ML20080E783
| ML20080E783 | |
| Person / Time | |
|---|---|
| Site: | Shoreham File:Long Island Lighting Company icon.png |
| Issue date: | 09/22/1983 |
| From: | Twana Ellis HUNTON & WILLIAMS, LONG ISLAND LIGHTING CO. |
| To: | Dynner A, Goddard R KIRKPATRICK & LOCKHART, NRC OFFICE OF THE EXECUTIVE LEGAL DIRECTOR (OELD) |
| Shared Package | |
| ML20080E777 | List: |
| References | |
| NUDOCS 8402100135 | |
| Download: ML20080E783 (40) | |
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O 707 CAST MAsN staccf P o. Bom 153s do, e e 6 e sw'tos=0 RicnMown. VasectxxA 23212 . . . . .c . ,6v. .. .. . . u c. .
e o so.soo . o .onisaao mas soso, hoevee camO63.ea 37.oa w..=e=oto , a c. aoose e.e. es . . . a r. Tctcenonc so4 - 7sm . a200 aos.ama.....
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r sc ao 24566.3 e........... September 22, 1983 o,.ce,..6~o..o. ... 8361 Alan R. Dynner, Esq.
Kirkpatrick, Lockhart, Hill, Christpher & Phillips 1900 M Street, N.W.
Washington, D.C. 20035 Richard Goddard, Esq.
U.S. Nuclear Regulatory .
Commission Washington, D.C. 20555
()
Dear Messrs. Dynner and Goddard:
In its Order dated June 22, 1983, the Board directed LILCO to discuss with the Staff and County the testing or inspection of the new rocker arm shaft bolts installed on the Shoreham diesel generators. As you will recall, the rocker arm shaft bolts currently installed on the diesel generators are of an improved design installed following the failure of one of Shorehan's original rocker arm shaft bolts. Although there was only one failure, all of the 96 rocker arm shaft bolts on the Shoreham diesel generacors were replaced. As the Board noted, the new bolts, unlike the old ones, were subjected to magnetic particle testing and, in addition, substantial testing hours were accrued on the Shoreham diesels since the installation of the new bolts with no problems. In its consideration of the rocker arm shaft bolt problem, the Board sancluded that the cnly remaining question related to LILCO's plans to inspect a sample of the i new bolts. Specifically, the Board stated ;
I The one remaining long term question i regarding the bolts directly should be l easily resolved without resort to liti- i gation. That question is the scope of LILCO's plans (undecided at the time of
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the conference of parties. Tr.-21,385-89 ,
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8402100135'840207 PDR ADOCK 05000322 G PDR.m
.s y' IIr;NTox & WILLIAxs O
September 22, 1983 Page Two (Youngling)), if any, to prudently inspect a sample of the new bolts at reasonable intervals of operation of the diesels (not too soon or too long), perhaps including before any fuel-loading given the substan-tial testing hours accrued with the new bolts. Tr. 21,368-69 (Goldsmith). We direct LILCO to discuss such a testing proposal with the Staff and the County, re-porting any agreement or disagreements.
Subject to our approval of such surveillance, or approval of any position by LILCO as to why such sampling should not be done, we find there is nothing left to litigate re-garding the reliability of the rocker arm bolts.
, , In connection with the replacement of Shoreham's original cylinder heads with new cylinder heads, LILCO took O the opportunity to conduct an inspection of a random representative sample of the bolts. More specifically, seven bolts from each engine, 21 bolts total, were randomly selected for inspection. Each bolt was cleaned with solvent to remove any lubrication and facilitate the inspection. The inspection consisted of visual observation for cracks, laps or seams on the threads, shanks or heads of the bolts. Attention was also given to the internal threads and to the junction of the head and shank portion. The visual inspection performed on the bolts is the same as that described in ASTM A614. No indica-tions or problems were observed.
Given the results of this inspection and the fact that all of the new bolts that have been installed were subjected to magnetic particle inspection before installation, LILCO does not consider that any further inspection or examination of the bolts is necessary.
Pursuant to the Board's Order of August 29, 1983, clease let us know whether you agree that further inspection is unnecessary so that we can report to the Board as required.
Sincer y,
/,/.V 1 O .i #e 7d' . Ellis, III 75/403 bc: Edward J. Youngling r- - -+-
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.. NEI . Persens Peebles - Electria Products, Inc.
l 17M OsAstene Iked
- Gwetand, Chlo 44112 -
i telephone:(216) 441 1500
} Teles: 941864 l f, i
November 7,1983
. 1
- . i Tranenseerica Delevel, Inc. !
! Engine a Casspressor Division i 554 85th Avenue l Oektend, Cellflemie test! -
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i Attention: Mr. John Witt
Subject:
Lang leland Ughting Co. '
! Repelr en Retor l i Gen tiessen:
4 We refer se eve report en the fbiture onetysis of the retor pole en e Lon2 falend i Ughting Co. generator and would like la ampHfy on their statement 'typies!
j enemple of merginal workanenship".
- What is meant by the wtatement la that we take every precaut!an to insure ipuod ,
- workmenship and good quellty sentrel. However, even with e!! the Inspecten '
end testing performed, in some Isolated Instances kults de occur la machines.
these feufts are rendose and difficult to find even efter feffure. In this perti-euler cose we applied a higher weltage to the pole to coues the thult to increase so that we could aestly detect the esatt location of the fault. When such a rendem l
fault is present. In the poettlon of this perticular fault, due to the continual host- :
Ing and cooling of the cell together with the normel v!bretion present in any retot- 1 Ing body. e felture Is likely to occur e*<er a period of use. This is not a generic !
fault and in order to put this fault in perseestive, we would state we have hutit 1 approximately 170 Class 18 generators in the post 18 years, and this flellure le the first such pela felfure we have enfa :f.
