05000317/LER-1981-066-03, /03L-0:on 810826,while Troubleshooting Control Element Drive Sys,Control Element Assembly 1 Dropped Into Core.Caused by Failure of Control Panel Off Switch.Switch Replaced

/03L-0:on 810826,while Troubleshooting Control Element Drive Sys,Control Element Assembly 1 Dropped Into Core.Caused by Failure of Control Panel Off Switch.Switch Replaced

ML20010J503
Person / Time
Site:	Calvert Cliffs
Issue date:	09/25/1981
From:	Pavis G, Rizzo P BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20010J501	List: 05000317/LER-1981-066, Forwards LER 81-066/03L-0 05000317/LER-1981-066-03, /03L-0:on 810826,while Troubleshooting Control Element Drive Sys,Control Element Assembly 1 Dropped Into Core.Caused by Failure of Control Panel Off Switch.Switch Replaced
References
LER-81-066-03L, LER-81-66-3L, NUDOCS 8110050167
Download: ML20010J503 (2)

LER-1981-066, /03L-0:on 810826,while Troubleshooting Control Element Drive Sys,Control Element Assembly 1 Dropped Into Core.Caused by Failure of Control Panel Off Switch.Switch Replaced

Event date:
Report date:
3171981066R03 - NRC Website

text

MRC F ORM 366 U. S. NUCLEAR REGULATORY COMMISSIOM (7 77)

LICENSEE EVENT REPORT CONT ROL Bt OCK: l l

l l

l l

l (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

I h

lo lil lM l D l C lC lN l1 lQ 0 l0 l-l0 l0 l0 l0 l0 l-l0 l0 l@l 4l llilil1l@l l

l@

7 8

')

LICENSEE CODE 14 15 LICENSE Nuveta 25 it>

L;JENSE TY PE 30

$1 L A T bH CON'T lol11 N l L l@l 0 l 5 l 0 l 0 l 0 l 3 l 1 l 7 l@l 0 l 8 l 2 l61811 l@l019 l 2 l 5 l 8 l1 l@

1 8

60 61 DOCKET NUVBEP 6H 63 EVENT DATE 14 15 RE PORT DAT E P0 EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h l 012 l [ At 2149, while troubleshooting the Control Element Drive System (CEDS).

1 [Ol3ll Control Element Assembly (CEA) #1 dropped into the core.

In accordance 1

1o l4 l l with T.S. 3.1.3.1 power was decreased to 70%. CEA #1 was withdrawn and l

10 l s i l 1eveled with its group at 2253. All other CEAs remained fully withdrawn l

l0 lc 11 during the event. This is not a repetitive event.

l l0l7]l l

I l 018 ; I 80 1

8 9 SYSTEM C AUSE

CAUSE

COP /P-VALVE CODE CODE SU8 CODE COYPONENT CODE SUBCCDE SUBCODE lajal l R 18 l@ U@ l8 l@ I r l N l S l T l R l U l@ l_S_j@ l Z.J @

7 8

9 10 11 12 13 P;

19 to SE QUE NTI A L OCCt % HE NCE HEPOHT HEVISION

_ EVENT YE AR REPOR T NO.

CODE TYPE NO.

@,"i [ q p g l 8] 1l

[--J l0l6l6]

y l0l3l l Ll

[-.--j l0l EJ,gj

_. 21 22 23 24 16 21 28 29 30 31 32 T KE ACTO ON PL AP T T

HOURS SUB ITT D F H SUB.

SUPP LI E MAN FACTURER l.A_jhl Zl@

l Z l@

l 0l 0l 0l 0l lYl@

W@

lNl@

lEl1l4l6l@

33 J, 4 Jti 3/

40 43 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h i o l During troubleshooting of an unrelated problem a logic module was in-l i i i serted.

Failure of the CEDs Control Panel "0FF" switch (Electro-1 l, i,1 l Mechanics Part No. 2380-19) prevented deenergizing the panel to stop the 1

[i13l l initiation of courious signals. The switch was replaced with a spare.

I gl No preventive action is deemed necessary.

l 80 I

1 8 9 ST S

i POWER OTHER ST A TUS D,5 0 i DISCOVEHY des iP TION NA l

lAl@l Operator Observation l

l i l ', l W@ l 0 l 9 l 0 l@l

'2 "a,vliv CO%N T RELE ASED OF RE t.E ASE AYOUN OF ACTIVITY LOC ATION OF RELE ASE NA l

l NA l

[TTo l W @ W@l 7

8 9 10 11 44 45 80 PE H50NNE L E XPOSUHLS NuYHE R TYPE DESCRIPTION -

1 LLid 1010 l0 l@lZ l@l NA PmONJ,wUAs oEscH PiiON@

NeverH

[~_O 101010 l@l NA l

80 H 9 11 17 L 055 Of OH DAY AGE TO F ACILI T Y r

TYPE DLSCHIPTIO%

l Z l@l NA l

i o

. 80 r

n 9 tu PUH t ICI T Y N HC USE ON L Y NA l

lllllllllllll%

[N jh] DESCRIPTION 19 men 2

2 o

• 4 8110050167 810925 PDR ADOCK 05000317 G. S. Pavis/P.G. Rizzo M-M-GSM 2

g pggyg S

PDR

o 9

LER NO.

81-66/3L DOCKET No.

50-317 LICENSE NO.

DPR 53 EVENT DATE 08-26-81 REPORT DATE 09-25-81 ATTACHMENT CAUSE DESCRIPTION AND CORPECTIVE ACTIONS Prior to the event, operating personnel had identified a perceived CEA Group 5 control problem and a second failure of the CEDS Control Panel power "0FF" switch. The technician who responded to the request for maintenance was given permission to troubleshoot the control prob-lem first due to its higher priority.

Normally, the Control Panel power is switched off before work proceeds at the CEDS Logic Panel. This action is taken to preclude spurious logic outputs from occurring. The group control problem was assessed as having little chance of causing spurious signals to be generated.

During troubleshooting, several Group 5 programmer module withdrawals and insertions were accomplished without incident. The technician inserted Group 5 programmer a last time and plant operators reported the dropped CEA.

Since CEA No. 1 Individual Control Module is physically adjacent to the programmer which was being inserted, it is surmised that bumping caused intermittent electrical connection and a resultant spurious signal from the logic cabinet. The module was securely mounted and its connector was tight. Further inspection of the connector revealed no contact problem.

The Control Panel power "0FF" switch (Electro-Mechanics Part No.

2380-19), a push-button style, was found failed mechanically and was replaced with a spare.

No preventive action is deemed necessary because of the unique double-failure circumstances and the fact that the panel power switch has not exhibited a high failure rate.

I 1

l