ML20105C435

Evaluation of Diesel Generator Failure at Shoreham Unit 1, Interim Rept on Phase 1,Failure Cause Evaluation, Interim Technical Evaluation Rept

ML20105C435
Person / Time
Site:	05000000, Shoreham
Issue date:	11/18/1983
From:	Herrick R FRANKLIN INSTITUTE
To:	Giardina R NRC
Shared Package
ML20105C438	List: ML20105C435 ML20114A985
References
CON-NRC-03-81-130, CON-NRC-3-81-130, FOIA-84-275 ITER-C5506-426, NUDOCS 8311230073
Download: ML20105C435 (41)

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_ , INTERIM TECHNICAL EVALUATION REPORT y

EVALUATION OF DIESEL GENERATOR FAILURE 4 AT SHOREHAM UNIT 1

! INTERIM REPORT ON PHASE 1, FAILURE CAUSE EVALUATION i

V NRC DOCKET NO. 50-322 FRC PROJECT C5506 NRC TAC NO. -- FRC ASSIGNMENT 20 NRC CONTR ACT NO. NRC-03-81-130 FRC TASK 426 Prepared by Franklin Research Center Author: R. C. Herrick 20th and Race Streets Philadelphia, PA 19103 FRC Group Leader: S. Ahmed Prepare'd for Nuclear Regulatory Commission Lead NRC Engineer: R. J. Giardina Washington, D.C. 20555 November 18, 1983 This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or

, responsibility for any third party's use, or the results of such use, of any information, appa-ratus, product or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights.

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Franklin Research Center A Division of The Frank!!n Institute The Benjamm Frankl.n Parkway. Phila.. Pa. 19103 (215)448 1000

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. INTERIM TECHNICAL EVALUATION REPORT  !

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4 EVALUATION OF DIESEL GENERATOR FAILURE i

AT SHOREHAM UNIT 1

INTERIM REPORT ON PHASE L FAILURE CAUSE EVALUATION

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. NRC DOCKET NO. 50-322 FRC PROJECT C5506 NRC TAC NO. -- FRC ASSIGNMENT 20 NRC CONTRACT NO. NRC-03-81-130 FRC TASK 426 Prepared by ,

Franklin Research Center Author: R. C. Herrick 20th and Race Streets Philadelphia, PA 19103 FRC Group Leader: S. Ahmed Prepared for Nuclear Regulatory Commission Lead NRC Engineer: R. J. Giardina l Washington, D.C. 20555 November 18, 1983 This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for any third party's use, or the results of such use, of any information, appa-ratus, product or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights.

Prepared by: Reviewed by: Approved by:

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ITER-CS506-426 CONTENTS Section Title Page j

1 INTRODUCTION . . . . . . . . . . . . . 1 2 ON-SITE INSPECTION . . . . . . . . . . . . 3 2.1 Primary Briefing . . . . . . . . . . . 3 2.2 Inspection Tour of Diesel Generators . . . . . . 3 2.3 Preparation of Requests for Information . . . . . 4 2.4 Public Meeting. . . . . . . . . . . . 4 3 PRELIMINARY TECHNICAL REVIEW AND EVALUATION. . . . . . 6 3.1 Review of LILOO's Master Plan . . . . . . . . 6 3.2 Rsview of Test Procedures . . . . . . . . . 6

3.3 Preliminary Review of Diesel Dynamics . . . . . . 6 l

l 3.3.1 Review of the TDI Mass-Elastic Model . . . . 7 3.3.2 Investigation of Additional Constraints in the Torsional Mass-Elastic Model . . . . . 8 3.3.3 Investigation of Other Mechanical-Electrical

- Dynamic Coupling . . . . . . . . . 11 3.4 Review of Torsional Testing . . . . . . . . 11.

3.4.1 Initial Tests . . . . . . . . . . 11 l

3.4.2 Completion of Torsional Tests . . . . . . 12 3.5 Review of Preliminary Metallurgical Examination, Diesel 102 Crankshaft . . . . . . . . . . 13 3.6 Preliminary Review of Diesel Status Prior to Crankshaft Failure. . . . . . . . . . . 14 iii

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ITER-C5506-426' I CONTENTS (Cont.)

Section Title Page 3.6.1 Review of Diesel Generator Test History. . . . 14 3.6.2 Review of Conditions at the Time of Crankshaft Failure . . . . . . . . . 16 3.6.3 Review of Previous Vibration Survey. . . . . 18 4 CONCLUSIONS. . . . . . . . . . . . . . 21 5 RECOpe(ENDATIONS. . . . . . . .. . . . . . 22 6 REFERENCES . . . . . . . . . . . . . . 23

APPENDIX A - INSPECTION COMMENTS CONCERNING DIESEL GENERATORS APPENDIX B . RECOMMENDATIONS FOR MECHANICAL AND ELECTRICAL COUPLING INVESTIGATION APPENDIX C - COMMENTS BY H. W. HANNERS ON THE

SUMMARY

OF SELECTED FAILURES AND EVENT REPORTS OF TDI DIESEL GENERATORS P

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, FOREWORD This Interim Technical Evaluation Report was prepared by Franklin Research Center under a contract with the U.S. Nuclear Regulatory Commission (Office of Nuclear Reactor Regulation, Division of Licensing) for technical j assistance in support of NRC licensing actions. A final report will be issued af ter reviewing the final analysis on the Shoreham Unit 1 crankshaft failure, which the Iong Island Lighting Company (LILCO) recently submitted to the j Nuclear Regulatory Commission.

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ITER-C5506-426

1. INTRODUCTION In August 1983, a crankshaft of one of three emergency diesel generators at the Shoreham Nu : lear Power Station, owned by the Long Island Lighting Company (LILCO), *ractured during plant preoperational diesel generator tests. Inspection revealed severe cracking in the crankshaf ts of the other two diesel generators.

Subsequently, the Nuclear Regulatory Commission (NRC) requested the Franklin Research Center (FRC) to provide an independent technical review of the cause of failure determination performed by the Licensee and thereby to provide a technical basis for the NRC licensing actions regarding these

, failures.

Phase I of the two-phase review included the following:

a. attend an on-s,ite inspection and review of the Shoreham diesel crankshaft failure and review operation and maintenance history provided by the Licensee. *

b. analyze the data and information obtained in the on-site visit and prepare an interim report providing initial findings and conclusions regarding the courses of the crankshaft failures.

c. provide in the above report any conclusions regarding the other mechanical problems the Licensee has had with these diesel generators.

This report constitutes Phase I of the Shoreham Unit 1 failure cause evaluation and will be followed by a report concluding the Phase II effort.