This fault reistes te one pele only. and we have ne reseen to espeet any further fhllures on this or any of the other machines based on our post eg1_.
We trust this wDI explain the altustien As#y.
Yours very truly, -
Ron g. petiti tieneger of Marketing e
_______[__" - _ _ '
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December 7, 1983 H. H. Milligan/W. M. Judge Integrity of'EDG Engine Bases Shoreham Nuclear Power Station - Unit 1 W.O. 44430/48923 Cracks have been reported in the engines of DG 102 and DG 103 following disassembly. Cracking has been primarily confined to the upper surf ce of the base between the main bearing saddles and the bearing cap stud holes and to the bore of the stud holes adjacent to the bearing saddles. The separation between the saddles and bolt holes at the top of the bases of DG 102 and DG 103 is approximately 0.125 inches, with some as small as 0.100 inches, and the edges of the holes are not chamfered. The separation is approximately 0.250" in the case of the DG 101 base, and the holes are chamfered approximately 0.125". Thus the DG 101 base, which was found not to contain cracks, is inherently stronger than the other two.
Concern was initia.lly focused upon the possibility of growth of these cracks under operating loads. Apparently other non-counterweighted DSR-48 engines in U.S. Coast Guard service have cra'cked severely. Dynamic loading is espccially severe
'at the main journals of cylinders No. 4 and No. 5, at which the connecting rod pins are simultaneously at top dead center, when the throws are not fitted with counterweights. The crack-ing problem in the Coast Guard engines has been attributed by TDI to insufficient main bearing cap stud preload. . Torque rcquirements for the bearing cap nuto were subscquently increased.
The SNPS diesel engines have reportedly always been operated with this increased torque. We analyzed the forces on the main bearing caps according to the results of a journal orbit analysis conducted by TDI. With the specified torque, the stud preload-is sufficient to prevent motion of the bearing caps, i.e., the.
side load is too small to overcome static friction. Therefore, the studs cannot hammer tne bore of the stua holes. Moreover, our calculations show that the frictional shear stress and normal stress in the vicinity of the stud holesfare too low to cause growth of the cracks, and we have not been able'to predict-any.other operating loads that would result in crack growth-in this area. .
4
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- December 7, 1983 M. H. Milligan/W. M. Judge Page 2 Subsequently we attempted to determine the cause of the obser* zed cracks. In the case of DG 102 it was logical to associate the cracks with high impact loads on the bearing cap 3 resulting from fracturing of the crankshaft and destruction of the No. 7 connect-ing rod bearing shells. Explanation of the numercus crack indica-tions in the DG 103 base is still uncertain, and TDI has not-yet provided their conclusions. However, we have observed use of a torque n.ultiplier to aid in removal of locking pins in the lower nut pockets of certain main bearing stud holes. Calculations show that the side loads developed between the scuds and the 1/8" wall adjacent to the bearing saddle are more than sufficient to fracture his wall. Furthermore, visual examination of the studs showed several to exhibit scratches and dents coinciding approxi-mately with the top of the base, and in at least one instance
- a. stud hole was found to be deformed by radial force directed towards the bearing saddle. We concluded that although other sources could have contributed to cracking, the cracks had probably been initiated in the course of disassembly and, in any event, could not be attributed to engine operation.
y C. H. Wells i
CHW : n.p cc: A. Earley C. K. Seaman SR2 i
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__ __ _ -_____ _ _-_____= ___________ _-____ _ - _ _ . . _-1
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December 15, 1983 M. H. Milligan Inspection of Jacket Water Pumps from Transamerica Delavel Diesel Engines, SNPS, FaAA No. PA07396 Shoreham Nuclear Power Station - Urit 1 ,
W.O. 44430/48923 On October 12-14, 1983, Dr. Donald O. Cox inspected jacket water pumps from the Transameric'a Delaval Incorporated " Enterprise" diesel engines used to drive standby generators at the Shoreham Nuclear Power Station.
A typical water jacket pump is shown in Photographs 1 and 2. The pump is driven through a gear at one end of the shaft which engages a gear on the crankshaft. The impeller is mounted at the cpposite end of the shaft and held in position by an interference fit, re-taining washer and nut as shown in Photograph 2. The jacket water pump has apparently undergone two major redesigns due to pump shaft fatigue failures in the region where the impeller is attached.
The " original" design incorporated a straight shaft and key to prevent relative rotation of the impeller. However, several units with this design failed during operation in Saudi Arabia, allegedly due to impeller looseness on the shaft.
A redesign was incorporated which used a tapered shaft to attach the impeller to shaft; use of a key was retained. However, LILCO experienced three pump failures in pumps with the tapered shaft / key attachment design.
TDI again redesigned the attachment, incorporating three major changes: 1) the impeller material was changed from red brass to ductile iron, 2) the diameter of the tapered portion of the' shaft in the area under the impeller was increased, and 3) the key method of antirotation was eliminated. Thus, the only force attaching the impeller to the shaft in the current design is the friction force due to the interference fit used during assembly.
During tear down aof diesel engine No. 102 after a crankshaft failure, the impeller of the water jacket pump was found'to have spun on the shaft. It was postulated that this pump could have i
been, exposed to unexpected impulse loads during - failure of the crankshaft. Therefore, an investigation was initiated'to establish that the current -impeller /shaf t attachment insures the impeller will remain firmif attached to the shaft. This effort involved T7
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- I December 15, 1983 M. H. Milligan i Page 2 disassembly of the pumps from DG 101 and 103, which had provided approximately 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> of service.
