ML20141N691

Trip Rept of 860227-28 Site Visit to Observe Fairbanks Morse Upper Crankshaft Main Bearings.Bearings from Engine 11 & 13 Looked Acceptable,But Showed Scratched Areas.Engine 12 & 14 Bearings Not Observed

ML20141N691
Person / Time
Site:	Fermi
Issue date:	03/07/1986
From:	Louzecky P ENGINEERED APPLICATIONS CORP.
To:	Hulman J NRC
References
NUDOCS 8603170526
Download: ML20141N691 (10)

Text

ODlWET f' SOOcff ENG/NE EN21NEERED APPLICATIONS CORPORATION ENGsNr system ENGINEERING AND DESIGN CONSULTANTS des /GN ANAL ysTS 1674 Witherbee Road. Troy, Michigan 48084 gpggggg,373 Phone 313-646 6439 1

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March 7, 1986 Mr. Jerry Hulman, P-822 Chief Plant Systems Br. DBL U. S. Nuclear Regulatory Coinmission Washington, D.C. 20555

Subject:

Visit to Ferni II Nuclear Power Plant on February 27th. & 28th., 1986 Order Number ER86-0823 rear Jerry:

Enclosed is my report on my visit of February 27th. and 28th.,1986, to Fermi II with Mr. Fred Maura.

We saw bearings from Engines 11 and 13 after they had run over 400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br /> and had about 40 pre-lube starts. Also, these engines were flushed before testing.

Engines 12 and 14 were also run about the same length of time but these two engines were not flushed, after the uuper crankshaft journals were polished in the engine. We did not see any bearings from these engines.

Sincerely yours, Paul J. Louzecky PJL/rll l

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P603170526 860307 PDR ADOCK 05000341 P PDR

1 VISIT TO THE FERMI II

. ENERGY CENTER OF DETROIT EDISON l TO LOOK AT SOME FAIRBANKS MORSE UPPER -

CRANKSHAPT MAIN BEARINGS INTRODUCTION A visit was made on February 27th, and 28th, with Mr. Fred Maura of.NRC to the Fermi II Nuclear Power Plant of Detroit Edison.

The purpose for the visit was to look at some of the upper crankshaft aluminum main bearings and journals of engines No. 11 and No. 13. Engine,yNov ilu.had e be.en,run for

.416ehb6Es while some of the bearings on engine No. 13 were

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.run;for2504th'ours. The engines were also started about 40 g

. tim.es,aboth:cfasttiand: slow 7but'in all cases the upper crank-shaft was pre-lubricated for about 2-2) minutes before start-f up.

UPPER MAIN BEARING SHELLS PROM ENGINE NO.11

, Initially four upper crank aluminum main bearing shells

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were examinted from engine No. 31?'The shells were NoT ,-3,,i5,",

6m and l3.W Shell No. 13 is both a radial and thrust bearing.

These1 bearings ~ had been';run forik16Etiours.. and.Thatf 30islowj andf0; fast 1sts.rts? The upper crank bearings were pre-lubricated W

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for about 2-2h minutes before starting. No dry starts were-made. All were planned pre-lube starts. (The engines,how-ever, d have a one gallon back up reservoir that supplies pre- ,

lubrication. oil at starting).

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the engine bearings were checked through the cover hand holes with a .002 inch -

thickness gage to see if some bearings had closed in due to

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. wore.found: good. iItiehouldu;,e wa #;g overheating.- All the bearinEs kiieT,asteditsud1F6iGIttiitIE6Episs _? NeI213Io annotlbe Lebec ked- b e -CGEEj]

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Also, prior to starting the endurance test this engine had been flushed for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

. The bearing shells,in my judgement, looked acceptable, but they all showed both polished and gray or scratched areas.

i The scratched a reas were caused by the journal scratching the bearings. See Figures 1 and 2. The polished and scratched

_ areas were quite irregular, no it might be concluded that the l

I hand polishing of the journals was irregular or slightly wavy and uneven.

The oil film thickness for these bearings is small,only about 100 micro inches, so the journal wavyness would only have to be about + .00005 .0001 of an inch to produce the resulta noted on the bearings.

The Fairbanks Morma people said that they used both the s

front and back of 250 and 100 4 grit paper with oil when polish-L ing the journals. The joural surface roughnses. in my judgment, was about 20 micro (mean) inches, which is rougher than desired for bearings of this size.

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'The bearing shells showed slight working on their backs but no working at the bearing joint.

This condition indicates r.

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very litple bearing crush even when hot. y ,

The oil for all the engines was changed from Shell to Robil Guard 450. This is the same oil used by other Fairbanks Morse Opposed piston engine operators.

