ML19312E740

Part 21 Rept Re Misoperation of K-600S Circuit Breaker at Facility.Possiblity of Small Number of K-600S & K-DON600S Circuit Breakers Assembled W/Undersized Secondary Latch Bushing During 1969-77.Results of Tests Encl

ML19312E740
Person / Time
Site:	Zimmer
Issue date:	05/19/1980
From:	Rhoads E GOULD-BROWN BOVERI
To:
References
REF-PT21-80-227-200 NUDOCS 8006090478
Download: ML19312E740 (4)

Text

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ATTACWD IS A PART 21 REPORT FROM IE f%Il UNIT - ROOM 359E/W d- %.

PART21IDBfflFICATIONNO. R o ,.20-oog COMPANYt#E DATE OF LEITER Sh7/fo DOCKET NO, So - 3rr DATE DISTRIPHIED 5/J 9/ f o ORIGINAL REPORTd SUPPLBEffARY Z DISTRIBUTION:

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REACTOR (R)[ FUEL CYCE & _

SAFEGUARDS (S) f%TERIALS(M)

NRR/DDR, DIRECTOR (2) AD/FFMSI- AD/SG-IE NRR/DPM DIRECTOR (2) NiSS/F0iS AD/ROI AD/RDI(2) REGIONS REGIONS AD/RCI IEFIES NRR/ DOR, DIRECT 0'R PEGIONS PDR M1SS/SG SS-881 IE FIES IfDR PDR CBffRAL FILES CENTRAL FIES-SS-396 LPDR

. CENTRAL FIES (CHRON) TERA

- PDR CalTf 016 FIES(CHRON)

IE FIES (2)

LPDR CENTRAL FIES 016 L0EB/MPA FIG 5715 CENTRAL FIES (CHRON)

LDEB/BPA- tiG 5715 E0D - IMBB-7602 CENTRAL FIES - SS-396 AE0D INBB-7602 LDEB/BPA IHB 5715

. AE0D IID3-7602 ACTION:

PRELIMINARY EVUALATION OF THE ATTACHED REPORT INDICATES LEAD RESPONSIBILITY FOLLGV-UP AS SH0hN BEL 0d:

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LEE ER E HSS. [ 0]lLERE GD I 8'006090 Y7 '

FFMSI JyjS DOCUMENT CONTAINS '

POOR QUALITY PAGES "

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1%;?~~ayiL, -> GOULO-BROWN BOVERI r um.f+w (215) C26 700 Hay 19,1980 QyJQg ~~~

h. S. Nuclear Regulatory Commission && M x005 Region III 5/S.4 50 -

799 Roosevelt Road ~ ~

Glen Ellyn, Illinois 60137 --- -

pgg At'.antio n: Mr. G. Flore li, Chief ,

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Reactor Construction and Enginccring

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Support Branch --

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RE: Wm. H. Zimmer Nuclear Power Station - Unit 1~

Docket No. 50-538, Construerion Permit CPpR-RH,

. . . _ Report of 10CFR50.55(e) - Gould-Brown Boveri Type K-600s, 480 volt Electrically Operated -

Cincinnati Cas & Electric Letters to NRC ,

of m rch 28,1979 & April 19,1979 ...- -

U.ar Mr. Fiorellit In the referenced letters, Cincinnati Gas & Efectric reported the minnpctnrinn of a Could-Brnwn Bnveri K-6005 circuit breaker at their 7.iremer Nuclear Power S tation. it was reported that the circuit breaker secondary latch was hant;ing -

up ori 'the shunt trip, causing an inadvertent circuit breakcr closurc when the spring charging motor was energized. --

Corrective action, at this time, was to replace the five (5) nccondary latches that had undersized bushings. At the same time, a chim spacer was added behind the cagnetic latch to provide addi.tional clearance to the secondary latch.

A total of fiva (5) circuit breakers were reported to have this conditinn out of a total of 135. No other reports of a similar condition have been reported either prior to this time or subsequent to it.

As a follow up to this incident, Could-Brown Boveri has detem ned that there is a possibilf.ty that a small number of X-600S and K-DON 6005 circuit breakeru- -

were assembled with an undersized secondary latch bushing during the period betvcen 1969 and 1977. This condition hus a further limitation' ~such~ that the --

circuit breaker. must be electrically operated, it must he drawout and it must have a static trip device. - - - -

The undcrsized secondary latch bushing unuld not *cause a probicm nor would it result in a misoperation of the circuit breaker during normal operations with -~

the circuit breaker in the connected position. Also, the condition would not manifest itself unless tha circuit breaker is operated in a acquence that is not connidered to he normal.

MM 2 21880, l

A jent venture of I.T E imoeial Coroui tion and Bivm. Bavvii Pc*e< Dehvery. Inc.