The signific. ant components of the DG 102 pump include the impeller, i
shaft, retaining washer and nut which are shown in Photographs 3 througn 5. The impeller is specified as ductile iron.
fabrica ted from a ferrous material, There was no evidence of cracking of the impeller, although some casting porosity was observed and there was venes.
some corrosion debris at internal portions of the impeller Impeller damage was confined to the bore of the hole where it is press fit to the shaft and the bearing surface at the periphery of the hole where the retaining washer contacts. These areas are shown in Photographs 6 and 7. The bore of the impeller hole was severly scored at two major locations consistent with major scoring of the shaft. There was minor damage to the remainder of the impeller bore. The surface around the hcle, on the suction side of the impeller, has been severely scored as a result of relative rotation between impeller and retaining washer (Photograph 7),
There was a circumferential lip approximately 1/32 inch in height around the hole, resulting from metal distortion as the impeller rotated relative to the washer. The lip was relatively uniform in height around the hole periphery. There was, however, no visual evidence of heat damage to the bore of the impeller or the hole periphery, suggesting the relative rotation between shaft and impeller occurred for only a short period of time.
The threads at the end of the pump shaft appeared to be in excel-lent condition, with some evidence of debris in the thread roots (mos t probably lectite or die penetrant) . The tapered surface of the shaft where the impeller seats has been severely scored in two major locations near the center of the contact area. This region is shown in Photographs 8 and 9. The two major areas of scoring on the shaft appear to match with the scores in the bore of the impeller.
There was evidence of minor scoring of the taper region over the entire area of impeller / shaft contact. However, there was no damage where the retaining washer was located. As with the impeller, there was no evidence of heat damage to the shaft taper, again suggesting that relative rotation between impeller and shaft did not occur for an extended period of time. Rockwell hardness tests at mid-length of the shaft showed the material hardness to be S4-86 HRB. The material was non-magnetic, indicating an austenitic grade of stainless steel.
The surface of the nut, which was in. contact with the retaining washer during operation, has a single circumferential score mark approximately 3/16 to 1/4 inch in -length as indicated in T7
- g. .c -. _ - .- - ._ -
December 15, 1983 M. B. Milligan Page 3 ,
- - Photograph 11. The direction in which this mark was produced indi- ,
cates that the nut / shaft rotated as a unit in their normal driven {
direction relative to the retaining washer. . This suggests the washer rotated with the impeller for at least a portion of one revolution. The washer surface which was in contact with the nut '
had a circumferential score mark consistent with the damage seen on the nut as shown in Photograph 12.
During a discussion with the mechanic who disassembled the pump, it was indicated that once the torque necessary to overcome the loctite in the threads was applied, the nut turned freely. This indicates that the nut was not holding the impeller in contact with l the shaft. Furthermore, when hydraulic equipment was used to push i
the shaf t from the impeller during disassembly, there was no " POP" as would be expected if the interference fit was still-present.
Thus, it seems quite apparent that at the time of disassembly the impeller was relatively loose on the shaft.
In summary, it is apparent that the impeller from the water jacket pump of the diesel engine from Unit 102 spun on the shaft after the crankshaft failure prior to disassembly. Visual evidence suggests relative rotation between shaft and impeller did not occur for an l extended period of time. This opinion is based on two obser-vations: 1) the major damage to mating impeller and shaft surfaces is confined to a small region of the overall contact area, and 2) there is no evidence of damage from frictional heating which would be expected if the impeller had spun on the shaft for a significant period of time.
during failure ofThus, the it is most likely that impulse loads imposed crankshaft were great enough to overcome frictional forces in the impeller / shaft joint. The impeller then rotated relative to the shaft for the short period of tina between crankshaft failure and engine shutdown.
In an effort to establish conclusively whether the damage to the water jacket pump of Unit 102 was a result of the traumatic events involved in the crankshaft failure, pumps from Units 103 and 101 l
were also disassembled and inspected. During disassembly of the pump from Unit 103, a torque exceeding 175 foot pounds was required to loosen the nut securing the impeller to the shaft. Furthermore, i
- a significant amount of force was required to separate, shaf t and.
- impeller and thess was a very definita " pop" as the interference fit of this joint was broken.
These observations are in direct l contrast to the situation in Unit 102 and indicate the impeller was still firmly joined to shaft at the time of disassembly of the Unit 103 pump.
The various components of consequence from the Unit 103 pump are shown in Photographs 13 through 15. There was some corrosion in-the vanes of the impeller as well as areas of casting porosity T7 t'-'t-,y-s'**P*tq'e T=ty'-pre =c +--**-g-Mg - ge w ,e'*rp = ewY-9 9 Wry-T eye m gwy3wmcre-gi,eg**g D- ewygy wp>t- We-f w v---*ge- - - * - e-v'e-Tv*wwr--We**
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J December 15, 1983 M. H. Milligan Page 4
-similar to those seen in the pump from Unit 102. However, the I
' impeller bore was in excellent condition with no scoring or other evidence that there was any relative rotation with the shaft. The machining marks were still evident and the bore surface was very smooth (Photograph 16) . The bearing face on the suction side of
! the impeller showed no evidence of wear from the retaining washer.
The shaft taper surface was in excellent condition with no evidence of scoring, wear or relative rotation between impeller and shaft (Photograph 17) . The only evidence of wear on any component of this pump was at the wear ring of the suction flange. This ring showed wear over approximately 120' of the circumference as shown in Photograph 18. There does not appear to have been any contact over the remaining portion of the wear ring circumference.
Mr. Gary Rogers observed the disassembly of the pump from Unit 101.
~
He likewise did not observe any evidence of relative motion between the impeller and shaft of that pump. Thus, in two of three water jacket pumps from the emergency generator diesel .ngines there was no evidence that the impeller loosened on the shaft during opera-tion.
