ML20044E717

LER 93-007-00:on 930425,manual Reactor Trip During Low Power Physics Testing Due to Negative Reactivity.Caused by Personnel Error.Reactor Engineer Counseled Re Importance of Attention to detail.W/930518 Ltr

ML20044E717
Person / Time
Site:	Vogtle
Issue date:	05/18/1993
From:	Mccoy C, Sheibani M GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LCV-0010, LCV-10, LER-93-007, LER-93-7, NUDOCS 9305250353
Download: ML20044E717 (4)

Text

{{#Wiki_filter:, Georg:a Peter Company 4 .s0 inse rss. CmW Fyt way Pos' 05ce Box '295 E c"'utig%" AidbyTia 3V.31 T etr inonf 225 077 7122 m c.K.uccoy Georgia Power

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May 18, 1993 m u w-r?eic e weev LCV-0010 Docket No. 50-424 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555 Gentlemen: VOGTLE ELECTRIC GENERATING PLANT LICENSEE EVENT REPORT MANUAL REACTOR TRIP DURING LOW POWER PHYSICS TESTING DUE TO NEGATIVE REACTIVITY In accordance with the requirements of 10 CFR 50.73, Georgia Power Company submits the enclosed report related to an event which occurred on April 25,1993. Sincerely, 0[41f ' C. K. McCoy CKM/NJS

Enclosure:

LER 50-424/1993-007 xc: Georgia Power Company Mr. W. B. Shipman - Mr. M. Sheibani NORMS U. S. Nucitar Reculamtv Commission Mr. S. D. Ebneter, Regional Administrator Mr. D. S. Hood, Licensing Project Manager, NRR Mr. B. R. Bonser, Senior Resident Inspector, Vogtle

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9305250353 930518

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y p yx, u.s. mLAR xtua.Am ww a>>wn A m g g a g m ias LICENSEE EVENT REPORT (LER) , l iACiciiY NAHt. li) UviAt6 nuMbik (2) F I E-- iil  ! V0GTIE ELECTRIC CENERATI!C PIMI - INIT 1 05000424 1 l0rl3 i IliLE (4)  ; MANUAL REACIIR IRIP DURING IN IWER Im' SICS TESTDC DUE 10 NIrATIVE REACTIVITY i i EWEhl DATE (5) LER HUMBER (6) REP 0kl DATL (7) DINER FAtlLillE5 IhWDLhED (6) f kDhlti LAT TEAR YEAk 5EQ hum kEW MChin, DAt YEAR FACILilt hAME5 DOCKET h'UMBEk(i) 05000 l t 04 25 93 93 007 00 05 18 93 05000  ! i InI5 El 15 50>M1 m M Ahl 10 inE W W Eh15 W 10 U R (H) [ CPERAT]hG MDDE (9) 2 20.402(b) 20.405(c) ^ 50.73(a)(2)(iv) 73.71(b) j POUER - 20.405(a)(1)(1) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c)- i LEVEL 0 20.405(a)(1)(li) 50.36(c)(2) 50.73(a)(2)(v11) OTHER (Specify in [ 20,405(a)(1)(111) 50.73(a)(2)(1) 50.73(a)(2)(vi11)(A) Abstract below) l 20.405(a)(1)(iv) - 50.73(a)(2)(ii) - 50.73(a)(2)(viii)(B)  ! 20.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x) , LILEh5EE C0h1ACI FOR INI5 LER (12) { hANE TELEPnchE hvM6ER j LREA LODE  : 1 MEHDI SHEIBANI. NUCLEAR SAFETY AND COMPLIANCE 706 826-3209 j 4 00MFLLIE Chi LlhL FOR EACn FAILLEE DE5CklbED lh Ir115 REP 0k1 (13) R P0RT R PORT CAUSE LYSTEN COMPONENT jgg FAhhurAC- h pOS CAUSE SYSTEN' COMPONENT NAhkUFAC-TU ER i t i 5bFFLEMEhThL REFORT EAFECTED (14L M0hln DAY VEAR EXPECTED ] SUBMIS$j0N

         ] YES(If yes, complete EXPECTED SUBMIS$10N DATE)                                               DATE (1s)                               (

)  % ho RFfRACT (16)  ! 'l  ! ] I y On April 25, 1993, low power physics testing was being conducted following unit } . refueling. Personnel were interchanging control rod banks as a part of rod  ! l worth testing, alternately stepping in control bank D and s::epping out shutdown  ! j bank B. When reactivity changes reached 20 percent millirho (pcm) during the j process, the reactor engineer (RE) would advise the reactor operator (RO) to  ; stop the insertion or withdrawal in progress. At 0835 EDT, while stepping in i control bank D, the RE observed reactivity go offscale low. Control rod i movement was discontinued as personnel investigated the reason for the , reactivity excursion. Unable to determine the cause'for a larger than normal  ; negative reactivity insertion and suspecting a dropped rod,.a manual reactor trip was initiated at 0859 EDT, as required by procedure, for excessive negative 1 4 reactivity. ~ The cause of this event was a personnel error on the part of the RE in not  ! . advising the RO to stop rod movement in a timely manner. There was no dropped

