ML20210D909
| ML20210D909 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 03/18/1986 |
| From: | DETROIT EDISON CO. |
| To: | |
| Shared Package | |
| ML20210D906 | List: |
| References | |
| VP-86-0025, VP-86-25, NUDOCS 8603270090 | |
| Download: ML20210D909 (70) | |
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VP-86-0025 March 18, 1986 Page 1 REVISION TO DESCRIPTION OF DIESEL GENERATOR BEARING RELIABILITY DEMONSTRATION TEST PROGRAM B60327009086gBy PDR ADOCK PDR P
VP-86-00251986 March 18, 1986 Page 2 REVISION TO DESCRIPTION OF DIESEL GENERATOR BEARING RELIABILITY DEMONSTRATION TEST PROGRAM Table of Contents I.
Introduction II.
Industry EDG Data III. History IV.
Demonstration Test Program IV.1 Purpose IV.2 Scope IV.3 Preparation IV.4 Test Procedure V.
Results of the Demonstration Test Program VI.
Test Results Evaluation VII. Basis for Not Continuing Routine Visual Inspections VIII Commitments for EDG Surveillance VIII.1 Lube Oil Filter Inspection VIII.2 Future Bearing Gap Checks VIII.3 Special Inspection of EDG 13 Thrust Bearing IX.
Supplemental Information IX.1 Issues Discussed In January 24 Meeting IX.2 Commitments For EDG Surveillance IX.3 Endorsement By. Colt Industries And Failure Analysis Associates IX.4 Independent Lab Bearing Evaluation IX.5 Study Of Oil Booster System X.
Conclusion XI.
References
Enclonu o 1 March 18, 1986 VP-86-0025 Page 3 I. INTRODUCTION A meeting with the NRC staff was held at the Fermi-2 site on January.24, 1986.to review the history of the Fermi-2 Emergency Diesel Generators (EDGs), their performance, and actions.taken and planned by Detroit Edison to restore the EDGs to reliable operation.- An important element of Detroit Edison's efforts to confirm the reliability of the EDGs, the Demonstration Test Program, was described in the January 24 meeting.
Handouts presented at the January 24 meeting and additional key. points were documented in Reference 8.
Subsequently, Detroit. Edison met with the NRC Staff in the. Region III offices.on February 14, 1986.. From this meeting and subsequent discussions with the Staff, it became clear that
~
additional information and clarification of this issue was required.
Detroit Edison is providing this report to delineate more clearly the maintenance history of the Fermi 2 EDGs, the scope and results of the Demonstration Test Program, and additional information requested by the NRC Staff.
This report expands the discussion of the recent EDG bearing issues beyond that provided in Reference 8 and is intended to supersede Reference 8 in its entirety.
II. INDUSTRY EDG DATA In its investigation of the Fermi-2 EDG bearing problems, Detroit Edison made a significant effort to determine how the Fermi 2 EDG operation / maintenance program compares with other programs in the nuclear industry.
Detroit Edison has initiated numerous conversations with others in the industry during the evaluations of the EDG bearing failure reviews.
These conversations have involved the engine manufacturer, NRC, -consultants and users of Fairbankt-Morse UX3s including nuclear utilities and the Navy.
A phone survey of nuclear utilities provided information from many sites and entailed conversations with plant and engineering personnel responsible for the EDGs during the past 3-6 years.
The p>0ne surveys were initially made to-determine both the methods and frequency of bearing inspections.
Information was also gathered relative to EDG starting /lcading, prelubrication, lubricating oils and overall engine performance.'
The industry information on manufacturer and type-of lube oil used is discussed in section IV.3 of this report.
F VP-86-0025 March 18, 1986 l
Page 4 i
i It 'was also determined that bearing gap checks are. currently i
being utilized by the utility and Navy personnel contacted.
Visual bearing inspections are' performed only if the bearing fails the gap check, or engine. maintenance has resulted in opening of the b' earing caps.
The Navy once performed visual inspections on a frequency based upon hours of operation, but they have abandoned this approach.
One utility contacted by Detroit Edison-used to perform some visual inspections of certain bearings, but they, too,' have abandoned this approach.
1 Edison's contacts confirmed that the frequency' of bearing gap checks is based upon the manufacturer's' inspection per Technical Specifications and is either 12 or 18 months.
The method for performing gap checks is based upon Fairbanks-Morse recommendations, and is usually performed by a representative of the engine manufacturer.
General'information from other nuclear utilities indicates a similarity in_ performance and requirements for the EDGs.
The i
EDGs are generally fast started (10-12 seconds) and loaded to 60-100% of continuous rated load for 1-4 hours on a periodic schedule of 14 or 31 days.
Prelubrication prior to planned.
starts was conducted by the utilities contacted, and ranged from i
1 to 4 minutes.
The utilities reported EDG maintenance ~
activities involving the air start system, bearings,. blowers, liners, wrist. pin extrusion, etc.
Based upon the 3-6 years'of l
information available from the phone interviews, isolated bearing
[
replacement has occurred, and has been detected in conjunction t
with the manufacturer's 12 or-18 month inspections.
III. HISTORY The history of operation and repair of the Fermi-2 EDGs was presented at the January 24 meeting.
The handouts distributed in l
this meeting are provided in Enclosure 2.
The handouts and the-discussion at the January 24 meeting, and the discussion of ChroSology in Reference 8, focused on EDG bearings. replaceo because they had " failed" or had significant surface scoring.
To date, formal discussions.in meetings with the Staff and in Reference 8 emphasized the replacement of these bearings only because Detroit Edison understood these to be of greatest interest to'the NRC Staff.
As the NRC Staff-knows, Detroit
-l a-
Enclosuro 1 VP-86-0025 March 18, 1986 Page 5 Edison also replaced bearings for reasons other than " failure".
Some bearings were replaced because of heightened concern about bearing surface conditions, such as yellow discoloration, black spots, stains, tracks left by foreign material, or very minor surface deformity, e.g.,
scratches or pitting.
Other bearings were replaced because the crankshaft was replaced.
To ensure that the Staff has a clear understanding of both the total number and reasons for bearing replacements, Edison' formally transmitted a summary of the EDG operating logs to the NRC in Reference 9.
To complement the information provided in Reference 9, a detailed ~ review of EDG bearing inspections and replacements is provided in Enclosure 3.
IV.
DEMONSTRATION TEST PROGRAM IV.1 Purpose The bearing problems at Fermi-2 occurred at a time of heightened NRC concerns about Emergency Diesel Generator (EDG) reliability,
.primarily because of problems encountered with Transamerica Delaval, Inc. diesel generators.
The type of EDG employed at Fermi-2, Fairbanks Morse (Division of Colt Industries), has a record of high reliability demonstrated in 49 nuclear applications.
The Demonstration Test Program was planned to restore confidence in the Fermi-2 EDGs as a reliable backup source of AC power.
The Demonstration Test Program simulated the number of slow starts and fast starts expected of an EDG over an 18-month fuel cycle, and the run-time that might be needed to assure safe shutdown of the plant if EDG operation were required following a Loss of Coolant Accident coincident with a loss of offsite power.
IV.2 Scope Emergency Diesel Generators 11 and 13 were selected for the Demonstration Test.
The selection of these two EDGs was based on the following considerations:
o Thece EDGs are in separate Divisions.
o Both have had bearing failures.
VP-86-0025 March 18, 1986 Page 6
+
o Both have had new upper crankshaf ts installed.;
4 o
EDG 11 experienced problems with the alignment of the bearing caps and, in general, had the most problems of the Fermi-2 EDGs.
)
IV.3 Preparation Before starting the Demonstration Test, Detroit Edison completed the following on EDGs 11 and~13:
.o A flush of the engine lube oil system was performed to help remove foreign material from-the system. (and reduce l
potential concerns about foreign material that may have been introduced by the bearing failures and crankshaft replacements in EDGs 11 and'13).
4 o
A new brand of lube oil (Mobil) was installed in all four 3
EDGs.
2 (Detroit Edison contacted other owners of Fairbanks Morse engines to determine the type of oil used by each.
Six of the other owners contacted use Mobil lube oil.
To 1
a determine whether the brand of lube oil contributes to the i
bearing differencas observed at Fermi-2, Detroit Edison initially decided to change from Shell lube oil to Mobil i
Subsequent to the January 24, 1986 meeting, Edison decided to use Mobil in all Fermi 2 EDGs.)
o Before the Demonstration Test was started, -EDGs 11 and 13 were run under load-for a minimum of 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> to " season" l-the bearings, per the manufacturer's recommendations.
j (After any future bearing replacements, a 100 hour-l
" seasoning" run will similarly be performed.)
The decision to flush EDGs 11 and 13 was based primarily on j.
experience with EDG 13.
As a result of the initial failure of EDG 13, debris from the failed #3 connecting rod and piston was a
introduced into the oil system. ~ Much effort was taken to remove the debris manually and to wipe down the internals of the engine.
After the cleanup and bearing repair, new oil and i
filters were installed.
Af ter post-maintenance.-testing, EDG 13 l
l i
2
Enclorure 1 VP-86-0025 March 18, 1986 Pcga 7 was run for over 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> and the upper crankline bearings.were visually inspected.