Similar negligible amounts of corrosion and porosity were seen on the Unit 102 and 103 jacket water pumps, and were found to be unrelated to the relative motion of the shaft and impeller, and unrelated to the reliable performance of the pumps.
The only instance where definite evidence that the interference fit -
between impeller and shaft was lost during service is the pump from Unit 102 which sustained the crankshaft failure. On this pump there is no evidence of heat damage, and major scoring is confined to a relatively small area of the shaft / impeller contact region.
.This indicates that rotation of impeller on shaft did not occur for a long period of time. FaAA therefore, concludes that the impeller did not separate from the shaft until the time of crankshaft failure. When the crankshaft failed, it is most likely that severe impact loads produced forces on the impeller / shaft joint which exceeded the str.ength of the interference fit.
i :
Donald O. Cox Failure Analysis Associates DOC:ss I Ellis, Hunton & Williams T.
cc:
G. Rogers, FaAA C. Wella, FaAA T7-
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1 PHOTOGRAPH CAPTIONS
- 1. Pump from Unit 103.
+
- 2. Pump from Unit 103 with suction flange mmoved.
- 3. Impeller from Unit 102 pump.
- 4. Shaft from Unit 102 pump.
- 5. Retaining washer and nut from Unit 102 pump.
- 6. Bore area of impeller from Unit 102 pump.
- 7. Lip around impeller bore of Unit 102 pump.
- 8. Shaft taper where impeller was mounted, Unit 102 pump.
- 9. Shaft taper where impeller was mounted, Unit 102 pump.
- 10. Shaft flange showing metal transfer. Unit 102 pump.
- 11. Nut from Unit 102 pump.
- 12. Retaining washer from Unit 102 pump.
- 13. Impeller from Unit 103 pump.
- 14. Shaft from Unit 103 pump.
- 15. Retaining washer and nut from Unit 103 pump.
- 16. Bore area of impeller from Unit 103 pump.
- 17. Shaft taper where impeller was mounted Unit 103 pump.
- 18. Wear ring in suction flange. Unit 103 pump.
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. EE Fe: Jons Peebles ' W+ h ' acts, Inc.
'725 Clarkstone Roaa
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. Llevelanc. O*uo 44110 Telepnene- (216) 481 1500 Telex: 241564
', FAILURE ANALYSI.S REPORT - EF-3060 ON 8
4375 kVA, 3500 kW, 4160V, 3-PH, 60 Hz, 450 RPt.1 CLASS 1E SYNCHRONOUS ROTOR SERIAL NO. 17404267 8
FOR LONC ISLAND LIGHTING COMPANY l
SHOREHAM PLANT, NEW YORK BUILT FOR
~
TRANSAMERICA DE LAVAL, INC.
P.O. BOX 2273 '
OAKLAND, CALIFORNIA 94614 gi CERTIFICATION
- 5i!.j'.,,This,is to certify that the contents of this report are a true and accurate
' ~
- stateriiniof findings mado during the inspection and diagnostic testing of i damaged equipment performed by skilled personnel of Parsons Peebles-Electric Products, Inc., October 6 and 7,1983. .
Engineering interpretations of these findings are correct to the best of my professional judgement and supported by my own qualification as a Registered Professional Engineer, duly licensed to practice in the State of Ohio.
& W.
Peter M. Silverberg, P... Parsons Peebles-Electric Products, Inc.
l State of Ohio License No. E-041988 Cicveland, Ohio Senior Engineer, insulation Oct@er 11,1983 e
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FAILURE ANALYSIS - ROTOR POLE 7: ROTOR 17404267
- 1. Summary l
I Engineering evaluation of the Class 1E equipment damage reported beinw resulted in the following conclusions:
I 1.1 The coil of Rotor pole #7 grounded as a result of mechanical damage to the insulation in the left rear upper corner of the i pole. The steel pole body in that location had a sharp corner I which was located sufficiently close to the winding. .
i Continued self-induced vibration allowed an opportunity for
' aforesaid corner to wear away the insulation resulting in a ground. This is classified as an irrelevant failure within the scope of Chapters 5 and 6 of IEEE Std. 308-1978 and totally unrelated to equipment design or materials.
1.2 Two roter poles had corners knocked off the tcp washers.
This is not a failure as the poles themselves are fully opera-tional . This is classified as minor, repairable mechanical l damage. -
1 l 1.3 The equipment was found repairable. The broken washer
- y corners were repaired per Engineering Specification ER-6.1
- I (Appendix B). Pole #7 was cleaned; its sharp corner rounded off; and its coil was rewound as per L-11027-
- i 2. Introduction j 2.1 Rotor 17404267 was found to have a ground by LILCO personnel i during an inspection of diesel engine problems.
2.2 This rotor was shipped to PP-EP for repairs under our Sevice No. 4-4138. It arrived 10/ 5 /83. The incoming inspection re-port (Appendix A) showed clearly a ground to Pole #7.
- 2. 3 Pole #7 was removed from the shaft and a diagnostic test set- ,
up. The diagnostic apparatus is a 1000W resistance in series
~
'f* with the 120 VAC feeder and the pole. Smoke from the ground
- m. - was marked with an arrow on the head. The outer la.yers of
.:. ~
wire were stripped from the pole down to the first turn. The
.k i first turn of wire was gently removed and the grounded spot =-
located at the left rear corner. The three reference photos ,
- show: Figure 1 - the first turn. The ground is at the left rear corner. Figure 2 - A close up of the burnt wire. -
. . Figure 3 - the grounded spot on the pole body.
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-p-d, 2.4 The insulating' paper was removed from the pole body and a sharp corner was found at the spot of the ground. The sharp corner was located at the edge of the insulating washer which is why it l did not cause a ground in manufacturing but required the vibration g ,
from running to wear through insulation.
