ML19308D367

RO-77-47:on 770513,regulating Rods,Group 7,out of Specified Limits.Caused by Gate Drive Relay Design Error.Relay Modified

ML19308D367
Person / Time
Site:	Crystal River
Issue date:	06/03/1977
From:	Stewart W FLORIDA POWER CORP.
To:
Shared Package
ML19308D360	List: ML19308D359 ML19308D367
References
NUDOCS 8002270821
Download: ML19308D367 (2)

Text

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O SUPPLEMENTARY INFORMATION

1. Report No: 50-302/77-47

, 2. Facility: Crystal River Unit #3

3. Report Date: 3 June 1977 .

4 Occurrence Date: 5-13-77

5. Identification of occurrence:

Regulating rods Group 7 out of specified limits conertry to Techni- -

cal Specification 3.1.3.6.

6. Conditions Prior to Occurrence:

Normal Mode 1 steady state operation. i

7. Description of occurrence:

At 1520, regulating rods Group 7 dropped into the core causing the overlap between Groups 6 and 7 to be less than the required overlap of 25%. Power was reduced and Group 7 was relatched. Group 7 was withdrawn and the overlap was manually adjusted to the specified limits in 12 minutes.

8. Designation of Accarent Cause of Occurrence:

Information from the manuf acturer. indicates that the gate drive relay, as designed, may be the cause of these trips.

9. Analysis of Occurrence:

At no time during this occurrence was the safety of the g.)neral public affected.

10. Corrective Action:

Plant Modification 77-5-i8 modifying the gate drive relay, as recom-mended by the manufacturer, was installed and checked out 22 May 1977 and should prevent ratchet trip of the Control Rods.

11. Failure Data:

, This _ was the third occurrence of - this type (Refer. L.ER 77-43) .

N 8002270 g *

-y w y , , - - _

,_y- - --m- -- 4

UCENSEE EVENT HEPL T l

eh.m CONTROL OLOCK:l l l l l l l (PLEASE Pn!NT ALL REQUtntD INFCAT.1M;O?J)

' a (V) "'"'!

Ao ' LetNSE ~uM.E. -

. 'O!' "'

7,'PE (7 l09Fl Ll Cl Rl P l 314l l0l0l-l0l0l0l0l0l-l0l0l l 4 l 1 l1 l1 l1 l l0l3l 15 25 26 30 31 32 CAttCony "'rr$ Oo$"CE coCnET NuwoEm EVENT cATE REPOAr cAtt EjCON T [ -l -l 'M lt i 10 i s 10 l-In 131012 l 10 i s l i l ,17 17 l 10 16 10 13 17 17 I 7 0 b7 bu 59 SO bl 68 09 74 73 uu EVLNT OCGCfl:PTION o l In Mode 1 operation, Control Rod Group 7 dropp' e d into the core causing the overlap l 7 09 tiO

@l 7 a0 between Groups 6 and 7 to be less than 2s% contrary to Technical Specification 3.1.3.6. l

~

eu 0 l Redundancy N/A. Third occurrence of this tvoe. Group 7 wAs retrieved and the overlao l 7 09 80

@l 7 u9 adiusted to within the specified limits in the recuired time frame.

e0 I

o l (LER 77-47) [

7 e9 mg ga SystEu CausE CoWuNtNT CoMPCNENr CODE CODE COMPONENT CCCE $uPP((A MANufACfufVA VoLArCN .

o 7 09 10

[Rl Bl { 11 l Cl Rl Dl Rl Vl El 12 17 lN l 43 lD l 1l 5 l 0l 44 47.

lNl 48 f, CAUCE DESCRIPTION p

@l 7 89 Probable cause was in design of the gate drive relav configuration. Relav configura-GO l

,[O[0] l tion modified per manufacturer's recommendation. j

/ 'l 9 60

\

N,/)g gl gg l*

FaC;ury METHoO oF Status  % power OTHER STATUS DISCOvEAv crSCOVERY DESCAIPTON 7 0 9 l El l1l0l0l l N/A l lAl l N/A l 10 12 13 44 45 46 80 ASrv Co4 TENT ACLEASEo AMOUNT QF ACTMTV LOCATCN OF AELEASE 3E l zl OF lzlr.ELEASE l N/A l l N/A l 7 8 9 10 11 44 45 00 PERSONNEL EXPOSunES

)

NUMBEA TYPE CESCRIPTCH '

7 89 M l0l0[0l 11 Wl 12 13 N/A GO l

RERSCNNEL INJunlEC Nuwatn DCSCHaPTON 3E l 01 ol 01 l N/A l 7 00 11 12 80 OFFSITE CONSEQUENCES DE l N/A l 7 OD 00 LOSS OR OAMAGE TO FACLITY TYPE CESCR:PTON DE LzJ l n/A -

1 1 7 00 10 LO I l PUBLICITY QlOD N/A j

OU '

! ADOITIONAL FACTOnS l See attached Supplementary Information. ,, l 7 0g i .a 8I 7 09 C

- __,1 un l

l MAML. 11. P . Stewart , ,_ h 'l{- / ,_, ,,_ niont__Q!1]) 866-4159