Two bearings were found that had significant foreign material tracks which appeared to have caused some secondary surface scoring adjacent to the tracks.
From these findings, Detroit Edison concluded that an engine flush was required to assure removal of all residual debris from the bearing and piston failure.
Because EDG 11 had experienced bearing failures, too, Edison decided to flush EDG.ll.
It was not necessary to flush EDGs 12 and 14 because they have not had the mechanical problems that EDGs' 11 and 13 have had that might have introduced an excessive amount of foreign material into the lube oil system.
IV.4 Test Prouedure The Demonstration Test included the following, in the order listed below:
1.
Gap check on the upper crankshaft main bearings using a 0.002" feeler gauge between the bearing and the bearing saddle, per the manufacturer's recommendation.
2.
Twenty (20) prelubed " slow" starts; after'each' slow start the EDG was run under load for a minimum of two (2) hours, including one (1) hour at a load of 2500 to 2600 kW.
3.
Gap check on the upper crankshaft main bearings using a 0.002" feeler gauge.
4.
Ten (10) prelubed " fast" starts;'
after each fast start the EDG was run under load for a minimum of two (2) hours, including one (1) hour at a load of 2500 to 2600 kW.
5.
Gap check on the upper crankshaft main bearings using a 0.002" feeler gauge.
6.
A seven (7)-day continuous run with the EDG under a load of 2500 to 2600 kW.
7.
Gap check on the upper crankshaft main bearings using.a 0.002" feeler gauge
Enclosuro 1 VP-86-0025 March 18, 1986 Page 8 After coupleting Step 7 above, Detroit Edison performed visual inspections of selected bearings to validate successful coupletion of the IDG Demonstration Test Program. 'Ihe visual inspections involved six bearings (#3,5,6,8,9 and 13) on EDG ll and five bearings (13,4,7,10, and 13) on EDG 13. 'Ibese bearings were selected by mutual agreement between Detroit Edison and the NIC. The selection was based upon consideration of the following factors:
'(1)
The engine manufacturer's recommendation (2)
The loading on the bearing (3)
Past performance of each bearing (4)
Detroit Edison's desire to conply with the engine manufacturer's recommendation to minimize bearing disassembly.
As discussed at the February 14 meeting in NIC's Region III office, the visual inspection was limited to the upper crankline, loaded-half bearings, since most of the EDG bearing concerns have been associated with the upper crankline bearings. The loaded-half bearing was selected because this part is subjected to engine loading during the starting transient and at load operation.
After reassenbling each engine, Detroit Edison ran-in the bearings, following the run-in schedule of Colt Industries Service Information Letter, Volume.A, Issue 5, sheet 1 through 3.
Upon conpletion of the bearing run-in procedure, the bearings were " gap checked" using a 0.002 in. feeler gauge. Following the gap check the EDGs were run continuously for a minimum of 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> at a load of 2500-2600 kW. At the conclusion of this run, the upper main bearings were gap checked again with a 0.002 in feeler gauge, and the bearings were found to be in satisfactory condition.
j V.
RESE.TS T THE IEBDEmWEIGi TEST PIOGIWlM All parts of. the Denonstration Test Program were conpleted successfully on both EDGs. The results of the Demonstration Test Program are summarized below:
i
VP-86-0025 March 18, 1986 Page 9 EDG 11 EDG 13 Post-Maintenance Run (hours) 152 162.5 Post-Maintenance Slow Starts 8
9 Post-Maintenance Gap Check Results Satisfactory Satisfactory Demonstration Slow Starts Completed 22 21 Demonstration Gap Check Results Satisfactory Satisfactory Demonstration Fast Starts Cmpleted 10 10 Demonstration Gap Check Results Satisfactory Satisfactory Demonstration Load Run (hours) 192.5 269 Demonstration Total Run Hours 263.5 341 Post-Demonstration Test Satisfactory Satisfactory Gap Check Results Grand Totals for Cmbined Post-Maintenance Testing arri Dmonstration Test Program:
Total Slow Starts 30 30 Total Fast Starts 10 10 Total Run Hours 415.5 503.5 All bearings on both EDGs passed the gap check. All bearings visually insgK:ted, except the #13 bearings on both EDGs, were in excellent condition, with no signs of surface scoring. The #13 bearing on EDG 11 had a trace of surface scoring on the bearing surface. However, there was no observable' aluminum transfer on the journal. With the concurrence of Fairbanks Morse, this bearing was reinstalled with no further work required. On EDG 13 the #13 bearing had a trace of surface scoring on the bearing surface, with a trace of aluminum about one-half-inch wide transferred to the area adjacent to the aft side of the oil groove area on the journal surface. The aluminum area was very thin and smooth, with no appendages that could penetrate the oil film while the machine was operating. Fairbanks Morse determincd that the bearing was in satisfactory condition. The aluminum was removed from the journal and the bearing was reinstalled.
VP-86-0025 March 18, 1986 Page 10 The following deviations occurred during the Demonstration Test.
None negate the results of the Demonstration Test.
Event Impact Oil Foaming, EDG 11 Changed oil, then continued (February 2, 1986)
Test Program.
Additional information was provided in Reference 9.
No impact on test results.
Low Lube Oil Trip, EDG 11 Trip occurred on low lube oil (February 13, 1986) pressure due to slow start with warm oil.
Corrective action was to raise governor setting slightly during slow start for increased oil pressure.
No impact on test results.
Fire on Exhaust Lagging, EDG 13
. Replaced damaged wiring and a (January 26, 1986) jacket cooling system gasket.
No impact on test results.
Loss of Inspection Cover Cap Screw, During bearing inspection, EDG 13 (February 7,1986) dropped inspection cover cap screw.
Unable to find cap screw inside or outside the engine.
No impact on test results.
In addition to the above, a small piece of a piston oil ring segment was found i: EDG 12 during a gap check.
Edison found no damage due to the presence of this piece and could not conclusively determine when 1
the piece was introduced into the engine.
Fairbanks Morse was asked to review their records to determine if the piece might have been introduced during manufacture of the engine.
Edison's findings are discussed further in Reference 9.
VI.
TEST RESULTS EVALUATION The Demonstration Test. Program was considered successful when the EDGs completed the twenty " slow" and ten " fast" starts, and the seven day run.
A successful Demonstration Test validates that the EDGs can
~
reliably perform their intended function.
VP-86-0025 March 18, 1986 Page 11 For the Demonstration Test Program and subsequent operation of the EDGs, Detroit Edison and Fairbanks Morse consider the gap check as the primary measure of bearing integrity.
As noted above, all bearings passed the gap check, confirming the " success" of the Demonstration Test Program.
The visual inspections performed to validate the " success" of the Demonstration Test Program supported the findings of the gap check.
Although some trace surface scoring was seen on the #13 bearings of EDGs 11 and 13, it was not significant J
enough to fail the bearings.
Final acceptance of these bearings was made by Fairbanks Morse.
The results of the Demonstration Test Program are supported by the followirg facts:
o All bearing disassembly and reascsmbly, as well as bearing inspection and acceptance for tha visual bearing inspection, were done by Fairbankc Morse personnel.
o The Fairbanks Morse personnel performing the visual examinations have, respectively, 9 and 19 years experience with Fairbanks Morse engines.
Both have received extensive training on Fairtanks Morse engines and have spent the referenced years supe ~ vising repairs and maintenance of engines.
~
o The Detroit Edison personnel -(maintenance foreme'1) supervising work on the EDGs were specially.traiaed for their assignment (or qualified by equivalent training on Fairbanks Morse diesels in the Navy).
Their experience meets Edison's commitment to ANSI-N18.1-1971 for the Maintenance Foremen and General Maintenance Journeyman positions (high school diploma plus four years experience in the craft or discipline they supervise).
VII. BASIS FOR NOT CONTINUING ROUTINE VISUAL INSPECTIONS Since November, 1985 Detroit Edison has removed all EDG bearings for visual examination, in part to satisfy the NRC's requests for information.
The NRC has suggested that Detroit Edison continue visual bearing inspections on a frequent basis.
Fairbanks Morse maintains that the risk of damage to the bearings during removal and reinstallation and the potential for system contamination or.
mis' assembly, outweigh the information obtained from direct visual inspection of the bearing surfaces.
Detroit Edison's experience
VP-86-0025 March 18, 1986 Page 12 I
l confirms the validity of Fairbanks' recommendation.
Fermi-2 EDG 14 had no ' bearing problems until the bearings were disassembled for visual examination.
The gap check is the accepted method for detecting bearing failure and
)
is used_by both nuclear and commercial customers of Fairbanks. Morse.
Detroit Edison is aware of no other owner of Fairbanks Morse engines who currently disassembles bearings 'for visual determination of bearing condition on a routine basis.. Fairbanks Morse maintains, as stated in the January 24 meeting with the NRC, that the gap check provides an adequate indication of bearing integrity.
Detroit Edison agrees with the manufacturer's position and will rely on the gap check.
as the primary measure of bearing integrity.
