ML19220B325
| ML19220B325 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/06/1974 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | John Miller METROPOLITAN EDISON CO. |
| Shared Package | |
| ML19220B326 | List: |
| References | |
| NUDOCS 7904250638 | |
| Download: ML19220B325 (4) | |
Text
.T UNITED ST ATES ptL g M' t, ATCMIC ENERGY COMMISSION p/s jg DI R E C T O R A T E O F R E G U t. A TO R Y O P E R A T I O Pe 5 4, i REGION l
\\
h
$31 P ARK AVENUE
/
".%Qf'O
.\\
KING cF pctVS$1 A, PENN SYLV ANI A 194C6
%,, v August 6, 1974 Metropolitan Edisen Cc=paa?y Docket No. 50-320 Attention:
Mr. J. G. Miller Vice President P. O. Box 542 Reading, Pennsylvania 19603 Gentlenen:
The enclosed DRO Eulletin No. 74-9, " Deficiency in the General Electric Medel 4KV Magne-Blast Circuit Breakers," is being sent to you relating experience with sc e of these circuit breakers at Ver:cnr. Yankee and Calvert Cliff s nuclear f acilitics.
This infor:ation may ha' iplicability at your facilities. Action en your part is identified.. Section 3 of the enclosed Sulletin.
Sincerely, f
-J ames P. O' Reilly Dir<ector
Enclosure:
DRO Sulletin No. 74-9 cc:
GPU Service Corporacica 200 Cherry Hi31 Road Parsippany, New Jersey 07054 Attentien:
- 3. G, Avers, QA Manager T. ". Crinnina, Jr., Cof af 0 Ls..o % '.macger R. W. Heward, Jr., Project Manager W. A. Verrochi, lice Presiccnt, Design L Construction Ca rn 1 <i c - a -, n ? F rannira Sc--
/ Fi'.:c
/-~'
r
- _1.
J..:s PCR
- r. -
m
=
- r9 M
,$ f N
- ', [ ',1 -
'['-
t
' T ' ; ' ~'
e s
i.
er- (-.
i 9 0 4 2 b D 6,5 8)-
_. ',. b--011 N
9 f
Directo. ce of Regulatory Operations Bulletin 74-9 August 6, 1974 DEFICIENCY IN CENERAL ELECTRIC MODEL 4KV MAGNE-3LAST 3REAKERS We have recently received Laf ertatien f rca Baltimore Gas and Electric Company (Calvert Cliffs Units 1 and 2) relating to circuit breaker s in the er.2 r.eered safety sys.e=s.
These circuit breakers, i
malfur General E2 ;ctric Model 4KV Magne-Blast, are used extensively at both FWR and SWh facilities. The =alfunctions, which could negate operation of engin eerec saf ety system co=ponents, were attributed to an oversized
- o11cr trip bar and improper clearances of related guide holes and linkages.
We have also received infor=stien frca the Vermon: Yankee Corporatica describing an installation deficiency of the auxiliary switch asse:bly installed in the General Electric Model 4KV Magne-31ast circuit breakers at the Ver: cat Yankee station. Although the circuit breakers are similar in model to the units used at Calvert Cliffs, they are of a different Pertinent details type and are used at both PWR and SWR f acili:12s.
relating to both problems are contained in Section A belcw, and the related action requested by this Sulletin is contained in Secticn 3.
A.
Descriocien of Circumstances Calvert Cliffs Units 1 and 2 On several occasicas in the past, there had been unexplained " trip Cn each cecasien, open" operations of several 4KV circuit breakers.
Oc close the the anc=aly occurred i==ediately f ollowing an attempt circuit breakers.
Investigation of the proble: disclosed that the cause of f ailure was attributed to an oversized spring discharge roller bar located on the right side of the breaker cubicle and imprcper clearances in the roller bar guide hole and associated linkages. The purpose of the roller bar is to trip cpen the breaker unit in the event it is inserted into the breaker cubicle while in its closed position.
However, the installed roller bars were found to be approximately 1/4" 1cnger than the design length, causing interfercnce with the breaker auxiliary switch linkage.
circuit Approxinately 116 General Electric Mcdel 4KV Magne-Elast breakers equipped wit'. the faulty rol?er bara and the above men-this tiened clearance p,blen are used.a the two nuclear units at farili:;
a r.2 r e w e s t i..., :ha: /cu de:craine 7._ : % r ~ nc: the Beca subjt.
scr1.rc u ;d ?T ST~ PIENNC ! to be un ;u 30 / Cur. l c i l i 'j the fA'~ i~ doraC 3 ara, rov. :cd f or / cur inf orma t ion :
W O12
1 R0 Bulletin No. 74-9 Manufacturer: General Electric Compaty Auxiliary Switch Assemblies in MC-4. 75 Horizontal Dravout Metal Clad Switchgear with AMH-4.76 ~ 50 Breaker Ver:ent Yankee The licensee reported that while investigating a proble: avolving a station service water pump 4KV circuit breaker, an elec rician noted that the breaker stationary auxiliary switch assemb.y rear counting bolt had loo aed and was ~ disengaged fre its counting plate.
The Icose bolt is cne of two bolts that assist in =ainta'ining proper switch contact align =ent.
The loosening and disengagement of the tie bolt caused =isalignment of the switch auxiliary contacts which cot.ld have rendered those contacts incperable.
Inspectica of sizilar switch asse:blies installed in forty-seven 4KV circuit breakers at this facility found that all switch asse:blies exhibited varying degrees of bolt loosening.
Because we are requesting that you deterzine whether or not the subject de rices are used or are planned to be used at your f acility, the following details are provided for your information:
Manufacturer: General Electric Cc=pany Type: Metal Clad,106 Switchgear (This switchgear has the auxiliary switch assembly =cunted to it and =ay be used with a large number of dif ferent circuit breakers.)
3.
Action Recuested It is requested that you deter =ine whether safety related (Class IE) circuit breakers of the described takes and models are installed at your facilities.
P12ase provide the RO Regicnal Office with your findings wi:hin 20 days fre receipt of this bulletin.
With regard to the proble= at Calver: Cliffs Units 1 and 2, if the subject breakers are installed, please include in your response a description and the results cf y ur progra: :: d::arnine if y:u hace oversized roller trip bars installed and the scheduled ccmpletien date of ycur corrective actions.
For f acili:i:s under c:nstruction, please infor us of your plans to assure that appr:priate ecc2: i:2-tict has been inplemented in all safe:y related cir:ui breakers of ur Tac.'.i:3 or.11 te i n s : _ '.
- co the type described that have been With regard to the 'le r: n:
- <. a arni~. i 1
,-.: n r.
" ~ c -' P
~ ' - "
ascertain the Sci: t ight r ? s.: ccc:i-' cf :"c questien and include in ru,
-~-..
a..;
of ycur inspect.cn irt requested that /ou in f,'
verification of bolt tig.
'jb 013
R0 Bulletin No. 74-9 Sheuld you have any question concerning this natter, we will be pleased to discuss then with you.
g 9
e
',b-014