On-site briefings and inspection of the diesel generators at the Shoreham

. plant on September 1 and 2, 1983, indicated thats o the crankshaft of diesel generator 102 had fractured o the extent of cracks in the crankshaft of diesel generator 103 precluded any additional operation of that engine l- o diesel generator 101 could be used for a limited experimental testing l program, as per the preliminary analysis performed by Failure Analysis

'- Associates, Inc. ,

l The briefings indicated that, with appropriate instrumentation installed, j limited operational tests would yield information that would assist the l

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. j ITER-C5506-426 .

I i identification of the cause, or causes, of the crankshaf t failures, as well-as provide information regarding previous problems.

Requests for review material were prepared by the NBC and the reviewer.

Part of the material has been received and is under review. With respect to the test program, it was determined that the reviewer should be in attendance 1

I and observe all aspects of the test program. While the test observation consumed considerable time, it provided the reviewer with insight regarding r the diesel's actual operational dynamics.

l Although the tests have been completed, the reviewer has not yet been able to review the test data that were recorded on magnetic tape to facilitate 4

data analysis, computation, and presentation. It is important for selected 1

i portions of the actual data to be reviewed so that an independent review and

• i evaluation of the test results can be provided. As such, the effort of Phase I is not yet complete. For the same reason, conclusions from these tests

.l cannot be drawn for this report. The report of the review of test results, analysis, and conclusions will be submitted later.

This review coordinated the efforts of Mr. H. W. Hanners, an independent

{ diesel engine consultant who was coauthor of NUREG/CR-0660, " Enhancement of ,

on-site Emergency Diesel Generator Reliability." Mr. Hanners' preliminary I

commentary concerning selected problems experienced over the past 3 years by diesel engines manufactured by Transamerica Delaval, Inc., (TDI) , is included l ,

! as Appendix C of this report.

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2. ON-SITE INSPECTION 2.1 PRELIMINARY BRIEFING On September 1, 1983, a preliminary briefing was held in the NRC Resident .

j Inspector's office with respect to the current state of events and plan of

action [1] at the Shoreham plant; a brief overview of the performance history o of the three diesel generators was included. The briefing was conducted by

! the NRC Senior Resident Inspector and supplemented by the Director of LILCO's .

Office of Nuclear Power.

r 2.2 INSPECTION TOUR OF DIESEL GENERATORS

! A visual inspection was made of the three diesel generators. Although  !

I the observations are described in Appendix A, a brief summary follows:

o Diesel generator 101 was located in its operational room and was being j prepared for a limited test program. This unit was reported by LILCO .

i to have performed the initial qualification

• testing program for i nuclear plant service and had been subjected to dynamic torsional

testing as a part of that program. However, cracks were observed in the crank pin fillets of cranks 5 and 7.

I l

, o Diesel generator 102 was the unit with the fractured crankshaft. The I diesel engine and generator had already been moved to the main turbine j deck where space and cranc. facilities were available to disassemble

the unit, make a thorough hspection, and rebuild it with the 13 x 12

• j crankshaft now recommended by Transamerica Delaval, Inc. Considerable l

attention was paid to the crankshaft fracture in this inspection

)

- because of the imminence and magnitude of the failure. The entire I engine was also studied to gain a perspective necessary for an adequate review of the many types of failures experienced previously

. by the Shoreham diesels in order to determine if there may be a root l cause not evidenced by the July 1983 study [2}.

[ o Diesel generator 103, reported to have crankshaft cracks developed to an extent that precludes further engine operation, was observed in its operational room. It was under preparation for movement to the main j turbine deck for disassembly, inspection, and reassembly with the 13 x 12 crankshaft. r

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2.3 PREPARATION OF REQUESTS FOR INFORMATION ,

A meeting with the NRC representatives was attended to discuss the immediate and past problems experienced by the diesels at the Shoreham plant and the'r implication for similar diesels at other plants. Questions were prepared concerning those aspects of the diesels and their performance records ,

that would be required for an adequate independent evaluation. These .

questions were submitted to LILCO by the NRC during the public meeting held at i

the Shoreham plant on September 2, 1983.

1 i

i 2.4 PUBLIC MEETING i l- ,

On-site activities included attendance at the public meeting held at the I

! Shoreham plant on September 2,1983 for discussion of the diesel engine problems. Representatives of the following organizations were in attendances Nuclear Regulatory Commission

$ Long Island Lighting Company *

• l i Hunton and Williams, LILCO legal counsel Stone and Webster I Failure Analysis Associates i

Counsel and Technical Consultant for Suffolk County j Newsday l

Franklin Research Center.

}

i During the meeting, the following points were established l

i o There is no nuclear fuel at the Shoreham plant and, consequently, l~

j there is no demand on the safety systems.

i

! o There is concern for similar diesels in other nuclear power plants. ,

l o The problems with the shoreham diesels are broader than the present

( crankshaft problem.

o The tests on the Shoreham diesels are significant for the whole i

nuclear power industry.

l l o The failure analysis team consists of Long Island Lighting Company, j Failure Analysis Associates, Inc., and Stone and Webster Corporation.

o Transamerica Delaval, Inc., is cooperating with the failure analysis team to provide disassembly, inspection, alternate crankshafts and

rework as necessary, and reassembly of the engines. i l?

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o Transamerica Delaval, Inc., management is committed to the failure analysis and engine rebuilding program and will submit its own assessment and recommended actions; for objectivity, however, the program is under the direction of an independent investigator, Failure Analysis Associates, Inc.

o Concern of the community is high as represented by counsel for Suffolk County and a technical consultant.

o A comprehensive failure analysis effort will be carried out to determine full understanding of the failures so that the corrective action will be most effective.

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ITER-C5506-426

3. PRELIMINARY TECHNICAL REVIEW AND EVALUATION 3.1 REVIEW OF LILCO'S MASTER PLAN A copy of LILCO's master plan [1] for the failure analysis and recovery .

of the diesel engines was received and reviewed. Comments [3] were submitted to the NRC, indicating where the reviewer's direct participation as an ,

observer would be advisable. In general, this review concurred with the plan.

3.2 REVIEW OF TEST PROCEDURES An early copy of LILCO's test procedure [4] for operational test of diesel generator 101 was also received. The procedure was reviewed and a copy was forwarded to Mr. Harvey Hanners, an independent diesel engine consultant.

Commentary and recommendations of this review were combined with those of Mr.

Hanners and reported to the NRC in early September before the start of operational, tests. In the course of operational testing of diesel 101, the original procedure and three revisions (5, 6, 7] were reviewed.