In reaching this position, Detroit Edison (and the NRC).must evaluate the benefits of periodic visual inspection.against:
o Recognition-that, industry-wide, the. contribution of bearing and lube oil prcblems to overall failure rates of Fairbanks Morse diesels. is small o
The potential for creating problems is~ increased by dicassembling the EDG to perform visual inspections o
The time needed to disassemble the EDG for the visual inspection, reassemble, and test the EDG to restore it to operable condition would significantly impact EDG availability, and could. impact plant availability Completing the visual inspection requires disassembly,' reassembly, and post-maintenance testing of the EDG.
The post-maintenance testing includes a bearing break-in run recommended by Fairbanks Morse (see ) and a 100-hour reliability run.
Even without considering time required for maintenance activities, the time required for testing following visual inspection exceeds the Technical VP-86-0025 March 18, 1986 Page 13 Specification Limiting Condition for Operation of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
This would require starting the other EDGs and, ultimately, would lead to taking the plant to Cold Shutdown.
In summary, Detroit Edison believes that routine visual bearing inspections are unwarranted because:
o Bearing disassembly and reassembly has a potential for reducing bearing reliability o
The vendor-recommended feeler gauge gap check is an adequate and sufficient method for detecting failed bearings o
Concerns about the EDG 11 bearings have been resolved and results verified by inspection of the #3, 5, 6, 8,
9, and 13 bearings o
Concerns about EDG 13 bearings have been resolved and results verified by inspection of the #3, 4, 7, 10, and 13 bearings.
A special visual inspection of the #13 bearing will be performed at the next scheduled 18-month Technical Specification surveillance inspection.
o Future gap checks will be performed every 6 months or after three non-manually-prelubed starts.
This frequency provides ample opportunity to detect bearing problems in a timely manner.
c The surveillances required by Technical Specifications and Regulatory Guide 1.108 provide adequate EDG testing to ensure reliability and operability on a routine basis.
VIII. COMMITMENTS FOR EDG SURVEILLANCE VIII.1 Lube Oil Filter Inspection In March,1985, Detroit Edison proposed more f requent inspection of the EDG lube oil filter as one element of the program intended to. detect incipient bearing failures.
Subsequent experience has indicated that inspection of the lube oil filter is ineffective in predicting bearing failures.
In addition, more frequent inspection of the oil filter increases the likelihood of contaminating the lube oil' system. -Therefore, Detroit Edison plans to eliminate the oil filter sampling program described in Reference 4. This letter is referenced in paragraph 2.C. (10). of the Fermi-2 Operating License.
Accordingly, Detroit Edison will seek a license amendment to revise the reference to th'e March 14, 1985 letter.
That request for license emendment will be filed separately.
a
~.
Encloruro 1 VP-86-0025 March 18, 1986 Page 14 VIII.2 Future Bearing Gap Checks' Successful completion of the Demonstration Test Program defines an " envelope of acceptability" within which the reliability of the EDG crankshaft bearings have been demonstrated.
Detroit Edison recognizes that all of the EDG starts during the Demonstration Test Program were manually-prelubricated starts.
Detroit Edison made a previous commitment to pre-lube all planned starts.
During plant operation, a limited number of non-manually-prelubed starts are expected to occur, in response to loss-of-offsite power and spurious or actual accident signals.
Recognizing NRC concerns about~the potential effects of non-prelubricated starts, Detroit Edison will revise the maintenance procedure pertaining to EDG bearing gap checks to address occurrence of non-manually-prelubed starts.
The procedure will require a gap check of the upper and lower crankshaft main bearings after three (3) non-manually-prelubed starts or six (6) months, whichever occurs first.
This frequency of gap checks will continue until experience confirms that it can be relaxed.
The limit of three non-manually-prelubed starts was defined, in part, by Edison's examination of the start history of the Fermi-2 EDGs.
The start history is summarized below.
Fermi-2 EDG Start History May, 1982 through January, 1985 (Starts Made Before Bearing Failures Occurred on EDGs 11 & 12)
Number of Occurrences for Type of Star _t Type of Start EDG 11 EDG I?
EDG 13 EDG 14 Prelubed 127 52 25 30 No Prelube, 112 89 78 72 Wet, Booster No Prelube, 63 63 56 68 Booster No Prelube, No Booster 0
0 0
1__
Total Starts 302 204 159 172
f VP-86-0025 March 18, 1986 Page 15
'In this table, a "Prelubed Start" is defined as manually prelubricating the EDG immediately before starting.
A " Wet" start is defined as starting the EDG within one hour of the. previous EDG shutdown, without manually prelubricating the EDG.
"No Prelube, Booster" means the start occurred more than one hour af ter the previous shutdown, and was assisted by the air / oil ~ booster system, t
without manual prelubrication.
No Prelube,. No Booster" indicates that the start occurred without assistance of the air / oil boost system and without manual prelubrication.
i Examination of this data indicates that EDG 11-experienced 63 "No Prelube, Booster" starts before a bearing failure occurred.
These starts would be identical to the conditions encountered in an j
unplanned start today.
Including.the 112'" Wet" starts in the total of non-prelubed starts would indicate 175 non-prelubed starts occurred before. bearing toilure on EDG 11.
EDG 12 experienced 63 "No Prelube, Booster" starts before bearing failure (identified.by gap check).
Through January 1985, each of the Fermi-2 EDGs experienced an average of 62.5 fast starts engine with air / oil boost and without manual i
prelubrication.
This supports Edison's view that the EDGs can j
tolerate at least 63 non-prelubricated starts before bearing failure
]
would be expected.
This demonstrated experience of approximately 60 non-manually-prelubed fast starts, and the EDG reliability specified in Generic Letter 84-15
- i (95% minimum), form the basis for Edison's recommendation to gap check the bearings after three non-manually-prelubed starts.
Gap checking the bearings after three (of 60) starts is commensurate with the Fermi-2 Technical Specification requirement to increase the frequency of testing when more than one failure has occurred in the last twenty valid tests of the EDGs.
It is important to note that the design life of the EDG bearings is.
j based on bearing wear (i.e., minimum thickness of. bearing shell).
The manufacturer typically experiences over 10,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> of operation on its. engines before bearing replacement is required due to wear'.
l Detroit Edison estimates that normal surveillance and operation will require each EDG to run typically less"than 100 hour0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />s-per year.
At this rate, each EDG would be expected to ' operate between,2000 and 4000 1
hours over the 40-year life:of the plant.
Therefore, the expected bearing life ' exceeds the anticipated hours of operation by a factor of 2.5 to 5.
Detroit Edison believes that the limit of ~three- (3) non-manually-prelubed starts or six months, provides a conservative criterion for triggering a gap check, without unduly restricting operability of the EDGs.
Detroit - Edison expects that this limit may F
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VP-86-0025 March 18, 1986 Page 16 be relaxed as EDG operating experience confirms the level of reliability.
VIII.3 Special Inspection of EDG 13 Thrust Bearing The feeler gauge (gap check) inspections of all main bearings will include the #13 main thrust bearing.
During the gap check, each main bearing is inspected for external indications of bearing degradation, such as formation of tin pimples,' changes in shape, and any.other abnormal condition.
To provide further assurance.that the #13 upper top half thrust bearing of EDG 13 is not degrading, Detroit Edison will perform a special-visual inspection of this bearing at the next 18-month Technical Specification surveillance inspection.
IX SUPPLEMENTAL INFORMATION IX.1 Issues Discussed in January 24 Meeting (1) Oil Viscosity In December, 1985, Detroit Edison's surveillance of the -EDGs revealed reduced viscosity of the lube oil in EDGs 12 and 14.
In EDG 14 the engine lube oil was changed and subsequent testing revealed that the viscosity of the replacement oil remained within limits.
This leads Detroit Edison to conclude that the reduced viscosity resulted from dilution of the lube oil with a small quantity of fuel oil.
Fuel oil is used to clean the crankshaf t journals and may have been introduced in excessive quantity during the bearing repairs and replacements.
A trend of decreasing viscosity was identified previously in surveillance of the lube oil of EDG.12.
Several steps were taken to resolve this condition.
The twenty-four fuel injector nozzles were tested for leakage in accordance with vendor procedures.
No leakage was observed.
The twenty-four fuel injector pumps were checked for plugging.
No distinctive differences were observed from the fuel injector leakoff points and no clean fuel leakoff lines were found plugged.
The seal on the main shaft-driven fuel' oil pump was replaced, but it was not possible to verffy that the new seal was leak-free, because of the configuration of the equipment and the lack of an inspection port.
The crankcase vacuum was decreased by replacing an orifice in the crankcase inductor.
The crankcase vacuum previously was slightly high,
Enclosurc~l VP-86-0025 March 18, 1986 Page 17 and might have induced oil flow into the crankcase.
Finally, the Shell Caprinus lubricating oil was changed to Mobilguard 450 lubricating oil in this and the other three EDGs.
' Af ter this work was completed, EDG 12 was restart'ed and run for several days.
Initially, the oil viscosity decreased slightly, then stabilized at a value between.137 and 138 Centistokes.
The-minimum acceptable value of viscosity is 120 Centistokes (40 degrees C).
The viscosity data from this run are shown below.