During this bearing examination the oil was felt and

, appeared to have dirt particles of about 3 microns. This dirt was so small it could pass through the 5 micron. oil 7

filter and it would not be expected to cause any bearing lub-rication problems. #

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> When these bearings were installed prno1 bearing 7 break?in 'g compound, such as "*Iime Saver", was used. 9 y,yre#

The following day main bearings No. 8,and 9:were removed, 3 for examination from this engine. The bearings looked similar to the previous bearings. However, it was noted that the bearing shells were somewhat dry. In other words, much of the oil had drained from the bearing surface after shut down. The crankshaft journals, however, were wet with oil.

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UPPER MAIN BEARING SHELLS PROM El:GINE No. 13 s r

Beurings,No.,3, 4,710 and,13 were; removed from this rf engine for examinat!7n, but by the time I arrived bearin68 No. 3, '4, and 10 had been reinstalled. I was told, however, by Fred Maura that they looked similar to these of Engine No.

11. ,,

Bearings 3 and 13 had been run for 504 hours0.00583 days <br />0.14 hours <br />8.333333e-4 weeks <br />1.91772e-4 months <br /> while the other bearings had been run for about 740 hours0.00856 days <br />0.206 hours <br />0.00122 weeks <br />2.8157e-4 months <br />. Also, on

this engine the crankshaft was removed from the engine for polishing the journals. They looked about the same as the journald on engine No. 11. These bearings had also experience 30 slow and 10 fast starts with about a 2 minute pre-lube be-fore starting.

Also,the" Time = Saver %compoundhad,beenused,.toJreak-}n m these bearings. When feeling the oil, no dirt was felt as it had been on engine No. 11. This engine had been flushed for 54 hours6.25e-4 days <br />0.015 hours <br />8.928571e-5 weeks <br />2.0547e-5 months <br /> before testing.

Bearing No.13, the combined radial and thrust bearing showed both the polished and gray or scratched area, but in addition it had a small pitted area.

The pitting indicated welding of the aluminum cnto the crank journal. The aluminum was smeared completel7 arou6d' the journal, forming a very thin band about i inch wide on the back half of the journal. See Figure -3.

Based upon my experience and after seeing other failed aluminum bearings and journals that picked up aluminum, I would expect this bearing to fail if engine operation had continued for an extended period. The aluminum pick-up on the journal was not great enough for immediate trouble, but it would grow to the point that the bearing would not support its load.

The subject of. aluminum pick-up on the journal and bearing failure was discussed at the January 24, 1986 meeting at Fermi II end it was the conclusion of Fairbanks Morse, Fail-ure Analysis Associates and the Fermi representatives that once the journal picks ~up aluminum, the bearing will eventually I

fail. The following day, main bearing No. 7 was removed from i the engine. The bearing loading pattern looked similar to the l

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others. The bearing seemed on the dry side even though the engine h,ad only been standing a couple of days. The journal, however,I. was wet with oil. As on Engine No. 11, prior to opening up the engine, all the bearing shells were checked for close in due to overheating with a .002 inch thickness gage.

The bearings checked out good but as previously menticned, No.13 bearing No. 13 could not be checked.

ENGINES No. 12 AND 1h No bearings were nulled from engine No. 12 and 14 during this inspection.

Engine No. 12 was run since the last overhaul about 400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br /> while engine no.14 had been run about 600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br />.

Both the engines had about 20 starts with the 2 minute pre-lube.

The crankshaft journals for both of these engines were polished in the engine, but the engines were not flushed.

Therefore, removal of the polishing dirt depended on the fil-ters. New upper crank bearirgs were installed only as re-quired.

After the extended running tests the bearings were checked for close in. All were checked except No. 13 and were O.K.

~ . _ _ _ _ . _ . _ _ _ _ _ _ . . _ _ _ - _ .

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CONCLUSI0t!S 1 (Theresultsofthetestsontheseenginesshowthat the upper crankshaft bearings if lubricated before starting will operate' satisfactorily.

2. Inspection of the upper crankshaft and bearings showed that they retain some oil after shut down but tend to drain dry in about three days. Therefore, if an emergency dry start is made within this time period the upper crankshaft bearings will probably not be damaged, but if a start is made after about three days the upper crank bearings will require pre-lubrication.

After runninE the engine should be allowed to cool down before stopping.

3. The one gallon pre-lube reservoir does not provide sufficient oil to the upper crank system for a dry start.

4 The upper rankshaft bearing loading patterns show that the operation of the engines must be monitored closely.

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g PA J. LCUZE KY March 7, 1986

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