Recommendations for modifications and additions to the last revision [7]

to the procedure were made on September 24, 1983, by a meno [8] sent via the l NRC Resident Inspector at the Shoreham plant for expediency. While the j technical aspects of these considerations are discussed at greater length in Appendix B of this report, they provided means to assure that (1) all voltage ,

! phase references would be available and known, (2) transients associated with attachment of the generator to the electrical grid and to major electrical i

1 loads would be recorded, and (3) testing at a significant synchronous loading ,

would be recorded for power factors ranging from 0.8 to 1.0. These considerations were included in the tests carried out on September 28. ,

3.3 PRELIMINARY REVIEW OF DIESEL DYNAMICS Since the crankshaf t failure and many of the earlier problems of the l

three diesels showed evidence of being associated with the dynamic response of the diesel engines, the torsional and lateral dynamics analysis summary I prepared by TDI as a part of the original design effort was reviewed. These l

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! Shoreham plant to be verified as sufficiently accurate by Failure Analysis Associates, defined the equivalent mass-elastic torsional dynamic model of the l mechanical system, including the flywheel and generator rotor. They included the calculated natural frequencies and critical speeds. This information was

needed to form a basis of understanding by which the reviewers could evaluate  !

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the test data and recognize the response of the various vibratory modes to the

. engine excitation orders in the course of the test runs.

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3.3.1 Review of the TDI Mass-Elastic Model  !

j The mass-elastic model (9) employed by TDI to represent the dynamic i natural frequencies and mode shapes of the engine is made up of 11 inertias and 10 torsional springs. The inertias, identified in their order of position

!l from the gear case end of the diesel to the generator, are:

o gear case and water, pump inertia ,. .

j o eight equivalent inertias representing the piston, connecting rod, and j . rotating portion of the crankshaft for each cylinder assembly o flywheel  !

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! o generator rotor.

l Torsional springs equivalent to that portion of the crankshaft or generator rotor shaft were calculated by TDI for application between the inertias in the ,.

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. model.

The analysis summary reviewed indicated that the inertia for each crank assembly is the equivalent average inertia. This is some average of the real l inertia comprised of a rotating crank, linear motion piston, and a connecting ,

I rod that combines both motions, all of which combine to form an inertia that  :

f varies with crank angle. Various methods are available to average these crank j angle-dependent inerties to equivalent average inertias for use in the mass-elastic model yielding the natural frequencies. The detailed methMs by which I

TDI calculated the equivalent inertia and torsional spring constant for each crank assembly are not evident from the analysis summary [9). Information that will identify the methods used was requested from TDI through NRC. When 1g JUU Flankliniesserch Center

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ITER-C5506-426 l l

available, it will be reviewed to provide commentary and recommendations regarding TDI's methods. Methods developed by the industry over many years have been known to yield generally reliable results for most engine designs, j This is not to imply that TDI did not use these methods correctly, only that they did not make their detailed methods evident in the analysis summary.

For this report, it is assumed that the calculated inertias and springs, ,

resulting natural frequencies, and critical speeds are sufficiently accurate.

This premise is based upon the facts that qualification testing was reported .

to verify these frequencies and that Failure Analysis Associates, Inc.

reported in briefings during the Shoreham inspection visit that it had obtained virtually the same values using more comprehensive computer methods.

Using its model for the resonant frequencier, TDI calculated the participation of the various orders of known engine excitation and plotted the amplification factors of the more dominant excitation orders as shown in Figure 1, which is a reproduction of the TDI chart from Reference 2. Note that the I-4 (4th order) curve of amplification factor remains the single largest participant, providing more than double thrs amplitude of the 41/2th order during operation at 450 rpm. The excitation frequency of the 4th order is that of 4 times per revolution. This is the firing rate of the cylinders l

which generates a sharp and dominant excitatien. In short, using its l analysis, TDI expected to experience a large component of oscillatory torque .

! at 30 Hz (engine firing rate) in the crankshaf t. However, a large cyclic l

torque at 30 Ha is not necessarily bad, provided the associated stress levels in combination with stresses from other sources in the crankshaf t are .

l adequately within the endurance limit of the material.

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3.3.2 Investigation of Additional Constraints in the Torsional Mass-Elastic

Model i

I The influence of rotor-stator electrical coupling upon the purely mechanical torsional model employed by TDI was investigated in this review.

i j Rotor-stator coupling of a synchronous generator may be approximated as an j equivalent spring rate between the generator rotor and the inertia of the l

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ITER-C5506-426 electrical load. When the generator is connected to the electrical power grid, this equivalent inertia can be very large. In such cases, it is valid to approximate the ef fect by calculating the equivalent spring rate of the rotor-stator system and inserting it into the torsional mass-elastic model between the generator rotor inertia and a new fixed rigid member (infinite inertia).

Review of TDI's mass-elastic system revealed thats o the generator inertia was exceptionally large .

o the flywheel inertia was only between one-third and one-half that of the generator rotor o all other inertias representing crank assemblies, water pump, etc.,

were very small by comparison.

1 Thus, while the introduction of the rotor-stator equivalent spring had an exceedingly small effect upon the natural frequencies of the rotor and their dynamic response under the engine excitation, it did define a new mode of vibration not heretofore available from TDI's torsional model. This was essentially a rigid-rotor oscillation of the combined crankshaft, flywheel, and generator rotor system with the rotor-stator spring connecting the rigid-rotor system to the nearly infinite electrical load inertia mentioned previously. The natural frequency (resonance) of this vibratory mode was independently calculated to be approximately 3.0 Hz. This vibration mode ,

contributed to the cyclic variation of power previously observed from the control room to be at 3.75 Hz, which is the frequency at which one complete set of eight cylinders fires, or the rate at which any one cylinder fires. ,

Fortunately, the natural frequency of just under 3.0 Hz was sufficiently far from the 3.75 Hz excitation to prevent large amplitude vibration with resulting large swings in power. Also, the amortisseur windings of synchronous generators provide damping under oscillatory motions to limit amplitude buildup.

For diesel generators that may be coupled to the electrical power grid, TDI should have addressed this electrical-mechanical, rotor-stator coupling.

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ITER-C5506-426 3.3.3 Investigation of other Mechanical-Electrical Dynamic Coupling When received, the torsional analysis report indicated that the 30-Hz firing rate of the engine (4th order) would be sufficiently close to the first .

mode natural frequency, 35.5 Hz, to build moderately high amplitudes of

• oscillation at 30 Hz, which is one-half the electrical generation frequency.