I
- 3. Probable Mechanism of Failure *
- 3.1 Based on the evidence described above, the failure of ground .
g insulation of wirding on Pole #7 was caused by accelerated wear of the pole body insulation due to normal self-induced vibration of the equipment. The rate of wear was accelerated by the im-properly blended radius of the coil support edge, resulting in
, a severe concentration of pressure on the pole body insulation
. ,1 material .
3.2 Repetitive differential thermal expansion and contraction of the coil (copper) and the pole body (steel) resulted in the fluctuating pressure on the insulating material sandwiched between the pole i and coil. This mechanism allowed abrasion due to self-induced I vibration during the operation (when hot) and applied increased pressure at the worn spot upon cool-down, eventually leading
- 9 to puncture.
3.3 With the exception of the incomplete blending of coil support surfaces during the edge grinding operation, there was no evidence of any abnormal conditions pertaining to design, ma-terial, workmanship or u:e. The incomplete blending of sur-
- faces in one of the four corners is a typical example of "marginai" workmanship and it is difficult to detect by routine inspection and normal NDT methods.
- 4. Recairs 4.1 Chipped washers on poles were repaired as per ER-6.1. ,
4.2 Pole #7 was completely cleaned and the sharp corner carefully smoothed. It was then rewound and vacuum-pressure impregnated in MV-10.15 (Isochem S-100) . It is current PP-EP practice to
- : use a wire insulation of heavy enamel plus single daglass instead . c l of double daglass as this substantially reduces.the possibility l , of interturn shorts. This change was made on the new winding.
The insulating paper now used is DMD which is'prefe7r'ed'to "Duroid" used on the original pole.
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- 3. Conclusions Ground insulation failure of Pole #7 was due to excessive wear at a high pr, essure spot fabricatiore that of the resulted pole piece. from marginal quality of workmanship in The cause was eliminated during the re-
! pair.
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s- . x. INSPEC'"ICN ?2 PORT
. I N _0-6-82 R-Order: h h118 Ni
- Transa= erica Delatal Type Equip
- nent: Sin. Gen Rotor I
t 11027 y a:ne : 170 volts: 1'25 Amps: 252.6
,150 Se__ea., . 17kO4267-200 CONDITICN OF UNIT %'EZ'T RICZIVID .
vas received :0=ted inside a vcoden crate. The rotor was covered with a heet. The shaft was supported by wooden cla:ps, and protected with rubber
- 1. Megger ?:le i7 - 0 Megs Re=='-der of Poles - 200 + Megs
- 2. Slip :. gs si.ightly grooved 3 3 Fan 10ckplates are ope::ed b k. L0ckplates On field cc: ections to slip rings were opened
- 5. Breken washers c: Poles l'3 & 14
- 7. "Separati::" c: Pole 16 either the vasher was b=ke and when repaired did ::: retun to original setting, or the 'over _
layers of the vi dings pushed it away, :o sericus probles.
- 8. Marks frc: lifting cable c shaf t - S. R. End. (Not curs) re:cyal of ?cle 17 frc: spdier,1 stud came out.) '
l ML F.IS'7LIS ,
_ _ _ ~ Pole .272 CEMS 3 21.5 'Deg C
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l ' Pole on spider .282 CEMS a 21.5 Deg C )
l i (for cc:parisen) 10-7-83 -
I
.; Pole . Lead to Orcu=d 30390 Ces )
VI 10-6-83 i
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.l , Pole)Outside Lead to Orcund 30,990 Oss) 1
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"#, ,afNaistING SPECIFICATION ta
.......... ....../78.... ....s 1 ........
SUP ER SED ES . . : .N1?.M . . . . . . . . . . . . . . . . j . . . .
SHEET N0....I... 0F.... 2......... SU P ER S ED ED BY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
' REPAIR PROCEDURE (FIELD) FOR BROKEN POLE WASHERS
.Scoce -
This procedure is limited to repairing rotor pole washers that were broken as a result of mis-handling and where the pole winding itself -
is intact electrically with no visible signs of damage. -
0 Materials k MI-10.1 Glass-Polyester aminate MV-20.10 Epoxy Coil Sealant MS-10.2 Solvent - MEK MS-10.4 Solvent - Acetone MV-10.5 Insulating Inamel
,0 Tein: De sicn rA The Service Technician shall cut the replacement piece and the remainder of washer to meke jotr.ts which are s%tched in order cf desirability. The -
dark line is the adhesive. The underside of the joint may be reinferced
, with a thin stiffener piece of MI-10.1 if accessible.:
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[ \ e Double buttlap - preferred H2 t ---d
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Scar # butt - usually practical .
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, Plain butt - acceptable in small inaccessible areas only.
N.0 Surface Preparation -
'h.:.
g P }.: , ". 4 .1
. Roughen all s'urfaces for adhesive with 100 grit emery cloth, c.l , 4.2 Wipe off dust with a soft cloth.
.j;'[ 4.3 Wash clean with acetone or methyl ethyl ketone. l 5
%rpaAFDBYrINC.,
Pt ELECTRIC SATE:
PRODUCTSDATE:
' PROVED BY:
DIVISION,1725 CLARK 5 TONE ROAD, Cl APPROVED SY: DATE:
MN_r:ssarsmume!-- --
CODE DATE SP EC. M 0.
- 7. 9N E E R I N G S P E C I F I C . A T I O N . . . .E. R. . . . . . . v. 2.
SUP ERSEDES . . . ..NEW , ,, ,,,,,,, ,,, ,
d al EET M0. . . 2. . . 0 F . . . . 2. . . . . . . . . SU P ER S E D ED BY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
f.