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rod, and the test was subsequently completed satisfactorily. The RE was counseled regarding the importance of close attention to reactivity during the  ; rod worth test. This incident will be discussed in future reactor engineering i training. l 1

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(fr83) g E WIRES: 4/30/92 TEXT CONTINUATION FACIL1-17 NAME (1) DOCKET NUMBER (2) LER NUMBER (5) PAGE (3) TEAR SEQ hum REW f V0GTLE EIICIRIC CINEPATING PLWT - UNIT 1 05000424 93 007 00 2 ,or 3 . IEM A. REQUIREMENT FOR REPORT This report is required per 10 CFR 50.73 (a)(2)(iv) because an unplanned reactor protection system (RPS) actuation occurred. { r B. UNIT STATUS AT TIME OF EVENT [ At the time of this event, Unit 1 was operating in Mods 2 (startup) at 0 l percent of rated thermal power with reactor power at 5 x 10 E-8 amps. Other , than that described herein, there was no inoperable equipment which contributed to the occurrence of this event. C. DESCRIPTION OF EVENT On April 25, 1993, low power physics testing was being conducted following unit refueling per Procedure 88002-C, " Reload Low Power Physics Testing." Personnel were interchanging control rod banks as a part of rod worth testing, alternately stepping in control bank D and stepping out shutdown i bank B. A reactor engineer (RE) was advising the reactor operator (RO) when to start and stop the stepping process, based on a chart recorder which showed changes in reactor core reactivity. When reactivity changes reached 20 percent millirho (pcm) during the process, the RE would advise the the RO i to stop the insertion or withdrawal in progress. At 0835 EDT, while stepping l in control bank D, the RE observed the recorder go offscale low and the RO l observed an indication on a computer screen of continuously decreasing flux t and negative startup rate. Control rod movement was discontinued as personnel investigated the reason for the larger than expected negative reactivity. Unable to determine the cause and suspecting a dropped rod, a i manual reactor trip was initiated as required for excessive negative l_ reactivity per Procedure 18003-C, " Rod Control System Malfunction." The reactor shutdown was completed at 0859 EDT, and the unit entered Mode 3 (hot j standby).  ; i D. CAUSE OF EVENT l The cause of this event was a cognitive personnel error on the part of the RE 'l in that he was momentarily distracted while monitoring reactivity changes  ! during_ rod worth testing. There was no dropped or decoupled rod. There were -{ no unusual characteristics of the work location that contributed to the f occurrence of this event by the Georgia Power Company RE involved. [ i Contributing to the occurrence of this event was the failure to anticipate l higher differential rod worth due to the shifting flux pattern during rod  ! worth measurements. During the rod worth tests, both control bank D and j shutdown bank B were inserted in the lower half of the core, distributing- .j more flux to the lower core regions and increasing the differentia 1' rod worth- ' of the bank being inserted. The test was subsequently completed satisfactorily, using smaller increments of rod insertion steps for control j bank D.  !

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.' grm setA u.s. matAn atwivu weunia Armgggw-cios LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACIll'IY hAME (1) DOCKET WUMBER (2) LER NUMBER (5) PAGE (3) YEAR 5EQ hbM REV VOGTLE EIICIRIC GENERATING PIANT - UNIT 1 05000424 93 007 00 3 0F 3 10.1 E. ANA1.YSIS OF EVENT Computer analysis and calculations based on available instrument readings showed that the negative reactivity value reached was approximately 132 - 142 pcm. This insertion of negative reactivity caused the reactor to go  ; subcritical. Furthermore, since the reactivity change was negative and because the reactor was below the point of adding heat, there were no adverse t neutron flux variations and no reactor coolant system thermal or pressure transients. Based on these considerations, there was no adverse effect on  ;

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plant safety or on the nealth and safety of the public as a result of this event. , F. CORRECTIVE ACTIONS t

1. The test was subsequently preformed successfully utilizing smaller l

increments of rod insertion steps for control bank D.

2. The RE was counseled regarding the importance of attention to detail, and  ;

this incident will be discussed in future reactor engineering training.  ; G. ADDITIONAL INFORMATION

1. Failed Components None

2. Previous Similar Events l

None j l

3. Energy Industry Identification System Code .

Control Rod Drive System - AA Reactor Coolant System - AB i l l l l 1 1}}