Accordingly, recommendations were made [8] to ensure that any possible

. electrical-mechanical interaction would not be missed by the recording of d

data. These recommendations are included in Appendix B.

3.4 REVIEW OF TORSIONAL TESTING 3.4.1 Initial Tests The torsional testing program, with operation of instrumented diesel 101, was conducted to establish correlation with a detailed computer dynamic model of the diesel formulated by Failure Analysis Associates, Inc., as well as to, ,

investigate the dynamic interaction of the diesel with various loadings and operational conditions. The torsional testing' program was primarily concerned with the catastrophic failure of the crankshaft in diesel 102 and near failure crack propagations in diesels 101 and 103. The testing was observed as a part of this review.

Listings of measured parameters, sensors and transducers, and data recording equipment are provided in the test procedures [4, 5, 6, 7] . These include most engine operational temperature and pressure data, that is, lubrication temperature and pressure, combustion air pressure, each cylinder exhaust pressure, etc.

Instrumentation for the measurement and recording of vital dynamic data included the followings o Cranks 5 and 7 were instrumented such that crankpin fillet and web dynamic strain were measured by three element strain rosettes bonded to the fillet and by a single gage on the crank web.

o Dynamic torque in the crankshaf t adjacent to the flywheel were measured by a strain gage torque bridge.

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ITER-C5506-426 I

c i o Cylinder firing pressure of cylinders 5 and 7 were measured with high-pressure piezoelectric transducers.

o Shaft dynamic displacement were measured by a torsional displacement transducer mounted on the gear case end of the diesel crankshaft.

o Linear acceleration of the engine base were measured by accelerometett

! mounted on the base at cylinders 5 and 7.

4

• o vertical, horizontal, and axial acceleration l vibration) were measured .

for the bearing housing next to the flywheel, o Crankshaf t position and revolution tachometer were referenced to toli .

dead center of cylinder 7 provided by an optical sensor mounted on the i generator shaft.

o Generator output voltages were recorded to measure (VA-V) B and (Vg - V C)+

i j o Generator output current was measured for individual recording of each  ;

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1 Instrumentation on the rotating crankshaf t was battery powered with ,

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signals transmitted by FM telemetry.

The initial tests were started on September 19, 1983, using the test

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4 procedure (6] dated September 15, 1983. Strain gage problems continued with l gages dropping from service until five of the eight strain gages in the fillets I and webs of the crankshaft were not operational. Testing was suspended at l that point to repair the strain gage instrumentation. However, the test 4 program had progressed through the initial checkouts, through the variable speed torsiograph tests, and included the 1750 kW synchronous load test with i the generator connected to the electric power grid. The full load tests, 3/4 .

load tests, and the TDI torsiograph tests remained to be accomplished. ,

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3.4.2 Completion of Tersional Tests i

j Following repair and improvement of the strain gage instrumentation in t;he j crank fillets and on the crank web, testing resumed at 2:44 an on September 28, f 1983. These tests included the test program in the test procedure [7] dated -

! September 23, 1983. The test program, with instrumentation performing satis-factorily, continued to completion at approximately 7:30 as that same morning.

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ITER-C5506-426 Testing began with Section 7.1 of the procedure [7], which involved measurements for verification of the analytic model at Failure Analysis Associates in Palo Alto, CA. This was a correlation procedure in which the initial dynamic measurements were telephoned to the Failure Analysis Associates offices and checked against the analytic (computer) model both to verify the model and to permit the model to predict the available run time on the engine before crack propagation would preclude further testing.

Testing continued through the balance of the test procedure, including measurements recommended by this review, and concluded with tests requested by TDI using its own torsiograph and associated instrumentation.

Observations of data during the acquisition and recording of data on magnetic tape'were somewhat liaited, but these observations disclosed no instabilities with the electrical system or adverse transients in these tests upon connecting the diesel generator to various loads. As expected, the crankshaft torque signal and the crank fillet strain gages showed a ,

significant 30-Hz component keyed to the pressure rise of each cylinder.

With the test data recorded on magnetic tape, the review plan at the completion of tests was to permit the Licensee and its contractors to review and verify calibration and zero settings of the various data channels in their home facilities before conducting an independent review of the test data.

Further commentary regarding the test results must await a review of the test .

data.

o 3.5 REVIEW OF PRELIMINARY METALLURGICAL EXAMINATION, DIESEL 102 CRANKSHAFT A copy of the p,reliminary metallurgical evaluation of the failed crankshaft from diesel generator 102 (10] was reviewed. This report of metallurgical examination and fracture analysis confirmed that the failure occurred by fatigue, with the fatigue crack originating at a machining mark on the fillet radius. While the report emphasizes that the findings to date are of a preliminary nature and that residual stress measurements are still in progress, the report does state that, from visual examination, "the fracture surface exhibited an obvious, unmistakable fatigue crack pattern."

Aw bFranMin Renaarch Center _

~

ITER-C5506-426 ,

i 4

Although no other review material concerning the crankshaf t has been

[

! received, the reviewer did observe, during the test completion at the Shoreham l Pl ant, a color photograph of a fractured surface reported to be that of the diesel 102 crankshaft fracture. The clarity of the photo was sufficient to depict a classic fracture pattern. Full' documentation is expected for review l

following completion of the analysis by Failure Analysis Associates, Inc.

~

The preliminary metallurgical report also stated that chemical analyses l

of samples of crankshaft material indicated that the crankshaft steel meets I

the ASTM A235-47 Class I specification said to be specified.

I The prelia'inary metallurgical report also indicated that hardness, grain

! flow, and tensile properties were generally in order.

l Again, items pertaining to the fracture analysis and metallurgical 3

j analysis will be reviewed as they are made available. A more comprehensive l evaluation of these subjects will be reported later.

.i 3.6 PRELIMINARY REVIEW OF DIESEL STATUS PRIOR TO CRANESHAFT FAILURE l'

3.6.1 Review of Diesel Generator Test History j

Documentation of the test program at TDI prior to delivery of the diesel

! generators to the Shoreham plant has not art.ived for review; however, statements made by LILCO and TDI at the September 1-2 briefing indicate that a number of manufacturer's operational tests were performed on the engines in i addition to the nuclear qualification program that was performed using diesel 4

I 101. It was stated in these briefings that the test data confirmed "to within

. i l It* the critical speeds calculated during design. No statements were made f concerning whether these tests confirmed the amplification factors of each I significant order of vibration.

l Reference 11 is a summary of Shorehan's test program for the emergency t

! diesel generators forwarded to this reviewer in advance of complete documenta-tion. This summary indicated that the test program was responsive to i f

Regulatory Guides 1.108 and 1.9 and IEEE Std 387, in accordance with LILCO's e commitments in the Shoreham FSAR. I

- t

! ~ l 0 L Franklin Research Center

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ITER-C5506-426 The test program was described as being of the " building block type" starting with checkout and initial operation tests for individual components, whereupon the components are combined into subsystems and tested again. The checkout and initial operation were stated [6] to consist of 138 test packages in addition to 12 flush procedures, followed by 15 functional test procedures.

