ML20106D132

Part 21 Rept Re Cracking of LPCI M-G Set Generator Coil Clamps & Rectifier Mounting Rings Mfg by Louis-Allis Co. Initially Reported on 841005.Components Returned to Vendor

ML20106D132
Person / Time
Site:	Browns Ferry
Issue date:	10/09/1984
From:	Parris H TENNESSEE VALLEY AUTHORITY
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
REF-PT21-84-484-000 PT21-84-484, PT21-84-484-000, NUDOCS 8410250008
Download: ML20106D132 (7)

Text

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TENNESSEE . VALLEY AUTHO RITY

-KNOXVILLE. TENNESSEE 37902 OCT 9 1984 8tl DC T 15 ' P l l cl 2

- Mr. James P.' O'Reilly, Regional Administrator

U.S.' Nuclear Regulatory Commission

,  ; Region ~II.,

101 Marietta Street, NW.,cSuite 2900

' Atlanta, Georgia' 30323

Dear .Mr. O'Reilly:

TENNESSEE VALLEY AUTHO - BROWNS FERRY NUCLEAR PLANT (BFN) UNITS 1, 2, AND 3'-' DOCKET NOS. 5 2 -260, AND -296 - FACILITY-OPERATING LICENSES DPR-33,- -52, AND CFR 21' REPORT During routiine inspections of the low pressure coolant injection (LPCI) motor. generator (ag) sets, increased vibration in the pillowblock bearing on unit 1 LPCI mg set IDN hao'been noticed since May 1,.1984 The mg set

.was removed from service for bearing replacement on July 10, 1984 The original bearing was reinstalled (because of material delivery difficulties in obtaining a new bearing) and the ag-set. restarted. The breaker feeding the.ag set motor tripped and investigation revealed that the generator had failed.. A spare og set was installed. The mg set was removed from

- service and returned to Louis-Allis Company on September 4, 1984, for failure analysis and repair.. The generator was disassembled at the Louis-

' Allis plant on September 5, 1984 Cracks were found in three.out of four of-the coil clamps and a rectifier mounting ring was loose. . On August.8, 1984, unit 2 mg set'2DA was removed from' service due to high vibration although it was operating properly. This generator was disassembled on August 14, 1984, at TVA's Power Service Shop, and inspection revealed that one of the coil clamps was broken apart and the other three coil clamps had cracked. The rectifier ring was also loose. This failure was similar to the unit 1 og set failure.

There 'are four of these og sets in each unit at BFN. They supply two separate sources of power from the 480V shutdown boards to the reactor MOV boards D and E. -These reactor MOV boards provide motive power to valves associated with the LPCI made of the residual heat removal system.

Failure of a single og set could result in a loss of a redundant power supply to either the D or E reactor MOV board associated with the set.

These og sets were manufactured by Louis-Allis Company 427 E. Stewart Street P.O. Box 2020 Milwaukee, Wisconsin 53201 8410250008 841009 PDR ADOCK 05000259 s S PDR OFFICIAL COPY An Equal Opportunity Employer /

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OCT 9 1984 Mr.c James- P. O'Reilly ' ,

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This' problemIis ~ reportable under.10 CFR.21 and was reported to me on October 5,l1984. ;I' made verbal' notification to you on October 5,1984 The~ enclosed'Part 21 report:from BFN contains additional information on this matter..

~

x Very truly yours, TENNESSEE VALLEY AUTHORITY H. G. Parris Manager of Power and Engineering

. Enclosure v

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Tennisse3 Vdhy Authority Form BF 119 Br:wns Ferry Nuclear Plant Page 1 of 2 BF 15.2 BF 15.23 5/30/84 EVALUATION LOGIC FOR PART 21 PROBLEM: Cracking of LPCI M-G Set Generator Coil Clamps and Rectifier Mounting Rings IDENTIFIED BY: Maintenance Request No. A-266169 A. Does the problem involve: -