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l  % 7 19. 1980 -> GUULO BROWN DOVERI

. Mr. C. Fiore111, Chief Reactor Construction and Engineering Support Branch U. S. Nuclear Regulatory Commission Region III Tents were conducted on a circuit breaker with a undersized secondary Intch to demonstrato that if a mechanical trip free operatinn is performed with the spring charging motor in the of f position and ' Anhnequently the charging nornr is energized that it would cause the circuit breaker to clone inadvertently.

This is caused by the secondary lutch hanging up on the magnetic lut ch housing.

i A simple ' c sequence has been devised to be:used during normal maintenance procedurer specifically check if this condition exists. It is as follows:

1.

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Rack the circuit breaker to the tewt position.

2. Charge the closing uprings, if uncharged.

3. Turn off the charring motor switch.

4. Push in occhsnical trip button and huld.

5. Push mechanical close lever upward.

6. Release trip and close devices.

7. Turn on the charging motor switch.

8. Tnadvertent cloning vill result if the condition exists.

The. enclosed Addandum (T.B.-9.1.7-6 Taaue F. Pages 1 & 2) dated March 4,1980 provides more details on th19 0080 sequence and instructions for enrrcction, if required.

On March 26, 1980, Gould-Brown Buveri visited the Enrico Fcrmi Fowcr Plant No. 2, to verify that the test sequence procedure and prnecdure for correction, if required could be readily understood by jobsite personnel. This was veri-fled by permitting the jnhnite personnel to read and demonstrate, the lustrue-tions provided.

If a shim is required, contact the nearest Gould-Brown Boveri Salen Office.

~If you have any additional questions, please call me at 215-678-7660.

Very truly youro, GOULD-BROWN BOVER1 Switchgear Syste=v Divieion

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. E. L RROADS, Nanager Quality Assurance Copy to K. P. Ehas Cincinnati Gas & Electric Co.

EWR/ rm

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.M CSUULUIBROWN BOVERI 4

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m.m ~.. n .u ,,1n I.B.-9.1.7-6 ISSUE F -

ADDENDUM 2, PAGE 1 MAECH 4, 1980 K-6005, K-DON 6005 FIELD TEST PROCEDURE CAUTION: REFER TO I .B.-9.1. 7-6 FOR CIRCUIT BRF2.KER . INSTRUCTIONS AND SAFETY PROCEDURES A. .This procedure is to be performed to determine if the secondary

. Close latch hangs up on the shunt trip device causing inadvertent closing of the circuit breaker at the completion of the closing springs charging. ,

1. . Rack out the circuit breaker to the test position.

2 Move the toggle switch to the "on" position to charge the closing springs.

3. Nove the toggle switch to the "off" position.

4 Perfom a trip free operation by holding the manual red trip button in and lifting the manual close lever to discharge the closing springs. (The breaker should not ,.

'closo)

5. Move the toggle switch to the "on" position to charge the-closing springs. Note at the end of the charging if the breaker inadvertently closed.

6. If the breaker closed during step 5, then it has failed and a .050 shim must be added per page 2 of this procedure.

7. If the breaker did not inadvertently close during Step 5,

than Steps 3 thru 5 should be repeated twel.vc timcc without failure. A .050 shim must ba added if any failures occur.

B. If it was necessary to install a .050 shim, then repeat Steps 3 thru 5 twelve times to check that the breaker does not inadvertently close.

Alomt.errture of I.T.E imperiet Corporatioo and Bro.=q Be,eri Power Detemy,lnc,

-> GOULO-BROWN BOVERI o . I.B.-9.1.7-6 ADDENDUM 2, PAGE 2

, MARCH 4, 1980 PROCEDURS FOR ASSEMBLING SHIM. IN.K-600S, K-DON 600S

. BREAKER WITHOUT REMOVING THE OPERATING MECHANISM _

CAUTION: REFER TO ID-9.1.7-6 PAGE 10 FOR CIRCUIT BREAKER REMOVAL (DRAWOUT TYPE) BEFORE PROCEEDING.-

DISASSEMBLY

-1. Tilt breaker back, loosen wires by removing cicat 650441-D, from left side of breaker frame.

2. Remove relay', from bottom of breaker, by removing screws that

. hold relay. Do not disconnect wires.

3. Bloc'k jack bar open to move arm away'from mag-latch.

4 Enter through left side of breaker and remove three screws, 54341-E2, that hold the ma Slide mag-latch and shunt' trip g-latch awayto from the mechanism side plate.

mechanism frame.

Use carc not to disconnect spring, 650216-All, between primary latch and mag-latch.

. ASSEMBLY 3

1. Slide shim, 711917-B, in between mechanism side plate and mag-latch, and reattach mag-latch with longer screws, 54341-E3.

2. Tighten screws, making sure spring, 650216-All, is connected.

3. Replace parts in reverse order.

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