After the above tests, the diesel generators were operated for the first o time as follows (11]:

Diesel generator 102, October 1982 Diesel generator 103, March 1982 Diesel generator 101, April 1982.

Testing of each diesel continued according to procedure, and the final test was performed to demonstrate the capability of the diesel generators to complete successfully a total of 69 consecutive starts. According'to Reference 11, "By June 24, 1983, the emergency diesel generator preoperational test program, including all mechanical, electrical and qualification tests, was compl'eted for all three diesel generators."

In August 1983, all three diesels underwent a cylinder head stud replacement program, and one diesel generator completed the high load retest (11]. LILCO's summary continues, stating that "one remaining demonstration of diesel capability was scheduled prior to fuel load; the integrated emergency core cooling system and emergency diesel generator operational demonstration." ,

It was not clear, in the review, whether each of the diesel generators was required to undergo this remaining test because the material reviewed clearly indicates that the engine failed during a retest.

LILCO reported (11] that, as of the August 12, 1983 crankshaft fracture, l the diesel generators had accumulated 2182 hours0.0253 days <br />0.606 hours <br />0.00361 weeks <br />8.30251e-4 months <br /> of operation as follows:

Diesel generator 101 -- 646 hours0.00748 days <br />0.179 hours <br />0.00107 weeks <br />2.45803e-4 months <br /> Diesel generator 102 -- 71C hours Diesel generator 103 -- 818 hours0.00947 days <br />0.227 hours <br />0.00135 weeks <br />3.11249e-4 months <br />.

i In response to a request for information by the NRC regarding the total number of operating hours on each diesel generator (DG) and the total number of hours at 3900 kW or greater, LILCO responded (12) as follows:

]

i 1

4 p3 l 0 ranklin Desearch Center

. . . .. __ . _ _ _ . _ . _ .. . ~

l ITER-C5506-4.26 Total Operating Hours for Each DG Unit at 2-hour Overload Rating (> 3850 kW)

Total Operating Hours (These hours included in total on Each DG Unit operating hours)

DG At At At At '

. Unit TDI Shoreham Total TDI Shoreman Total 101- 128 518 646 3 16 19 102 30 688 718 3 19 22

, 103 40 778' 818 3 20 23 ,

i i  !

j 3.6.2 Review of Conditions at the Time of Crankshaft Failure l

In response to a request for information by the NRC about the test procedures in use at the time of the crankshaft failure, LILCO responded with the following description of the test (13):

" Cylinder heads on DG 102 were replaced under R/RR R43-1001 with new design stress relieved heads. With all eight cylinders equipped with the . ,

new heads, the 102 DG was run for 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to allow hot torquing of the exhaust header bolts and air start valve nuts. Following this run, a j retest of the engine was begun under 8.7-R43-042. The specific scope of 1 -

the retest under this 8.7 Form was tos

1. Verify proper diesel generator start to synchronous speed and rated voltage in less than 10 seconds.

l, l

2. Verify proper DG operation for four hours at the continous load -

l rating.

i l 3. Verify proper DG operation for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> at the two hour overload rating. ,

l i Refer to the response to NRC Request for Information II.2, pages 10.5 through 10.17, for a copy of the retest procedure 8.7-R43-042, as *

} completed up until the time of the failure of DG 102."

On page 10.1 of Reference 14, LILCO provided the following detailed description of the events just prior to the failures l "The diesel generator prior to the performance of 8.7-R43/42 was in its normal standby condition. An interin operating instruction was performed I to ensure proper breaker positions, proper valve lineup and correct "

initial conditions. The diesel engine was started from its remote location, the main control room. Proper starting, acceleration to i

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ITER-C5506-426 synchronous speed and rated voltage within 10 seconds was verified by the I

• test engineer and the OQA inspector. Plant Operator synchronized the j diesel generator to BUS 102 by closing ACB 102-8 and then proceeded to I increase the diesel generator load to 3500KW in less than 60 seconds.

' Once at the 3500 KW/300KVar load the operator was instructed to maintain this load for four hours. He was instructed that any deviations, caused by the LILCO grid, away from 3500Kw/300Kvars should be corrected.  ;

3 Another plant operator was stationed in the engine room with verbal i communications established between operators via headsets. During the e

' course of the four hour full load run, a LILCO technician was also

' - stationed in the diesel engine room with the task of recording all pertinent test information every 30 minutes. No abnormal readings were j observed by either operator nor-was the data written down by th's technician found to be out of its normal operating range as specified by the engine manufacturer for this size load.

q j Since this test was handled similar to a Station Surveillance Procedure

' no special test equipment was utilized for data recording. All data j written down was taken off of normal plant gauges either in the main

control room or in the diesel engine room. The two exceptions were the j generators bearing temperature and the generator stator temperature, both j of which were read off M&TE calibrated instruments. As stated in the 8.7

• - form high. speed recorders were not used to record data on chart paper as

• I a permanent record. Once, during the full load run the individual I

! cylinder firing pressures were recorded and found balanced within

~

l manufacturer specified tolerances.

l At the conclusion of the four hours the. control room operator slowly l increased the 102 generator load up to 3900KW/300 KVars. This load was to be maintained at this level for the remaining duration of the test and the operator was allowed to correct for any load deviations. During the  :

increase'in load, the lube oil low level alarm came in. The dipstick was l checked and found to be below the shutdown level nark by 7-8". (This i l

level is normal for high load operation of the DG units, and the alarm has been an occasional occurrence on all three engTnes) . Lube oil pressure and turbocharger pressure were normal and the test was allowed to continue. Data readings were taken every 15 minutes. No abnormal noises were heard by the technician nor the local operator. Vibrations did not sppear anything out of the ordinary; in fact the diesel engine seemed to be running fairly well. ,

The overload portion of the test was some one hour and 45 minutes into the two hour run when the diesel generator vibration was felt in the control room. The local operator reported no abnormal vibration.

