05000302/LER-1979-026-03, /03L-0 on 790318:during Reactor Startup,Discovered Absolute Position Indication for Rod 8 Was Inoperable.Caused by Sticking Reed Switch.Variable Ac Frequency,Applied to Reed Switch Circuit,Eliminated Sticking

/03L-0 on 790318:during Reactor Startup,Discovered Absolute Position Indication for Rod 8 Was Inoperable.Caused by Sticking Reed Switch.Variable Ac Frequency,Applied to Reed Switch Circuit,Eliminated Sticking

ML19274E685
Person / Time
Site:	Crystal River
Issue date:	04/05/1979
From:	Cooper J FLORIDA POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19274E683	List: 05000302/LER-1979-026, Forwards LER 79-026/03L-0 05000302/LER-1979-026-03, /03L-0 on 790318:during Reactor Startup,Discovered Absolute Position Indication for Rod 8 Was Inoperable.Caused by Sticking Reed Switch.Variable Ac Frequency,Applied to Reed Switch Circuit,Eliminated Sticking
References
LER-79-026-03L, LER-79-26-3L, NUDOCS 7904170171
Download: ML19274E685 (2)

LER-1979-026, /03L-0 on 790318:during Reactor Startup,Discovered Absolute Position Indication for Rod 8 Was Inoperable.Caused by Sticking Reed Switch.Variable Ac Frequency,Applied to Reed Switch Circuit,Eliminated Sticking

Event date:
Report date:
3021979026R03 - NRC Website

text

e t

r NRCPORM045 U. 5. NUCLEAR REGULAfoRY COA' ',55tCN t.tCENSEE EVENT REPORT EXHISIT A l

l, l l t } l l@

(PLEASE PRINT CR TYPE ALL REQUIRED INPORMATICM l

CcNTRot sLcC(

0 jg 4 ; 1l 1 l1 l 1 [g,_e-l _ul g l F ; LJ Q R\\ PI 3 lg-l 0101-t 01 0l 0 1 0j0l-l0 i o

i a

2.

u u ss. rv..

u r

, e vas...cco, i.

va ss. ~o..

C0YT

,To"' &@l 01 5l0I -to ; 3 o i 2 gj 0 ; 3 1l8l 7l9 g l0; 4i01 51 7l 9 l@

i o

i c

u ooc. 1 % e...

.., r c.r.

1.

...c ro.,i u

EVENT QESCRIPTLCN AND #RC9ASLE COreSECuENCES h oi: I At 1921, durine a reactor startun. It was discovered that the absolute o:2 t position indication for rnd 8 n rnim 6 u,n innnor,ble This crn,rna

,n event contrary to Technical Specification 3.1.3.3.

Entered action statementg.

"a".

No effect upon public health and safety. Rod position was verified y

,,, 9 through relative rod position indication. Operability was restored in one I

ae, l hour following maintenance.

This is the seventh occurrence reported.

I a,4 i Peference LER's (77-71, 112, 125) and 08-49, 62. 68).

80 3 9 CC 8 5

r.

O E COA 8PQN E N, 0008

$b.COCf 0 g I I t 0 l@ [,x_J@ LJJ @ l T I NI S I T I RlII l@ l,,,IJ@ (.JJ @

oi4 u

o i.

i, a

CCOUsagNc3 pgpcgr 84 4 T'0"8 13 Cu t.NTI.L Eac r No.

Coog tvet ga E

evt%rvt..

@,.(eg. ao l7 19 l

[-_j l o f 216 l y

l 013 i LL_j l--j [0]

_a, u

u z.

u a

a u

v u

• 2%'

',7.%n',e':~a;',

2".*EN,.

LXJ@L.Z.J@ 1Z'@

EJO I0Iof0@1 W3: 'lew o'::Wr

- au.,

4 L.sJJ@ l Ni@

W@

lD11l5iOf@

u s

u v

.a

.a n

u cAusE oEsCRieTioN ANo CoRREcnvE Acricss @

,,. [ The cause of this event can be attributed to a sticking reed switch. The

application of a variable AC frequency to the reed switch circuit eliminatest yl the stickine reed switch and restores enernbili m No N " h e v-cor e -ive f

g action required.

1 f

80 8 9 om.,r m @ s',ns:

.m...v :,,c..,, @

,=

(,C_J@ l O f 0 10 J@l NA l d @l Operator observation l

,19

• !r. sir, c:Dist

.v2usr a..: mirv @ I tec r.3 e.. a u, @

uj J L7J ($...au.l.3J@l

..u uio n

I u

i

..soss't...e,s " o

=u...r.2, @ NA rm'l P 1010 l@LZj@l l

',,,.ssd'.,,.'!.isein....,es@

,o I 01010 l@l NA fnYridfnl SIii'N.0IlIMlh l

'.':.Ac,:.4.c'i..ciur, (f @WMn @UuuWJuu\\Rni

=>

2.n...,o NA l

L, Zj@l i

a 9,, g 15 4. '. Os

lol lyQa l m

n i

ll isiili! il'l e,

,a

.a J. Cooper, Jr.

(904) 79 sy-6486 u..E

,,.E.2R,,

,,,, c s.,

M(SEE ATTACHED SUFPLE.MENTARY INFORPEIGN 7 9 0417 o / ~7/

SUPPLEMENTARY INFORMATION Report No.:

50-302/79-026/03L-0 Facility:

Crystal River Unit #3 Report Date:

5 April 1979 Occurrence Date:

18 March 1979 Identification of Occurrence:

Absolute rod position indication inoperable contrary to Technical Specification 3.1.3.3.

Conditions Prior to Occurrence:

Mode 2 operation (reactor critical)

Description of Occurrence:

At 1921, during a reactor startup, following criticality, absolute rod position indication for rod 8, group 6, tas inoperable. Entered action statement "a".

Reactor maintained in a stable condition. Verified nuclear overpower trip set-point at 5%.

Verified rod 8, group 6 position through relative rod position indication.

Operability was restored at 2020 following maintenance.

Designation of Apparent Cause:

The cause of this event can be attributed to a stuck reed switch. Magnetization, eminating from spurious magnetic fields generated during control rod operation,causes the reed switch to stick.

Analysis of Occurrence:

There was no hazard to the plant or general public as rod position was verified through relative rod position indication.

Corrective Action

The application of a variable AC frequency to the reed switch circuit eliminates the magnetic field.

This maintenance action restored operability. No further corrective action required.

Failure Data:

This is the seventh occurrence reported. Reference LER's (77-71, 112, 125) and (78-49, 62, 68).

/rc