1. Failure of goods and services to comply with applicable NRC requirements (regardless of whether these requirements are included in the procurement g document). Yes / / No /X/ (if yes, go to D)

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. osusuoy iri e turiuiuon or circumstance that could contribute to exceeding a safety limit as defined by plant technical specifications. Yes / v/ No / / (if yes, go to B)

3. Departure of a delivered component or service from the technical requirements of a procurement document. Delivery occurs upon acceptance 1 by NUC PR (e.g., at receipt inspection). Yes /

go to B)

~ No / X / (gr yes,

/

E Q 0 Answer all 3 questions above..........................................._........................................

If all "No's", GO TO C. If any "Yes's", GO TO o "B."

B. Is component necessary to ensure:

1. The inteo. rity of the reactnr e.n.n. la..n. .t.

, ao_ e_ c-.o ra.

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2.

The capability to shut down the reactor and maintain it Yes /X / No / .

o in a safe shutdown condition (example, IEEE Class 1E Electrical, Seismic cat.1) t r s. .. _. ,., _, w - .i r- i .+ .,. -,

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unuyasc u se we ase4 WU8 8Lt*b Y es / 3 / No / /

of accidents 0 4 Is security system deficiency involved? Yes / / No /X /

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O C. Evaluation for Serv _ ices *

• 0 l9 1. If this is a repair service, would the item being h.3 6 Yes / / No / /

0 repaired be procured as a " Commercial Grade" item?

0 f f "Yes",10. CFR 21 does not apply, go to "E."

if "No", go to C.2.

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2. Could the service being procured cause a defect in 0

a basic component or are the services connected with Yes /-~~~/ No / /

0 the design, inspection, testing, or consulting services l0 O O

important to safety that are associated with a basic component, if "Yes",10 CFR 21 applies Go to " E . " .

If "No",10 CFR 21 does not apply; go to "E."

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D. Could the defect have caused a substantial safety hazard?

(By definition, item A2 constitutes a substantial safety hazard.) Yes / X/ No O 1 -

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If No . th.i s i t em. i *. n_ _o_t . ra_ n_ .n.r e a. b. .l e. . . . i.f. .m. . . . .t.h.i.c..c.i n.a m_ . . s

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• Revision y m -

Form BR 119

• Page 2 of 2 Tennessee Valley Authority .

m BF 15.2 Drowns Ferry Nuclear Plant g BF 15.23 5/30/84 EVALUATION LOGIC FOR PART 21 (Continued)

'n Submitted: hU, Thby /Date 9////8 4 I

Reviewed: N s

Com liance Staff Supervisor

/ (0/4/6y Date '

l Approved: /, < [ v- / /#Date

1. [#

// POltC Cliairman ec: Compliance Supervisor

_ Retention : Period - Lifetime; g Responsibility - Document Control Fupervisor "

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+ Addendum l t

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Tennessoa Valley Auth rity

'BrCwns Fcrry Nuclear Plant Page 1 sq Form BF 145 1

BF 15 23 7/26/82 Attachment 1 Part 31 .

Report # _ * - .

PART 21 REPORT , 5 Plant _ Browns Ferry Nuclear Plant TechnicalSpecifico*.i$ns References Sections 3.5 and 3.9. -

Component or System Identification seeAttac{mntA Suonlier of Companaa' T*"i"-Alli" Pa*"""?

• Nature of Defect or Noncompliance and cause ,

See Attachment A Extent of Safety Hazard _ _ See Attachment A g

Date Which Defect or Noncompliance Was Discovered September 5, 1984 Number of Identical Components in Use Twelve (four per unit)

Location of Components Elevations 62) and 639 of Reactor Building Corrective Action and Recurrence Control Taken or To Be Taken See Attachment A t .

g -

_2 -

. g' Expected Completion Date See Attachment A (Corrective Action and Recurrence Control Taken or To Be Taken) j lias defect or noncompliance been reported previously? Yes /

If yes, by what means? N/A.