Sample Identification Measured Viscosity (Date. Time)
(Centistokes, 40C) 2/22/86, 0630 144 2/23/86, 0535 144 2/24/86, 0035 142 2/25/86, 0351 140 2/26/86, 0049 138 2/27/86, 0210 138 2/28/86, 0110 138 3/1/86, 0245 136.5 3/2/86, 0145 137.8 3/3/86, 0045 137.6 3/4/86, 0115 137.8 3/5/86, 0125 137.4
-The EDG was shutdown on March 5, 1986.
Because the viscosity has stabilized,. no further corrective action is considered necessary.
Routine surveillance will assure that viscosity values remain within limits.
This surveillance includes an oil sample obtained during each monthly surveillance test run of all EDGs.
(2) EDG Alignment During Installation At the January 24 meeting with the NRC, a question was raised j
concerning the skid-to-foundation alignment of the Division 2 EDGs.
Detroit Edison has reviewed the installation records for the EDG skids and verified that the alignment was held to within
+/- 1/16th inch.
Fairbanks Morse specifies tolerances of +/-
1/8th inch at the skid corners and +/- 1/16th inch at the midpoint of the skid.
Fairbanks Morse has stated that the design of the EDG skid makes it unlikely that misalignment of the skid on -its foundation would distort the engine block.
If the engine block had been f
i
' Enclosure l' VP-86-0025 March 18, 1986 Page 18 distorted, a distinctive bearing wear pattern would have been seen.
During.the inspection of EDG ll, no such wear pattern was
{'
observed.
IX.3 Endorsement'by Fairbanks. Morse and Failure Analysis Associates In the' January 24 meeting, the NRC asked ~ representatives of l
Fairbanks Morse and Failure Analysis Associates (FAA)., whether.
i
-they agreed with the course of action proposed by Detroit Edison -
l to restore confidence in the reliability of the Fermi-2 EDGs.
The representatives indicated their approval of the Edison j
Demonstration Test Program presented'to the NRC.
Detroit' Edison later requested that FM and FAA put their endorsement in. writing for inclusion in both Reference 8 and this _'eport.
Copies.of j
their letters of endorsement are provided in Enclosure 5..
Af ter the February 14 meeting with the NRC, Detroit Edison requested Fairbanks Morse to more definitively document their position on the need and advisability of visually inspecting bearings af ter the Demonstration Test Programs operability runs.
The subject response is also-provided in Enclosure 5.
l IX.4
' Independent Lab Bearing' Evaluation -
l Detroit Edison has committed to have an independent laboratory analyze several bearings with different ' conditions noted on each.
The subject bearings were selected from bearings removed
~
j in the November-December, 1985 inspections.. This will provide an i
. independent determination of the cause amE,the various conditions noted on several bearings.
Detroit Edison will evaluate the.
results of the laboratory's analysis when they become available.
Detroit Edison will factor these -results into future corrective action, if appropriate.
IX.5 Study of oil Booster System 1
~
i In Supplement 5 to the Fermi 2 Safety. Evaluation Report,'the NRC j
stated:
i
".....we recommend that the~ applicant: study whethersit should increase the (oil booster / accumulator system) i reservoir tank ~ volume-to some' appropriate volume larger than 1.25 gallons so'that it will provide a proper amount
~
of lube oil, adequately distributed, -and in the shortest possible time.
The'results of-such a study should be.
submitted to us."
I i
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_VP-86-0025 March 18, 1986 i
Page 19 In response to this, a study of.the' oil booster / accumulator system - has. been prepared by Fairbanks Morse - and a draf t report is currently in the review process.
The draft repor.t concludes that
. the oil booster empties during the first one second, providing approximately one cup of' oil to the bearings.at essentially zero pressure.
After approximately three seconds, the engine driven-pump has filled all passageways with oil, and has established pressure at the upper main bearings. -The subject. draft report indicates that increasing the volume of oil in the reservoir will I
only result in the same oil flow rate being provided for a longer period of time.
The lube oil. modification kit installed by Detroit Edison j
included more'than the air / oil botster.. This modification 1
reduced voids in the lube oil system from approximately 60 gallons to less than 5 gallons,,thus improving the response time-
~
i for the' engine-driven lube oil pump. 'The lower crankshaft is continuously lubricated by circulating lube oil.-
With the keep-warm system, the lube ~ oil is maintained-at an elevated 1
temperature, approximately 135F, by a large lube oil heater.
As noted, the draft report is in the review cycle and. completion of this review has been delayed due to the recent EDG bearing i
concerns discussed in this submittal.
The contents of this draft
}
report, as well as the' design of the en~ tire oil booster / accumulator systemi have been considered by the. Detroit Edison EDGETask Force in discussions of bearing failures; but i
Task Force conclusions have not implicated the oil j
booster / accumulator as one of the causes of the recent EDG j
problems.
Detroit Edison is aware that other nuclear facilities' EDGs have operated successfully with~and~without'the booster.
j The results of the oil booster study will be submitted -
[
separately.
X.
- CONCLUSION Detroit Edison is confident that the Demonstration Test Program' and the post-test visual bearing : inspection documented above
{
confirm the reliability of the Fermi-2 EDGs.
The bases for this l
conclusion include:
f o
Fairbanks Morse engines have a proven record of j
reliability in the nuclear industry.
This' reliability is 4
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s Enclocure 1 VP-86-0025 March 18, 1986
-Page 20 based upon an integrated program involving training, technical specification and surveillance requirements, and periodic maintenance including bearing gap checks.
o The Demonstration Test Program included 30 starts per engine.
This is more than the 23 starts required by Regulatory Guide 1.108 for the initial demonstration of EDG reliability.
o The Demonstration Test Program simulates the total number of starts that would be expected over an 18-month fuel cycle and the run time that would be needed - to assure safe shutdown following a design basis Loss of Coolant Accident coincident with a loss of offsite power.
o All bearings passed the' gap checks which were performed throughout the Demonstration Test Program.
o Visual inspections were performed on several bearings on EDGs 11 and 13 to validate the results of the Demonstration Test Program, and to confirm that the gap check provides adequate assurance of bearing integrity.
All visually inspected bearings passed.
o Engine disassembly should be minimized.
1 o
Both the engine manufacturer (Fairbanks Morse) and Detroit Edison 's consultant (Failure Analysis Associates) stand behind the Fermi-2 Demonstration Test Program.
o The slow - start modification, installed in 1985, further reduces the wear on the EDGs caused by planned surveillance runs.
Detroit Edison maintains that the Demonstration Test Prs. gram provides the basis for the NRC to conclude that the Fermi-2 EDGs are a reliable backup power source.
I VP-86-0025 l
~ March 18, 1986 Page 21 XI. REFERENCES 1.
Detroit Edison letter to NRC, NE-85-0329, " Request to Revise Draf t Fermi-2 Technical Specifications", dated February 14, 1985.
2.
Detroit Edison letter to NRC, NE-85-460, " Additional Information on Diesel Generators", dated March 6, 1985.
3.
Detroit Edison letter to NRC, NE-85-0455, " Additional Change-to Draft Fermi-2. Technical Specification for Diesel Generators", dated March 9, 1985.
4.
Detroit Edison letter to NRC, NE-85-0459, " Clarification of Diesel Generator Commitments", dated March 14,1985.
5.
Detroit Edison letter to NRC, NE-85-0461, " Letter -
Correction", dated March' 15, 1985.
6.
Detroit Edison letter to NRC, NE-85-0462, " Transmittal of Additional Information Relative to Diesel Generator Commitments", dated March 15, 1985.
4 j
7.
Detroit Edison letter to NRC, VP-85-0216, " Emergency Diesel Generator Status", dated December 13, 1985.
)-
8.
Detroit Edison letter to NRC, VP-86-0010, " Emergency Diesel Generator Crankshaft Bearing Reliability Demonstration Test Program", dated February 5, 1986.
9.
Detroit-Edison letter to NRC, VP-86-00ll, " Emergency Diesel Generators (EDGs). Testing and Operating Chronology", dated : March 1, 1986.
1 i
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March 18, 1986 VP-86-0025 Copy of' Handouts Presented in January 24,'1986 Meeting with NRC Staff.on EDG Bearings Reliability Demonstration Test Program 1
[ NOTE As reflected in Enclosure 1, " History", the intent of the presentation for which the enclosed slides were used was to focus discussion on EDG bearings replaced due to
" failure" and significant surface scoring.
The enclosed slides may not, by design, fully delineate bearing replacements prompted by other concerns.]
