ol'R iAXIL'ROXI DIS'I'RiffI."I'IOi LIS'I'S FOR D()CI') fl i'I'S Y()I ')Oi "II I:.I)!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 26 ENCL 26

Cl

'f

OCT 20 tgg~

L-94-252 10 CFR 50.73 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Gentlemen:

Re: Turkey Point Unit 4 Docket No. 50-251 Reportable Event: 94-005-00 Manual R a t r Tri The attached Licensee Event Report, 251/94-005-00, is being provided in accordance with 10 CFR 50.73(a) (2)(iv) .'f there are any questions, please contact us.

Very truly yours,

~

// Plunkett T. F..

/

Vice President Turkey Point Plant JEK enclosure cc: Stewart D. Ebneter, Regional Administrator, Region II,,

USNRC Thomas P Johnsonr Senior Resident Inspectorr USNRCI Turkey Point Plant 941lplp22g DR ADOCK 941p2p.

S K Pgppp2~

PDR an FPL Group company

~ I 0 LICENSEE EVENT REPORT (LER)

DOCKET NUMBER (2) PACC (3)

FACI(.ITY NANX ('1)

TURKEY POINT 'UNIT 4 05000251 oF 3 TITLE (4)

MANUAL REACTOR 'TRIP DUE TO PARTIAL LOSS OF ROD POSITION INDICATOR EVENT DATE (5) LCR NUMBCR(6) RPT DATE (7) OTHER FACILITICS INV (8)

MON 'AY YR SEQ 6 R( MON DAY FACILITY NAMES DOCKET I (S) 09 005 00 10 20 OPERATINO MODE (9)

POWER LEVEL (10) 10 CFR 50.73 a 2 iv 0%

LICENSEE CONTACT FOR THIS LER (12)

TCLCPHONC NUMBER J. E. Knorr, Regulation and Compliance Engineer 305-246-6757 COMPLCTC ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSC SYSTEM COMPONCNT MANUFACTURER NPRDST CAUSE SYSTEM MANUFACTURER NPRDS?

COMPONENT AC G272 NO SUPPLEMENTAL REPORT EXPECTED (14) NO YB$ 0 EXPECTED SUBMISSION MONTH DAY YEAR DATE (15)

'(ll yes, complete EXPECTED SUBMISSION DATE)

ABSTRACT (16)

On September 24, 1994, Unit 4 was manually tripped because of the partial loss of rod position indication. Unit 4 was in Mode 3 in the process of a reactor startup with one shutdown bank fully withdrawn,and one shutdown bank and all control banks fully inserted. An operator noted that a position indicating light bulb for one rod in the fully inserted shutdown bank was not illuminated. The operator touched the light to check burned out and noted a flash. After the flash, the indicated position on if the light was the analog rod position indicating system for the withdrawn bank dropped to about 60% full scale. After the drop in rod position indication, a manual reactor trip was initiated. All systems responded as expected to the manual reactor trip.

LICENSEETENT REPORT (LER) TEXT +4TXNUATXON FACILITY NAME DOCKET NUMBER LER NUMBER PAGE NO.

TURKEY POINT UNIT 4 05000251 94-005-00 02 OF 03 Z. DESCRZPTZON OF THE EVENT On September,24, 1994, Unit 4 was manually tripped because of a partial loss of rod position indication [AC:ZI]. Unit 4 was in Mode 3 and in,the process of a reactor start'up. Shutdown bank A [AC:ROD] was fully withdrawn at 228 steps. All other shutdown banks and control banks were fully inserted. An operator was sent to a display panel [IG:PL] located on the back of the Unit 4 control boards in the control room to check. on the condition of status lights. The rod position lights [AC:ZI] on the panel, for all rods not withdrawn (i. e., all rods except shutdown bank A), should have been in the

'lights on.'ondition. In this case, light number 4 in shutdown bank B, which should have been on, was not lit. The operator touched the light to ascertain whether the light bulb was burned out. When the light was touched, a flash occurred. At that time, the rod position indication for shutdown bank A dropped from 228 steps to an indicated 135 steps. However, shutdown bank A rods did not drop into the core until the manual reactor trip.

The decision was made to manually trip the plant, since the indicated position and demand position for shutdown bank A were far apart. All systems responded as expected to the manual reactor trip.

The NRCOC was notified at 0736 on September 24, 1994. This event is being reported in accordance with 10 CFR 50.73(a)(iv), as a manual actuation of the reactor protection system.

ZZ. CAUSE OF THE EVENT The immediate cause of,the trip was a manual actuation. The manual actuation was selected because of the mismatch between the indicated ~

position of shutdown bank A and the position indicated by the analog rod position indicating sy'tem.

The mismatch was caused by the following chain of events. When the operator touched the light bulb on the number 4 control board status light, the remaining short filament on the burned out bulb relanded inside the bulb and caused a higher current than usual. The fast .acting breaker (4 20 on panel 4P07) for the rod deviation cabinet opened due to the higher current. This breaker provides power to the rod deviation cabinet. Upon the opening of the breaker, the impedance in the common circuit between the rod deviation cabinet and the rod position indication circuit decreased causing an approximate 60% of full scale reading on. the analog rod position indication meter for shutdown bank A. See figure 1 on page 3.

ZZZ. ANALYSIS OF THE EVENT At the time of the manual reactor trip, shutdown bank A rods were the only rods withdrawn. The reactor was in Mode 3. All rods returned to the bottom of the core upon the demand of the manual trip. No other engineered safety systems or reactor protection systems actuated during or after the trip.

Therefore the health and safety of the public were not affected.

S LICENSEE ENT REPORT, (LER) TEXT (ITINUATION FACILITY NAME DOCKET NUMBER LER NUMBER PAGE. NO.

TURKEY POINT UNIT 4 05000251 94-005-00 03 OF 03 XV. 'CORRECTIVE ACTIONS

1. The light bulb and socket were replaced.

2. The cause of the change in .the analog rod position indication was verified'y test.

V. ADDITIONAL XNFORMATZON EIIS Codes-are shown in the format [EIIS SYSTEM: IEEE component function identifier, second component function identifier (if appropriate)].

Control, Board IlndIcation

%No'cI,,":;.:;.:Pos':; f.t':;.i;,'.'op@";;,',::~

II,,nd::1':::iat'":f::.os,:,:::,';,,'".::,,i'"';.,';

Rod Off Top Indicator Lamp v+vh+hv vhXhv+vhX .iv $%vggghwAvlPP

(,.:':Rod':"'::;'.0'ev',:I:at~i o"n)

) (10:amp)

Breaker 20 Fast Act I ng WP07 Figure 1.

~I