REPAIR PROCEDURE (FIEI.D) FOR BROKEN POLF. WASHERS N
. H L
E if Adhesion .
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5 .1 Mix epoxy per instructions given in MV-20.10.
- u 5.2 Spread to make adhesive jointand exposed conductor seal. ,
5.3 Clamp repair piece in place.
5.4 Cure for 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> at or above 70U F. . ,
5.5 Sand any bumps smooth.and restore finish coat. .
Quelttv Check
- l Iap two scraps of MI-10.1 together with excess MV-20.10 and let cure -
same as the washer. Try to break the adhesive joint, If of proper f strength, the laminate will tear or break, s
[
Documentation '
b ! .
All field repairs per ER-6.1 performed on Class IE equipment are subject to inspecticn and certification by the authorized E.P. Service personnel. -
- All materials used in the repairs must be certified as required by the applicable Material Specifications. E.P. warranty is conditi:nal u; r. ,
L compliance with the abcve.
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TEC INC., ELECTRIC ""ODUCTS DIVISION,1725 CLARKSTON.E ROAD, CLEVELAND 44112 wmern av. 01.86- AP* #0 V FD B. Y. : .. . , DATF: ,
APPPOYED BY: DATE: i 1
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M4T3/ 7396 4
ANALYSIS OF THE REPLACEMENT CONNECTING R00 BEARINGS f
- FOR EMERGENCY DIESEL GENERATORS, FATIGUE LIFE PREDICTION SHORElfAM NUCLEAR POWER SIATION f
t q
j g' Prepared ay j Failura Analysis Associates ~
2225 East Ba/shcra Roait j Palo Alto, California yJ 3fj3
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Dece nber 15,19d3 4
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'l 1.0 Sl2HARY AND CONCLUSIONS Four upper connecting rod bearing shells in two Transamerica Delaval Incorporated (TDI) Enterprise diesel engines at the Shoreham Nuclear Power
)
' operation.
Station (SNPS) were found to be cracked after about 250 hou: s of full load; 1
An earlier Failure Analysis Associates (FaAA) report [1] has been issued analyzing the cracking in qualitative terms. That report cited high peak oil film pressure, lack of bearing shell supoort at connecting rod cham-I fers, concentration of load at bearing ends, and voids 0.5m to 0.7mm in ciameter as contributing to the cracking.
Along with new crankshafts of modified design, new connecting rods and new connecting rod bearings have been installed in the the SNPS diesel en-gines.
Tne new connecting rods have a smaller bore chamfer, eliminating the unsupported tearing ends. The inuease in crank;:in diarreter from 11 inch to f
12 inch was shown to reduce peak oil fil:n pressure fecm 29,745 psi to 26,780 psi.
This pressure is slightly acove an industry-accepted guideline for peak value and suggests the need for fatigue lifetine calculations.
Suosequent finite elenient metnod (FEM) stress analysis and a fracture q
mechanks analysis of the fatigue cracking of the bearings nave shown that the tensile stress in the bearings, that caused cracking in the original bearings, is reduced by 50.5% in the new bearings. The predicted fatigue life of the new bearings is 513,000,000 stress cycles, or 38,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> at full loac, despite the fact that the peak oil film oressure is slign:1y above an industry guideline [3).
These industry guidelines are not absolute maximum allowable val ues .
Some engine manufacturers successfully operate engine sleeve bearings above industry guidelines in specific applications, by exercising careful control of engine co'mponent design, manufacturing, and operating conditions.
1.ILC0 appears to be exercising the degree of control necessary for successful W
Assowes i
I, operation at 26,780 psi peak oil film pressure. In addition, the FEM and fracture mechanics analysis ~ of tne connecting rod bearings, performed by FaAA, is a much more detailed analysis than is performed by engine builders and bearing suppliers in the course of normal applications engineering. This j
detailed analysis provides the basis for the calculated bearing fatigue life.
This expected fatigue life is conservatively calculated in that it does nei. include any reduction in edge loading of the bearings obtaining from tne increased pin diameter and concomitant reduction in torsional yawing of . .; e I .
crankshaft pin.
The expected fati;ue life is approximately an order of magnitude greater than the total anticipated full-load test time during the 40 year life of SNPS.
Also, the routine maintenance procedures planned by LILC0 require periodic inspectica of all tNe surfaces, including nondestructive examination t
for fla s and bearing tnickness neasurement, eacn scheduled plant outage.
I d
2.0 INTRODUCTION
An earlier report by Failure Analysis Associates (FaAA) [1] identified the primary causes of damage of some of the connecting rod bearing shells in the TOI Enterprise diesel engines at SNPS. Records indicate that after approximately 250 hours0.00289 days <br />0.0694 hours <br />4.133598e-4 weeks <br />9.5125e-5 months <br /> of operation, at or above 100" power, four of the twenty-four upper connecting rod bearing shells had cracked about s/ e-incn
) from one end. These cracks extended radially througn the thickness -of the
) bearing and circumferentially to a lengen of approximately 4 inches.
Four factors contributing to tne cracking were identified in the earlier report.
d First, the peak oil film pressure in tne hydrodynamic oil 1 film separating the crankshaft and the bearing exceeded One guidelines of a l
major independent supplier of engine
Dearings oy 14",
[2, 3]. Second, the geometry of the connecting rod bore left the end of the bearing unsupported.
l inducing ca'ntilever tending. Figure 1 snows tne configuration of tne connect-l ing rod relative to the bearing. Third, the cortact patterns in t!1e electro-plated babbitt overlay on the bearing inner diameter showeo tnat the cracked I
s bearings had betn subjected to edge loading, or a concentration of load on the
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bearing ends due to lack of parallelism between the crankshaft journal and the bearing surface. The fourth cause was thougnt to be tne presence of voids ranging in size from 0.Em to 0.7mm.
