ML20126C690
| ML20126C690 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs, Peach Bottom, Arkansas Nuclear, North Anna, Vermont Yankee, Crystal River, Duane Arnold, Farley, 05000000, Crane |
| Issue date: | 06/05/1985 |
| From: | Moriarty J COLT INDUSTRIES, INC. |
| To: | Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| REF-PT21-85, REF-PT21-85-282-000 PT21-85-282, PT21-85-282-000, NUDOCS 8506140498 | |
| Download: ML20126C690 (7) | |
Text
e 1
3 Colt industries F;lrbankp Morse Engine Dms on 701 Lawton Avenue A
Beloit, Wisconsin 53511-5492 Telephone: 608/364-4411 Telecopier.608/364-0382 9-36
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,y, June 5, 1985 1j
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'l Dr. Thomas E. Murley U.S. Nuclear Regulatory Commission W
Region 1 631 Park Avenue King of Prussia, PA 19406
'9 9
Subject:
10 CFR 21 Report, Generator Failure
[Lg Baltimore Gas and Electric - Calvert Cliffs
Reference:
A)
Louis Allis (H. Leusink) Letter of May 29, 1985 to U.S.N.R.C. (T. Murley)
Enclosure:
1)
Louis Allis (H. Leusink) Letter of June 3, 1985 to Colt Industries (M. Moriarty) with attachments Centlemen:
Reference A) indicated Louis Allis would be forwarding a report on the subject incident to Colt for our corrective action.
The Enclosures contains Louis Allis's analysis of the incident and their recommended course of action.
Colt concurs with Louis Allis's opinion.
It is Colts recommendation that the interpolar connectors be removed from the units at the 4 affected sites as outlined in procedure No. 1 on the bottom of Page 2 of the enclosed letter.
A copy of this letter is being sent to the affected utilities who in some cases have taken corrective action.
If you have any questions or require additional information please advise.
Yours very truly, J
- 1. #
Moriarty Manager Uti Sales JMM/jl 8506140498 850605g1 y/pe l gDR ADOCK 0 4 om on or in. con inousin 6..imo com
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~
.,Dr. T.'Murity Juna 5, 1985
- cc:- with enclosures:
Baltimore Gas & Electric P.O.. Box 1475 Baltimore,.HD 51203 Attn:
Mr. Richard Buttner Vermont Yankee Co.
P.O. Box l' Vernon, V' Attn:
Don Dyer rations Quality Coordinator Philadelphia Electric.Co.
2610 South Delaware Ave.
Philadelphia, PA 19148 Attn:
Mr. Bruce Allshouse GPO Nuclear 3 Mile Island P.O. Box 480 Middletown, PA 17057 Attn:-
Mr. Paul Levine (Trailer 137)
Louis Allis 427 E. Stewart St.
Milwaukee, WI 53201 Attn:
Mr. Harland Leusink U.S. Nuclear Regulatory Commission EEW-359 Washington, D.C. 20555 Aten:
Kamalakar R. Naidu
r o.w a ue ec 427 E. Stewart St., P.O. Box 2020, Milwaukee, WI 53201-2020 414-481-6000 TWX 910-262-3115 June 3, 1985 Mr. Michael Moriarty Colt Industries Fairbanks Horse Engine Division 701 Lauton Avenue Beloit, Wisconsin 53511
Subject:
10CFR 21 Calvert Cliffs Nuclear Station Alternator Failure / Colt Order #205706
Dear Mr. Moriarty:
In my communication to Chuck Ankrum on May 29, 1985 I reported Louis.Allis was waiting for a trip report from a service representative who had visited the site to analyze the failure. His report is attached for your review.
In the design of synchronous machines there is a winding in the rotor called on "amortisseur circuit".
It consists of several copper bars. imbedded into the face of the main pole face, commonly called a damper bars. A copper strsp brazed to the damper bars forming the damper circuit, and an interpolar connector connects the damper circuit of each of the main field poles together.
In the design of alternators, the inclusion of the interpolar connector is not always necessary.
In our opinion it will be. difficult to pin down the exact cause of the failure on the subject unit, however it is probably linked to work hardening of the material at the time of original fabrication of the Ahorting strap or assembly of the chorting strap to the interpolar co..nector,(however not all aren cintercon~ifecEe~d?
x_ _-
The inclusion of interpolar connectors into the desigc) of an. alternator of this type is usually a result of a specification requirement. All of the diesel engine driven gencrators manufactured by Colt, its successor Beloit Power
/
Systems, and now Louis Allis for nuclear applications have damper circuits located in the main field pole faco co rredw b R LewS K 4 M erd g
y 7
GfAl8S There are two principle functions of an amortisseur vinding:
1.
They provide some damping in voltage (and power) fluctuations caused by transient load disturbances and are beneficial in reducing power pulsations caused by reciprocating prime movers where dissimilar generating units are involved. So far as ce could see, neither of these conditions exist in the nuclear standby environment.
2.
They reduce the harmonic voltage present on three phase generators, and the subsequent heating, during operation under unbalanced load conditions. This is seldom of concern except on very small units since unbalanced loado in.excese of 10% are not generally encountered on larger units. Nuclear backup service does not involve unbalanced loads of any significance.
m
-e.
,_i 110CFR 21'
'Calv;rt Cliffs Nuc1 car Stction Page 2;.
June 3, 1985 From 1970'to 1973 Colt Industries ~ supplied diesel. generator sets for ten (10)L nuclear plants with essentially the same main field pole construction es Calvert_ Cliffs,Thowever.only four:(4) of these installations have field
. pole construction with interpolar connectors.: 1The installations are as.
followst; POLAR INSTALLATIONS-COLT ORDER #
- OF' UNITS FRAME CONNECTORS 1.