~~
'9
~
AGEf0A 9
EQUIPMENT HISTORY PROBLEMS OTHER CAUSES CORRECTIVE ACTION SCHEDULE
. i l
l
i EQUIPMENT FOUR EMERGENCY DIESEL GENERATORS (EDG'S)
TWO EMERGENCY DIESEL GENERATORS PER DIVISION DIVISION 1 EDG 11 a 12 DIVISION 2 EDG 13 a 14 BACKUP ON-SITE A.C. POWER SOURCE REDUt0 ANT POWER SOURCES FAIRBAfES MORSE DIESEL ENGINES NAVY 400 l
NUCLEAR PLANTS 49 OTHER SURVEILLANCE TEST PROGRAM 4
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I TURBOSUPERCHAROED T
84310 QR ENONE 12 CYL CROSS SECTK)N
'ur
HISTORY 4
i
. BUILT 1974 - 1977 1
t INSIDE STCRAGE PERMANENT LOCATION ONE ENGINE SOLD Af0 REPLACED (EDG 14)
OIL SYSTEM MODIFICATION
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2 TERMS 1
l FAILED BEARING (.002 IN. GAP CHECK)
SURFACE SCORING' HEALED SURFACE SCORING L
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Dete.
l********l Jan 85 l'********l Dec 3,85 l********l Dec.27,851****
I I
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Bearinos 1
X 2
X 3
X o
o 4
X 5
X o
X 6
X o
X 7
8 o
9 o
10 11 12 13 o
o (Lower'&
o 14 Upper) i l********l l********l l********l l****
I I
l i
l 1
I Run Hours 346 125 20 i
Starts-Fast (PLM) 127 25 0
Fast (NPL) 175 1
0 Slow 0
8 10 i
Total 302 34 10 Hours / Start 1.1 3.6 2.0 Notes
-Replaced the
-Replaced all
-Realigned Caps Upper Crank Upper Bearings
-Replaced Failed
-Replaced all
& Distressed Upper Bearings Bearings
-Flush Engine NOTE: THE ASSOCIATED CONNECTING RODS FAILED IN JAN 85.
s PLM= Manual PreIube, NPL=Not Manual 1y'Prelubed 1
)
EDG 12 h
I********I Jan 85 1********I Dec 85 l********I I
I I
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8earinos 1
X
{
2 X
3 X
4 5
6 7
X 8
X 9
1 10 11 12 13 o.(Lower) 14 4
I********I-I********I i********I I
I I
I l
l I
Run Hours 292 137 240 l
Starts Fast (PLM) 52 23 0
Fast (NPL) 152 1
0 Slow 0
7 8
Total 204 31 8
Hours / Start 1.4 3.6 30 L{o t e s
-Replaced
-Replaced upper crank 13M lower-bearings
-Inspected 14M, 12M, 10M and 8M on lower crank
-Gap checked 1
all other bearings l
PLM= Manual Prelube, NPL=Not Manually Prelubed i
)
=
I EDG 13 Qatt l********l Jan 85 l********l Nov 85 l********l
~Dec 85 1****
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I Bearino 1
2 3
X o (Groove) 4 o (Lower) 5 6
7 o-(Groove)
S 9
10 11 12 13 o
o 14 l********1 1********l l********l l****
I I
I I
I I
I Hours 214 94 234 Starts Fast (PLM) 25 24 3
Fast (NPL) 134 0
0 Slow 0
6 46 Total 159 30 49 Hours / Start 1.3 3.1 4.8 Notes
-Inspected Upper
-Replaced the
-Replaced 3M, Crank Bearings Upper Crank 7M & 13M 1
-6
-Replaced all
-Flushed Engine Upper Bearings
-Demonstration
-All Other-
-Replaced 4M Bearings we e Lower Bearing gap checked PLM= Manual Prelube, NPL=Not Manually Prelubed
EDG 14 Date l********l Jan 85 l********l Dec 85 l********l Jan 86 l****
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i Bearinos I
o 2
3 4
5 6
7 8
9 o
10 11 12 13 o
14 l********l l********l l********
I l
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I i
1 Run Hours 270 117 250 Starts Fast (PLM) 30 20 0
Fast (NPL) 142 2
o Slow 0
7 g
Total 172 29 8
Hours / Start 1.6 4.0 31.3 Notes
-Inspected
-Inspected
-Three Bearings 1-6 all upper and bearings l ower bear i ngs reused
-Observed some bearings had
-Replaced all a dull matte upper crank-partial finish line bearings PLM= Manual. Prelube, NPL=Not Manually Prelubed 4
l i
a
TYPICAL CAUSES OF BEARING FAILURE j
DIRT OR FOREIGN MATERIAL IN OIL l
lNSUFFICIENT LUBRICATION MISASSEfELY i
MISALIGNMENT i
OVERLOAD CORROSION DESIGN OTHER t
i 1
t
1 i
NOVEMBER 1985 j
EDG 13 EVENT:
OPERATOR SHUTDOWN EDG 13 DUE TO NOISE CHANGE PROBLEM: BEARINGS 3CR,-3M AND 4M FAILED 13 M HAD BEARING WEAR CAUSE:
PRIMARY - BEARING 3CR FAILED DUE TO MISASSEMBLY IN JANUARY 1985, THE BEARING WAS INSPECTED NO DISCOLORAT10N = N0 HIGH TEMPERATURE ALUMINUM DID NOT EXPERIENCE A HIGH TEMPERATURE FRETTING ON CONNECTING R0D FACES BENT CONNECTING ROD BOLTS BEARING FRAGMENTED SEC0f0ARY - BEARING 3M FAILED DUE TO DECREASED OIL FLOW TO BEARING FACES BEARING 13M BEARING TO JOURNAL CONTACT 4
ACTION:
o CHECKED ALL OTHER PREVIOUSLY REWORKED BEARINGS.
NO OTHERS WERE FOUto TO BE A CONCERN, o
REPLACED UPPER CRAtKSHAFT o
REPLACED ALL UPPER BEARINGS
JANUARY 1985 EDG 11 1
EVENT:
EDG 11 SHUTDOWN AUTOMATICALLY ON A LOW LUBE OIL PRESSURE SIGNAL PROBLEM: SEVEN FAILED BEARINGS CAUSE:
BEARINGS FAILED DUE T0 1NADEQUATE LUBRICAT10N DURING FAST STARTS ACTION:
PRELUBE ALL PLANNED STARTS TEST EDG'S AT PLANT SPECIFIC LOAD LEVELS IWROVED OlL SAWLING PROGRAM INAUGURATED OIL' FILTER SAMPLING PROGRAM REVISED PROCEDURES REVISED TECHNICAL SPECIFICATIONS INCORPORATE SLOW START FEATURE (DELAYED) i (ACTION STEPS APPLIED TO ALL EDG'S)
EDG 12 i
EVENT:
GAP CHECK l$SPECTION PROBLEM:
FIVE FAILED BEARINGS CAUSE:
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DECEMBER EDG 13 EVENT:
VISUAL INSPECT 10N OF UPPER BEARINGS FOLLOWING SUCCESSFUL COMPLETION OF DEMONSTRATION PROBLEM: BEARINGS 3M, 7M A m 13M FOU W WITH SURFACE SCORING CAUSE:
BEARINGS 3M AND 7M - FOREIGN MATERIAL IN OIL BEARING 13M - BEARING TO JOURNAL CONTACT ACTION:
REPLACED THREE BEARINGS
-.w..
l NOVEMBER 1985 EDG 14 EVENT:
VISUAL INSPECTION OF ALL BEARINGS PROBLEM: NONE CAUSE:
N/A ACTION:
REPLACED ALL UPPER CRAM ( BEARINGS TO ELIMINATE.A " DULL ROUGH" SURFACE APPEARANCE JANUARY 1986 EDG 14 EVENT:
SECOND VISUAL INSPECTION PROBLEM: 3 BEARINGS WITH A TRACE OF SURFACE SCORING CAUSE:
BEARING TO JOURNAL CONTACT ACTION:
REINSTALLED BEARINGS i
I L
NOVEMBER 1985 EDG 12 EVENT:
VISUAL INSPECTION OF ALL BEARINGS PROBLEM: BEARING 13M LOWER FOUt0 WITH SURFACE SCORING CAUSE:
BEARING TO JOURNAL CONTACT ACTION:
REPLACED BEARING I
i
DECEMBER 3, 1985 EDG 11 EVENT:
VISUAL INSPECTION OF ALL BEARINGS PROBLEM: BEARINGS 3M, SM, 6M, 8M, 9M, 13M(UPPER AND LOWER)
FOUND WITH SURFACE SCORING CAUSE:
BEARING TO JOURNAL CONTACT AGGRAVATED BY ALIGMENT ACTION:
REPLACED ALL. UPPER MAIN BEARINGS AND ONE LOWER BEARING DECEMBER 27, 1985 EDG 11 EVENT:
INSPECTION DURING BEARING RUN-IN PROBLEM: TWO FAILED BEARINGS AND TWD BEARINGS WITH SURFACE SCORING CAUSE:
BEARING TO JOURNAL CONTACT AGGRAVATED BY ALIGWENT ACTION:
DETAILED REALIGNMENT-OF UPPER BEARING CAPS
ENGINE BEARINGS FUNCT10NAL REQUIREMENTS o
PROVIDE LOW-FRICTION, LOW-WEAR JUNCTION BETWEEN MAJOR ENGINE C0WONENTS:
PISTON - NRIST PIN WRIST PIN - CONNECTING R00 CONNECTING ROD - CRAM (SHAFT CRAM (SHAFT - ENGINE BLOCK o
PROMOTE FORMATION OF LUBRfCATING OIL FILM BETW EN BEARING Af0 ADJACENT SHAFT OR JOURIML.
1.