The failure analysis of the connecting rod bearing shells indicated that voids in the size range of 0.6m to 0.7m were the initiation sites for
- ne cracks that formed. However, analysis since issuance of the initial report showed that these voids are not atypical of' cast aluminum bearings, and in the abscr.ce of abnormally high stressa would not normally be detrimental to oearing life.
The computations described in tnis report were performed in crder to develop a conservative estimate of the expected life of the new connecting rod bearings in the TDI Enterprise' diesel engines. Along with the new crank-snafts, new bearings and new connecting rods nave been put into the engines.
Two of the causes of the bearing cracking have thereby been addressed: the unsupported bearing encs have been eliminated with the new components, as sr. awn in Figure 2, and the calculated peak oil film pressure has been reduced to 26,780 psi in the new connecting rod bwings [2]. Througn finite element stress analysis and fracture mechanics c6:cul3*. ion of fatigue crack growth, the fatigue lifetime of tne new configuration can be estimateo to determine a suitaole inspection or reolaceirent interval fer the connecting rod bearings.
3.0 BEARING STRESS ANALYSIS Finite element analysis of bota tne criginal and replacement ccnnecting rod bearings was performed using tne ANSYS code. The results of the journal occit analysis [2] -ere used as the basis for tne applied loads on tne bear-ing. Since the journal orbit analysis assumes perfect parallelism between the bearing and the journal [4], the pressure distribution was skewed tcwird the end of the bearing to correlate witn the contact patterns in the babbitt. The loading was skewed so tnat 82.6t of tne applied load is carried on the outer 28.2". of the bearing length. Both the cast aluminum bearing snell and the so rged steel connectjng rod were included in the finite element model . In accition, the cor.;pressive preload on tne bearing resulting from the inter-ference fit of the bearing in the connecting rod was included in tne model.
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The maximum tensile stress was found to occur in the longitudinal direction, at the inner surface of the bearing shell, at a node 0.879 incn from the end of the bearing. The values of tnese Stresses are listed in Table 1.
Table 1 Maximum Tensile Stress:
Longitudinal direction, on bearing inner diameter Original bearings,11 inch diameter crankpir.s:
tensile stress - 10,931 psi New bearings, 12 inch diameter cranksins:
tensile stress - 5,412 psi The maximum tensile stress in the new bearings is predicted to be only nalf the stress in the original bearings that cracked af ter about 250 hours0.00289 days <br />0.0694 hours <br />4.133598e-4 weeks <br />9.5125e-5 months <br /> of full-load operation.
About one-fif tn of the reduction in stress results from a reduction in the calculated peak oil film pressure, a direct consequence of tne larger journal diameter. The remaining four-fiftns of tne reduction in stress is directly attributable to the elimination of the unsupported bearing ends via reduction of the bore chamfer in the new connecting rods.
4.0 BEARING LIFE PREDICTION .
The known behavior of aluminum in response to cyclic stressing can be usea to predict the fatigue life of the new cearings installed in the TOI I Enter: rise diesel engines. In the elastic strain, high-cycle-fatigue region (numcer of cycles greater than 106), the bena<f or of aluminum can ce described l Dy the equation [5]:
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'f (2N)b wnere ea = stress amplitude ~
ej= fatigue strength ccefficient N =
number of cycles b = fatigue strength expenent.
The stress amplitude for the connecting rod bearings is one-half of tr.e maximum tensile stress computed by the FEM analysis described in Section 3.0. The coefficient ) has not been determined for tne 8850 aluminum hearing alloy, but in using the ratio of tne stress amplitudes to compute the ratio of tne numoer of cycl es to failure, the coefficient drops out of the ex pression. The fatigue strength ex ponent , b, also has not been determined for the B850 alloy, but from work on a wide variety of metals and aluminum alloys, it has been determined that the value for b is in tne range of -0.06 to -0.14 The most conservative computation is to use b = -0.14, whicn yields the smallest change in N for a given change in ea -
( o cear = .495 =
ej (2N (New bearing)) -0 3 ej (2N (dlc oearing)) w l' N (New bearing) = M2
.5 (vic oearingj This calculation predicts that the new Narings should not fati by fatigue until tney have experienced 152 timer the number of cycles tnat failed the original bearings.
The connecting roc bearings are subjected to one stress cycle in every two rotations of the crankshart, or 225 cycles per minute. The original bear-ings were cracked after approximately 250 nours, or 3,375,,000 cycles. The new betrings would not ,e b expected to begin to exhibit cracking until after 513,000,000 cycles, or 38,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> of full-load operat'.on nave occured.
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5.0 DISCUSSION -
Calculations have demonstrated that the major contributor to the crack-ing of the original connecting rod bearings in the TDI Enterprise diesel engines was the unsupported bearing eno, the resdit of a 0.25 inch chamfer in the connecting rod bore.
Eliminating thi.s unsupported end, along with lowering peak oil film pressure by 101, results in a predicted fatigue life of 38,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> at full-load.
This life is appruximately a tactor uf 10 greater than tne expected time of full-load operation during the lifa of the plant. Consequently, FaAA is abl a to conclude that the connecting rod bearings have adequate design fatigue lifetime without the need for replacement during normal plant operation despite tne fact that tne oil film pressure is still slightly above an industry guideline for peak value [3].
The fatigue life of the new bearings nas been conservatively calculated in tnat no reduction in yawing of tne crankpin journals relative to tne bear-ings nas been assumed; sucn reduction is expected as a consequence of the increased tors'ional stiffness of the new crankshaft. This yawing contributes to the edge loading that was evident on every cracked bearing.
t change in materials properties or structure was assumed. The 38,000 hour0 days <br />0 hours <br />0 weeks <br />0 months <br /> predicted life for tne new bearings is in the presence of the 0.5mm to 0.7mm voics found in the old bearings.