Vermont Yankee-205668-2 U1-30 Yes Vernon, VT 2.
Peach Bottom 2 & 3.
-205700 4
U1-30 Yes Philadelphia Electric
~
3.
Calvert Cliffs 1 & 2 205706 3
U1-30 Yes Baltimore Gas & Electric-4.
Three Mile Island #1' 205672 2
U1-30 Yes Metropolitan Edison
- 5.. Arnold #1 205836 2
U1-30 No
' Iowa Power & Light 6.
Crystal River #3 205713 2
U1-30 No Florida Power Corp.
7.
North Anna 1 & 2 205857 i
U1-30 No Virginia EEP 205858
- 8. -Farley #1_
.205917 2
U1-30 No Alabama Power
- 9.. Arkansas Nuclear 205925 2
U1-30 No
' Arkansas Power V
- 10. Three Mile Island #2 205732 2
U1-30 No
-Jersey Central
' Based on the views expressed in the " principle functions" discussion above, and in view of the above ' listed installations, it is the recommendation of Louis ~ Allis that the interpolar connectors be removed from the units at Installations 4 as noted above.
'The procedure for removal will be one of the following:
1.
Since the shorting strap under the damper bars is made of soft material, it may be possible to reach into the generator with a bolt cutter and cut the connector and part of the shorting' bar in two and remove tne connector. Care nust be taken not to allow chips or slivers from the severed part; to drop into the machine.
2.
Disassemble the rotor from the unit and proceed with Item 1 above.
---n,--n.----.n-.n-----
10CFR 21-Cc1vsrt Cliffo Nuc1str Station Page 3 June 3, 1985 Enclosed is a sketch #53085 indicating where the shorting bar should be severed.
Louis ' Allis has been requested by the NRC for a copy of the trip report enclosed. I assume you will forward if you want to respond to that request. The gentleman requesting the report is:
Kamalakar R. Naidu United States Nuclear Regulatory Commission EWW-359 Washington D.C.
20555 Sincerely,
- H. H. Leusink Vice President, Engineering HHL:sd Enclosure cc: Louis Allis Colt Industries E. Klessig C. Ankrum J. Borman B. Saylor A. Giesecke H. Schreiber t
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l t DATE May 30, 1985 FROM C. Anderson A Dvoonof MagneTek inc To Bruce Albertson cc:
H. Leusink H. Schreiber D. Gaylord SUEMECT Service Trip to Calvert Cliffs Nuclear Power Plant, Lusby, Maryland Arrived Martha Washington Motel in Waldorf, Maryland approximately 3:45 p.m., Monday, May 20, 1985.
Unable to contact Gary Pavis, but made contact with '
Joe Crunkleton (301-260-4933), Engineering Analyst for BG&E Also same phone conversation, was informed new unit (g 9/21/85.
and made arrangements to meet at plant Tuesday mornin our 275851) was on site, and a receiving insp check indicated grounded bearing insulation.
I was not concerned at this time, as it is difficult to have rotor in proper alignment in shipping skid to prevent shaft from touching inner closure.
Arrived at plant approximately 7:30 a.m., Tuesday, 5/21/85.
Mr. Crunkleton and I were joined by Phil Hebrank of Electrical Engineering Department.
It is requested that any Engineering decisions from Louis Allis be directed to Phil Hebrank, P. O. Box 1475, Baltimore, Md 21203, or phone at (301)-234-7113 Keystone Electric of Baltimore is the service shop they have.
been in contact with in regard to this unit, which is S/N 502564R1.
Unit was running on an overspeed test after normal tear down and inspection of engine had been accomplished.
Part that failed was interpolar connector between two poles.
BG&E feel that the
" ear" broke off the pole first, which flew out into stator winding and catching, then ripping connector off the adjacent pole.
The " ear" was still attached to the pulled off interpolar connector.
They heard a clicking or tapping noise before it started " banging".
When unit stopped, part was found in bottom of unit and rather bent and beat up.
Part is presently in Metallurgical Lab in Baltimore, but will be sent to Louis Allis, attention Dave Gaylord.
Completely unofficial " thought" from Lab is possibly " flutter" induced by windage and/or magnetic field, of high frequency causing a possible fatique fracture.
Had a short conversation with a Mr. Bond of BG&E, saying they are planning on running Eddy Current tests on remainder of connectors for further checks of cracks, followed up by radiograph inspection on any suspect parts.
Thy anticipate the Eddy Current checks to be completed this week.
I asked that we be informed of results.
If not notified, suggest calIng and inquiring next Monday or Tuesday.
i C. Anderson' Service Trip to Calvert Cliffs Nuclear Power Plant Lusby, Maryland 5/20/85 Mr. Hebrank and Mr. Crunkleton expressed interest in possibility of removing interpolar connectors from units, and request full information of any limitation of operation of units after removal of connectors, in the case our Engineering Department should issue a directive to do so.
Collector ring grooving, predominently on positive ring, f
Mr. Hebrank asks if possible to ocasiona11y reverse the polarity of the D.C. input to main rotor.
He feels this would help this situation.
Q.A. won't allow them to do this as there is nothing in our operating procedure to allow this.
Possible revision of operating procedure?
Also asked if Engineering from Louis Allis might be able to recommend a different grade of brush for better ring wear.
s Mr. Hebrank would also like to know how many nuclear service alternators of similar size and type that have been supplied to other utilities, and if there have been any other failures of this type?
Also, have there been any furnished without interpolar connectors?
Failure was on engine end and several pictures taken of failed area and other connections on that end.
Also have pictures of one connector on connection end that at least shows a varnish crack in center of connector at the "V" bend.
Also a picture to enable tying in failure location with keyway in rotor.
h W Charles Anderson l
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