Generator load swings of 2.0 MN were observed in the control room meters, i the operator reduced load to 1.0 MW and the oscillations, subceeded. It was at this point that the generator load shot up to 4.0 MN where the operator tripped the output breaker ACB 102-8 and manually depressed the

'stop' pushbutton. It was later observed that the engine overspeed trip had been activated and its alarm had been initiated. Other detailed L

- 3 0 N "* __._ _ __ _ _ _ _ _ _ _ __

t ITER-C5506-426 descriptions of this failure are attached, as well as a copy of the data sheets. Again no traces are available for analysis. Inspection of diesel crankcase internals showed the crankshaft web in the area of No. 7 i connection rod was cracked." )

On page 10.3 of Referenc<a 14, LILCO provided the following sequence of i

events when fracture is believed to have occurred i

"(Times are approximate and are intended to illustrate sequence rather ,

i than exact time of occurrence)

Backgrounds. EDG at 3.9 m for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and 45 minutes, 15 minutes from ,

completion of scheduled 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> run.

NASO - S. Livingston on headset at EDG 102 panel in Main.

Control Room, E. O. - M. O'Brien on headset in EDG 102 room.

5:15:00 Noticeable increase in vibration in Main Control Room - W.

Uhl, W. Nazzaro, W. Gunther approached Main Control room panel. Slight, but normal, fluctuation in load around 3.9 W - no other indication of problem. Communication to EDG 4 room for observation of any problem - only response was technician was in area taking readings.

5:15:45 Vibration continued and suddenly load swing of 1.5 to 2.0 MW coa.nenced between 2 MW and 4 MN. Communication from CR to

! field 'are you doing anything'. Within 15 seconds, load I was reduced by CR operator to 1 MN. Vibration ceased. This load was carried for about 15 seconds.

I 5:16:15 Load increased without cause to 4.0 MN. Vibration increased i again. Again communication between CR and EDG room i

regarding what was going on. W.,Nazzaro, instructed' ,

! Livingston to decrease load. Ioad would not come down.

i j 5:16:30 W. Nazzaro instructed Livingston to trip the machine who i- immediately opened the output breaker. Speed was noted to reach 600 RPM before coasting down to rest. .

d I

! Flapsed Time - 1 1/2 minutes" q .

I. 3.6.3 Review of Previous Vibration Survey o

lj There was ample evidence of concern over the vibratory amplitudes of the U diesels. Review of the partial listing (15] of selected previous problems l; with the diesel generators also provided evidence of high dynamic forces that lt had the potential of being associated, on preliminary evalua': ion, with large l, amplitude torsional vibration. Should subsequent thorough evaluation prove o

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._ _ _ _ , _ _ n _ _ .. & _ _ ; m._ m ._ - - _ _ ._. m ITER-C5506-426 i this to be true, then many of the various component failures would no longer -

- be isolated independent events as previously reported but linked to a common cause.-

Until more information is available, the following evidence of repeated failures in components directly connected to the crankshaf t remains circumstantial l Date- Failure Description

! 3/30/83 Bolddown capscrews, rocker arm assembly (EDG-103) 9/17/82 Jacket water pump shaft (EDG-102 & 103)

10/05/81 Piston crown separated from skirt Failure of attachment stud bolts 4

! Grooving of crankshaft bearing and crank pin discolored wrist pin grooved and pitted, wrist pin discolored I

TDI's torsional analysis summary [9] does indicate a strong 30-Hz cyclic torque component expected in the crankshaft, as discussed earlier in this report. Subsequent analysis of these failures using TDI's torsional model would be meaningful, but, by that time, the full results of the cyclic amplitudes measured in the torsion testing program under various loadings using instrumented diesel generator 101 would be available. Test data will l more accurately reflect the real life situation.

i

' - Concern over vibration was sufficient to initiate a vibration testing program in the late spring and early summer of 1983 [2]. The conclusion of this study states:

i "On the basis of comparisons of vibration data taken, the Shoreham .

diesels have only the expected and normal vibration and are not subjected to any excessive vibration and this normal, expected vibration does not

prevent the diesels from reliably performing their functions."

f It is noted that the study was based entirely on linear vibration

( measurements without any measurement of torsional vibration. It is true that l

i wip l $uFMT "mM Center

ITER-bS506-426 rotating machinery can suffer from high torsional-vibration with little evidence of linear vibration. However, the crank mechanisms of diesel engines provide coupling between the torsional and linear vibratory systems so that there is usually evidence of linear vibration associated with torsional vibration. -

A more thorough review of possible vibration coupling giving rise to a ,

common cause will be performed in Phase II.

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i ITER-C5506-426 l

4. CONCLUSIONS Although there is conjucture at this time regarding common cause linking of past failures with the crankshaft failure, the major conclusion that can be

. drawn is the followings the mechanism of crankshaft failure was fatigue; however, the source and nature of the fatigue cannot be established at least until the torsional test data are analyzed and compared to mathematical models of stress and to verified material properties in the crankpin fillets.

It is concluded from the torsional analysis performed by Transamerica Delaval, Inc. that a significant cyclic torque was expected in the crankshaft. However, additional design information must be reviewed to conclude whether the resulting design stresses in the crankpin fillets were calculated using the full stress concentrations at critical points.

O e

I I

l l

anklin Research Centar

ITER-C5506-426 l

i

5. RECOMMENDATIONS  !

I It is recommended that the NRC continue to encourage the completion of the comprehensive failure analysis being conducted as a result of the Shoreham diesel generator failures, and that the resulting data and analysis be employed to establish an increased state of reliability for diesel generator applications in nuclear power plants.

It is also recommended that a survey program be established throughout the nuclear power industry employing the findings of this endeavor to identify failure potentials in other installations and to identify possible cases of Common Cause.

( .

000 Franklin Research Center

[

A Ohuman eiThe Manten Inseue

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_ _ ...._ _ _ _._ _ _ , li. .

ITER-C5506-426 4

6. REFERENCES

1. Master Plan, Crankshaft Failure Analysis / Recovery, Emergency Diesel Generator 102 Shoreham Nuclear Power Station August 23, 1983

2. P. J. Holden, Project Engineer 4

Diesel-Generator Operational Review Program, Prepared for LILCO, Submitted to E. J. Youngling, LILCO July 14, 1983

3. S. Ahmed, FRC Informal Technical Communication to J. T. Beard, NRC

Subject:

Regarding LILCO Master Plan for Recovery from EDG 102 Crankshaft Failure September 9, 1983 -

4. Procedure for Crankshaft' Testing, Emergency Diesel Generator No. 101 September 2, 1983

5. ' Revision, Procedure for Crankshaft Testing, Emergency Diesel Generator No. 101 -

September 9, 1983

6. Revision, Procedure for Crankshaft Testing, Emergency Diesel Generator No. 101 i

September 15, 1983

7. Revision, Procedure for Crankshaft Testing, Emergency Diesel Generator No. 101 ,

September 23, 1983

8. R. C. Herrick, Principal Engineer, FRC Memo to C. Petrone, NRC Resident Inspector, Shoreham Nuclear Plant

Subject:

. On-site for Tersion Test Monitoring

- September 24, 1983

9. Delaval Engine and Compression Division Torsional and Lateral Critical Speed Analysis, Prepared for Long Island

-Lighting Co.