As a check on tne influence of the voids, tne stress intensity factor range, AK, ans computed for these voids and the stresses ccmputed by FEM analysis. For the original bearings, tx = 1.3 ksi v' in. For the new bearings, AK = 0.9 kst [in. ~
The threshola value of AK for growth of a pre-existing void in fatigue is not known precisely for this alloy, but in comparison to other aluminum alloys, is estimated to be aopecxt-mately [5] AKth = 2.0 ksi v in. [5]. Therefore, since tne t.X vclue for the i new baarings is celow tne thresnold val ue for growtn of pre. existing voids, tnis presence of 0.5mm to 0.7mm volds will not nave an impact on fatigue cr.acking.
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. v The state of stress in the old bearings is close to that required to cause the voids to initiate cracks, while the state of stress in the new bear-ings is well below that necessary to initiate fatigue cracks at the voids.
The inspection procedure at Shoreham planned by LILCO calls for inspec-tion of all surfaces of the connecting rod bearings, including nondestructive inspection for flaws and measurement of the thickness in six places, including the 2nds subjected to edge loading, during every scheduled refueling outage.
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- REFERENCES
- 1. Fatitre Analysis Associates " Emergency Diesel Generstor Connecting Rod Bearing Failure investigation. Snorenam . Nuclear Power 5tation, Pa l o Al to ,
, California, Octocer 31, 1983.
- 2. Journal Oroit Analyses of TDI Enterprise R-48 Diesel Engine performed by Imperial Clevite Inc. for Failure Analysis Associates, Octooer 6,1983,
- 3. W. A. Yanraus (Hanager of Product Analysis, Imperial Clevite Inc., Engine Parts Division), private comunic?tien witn L A. Swanger (FaAA), Octecer 4, 1983.
- 4. Ross , J. M. and R. R. Slaymaker, "Jourr.al Center Orot ts in Piston Engine Bearings, " SAE Paper 690114, Society of Automotive Engineers, Warrendale, Pennsyl vani a , 1969. '
- 5. H. 0. Fuchs and R. I. Stephens, Metal Fatigue in Engine 3 ring, John Wiley &
Sons, New York, 1980, p. 78.
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,. LILCO, Fcbruory 7, 1984
% d-CERTIFICATE OF SERVICE T4 FE3 -9 A10:39 In the Matter of CFic. . . . e .
LONG ISLAND LIGHTING COMPAgCXEin.G e, SEsp (Shoreham Nuclear Power Station, Unit ypCH Bf Docket No. 50-322 (OL) i I, hereby certify that copies of LILCO's Response to Suffolk County's Motion to Admit Supplemental Diesel Generator Contentions were served this date upon the following by first-class mail, postage prepaid, or by hand as indicated by an asterisk:
Lawrence Brenner, Esq.* Secretary of the Commission Administrative Judge U.S. Nuclear Regulatory Atomic Safety and Licensing Commission Board Panel Washington, D.C. 20555 U.S. NRC 4350 East-West Highway Atomic Safety and Licensing Fourth Floor (North Tower) Appeal Board Panel '
Bethesda, Maryland 20814 U. S. Nuclear Regulatory Commission Dr. Peter A. Morris
- Washington, D.C. 20555 Administrative Judge Atomic Safety and Licensing Atomic Safety and Licensing Board Panel Board Panel U.S. NRC U.S. Nuclear Regulatory 4350 East-West Highway Commission Fourth Floor (North Tower) Washington, D.C. 20555 Bethesda, Maryland 20814 Robert E. Smith, Esq.
Dr. George A. Ferguson* Guggenheimer & Untermyer Administrative Judge 80 Pine Street School of Engineering New York, N.Y. 10005 Howard University 2300 6th Street, N. W. '
Washington, D.C. 20059 l
L .
l _ _ . _ _ _ . . . - . . - -
_2
/
Bernard M. Bordenick, Esh.* David J. Gilmartin, Esq.
. David A. Repka, Esq. Attn: Patricia A. Dempsey, Esq.
t
,. - U.S. NRC County Attorney
- Maryland National Bank Bldg. Suffolk County Department of Law 7735 Old Georgetown Road Veterans Memorial Highway Bethesda, Maryland 20814 Hauppauge, New York 11787 l . Herbert H. Brown, Esq. Stephen B. Latham, Esq.
Lawrence Coe Lanpher, Esq. Twomey, Latham & Shea Alan R. Dynner, Esq.* 33 West Second Street Kirkpatrick, Lockhart, Hill, P. O. Box 398
, , Christopher & Phillips Riverhead, New York 11901 8th Floor 1900 M Street, N. W. Ralph Shapiro, Esq.
4 Washington, D.C. 20036 Cammer and Shapiro, P.C.
9 East 40th Street Mr. Marc W. Goldsmith New York, New York 10016 Energy Research Group 4001 Totten Pond Road James Dougherty, Esq.
Waltham, Massachusetts 02154 3045 Porter Street Washington, D.C. 20008 MHB Technical Associates 1723 Hamilton Avenue Howard L.'Blau Suite K 217 Newbridge Road San Jose, California 95125 Hicksvillo, New York 11801 Mr. Jay Dunkleberger Jonathan D. Feinberg, Esq.
New York State Energy Office New York State Agency Building 2 Department of Public Service Empire State Plaza Three Empire State Plaza Albany, New York 12223 Albany, New York 12223 h e ds k W~ & n L (nthony F. Earl'ey, Jr.~
g
. Hunton & Williams 707 East Main Street P.O. Box 1535
, _ Richmond, Virginia 23212 DATED: February 7, 1984
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