ENGINE BEARINGS SPECIFIC REQUIREMENTS o
DESIGNED TO CONTROL STRESSES WITHIN PROVEN CAPABILITIES o
MANUFACTURED TO CLOSE DIMENSIONAL TOLERANCES o
MATERIALS SELECTED TO PROVIDE:
LOW FRICT10N WITH JOURNAL ABILITY TO ABSORB AND NEUTRALIZE ABRASIVE PARTICULATES STRENGTH FOR LONG, RELIABLE LIFE C0ffATIBILITY WITH ENGINE OIL o
VIABLE MATERIALS:
FOR BEARING PHASE TIN, LEAD, CADMlUM, If0IUM FOR MATRIX PHASE COPPER, ALUMINUM 1
k i
2 s
2
i ENGINE BEARINGS DESIGN PROCEDURES 1)
C0WUTE LOADS IWUTS:
HORSEP0ER COMBUSTION PRESSURE FIRING ORDER COMPONENT E IGHTS 4
COUNTEREIGHTS GEARS AND ACCESSORIES 2)
SELECT SIZES LENGTH AND DIAMETER GROOVES, OIL H0LES CLEARANCES i
3)
SELECT LUBRICANT VISCOSITY Af0 VISCOSITY If0EX SUPPLY PRESSURE SUPPLY TEWERATURE 3
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~.
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ENGINE BEARINGS.
ANALYTl CAL TECHNIQUES UNIT LOAD
- 1 MAIN BEARING 24343 LB.
UNIT LOAD 1316 P.S.I.
=
=
8" x (2.75".4375")
JOURNAL ORBIT ANALYSIS SOLVES DIFFERENTIAL EQUATIONS OF FLUID FLOW IN BEARING FOR EVERY lo 0F CRAfESHAFT ROTATION.
OUTPUT:
PEAK OIL FILM PRESSURES MINIMUM OIL FILM THICKNESSES INTERPRETATION:
COMPARISON TO GUIDELINES ESTABLISHED BY THE ANALYSIS OF MANY DIFFERENT ENGINES 5
[EIE PARIS BIVISIO CL[Vil[
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ItG Giv (I)360-KG Bit PESSURE 35.N SIL IDF 171.N A MXIM DilIILM PRISSURI K 10171 PSI KCuts Ri A Cret h6LIII 20 KGIIIS U11N k A6t[ KLR11K 10'IE KMIE Of 183 Kit [IS K h ELE t[LRf!K 10 IE J00tmRL If 163 KIKES 1h[ LORD R? IMll POINI 15 21313 PIUes KIIE Al k ELI Of 176.9 K6ftIS IE KRM OIL IILM PICSSut[ IS 3331 PSI A MINIM lil IILM INICIESS Of.000169 LUCES KtutS Al A Ctm RMGLE Of 276 MitIIS WliN RM NL[ KLRi!UE 10 TE KMIG Of 218 KIRCIS K RN ML[ KLATIUC 10 IE J0utML If N2 Mit[IS It LORD H INIS POINT IS 5255 POUSS Ki1E M h NLI Of 230.2 Kit [IS TE [CC[ Nill [1!Y trita Al INIS Polui 15 1.96558 IE MDIM Olt I!LM INlttESS IS.000407 IKES 1
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ENGINE BEARINGS CONCLUSION FOR FAIRBAN(S-MORSE DIESELS AT FERMI II i
o BEARING STRESSES DUE TO PEAK OIL FILM PRESSURE ARE SAFELY WITHIN l
CAPABILITY OF ALUMINUM - 6% TIN BEARINGS, P.O.F.P. CAPABILITY 25000 PSI
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o OlL FILM THICKNESSES ARE I
GENEROUS IN CONNECTING R00 ACCEPTABLE IN MAIN BEARINGS FOR TYPICAL MEDIUM SPEED DIESEL ENGINcS 0
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OTHER CAUSE I-4 BEARING SCORING MOST LIKELY OCCURS 1
o WITH A NEWLY LAPPED JOURNAL Am NEW l
BE\\ RINGS PRIOR TO SHAFT SEASONING I
o LOW OCCURRENCE PROBABILITY e
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SUMMARY
FAILED BEARINGS EDG 11 INADEQUATE LUBE I
ALIGtNENT i
EDG 12 INADEQUATE LUBE BEARING CONTACT EDG 13 MISASSEMBLY i
WDRN BEARINGS (VISUAL INSPECT.10N)
EDG 11 ALIGtNENT EDG 12 BEARING CONTACT EDG 13 FOREIGN MATERIAL BEARING CONTACT l
EDG 14 TRACE BEARING CONTACT 4
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1 4
CORRECTIVE ACT10N o
REPLACED FAILED Af0 SCORED BEARINGS EXCEPT 3 ON EDG 14 (TRACE) o CONTINUE OIL SAMPLING PROGRAM o
ELIMINATE OIL FILTER SAMPLING PROGRAM o
FLUSH EDG'S 11 Af013 WHICH EXPERIENCED BEARING FAILURES o
CHANGE OIL TO MOBIL (ONE DIVISION) i i
o SEASON BEARINGS FOLLOWING REPLACEMENT o
MINIMlZE DISASSEMBLY o
CONTINUE REQUIRED SURVEILLANCES o
GAP CHECK BEARINGS EVERY 6 MONTHS i
o PROCEED WITH BATTELLE LABS ANALYSIS OF BEARINGS o
RESOLVE EDG 12 OIL VISCOSITY PROBLEM o
C0f0UCT A RELIABILITY DEMONSTRATION 4
o SIMULATE A FUEL CYCLE o
100 HOURS SEASONING RUN o
20 SLOW STARTS o
10 FAST STARTS o
RUN FOR 7 DAYS (168 HOURS)
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SCHEDULE i
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ALL EDG WORK Af0 TESTING TO BE COMPLETED BY FEBRUARY 19, 1986 i
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COLT'S POSITION 1
Long storage time (1975 - 1982) 7 years.
2.
Galvanic action as shown by Technimet report.
3.
Bearings were subjected to large number of fast starts (with qu.tntity not pre-lubed) prior to bearings being conditioned to crankshaft.
4.
As a result of the failures in Unit #11 in January 1985, all units were subjected to disassembly and replacement of bearings in Unit #12.
l 5.
Units #13 & 14 - The upper bearings in position 1 thru 6 were removed, visually accepted and re-assembled. All bearings inspected were good.
6.
Unit #13 failed #3 upper conn rod bearing due to improper re-assembly.
As noted in brinnelling of cap a rod fits.
7.
DECO & NRC decided to disassemble all engines to visually inspect
- bearings, a)
Problem - Any disassembly of engine bearings places jeopardy on proper re-assembly.
i b)
DEC0/NRC replaced bearings against Colt's recomendation. Example -
- 14 unit upper main bearings.
No problems until bearings were replaced.
c)
Opening crankshaft / bearing assembly introduces debris into bearings
- As noted in #4 & 7 main bearings on #13 unit.
8.
Colt recomends imediate stop to disassembling components for visual inspection of bearing surfaces.
Inspect bearings with feeler gauge check only.
9.
Correct problem with lube oil dilution on Unit #12 & 14.
10.
Run engine per:
a Extended wear in - 40 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> b
Continuous load - 2500/2600 kw - 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> c
Check bearings w/ feeler gauge d
Run NRC qualification tests e
Re-check bearings with feeler gauge.
i
e
SUMMARY
o USE PROVEN SIESELS o
EXTENSIVE DIESEL SURVEILLANCE PROGRAM o
HAD SOME BEARING PROBLEMS AND SURFACE INDICATIONS o
IDENTIFIED CAUSES (MISALIGNMENT,. STORAGE, j
MISASSEMBLY, LACK OF PRELUBE, PARTICULATES o
TAKING APPROPRIATE CORRECTIVE ACTIONS (ALIGNED, CONDITIONING, REASSEMBLED, PRELUBE, FLUSHED) o IMPLEMENTED SLOW START CAPABILITY o
BELIEVE DIESELS WILL RELIABLY START AND OPERATE WHEN CALLED UPON o
PLAN TO RESTART ABOUT 2/19 AND NEED TO IDENTIFY REGULATORY PROCESS S0 THAT OUR ACTION SUPPORT TIME FRAME
m VP-86-0025 March 18, 1986 Page 1 Chronology of Bearing Replacements In January,1985, EDG 11 tripped on low oil pressure and high crankcase pressure.
Detroit Edison identified problems with the upper crankshaft bearings.
Detroit Edison replaced the upper crankshaf t and a total of 14 main bearings and 12 connecting rod bearings in EDG ll:
EDG 11-January, 1985 Bearings Replaced Due To Failure Upper Main Bearings:
Nos. 1,2,3,4,5,6 Upper Connecting Rod Bearings:
Nos. 1,2,3,4,5,6 Bearings Replaced.Due to Surface Scoring None Bearings Replaced for Other Reasons Upper Main Bearings:
Nos. 7,8, 9,10,11,12,13,14 Upper Connecting Rod Bearings:
Nos. 7,8,9,10,11,12 To determine root cause of the problem and the extent of the damage, Detroit Edison also examined the bearings of EDGs 12,13, and 14.
Detroit Edison replaced a total of 14 main bearings and 12 connecting rod bearings in EDG 12:
EDG 12-January, 1985 Bearings Replaced Due To Failure Upper Main Bearings:
Nos. 1,2,3,7,8 Bearings Replaced Due to Surface Scoring Upper Connecting Rod Bearings:
Nos. 1,2,3~
Bearings Replaced for Other Reasons Upper Main Bearings:
Nos.