Augudt 1974; detvised March 18, 1975 l 10. Failure Analysis Associates, Inc.

! Preliminary Metallurgical Evaluation of Failed Crankshaft from DG102 (No date) 1 00 Franklin Research Center - _ ,_ .

ITER-C'5506-426

11. LILCO Preliminary Response to NRC Request for Information I.3 Transmitted September 20, 1983 *

12. LILCO Response to NRC Request for Information: 5

13. LILCO Response to NRC Request for Information II.1 Transmitted September 20, 1983

14. LILCO Response to NRC Request for Information II.2 Transmitted September 20, 1983 -

15. J. T. Beard, NRC Memo to Gary M. Holahan, Chief, Operating Reactors Assessment Branch, NRC -

Subject:

Recent Failure Experience of Transamerica Delaval, Inc.,

Emergency Diesel Generators .

August 22, 1983 400UU Franklin Research Center A Chaman of The Franten Inseame

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APPENDIX A P

1 INSPECTION COMMENTS CONCERNING DIESEL GENERATORS l

l

. . . _ Franklin Research Center A Division of The Franklin Institute The Benjanan Frankhn Parkway, Phila., Pa. 19103 (215)448 1000

___._a-_-~.- -

- . - - a- ~~~.~~=~1--w A.1 Diesel Generator 101 Diesel generator 101 was located in its operational room and was being prepared for a limited test program. Accordingly, the crankshaf t was exposed )

for inspection, cracks in cranks 5 and 7 were being ground out to reduce the associated stress concentration, and preparatior.s were being made to install instrumentation. Instrumentation specialists at diesel 101 indicated that the I

- planned instrumentation included a strain' gage torque bridge on the cr'ankshaft  !

adjacent to the flywheel, strain gage rosettes in the crankpin fillets of

. cranks 5 and 7, vibration transducers (accelerometers) on various bearing journals, pressure transducers in two combustion cylinders, an angular displacement transducer (torsiograph) on the free end of the crankshaf t (opposite the flywheel and generator), and a sensor on the generator shaf t to '

indicate shaft position relative to top dead center of crank 7. This instrumentation was in various stages of preparation and installation.

The cracks on the crankshaft appeared to have been nearly ground out in accordance with the torsional test procedure [7]. Cracks in the crankshaft of diesel 101 were reported at the time to be approximately 1 inch deep prior to grinding. Crack locations included cranks 5 and 7, with the cracks making an f approximate angle of 45* relative to the crankshaft (or crankpin) longitudinal axis. The crack on crank 7 was located in a 5 o' clock position relative to top dead center of crankpin 7 and on the fillet toward crank 8. The crack on crank 5 was located in a similar manner but in a 7 o' clock position on the crank pin fillet toward crank 6.

, A.2 Diesel Generator 102 Diesel generator 102 was the unit with the fractured crankshaft. Diesel

.102 had already been moved to the malr. turbine deck where space and crane facilities were available to disassemble the unit, make a thorough inspection, and rebuild it with the 13 x 12 crankshaf t. Disassembly and inspection of the whole engine was progressing part by part, and while it had not progressed to the point of removing the fractured crankshaf t, the fracture was clearly visible and open to close inspection through the sides of the engine block where the cover plates had been removed. Inspection of crank 7. revealed a

_ (DfCO{tCCR00CGEP _ _ _

fracture through the crank web and partially through the crankpin, with the fracture passing through the crankpin fillet at approximately the 5 o' clock and 7 o' clock positions with respect to top dead center of that crank. The tip of the V-shaped crack propagating out into the crankpin reached approximately to the midpoint of the crankpin bearing surface.

Further inspection of the fractured crankshaft (still assembled in diesel 102) revealed that one edge of the web at the fracture evidenced a large discolored area characteristic of heating to a temperature range of 400*F to .

600*F. This discoloration was attributed to the considerable energy dissipated in sliding contact at the point of fracture and against the connecting rod ,

during the relatively short time (approximately 1 1/2 minutes) that the diesel was believed to be under power (see page 3 of Reference 14) following the fracture.

Inspection of the sump revealed considerable debris under crank 7 as compared to other crank positions. -Although accumulated dirt in the engine j sump was heaviest toward the flywheel and generator end of the sump, the excessive accumulated deb.ris of crank 7 proved to be mainly bearing material ,

j scraped out.of the connecting rod bearing by the displaced fractured segment of the crankpin that acted as a sharp cutting tool during those moments of operation following crankshaft fracture.

Inspection of the crankshaf t failure beyond that reported here was not conducted because the crankshaft was to be removed over the holiday (Labor Day) weekend and transported to the facilities of Failure Analysis Associates, ,

Inc., in Palo Alto, CA, for immediate extensive examination.

l A.3 Diesel Generator 103 -

l Diesel generator 103 was observed to be under disassembly in its opera-l tional room in preparation for moving it to the turbine deck. .

l l The crankshaf t of diesel 103 was reported in the initial briefing to l

contain cracks of sufficient depth and magnitude to preclude further operation. Testing will be performed using diesel 101 only. The action plan for diesel 103 reportedly calls for complete disassembly, inspection, rework l

l 4 A-2 000U Franklin Research Center A DMmon of The Frerdenlasuue

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4 1

as necessary, and reassembly with a 13 x 12 crankshaft (13-in journal bearing

- diameter and 12-in crankpin diameter) now recommended and supplied by Transamerica Delaval, Inc. Analytical studies of the engine with this crankshaft will be carried out concurrently, with updates to the analysis being made as test data on diesel 101 become available.

4 i

i l

i t

I l

l l

l l

l A-3 0 Frankhn Ranmarch Cantar

m i  !

I APPENDIX B

- RECOMMENDATIONS FOR MECHANICAL AND ELECTRICAL COUPLING INVESTIGATION 1

i l

1 O

~

. . . . Franklin Research Center A Division of The Franklin Institute The Bentarrun Frankhn Parkway. Phita.. Pa. 19103 (215)448-1000

- m _.a __ . _ _ _

The following three recommendations were made [8] to ensure the recording of possible electrical-mechanical dynamic interactions in the course of diesel generator testing.