/ No /X/

Submitter y

.$/!1/89 Date LA#m PoliC lleview ~

2/wtt' Da t6

. -L g Superintendent Approval -

Date Ret en tion : Period - Lifetime. Responsibility - Document Control Supervidor 1_0 2 0_9 _ 1.3 1 3 7 _ _ - ____________ 7203053 # 020 F fM

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/ ATTACIMENT A j

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CorionentorSystemIdentiQcation Iowhrehute Coolant Injection-(LPCI) Motor Generator (mg) sets, system No. 268.

j' 9 ,?p Na'kup 'of Jefect or Noncompliance and Cause The coil clamps and rectifier mounting ring in the generator rotor are cracking. The cracking appears to be caused by thermal expansion of the phenolic material of which the clamps and rings are made. This defect increases the probability of a generator failure.

Extent of Safety Haza d the LPCI mg seta pr6 side power to 480V reactor motor-operated valve (RMOV)

% nds D and E.' Each RMOV board has two LPCI mg sets associated with it,

' '% .e for the normal power supply and one for the alternate power supply.

s These RMOV boards provide motive power to valves associated with the LPCI mode of,the Residual Heat Removal System (RHR). Failure of a coil clamp or rectifier mounting ring can result in a generator failure which would result in a loss of redundant power supply to the RMOV board associated w/th the mg, sets.

The ).PCI mg sets were inacslied during the following refueling outages:

unit A evele 4, unit 2 cycle 4, and unit 3 cycle 3.

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%e cracked coil clamps and loose rectifier mounting ring problem was identified by the foMowing two in :idents:

] lichhanical Rec 21t's Section had noticed increased vibration in the

~ pillowblock bearing (motor side) on LPCI mg set IDN since May 1, 1984 On July 10, 1984, the mg set was removed from service for bearing

', replacement. During the bearing changeout, due to material receipt

problems,tthe original bearing was reinstalled and the mg set

. > restarted. The breaker feeding the mg set motor then tripped.

, Investigation revealed that the og set generator had failed.

The uig set was returned to Louis-Allis, the manufacturer, for a

} l, failure analysis. On September 5, 1984, the generator was disassembled by Louis-Allis.. Cracks were found in three out of four of the coil f

c) amps, aad the rectifier mounting ring was loose. The actual cause of

'che generator fd lure has not yet been determined.

s 4 On August 8,1984, ISCI mg set 4DA was removed from service due to e 2 4

high vibracion. Initial inspection revealed pieces of a phenolic material in the end caps. On August 14, 1984, the generator was ifisassembled. One coil clamp was found to have completely broken apart a Q the remaining three c. lamps were cracked. The rectifier mounting ling was loose. There was no generator failure on this mg set.

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s Corrective Action and Recurrence Control Taken or To Be Taken l

Loss of the following LPCI mg set generators would be annunciated in the l respective unit main control room: IDA, IDN, 2DA, 2DN, 2EN, 3EN, and 3DN.

Loss of LPCI mg set generators IEA, 2EA, 3DA, and 3EA would not be annunciated. The normal and alternate supply voltage level to RKOV boards IE, 3D, and 3E will be checked once per shift until repairs are complete.

The supply voltages to 240V board 2E will not be checked since unit 2 is in a refueling outage and repairs will be complete before the unit is restarted. Mechanical Results Section also checks vibration levels on all LPCI mg sets once per month. The annunciation and voltage checks will provide early detection of a generator failure and vibration checks will provide early indications of coil clamp and/or rectifier mounting ring problems.

Louis-Allis has revised the design of the coil clamps such that they will maintain the same physical dimensions but will be made of 6061/T6 aluminum block. Louis-Allis is currently in the process of designing a new rectifier mounting ring. The new coil clamps and rectifier mounting rings will be installed in all LPCI mg sets by the end of the next refueling outage for each unit (unit 2 cycle 5, unit I cycle 6, and unit 3 cycle 6).