4,5,6,9,10,11,12,13 14 Upper Connecting Rod Bearings:
Nos.
4,5,6,7,8,9,10, 11,12 Detroit Edison also replaced one connecting rod bearing in EDG 13:
EDG 13-January. 1985 Bearings Replaced Due To Failure None Bearings Replaced Due to Surface Scoring None
VP-86-0025 March 18, 1986 Page 2 Bearings Replaced for Other Reasons Lower Connecting Rod Bearing:
No. 5 One upper main bearing was replaced in EDG 14:
EDG 14-Januarv. 1985 Bearings Replaced Due To Failure None Bearings Replaced Due to Surface Scoring None Bearings Replaced for Other Reasons Upper Main Bearing:
No. 6 The apparent cause of the bearing failures in EDGs 11 and 12 was determined to be inadequate lubrication during repeated fast starts.
Following this repair, Detroit Edison performed the vendor-recommended bearing break-in procedure, in addition to a 40-hour seasoning run.
Corrective actions were documented in. detail in earlier reports to the NRC (References 1-5).
The Fermi-2 EDGs completed this demonstration successfully in March, 1985.
~
In November, 1985, EDG 13 was manually tripped when operators heard unusual noises from the EDG.
Detroit Edison examined EDG 13 and determined that one of the upper main bearings.and upper connecting rod bearings had failed.
Detroit Edison elected to replace the upper crankshaft and all upper main bearings.
Detroit Edison replaced a total of 22 main bearings and 13 connecting rod bearings in EDG 13:
EDG 13-November. 1985 Bearings Replaced Due To Failure Upper Main Bearings:
No. 3 Lower Main Bearings:
No. 4 i
Upper Connecting Rod Bearings:
No. 3 j
Bearings Replaced Due to Surface Scoring Upper Main Bearing:
No. 13 Bearings Replaced for Other Reasons Upper Main Bearings:
Nos.
1,2,4,5,6,7,8,9, 10,11,12,14 Lower Main Bearings:
Nos.
2,5,6,7,8,10,13 Upper Connecting Rod Bearings:
Nos.
1,2,4,5,6,7,8,9, 10,11,12
VP-86-0025 March 18, 1986 Page 3 Lower Connecting Rod Bearings:
No. 3 Detroit Edison's investigation of the #3 connecting rod and main bearing failure is provided in Enclosure o4.
The other bearings replaced were replaced to eliminate any questions about their integrity.
The f4 lower main bearing had failed the gap check; however, it was performing its intended function.
The bearing did reflect surf ace distress that was well healed.
Following a demonstration test run of EDG 13 in December 1985, visual inspection of the upper crankline revealed three bearings with questionable surface conditions.
Detroit Edison replaced a total of 4 main bearings in EDG 13:
EDG 13-Late December. 1985 Bearings Replaced Due To Failure None Bearings Replaced Due to Surface Scoring Upper Main Bearings:
Nos. 3,7,13 Bearings Replaced for Other Reasons Upper Main Bearing:
No. 4 Surface scoring of upper main bearings 3 and 7 is attributed to foreign material in the lube oil.
Detroit Edison considers both the damaged bearings and the extensive repairs performed earlier to be the most likely source of the foreign material introduced into the lube oil system.
When the scored bearings in EDG 13 were initially found, Detroit Edison inspected all upper and lower bearings of EDG 14.
No scoring was found.
Nonetheless, Detroit Edison elected to replace all of the upper crankline bearings in EDG 14 to eliminate concerns related to the gray, matted surface appearance of several bearings.
Detroit Edison replaced a total of 14 main bearings and 14 connecting rod bearings in EDG 14:
EDG 14-December, 1985 Bearings Replaced Due To Failure None Bearings Replaced Due to Surface Scoring None Bearings Replaced for Other Reasons Upper Main Bearings:
Nos. I through 14 Upper Connecting Rod Bearings:
Nos. I through 12 i
VP-86-0025 March 18, 1986 Page 4 Lower Connecting Rod Bearings:
Nos. 2,6 Because of the findings in EDG 13, Detroit Edison elected to inspect the bearings of EDGs 11 and 12 (which are the Division I EDGs).
Detroit Edison replaced a total of nine main bearings and one connecting rod bearing in EDG 12:
EDG 12-December. 1985 Bearings Replaced Due To Failure None Bearings Replaced Due to Surface Scoring Upper Main Bearings:
Nos. 6,6,13 Lower Main. Bearing:
No. 6,13 Bearings Replaced for Other Reasons Upper Main Bearings:
No. 14 Lower Main Bearings:
Nos. 1,3,5 Upper Connecting Rod Bearing:
No. 3 When EDG 11 was opened in early December, Detroit Edison found questionable surface conditions on six bearings, and elected to replace all upper main bearings.
Detroit Edison replaced a total of 16 main bearings and 1 connecting rod bearing in EDG ll:
EDG ll-December, 1985 Bearings Replaced Due To Failure None Bearings Replaced Due to Surface Scoring Upper Main Bearings:
Nos. 3,5,6,8,9,13 Lower Main Bearing:
No. 13 Bearings Replaced for Other Reasons Upper Main Bearings:
No.
1,2,4,7,10,11,12, 14 Lower Main Bearings:
No. 1 Lower Connecting Rod Bearing:
No. 4 During the process of returning EDG 11 to service, two bearings failed.
Subsequent investigation revealed an undesirable upper crankshaft bearing cap alignment pattern.
Detroit Edison replaced a total of 5 main bearings and four connecting rod bearings, and performed a detailed realignment of bearing caps.
o VP-86-0025 March 18, 1986 Page 5 EDG 11. Late December. 1985 Bearings Replaced Due To Failure Upper Main Bearings:
Nos. 5,6 Bearings Replaced Due to Surface Scoring Upper Main Bearings:
Nos. 3,13 Upper Connecting Rod Bearing:
No. 6 Bearings Replaced for Other Reasons Upper Main Bearings:
No. 7 Upper Connecting Rod Bearings:
Nos. 3,4,5 Since December, 1985, there have been no further bearing replacements on any of the EDGs.
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O March 18, 1986 VP-86-0025 Page 1 Additional Information on the Failure of EDG 13 No. 3 Main and Connecting' Rod Bearings In a conference call on February 21, the NRC staff requested additional information about the failure of the No. 3 main and connecting rod bearings in EDG 13 which occurred in November, 1985.
The additional information, describing Edison's evaluation and -
determination of root-cause, is provided below.
In January 1985 the EDG-13 #3 main and connecting rods were disassembled for visual inspection.
The 43 main and connecting rod bearings were found to be in satisfactory condition.
No abnormal conditions such as fretting was observed on the connecting rod cap surfaces.
The most severe duty on.the bearing occurred.before this inspection, yet the the bearing was found to be in good condition.
Before the visual inspection, the bearing had been subjected to 25 prelubed starts, 78 wet starts, 56 booster no-prelube starts,;159 total starts, 214 total run hours and an average of 1.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> per start.
There were no indications of overheating on the connecting rod or connecting rod bearing cap.
In contrast the connecting rod. failures found on EDG 11 in January 1985 showed signs of high temperature..
Edison concluded that there was substantial ' oil flow present and that the failure was not accompanied by high temperatures and ~ was not related to inadequate lubrication.
Examination of the bearing fragments found in the engine did not indicate that they had experienced melting, which would have resulted if high temperatures had been present.
The fragments appeared to have undergone some degree of cold forming from the hammering effect of the failure.
Testing has also indicated that the hardness of the bearing material had not changed, another indication that high temperatures were not present.
This is further evidence that the connecting ' rod bearing did not fail as a results of inadequate lubrication.
Fretting was observed on the mating surfaces of the connecting rod and cap as well as on the cap nut faces.
Fretting of this nature was not observed on any other failure, especially with the three connecting rod bearings that failed on EDG 11 in January 1985.
Edison concluded that fretting normally should not be expected when a connecting rod bearing fails.
The fretting indicates relative movement between the
VP-86-0025 March 18, 1986 Page 2 connecting rod and cap and indicates that either the cap was not clamped as tight as it should have been or that the failure of the bear.ing caused the relative movement.
None of the bearing fragments found were larger than the size of a half dollar.
No fragments were found.in the journal area.
In contrast, significant pieces of smeared bearing material were found in the January 1985 EDG 11 connecting rod journals, though the bearing failures allowed the pistons to withdraw from the cylinder liners beyond the first piston ring.
The relatively small size bearing fragments associated with this failure indicate a fatigue failure, rather than failure from a lack of lubrication.
In conclusion, Edison considers the following points to be particularly significant:
o The bearing was functioning properly prior to the January 1985 visual inspection, o
The bearing was worked on in January 1985, o
There were no signs of excessive temperatures, o
There was movement of the bearing cap relative to connecting rod o
The bearing failure was a fatigue failure rather than a failure due to the lack of lubrication.
It is concluded that the connecting rod bearing failed due to fatigue.
The above information suggests that the fatigue resulted from an inadequate clamp on the bearing cap.
The root cause, however, could not be determined conclusively from inspection of the failed components.
The #3 main bearing failed as a result of the #3 connecting rod bearing failure.