First, the generator output voltages for the three phases were not all slated for recording - only (Vg - V B) and (V B ~

I C* *"

electrical interactions occurred during the tests, a positive voltage phase reference would not be assurad, but would be dependent upon the 3-phase generator voltage output remaining balanced. That is, only two measurements were being made, and that fact required the third voltage to be calculated from the 3-phase electrical vector relationship. This is possible only with 4

the assumption that the voltage remains balanced on all three phases. When it was reported that the third voltage for recording could only be obtained with considerable difficulty, it was recommended that the voltage on each of the three phases be read and recorded separately (from the control room) so that each voltage would be known, should it be required for vector calculations.

} Although it was believed thct the electrical power grid would certainly remain balanced during the recording of data during the synchronous load tests, the

~

reading of the voltages would remove all doubt. For loadings derived from f plant equipment (core spray, etc., versus the electrical power grid), the measurement of voltage was more meaningful.

Second, even though the generator rotor inertia was large, it was 7

believed prudent to provide for the investigation of generator instabilities, l

especially since there could be significant cyclic torque at 30 Hz. Accord- ,

ingly, it was recommended [8] that all vibrational data be recorded at power l

- factors between 0.8 and 1.0 in synchronous load tests under as high a load as I

feasible. A load of 2550 kW was chosen from the test procedure to minimize engine run time at or near full load.

The background of this recommendation is that synchronous generators tend to be more unstable with low excitation (1.0 power factor) than with higher excitation (0.8 power factor) . - Also, page 1 of Reference 14 indicated that a

~

significant amount of the testing on diesel 102 was performed at a power factor of 1.0. Diesel 102 was operating at power factor of 1.0.at the time of failure (14]. Further, means were not available i mediately prior to the test to determine if the 30-Hz cyclic torque could aggravate generator instability.

Hence, this consideration appeared to be a prudent course of action for B-1 pQ00 U

er. naso n ,th coni.,_

l .

- thorough coverage of possible instabilities or mechanical-electrical interac-tions.

The third recommendation was that assurance be provided for the recording of any transients, mechanical and/or electrical, associated with synchroniza-tion and attachment of the diesel generator to the electrical power grid, and to any of the isochronous loads.

n B-2 000u Fianklin Research Center A Dammen of The hensen inseue

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i APPENDIX C COMMENTS BY H. W. HANNERS ON THE

SUMMARY

OF SELECTED FAILURES AND EVENT REPORTS OF TDI DIESEL GENERATORS i

\ -

. . . . Franklin Research Center A Division of The Franklin Institute The Benjamin Frankhn Parkway, Phila.. Pa. 19103 (215)448 1000

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4 APPENDIX C l l

COpmENTS BY H. W. HANNERS ON THE

SUMMARY

OF SELECTED FAILURES AND EVENT REPORTS OF TDI DIESEL GENERATORS j l

Comments on the items as dated:

08/12/83 The broken crankshaft is believed to have been the result of excessive stress due to torsional vibration.

03/30/83 These screws may have failed as the result of inertial forces from engine operation at or near a torsionally critical speed as well as possible low quality in material, design or manufacture.

i 03/08/83 The cracked cylinder heads could have been the result of design, but the 4

new design apparently needs to be tested'by actual use and acceptance tests. - -

03/03/83 The high pressure fuel line failures could surely be reduced by design improvements of the shroud (usually called sleeve) . Again, sufficient proof remains to be seen through in-service experience and acceptance tests. .

, 12/13/82 Better quality obviously needed.

~

09/17/82 The omission or removal of the keyway in the water pump shafts could be avoided by eliminating the " stress raiser" effect of the keyway in torsional

--vibration. An impeller design change to reduce the rotary moment of inertia could also help.

i C-1 00 r,.nioin n ,eh c.n , _ _ __

07/22/82 .

Probably fixed by the change of design.

06/23/82 Change to neoprene is certainly an improvement over isoprene.

i

! 05/13/83 This probably should have been 05/13/82 from the "becktracking" review scheme being used.

A 05/13/82 The shorter capscrews may be satisfactory, but were the original screws 4

actually too long or the threaded tapped holes too shallow?

! 03/19/82 Neither the problem nor the solution (or fix) are clearly

• explained. The ,

53-minute bleed down time is too long as a practical fix. Even 53. seconds is rather a long time to consider acceptable. Successive starts should certainly be allowed more often than 53 minutes apart. Seismic qualification of the sensing line is recommended.

ii 03/15/62 ,

This implies that the rear crankcase cover is a stress bearing part.

Neither the strongest bolts nor_the reasons for the basic failure give faith in the TDI remedy or explanation of the failure. More proof and further- *

! explanation are needed.

I 12/09/81 The TDI remedy of a lower oil cooler mounting seems reasonable, but the complete system should be reviewed.

t u00 Fr.naiin a rch c.nier

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e 11/05/81 .

The use of Belleville washers in the two-piece piston design may or may not be satisfactory, depending on whether the heat from the hot piston crown anneals the Belleville washers. Heat barrier design may also be required for

{ success.

The cylinder liner grooving and the bearing grooving may very well ba caused by " built in" dirt and chips in the original factory assembly. All three engines should certainly have the crankcases ce bedplates thoroughly cleaned and all bearings examined and replaced as needed. A tedious, careful, and expensive job is indicated. This means not only the bearings, but also the surface of the mating parts such as the crankshaft crankpin and main journals and other parts would be damaged.

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07/14/83 (or 07/14/81)?

Another indication of possible excessive vibration and or lack of proper clamping to prevent cracking of oil lines. Danger of fire from oil line fracture should certainly be given more attention..

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1 03/23/81 Motors should certainly be qualified and not merely be stated to be j equivalent.

12/16/80

• A .edesign of the lube oil system is indicated as necessary so that the i turbocharger bearings get oil immediately after a start. This may mean a

- change to an intermediate drain back sump in addition to the main oil sump of the turbocharger. Acceptance of occasional " fast starts" is not sufficient as this is tantamount to saying that dry bearings are tolerable.

l All of the remarks and critique of the items regarding the TDI engines I are intended to be constructive and helpful. However, practically all of the suggestions are subject to testing in actual service and qualification under NRC regulations.

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--0 FCCD R$ Center _ _ _

During the nuclea'r power plant survey and inspections done in 1978 and

= 1979, performed at the University of Dayton (Dayton, Ohio) , a grand total of 288 items were investigated. Most of these subject items were found in every power plant of this survey.

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