ML20087B650

Ro:On 710514,reactor Trip Breaker Failed to Open When Trip Signal Was Applied.Caused by Malfunction in Circuit Breaker Undervoltage Device.Affected Breaker Replaced

ML20087B650
Person / Time
Site:	Robinson
Issue date:	08/27/1971
From:	Utley E CAROLINA POWER & LIGHT CO.
To:	Morris P US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20087B648	List: ML20087B645 ML20087B650 ML20087B705
References
3908, NUDOCS 8403090312
Download: ML20087B650 (2)

Text

-

c..

o_

So-ad/

g.h=

Carolina Power & Light Company Raleigh, North Carolina 27602

'W f.

August 27, 1971

'f Q

%[vp,X'y.

a.

1,o _ g ", p)/

Dr. Petcr A. Morris

,Q

.~* N ';p 3 b(D /5Cph*h Division of Reactor Licensing U. S. Atomic Ene rgy Cocnission 3,

Washington, D. C.

20545 N 'Q i G

H.

B. ROBINSON STEAM EIECTRIC PLANT LWIT NO. 2 LICENSE DPR-23

Dear Dr. Morris:

On May 14,1971 one of the reactor trip breakers failed to open when a trip signal was applied. An investigation of the failure disclosed that a malfunction in the circuit breaker undervoltage trip device prevented the breaker from operating.

The faulty component was a Westinghouse Elec-tric Corporation, Style 23A9019G61, undervoltage trip device installed in a Westinghouse, type DB50, 1600 amp frame size, code A, circuit breaker.

The latch pin, shown on the enclosed drawing, broke causing the latch to bind and preventing the trip lever from operating.

The trip device in the affected breaker was replaced. Additionally, the latch pins in the other trip breakers were inspected for signs of brittle fracture or other indications of impending failure.

No additional abnormal conditions were detected.

It was concluded that the latch pin failure was a random event and that the design of the device was satisfactory for the intended service.

Is g g g gj,!

Yours very truly,

. __ / y y [ k x

b(

p E. E. Utley J

Manager

/

Generation & System Operations NBB:HE Enclosure cc:

Mr. G. P. Beatty Mr. N. B. Bessac Mr. C. D. Barham

&,um D s rt ne. /~ s t)c< Tim -

C' ~ d' TW

~

j)*rc uts'bn /M

[0 I" AS)

I ~

8403090312 711221 PDR ADOCK 05000261 1 4390

/[

G PDR COPY SENT REGION i

xm

q e

,~

p

.. ~. i.

• Q)

V P.c,. a

• j q-5.f}

u,x.xc.,,. c,.. :..

+ AO

,i i

1.H H d.b 4] i 1

u r,,c._.-_.n.,.1x Rtsli liver CROSS BAA i

(ATCH e

FRAW D

Ldek rh 6'df

-M T

!' b. f,

~

s.

, s. %,

Q&w':'cy. '..g

SCREW

• ,, Ql 9

,f

., i z

'l

,,3, y -

l 9

y

%.l

o c.rene_.2-ROD

~

~

w-ua sTAro=An fair /

Tai, coat sea;=c teven j

I.

.t i

. l.

t, h

a

~

.}.

1

.(

.C.t

-- y q

L-3908?

i t'

f Ar

• _'. ' ' Eff g}f,

'