When the #3 connecting rod bearing failed it allowed the lube oil to bypass directly to the crankcase.
The bypass flow reduced the pressure in the main bearing cavity to such an extent that oil was no longer being fed to the bearing surfaces in adequate quantity.
With inadequate lubrication to the bearing faces, the #3 main bearing' failed.
After this failure, all upper and lower crankline bearings were visually inspected and no other indication of fatigue failure was found.
The Demonstration Test Program reconfirmed the reliability of all EDG bearings.
Enclo:uro 5 March 18, 1986 VP-86-0025 Page 1 Endorsements of Fermi-2 Emergency Diesel Generator Crankshaft Bearing Reliability Demonstration Test Progitam by Colt Industries and Failure Analysis Associates 1.
Memorandum from C. Ankrum to Ed Greene, Colt Industries, Fairbanks Morse Engine Division, " Detroit Edison 205981 Contract, Special Engine Run-In Procedure", dated January 30, 1986.
2.
Letter from Dr. L. Swanger, Failure Analysis Associates, to Mr. J. Nyquist, Detroit Edison, "Fairbanks Morse Diesel Engine, FaAA Case No. WDC17064", dated January 31, 1986.
3.
Letter from E. D. Greene, Colt Industries, Fairbanks Morse Engine Division, to Mr. J. Nyquist, Detroit Edison,
" Bearing Inspection - Detroit Edison EDG #11 and #13",
dated February 26, 1986.
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C. Ankrum Detroit Edison 205981 Contract Special Engine Run-in Procedure o.i.:
January 30. 1986 This memo is to confirm our verbal agreement with Detroit Edison to formalize the special run-in procedure recommended for the engines at the Enrico Fermi !!
plant.
All engines are to be run-in per the standard Fairbanks Horse Service Inforcation letter Volume A, issue 5. sheet 1 through 3. dated August-13,1985.
Use the column for 900 rpm engine speed referenced in sheet 3.
The 110%
overload run will not be required.
Upon completion of bearing inspection by feeler gauge after engine run-in, the engine will be subjected to the fo11cwing continuous runs:
b) 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> 9 2500-2600 kw.
a 40 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> 9 2000-2200 kw.
J Upon completion of the 100 hour0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> run, a bearing inspection is to be made with feeler gauge.
If units #12 and 14 pass this inspection. these units may be
(,
returned to service.
It was agreed in the meeting with DECO /NRC/ Colt on January 24, 1985 that units
- 11 and 13 were to receive additional testing per the fo1 Towing:
al 20 slow starts bh 10 fast starts ch 168 hour0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br /> continuous run at 2500-2600 kw.
At the completion of these tests, the bearings are to be inspected by feeler gauge and if acceptable, the units can be returned to service.
If at any point, a conn rod or main bearing fail the feeler gauge check, only that bearing and the bearing connected by the oil passage in t1e crankshaft are to be removed for rework.
No other bearings are to be disassembled.
should be subjected to the full re-run as originally specified.After rework, the. engin All scheduled starts, including the fast starts, the engines are to be pre-lubed I
prior to starting per previous agreement and Detroit Edison procedures.
After engines are returned to service. it is understood that for all future surveillance testing, the engines will be slow started and pre-lubed.
Utilizing the above procedures should provide the best assurance the engines wt meet future demands of their intended service.
(
cc: P. Brown
- 7. Skinner G. Slaymaker T. Miller e
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Failure Analysis ENGrNE EasNG AND WETattumGiCAL CONSULTANTS Associates
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January 31, 1986 Mr. John Nyquist Detroit Edison Co.
Fermi II Nuclear Power Plant 6400 North Dixie Highway Newport, MI 48166 Re: Fairbanks Morse Diesel Enoine FaAA Case No. WDC17064
Dear Mr. Nyouist:
Following up on questions asked by the NRC staff on January 24, 1986, I have the following observations and comments.
The demonstrations planned for EDG 13 and either EDG 11 or EDG 12 will be fair tests of the availability of the Fairbanks Morse diesels during an 18-month refueling cycle at Fermi II.
Use of the.002 in. gap check to detect loss of free spread on the upper crank line main bearings is an appropriate acceptance criteria for this test.
The loss of free spread that is revealed by a gap check failure is due to the non-uniform heating of the bearing's inner surface by friction after interruption of the hydrodynamic oil film.
The thernal stresses cause the inner surface to yield in compression, creating a residual stress state that pulls the bearing parting lines in toward the crankshaft after cool-down.
Interruption of the oil film is caused by substantial transfer of aluminurn from the bearings to the crankshaft, creating geometric deviations so large that hydrodynamic lubrication can no longer be developed.
Transfer of aluminum from the bearing to the shaft can occur in an amount low enough to avoid disruption of the oil film, but still cause~ some pitting or surface scoring of the bearing where aluminum is removed from its surface.
i SOSTON
- DETROIT e MOUSTON
- LO$ ANGELES e PALO ALTO e PHOENIX e WASHINGTON O C
r ".,
s Y 'Mr. John Nyquist January 31, 1986 Page 2 Considering the case where surface scoring has occurred, but not of sufficient intensity to disrupt the oil film and reduce free spread (i.e.,
cause gap check failure), the future reliability of such a bearing / journal pair is of concern to the NRC staff. Even in the presence of surface scoring, the retention of free spread (i.e., passing the gap check) shows that a hydro-dynamic oil film continues to separate the bearing and journal, preventing a high friction, high temperature failure.
The resulting oil film will be thinner than the oil film in a bearing without surface scoring, making the bearing more sensitive to oil-borne particulates, subsequent fast starts, or excursions in operating conditions.
However, the surface scoring is not an inevitable precursor to failure as conservatively defined by the gap check.
At Fermi II, there has been evidence of recovery from the condition of surface scoring. Through the processes of normal wear and plastic flow of the bearing material, healing of scored bearings can occur and has been observed, e.g., ECG 13, lower crankshaft #4 main bearing.
If every bearing survives the planned demonstration without failing the gap check, then the future availability of the diesels is reasonably assured with respect to bearing problems.
The incorporation of the seven-day run at the end of the start cycles would allow even bearings that hypothetically had suffered surface scoring to begin the recovery process.
The upcoming demonstrations will show the benefit of " seasoning" crankshaft journals.
The reported surface finish of a " seasoned" journal versus a freshly lapped journal decreases the probability of harmful bearing-to-journal contact and excessive transfer of aluminum to the journal.
Very ruly rs Lee A. Swanger, Ph.
, P.E.
Mechanical & Metal rgical Engineer Director, Washington Office LAS2/MSW/L-FermiWDC17064 e
e Colt Industries N aak* * **
Engine DMelon Via Telecopier #313/586-5295 701 t.awm Avenue 5
seios.wecor insssis.54s2 Telephone 608/364 4411 Tofecop.er: 606/344-0382 February 26,1986 l
948-1679/86 Mr. John Nyquist Detroit Edison 6400 N. Dixie Highway Newport, MI 48166
Subject:
Bearing Inspection Detroit Edison EDG #11 & 13
Dear John,
We are submitting our letter from C.A. Ankrum, Engineering Department, reaffiming Colt s position on bearing inspection after the extended run-in on unit #11 and 13 ha.s been completed.
For the reasons we discussed during several meetings with Detroit Edison and the NRC; most recently during a joint meeting on 2/14/86 in Glen Ellyn Illinois, we feel that disassembly of the engine after proving its capabilities during the endurance running will not be of benefit and, in fact, creates the possibility of reduced reliability due to the opportunity for introduction of foreign material and/or disturbing the geometry of running bearing surfaces when hold down torque is removed and subsequently re-applied.
Our submittal dated 2/18/86 was considered a compromise position in lieu of complete upper crankline disassembly as requested by the NRC.
If the NRC wishes tc extend the inspection procedure we request that they submit their proposal in writing.
Very truly yours, COLT INDUSTRIES OPERATING CORP.
FAIRBANKS MORSE ENGINE DIVISION Ed D. Greene, Supervisor Product Service Department EDG/1m Enclosure cc:
C. Ankrum T. Skinner A 8%en Of the 004 Nusras Ope *9t1009
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Colt industries
[y,'?'"M 701 Lawton Avenue o
e.wt. wisconern sas11 xem4.un weremoe Ed Greene To:
pra C. A. Ankrum sweet Bearing Inspection Detroit Edison o.m February 25,1986 Ref:'
a)
C. Ankrum memo to Ed Greene dated 2/17/86-b)
Telecon - John Nyquist to C. Ankrum dated 2/25/86 i
Per reference (b), Detroit Edison requests that Colt clarify our position again on bearing inspection for the Unit fil & 13 after extended tests.
The reference (a) memo was written as an alternative to break the deadlo between Colt's position to inspect bearings by.002" feeler gauge vs the NRC position that they want the bearings removed for visual inspection.
It was only to give them some correlation between the feeler gauge check and visual inspection.
This memo is to restate (again) Colt's position that the engine should not be disassembled for visual bearing inspection. The satisfactory completion 'oTthe extended tests adequately insure the bearing are in serviceable condition.
Disassembly and reassembly can only diminish the present condition.
John asked if you would relay this to him right away, cc: P. Brown T. Skinner G. Slaymaker T. Miller i
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