|
---|
Category:GENERAL EXTERNAL TECHNICAL REPORTS
MONTHYEARML20069F0001994-01-24024 January 1994 Vols 1-4 to Shoreham Decommissioning Project Termination Survey Final Rept ML20045C8881993-06-0808 June 1993 Vols 1 & 2 to Refueling Jib Crane 1T31-CRN-008A Incident Root Cause Analysis. W/One Oversize Encl ML20128P6451993-02-28028 February 1993 Snps Decommissioning Project Termination Survey Final Rept for Steam Turbine Sys (N31) ML20128P7431993-02-19019 February 1993 Rev 3 to 93X027, Nuclear QA Surveillance Rept ML20099H5781992-07-31031 July 1992 Rev 4 to Shoreham Defueled Sar ML20101K5791992-06-25025 June 1992 Long Island Power Authority Shoreham Decommissioning Project,Shoreham Nuclear Power Station,Technical Rept on Water Processing & Water Mgt Activities for Reactor Pressure Vessel & Wet Cutting Station ML20082M5081991-08-26026 August 1991 Rev 3 to Shoreham Defueled Sar ML20005F2511990-01-0505 January 1990 Shoreham Nuclear Power Station Defueled Sar. ML19332G1991989-09-18018 September 1989 Rev 0 to Radiological Safety Analysis for Spent Fuel Storage & Handling. ML20245E0181989-06-19019 June 1989 QC 1989 Staffing Rept ML20153G8941988-08-31031 August 1988 Rev 1 to Shoreham Nuclear Power Station Prompt Notification Sys Rept ML20196K6311988-06-29029 June 1988 QC Div 1988 Staffing Rept ML20148A4851988-02-29029 February 1988 Shoreham Nuclear Power Station PRA W/Supplemental Containment Sys ML20214U2021987-01-31031 January 1987 Technical Rept 86.2SH Verification of IPE for Shoreham. W/ 870313 Release Memo ML20210M6001986-12-31031 December 1986 Emergency Planning Federal Involvement in Preparedness Exercise at Shoreham Nuclear Plant. Related Correspondence ML20214T6021986-12-31031 December 1986 Rev 6 to Plant Design Assessment Rept for Safety/Relief Valves & LOCA Loads, Vols 1 & 2.Proprietary Suppl Withheld (Ref 10CFR2.790) ML20210K2961986-12-31031 December 1986 Nuclear Regulation,Unique Features of Shoreham Nuclear Plant Emergency Planning. Related Correspondence ML20214U3641986-10-31031 October 1986 Shoreham Startup & Low Power Testing Operations,Special Rept:Lilco QA Audit on Training & Qualifications ML20237H6381986-07-31031 July 1986 Compliance W/10CFR50,App I ML20211P6851986-06-30030 June 1986 Implications of Chernobyl-4 Accident for Nuclear Emergency Planning for State of Ny ML20203N4171986-04-30030 April 1986 Rev 2 to Tdi Owners Group App Ii:Generic Maint Matrix & Justifications SNRC-1207, Vols 1 & 2 of Colt Emergency Diesel Generator Info to Be Incorporated in Fsar. W/11 Oversize Drawings1985-11-30030 November 1985 Vols 1 & 2 of Colt Emergency Diesel Generator Info to Be Incorporated in Fsar. W/11 Oversize Drawings ML20128N9651985-05-31031 May 1985 New York Power Pool,1985 Summer Operating Reserve, Projection & Analysis ML20111C0961984-11-20020 November 1984 Rev 1 to Long Island Lighting Co,Shoreham Nuclear Power Station,Prompt Notification Sys Design Rept ML20091Q8851984-06-30030 June 1984 Colt Diesel Generator Summary for Shoreham Nuclear Power Station - Unit 1 ML20092N6631984-06-12012 June 1984 Seismic Survivability Study for MP-45 Diesel Generators ML20091M5451984-05-31031 May 1984 Design Review of Connecting Rods for Tdi DSRV-4 Series Diesel Generators, Final Rept Prepared for Tdi Diesel Generator Owners Group ML20091M5511984-05-23023 May 1984 Investigation of Types AF & Ae Piston Skirts, Final Rept Prepared for Tdi Diesel Generator Owners Group ML20091M5201984-05-22022 May 1984 Draft Final Rept, Evaluation of Emergency Diesel Generator Crankshafts at Shoreham & Grand Gulf, Prepared for Tdi Diesel Generator Owners Group ML20084E5421984-04-30030 April 1984 Emergency Diesel Generator Engine & Auxiliary Module Wiring & Termination Qualification to IEEE-383-1974 ML20087L3511984-03-31031 March 1984 Emergency Diesel Generator Air Start Valve Capscrew Dimension & Stress Analysis, Prepared for Transamerica Delaval,Inc (Tdi) Diesel Generator Owners Group ML20081C4721984-03-12012 March 1984 Design Review of Connecting Rod Bearing Shells for Transamerica Delaval Enterprise Engines ML20087L2851984-02-27027 February 1984 Control Bldg Category I Equipment Balance-of-Plant Qualification Level, Monthly Status Rept ML20086S2221984-02-27027 February 1984 Investigation of Types AF & Ae Piston Skirts ML20080U3971984-02-10010 February 1984 Rept on Special Lifting Devices ML20083F6511983-12-15015 December 1983 Analysis of Replacement Connecting Rod Bearings Emergency Diesel Generators,Fatigue Life Prediction,Shoreham Nuclear Power Station ML20083C6681983-12-0808 December 1983 Metallurgical Analysis of Cracked Piston Skirts from Emergency Diesel Generators,Shoreham Nuclear Power Station ML20081C1571983-10-20020 October 1983 Diesel Generator Status Rept ML20112J2501983-08-31031 August 1983 Critique of Hudson Inst/Lilco Defense of Shoreham Economics. Related Info Encl ML20082D8831983-08-30030 August 1983 Suppression Pool Local-to-Bulk Temp Difference,Shoreham Nuclear Power Station - Unit 1 ML20112J2981983-08-30030 August 1983 Lilco/Hudson Inst Rept on Shoreham:Analysis of Errors Re Property Taxes & Employment. Related Info Encl ML20081L6891983-08-29029 August 1983 Excerpt from Draft FSAR Section 5.2.8, Inservice Insp Program, & Section 5.2.8.1 Provisions for Access to Rcpb ML20085D8921983-07-26026 July 1983 Books 1-3 of Independent Design Review for Shoreham Nuclear Power Station, Final Technical Rept ML20072J9521983-06-30030 June 1983 Independent Design Review for Shoreham Nuclear Power Station, Executive Summary of Final Rept ML20058N6071983-06-30030 June 1983 Environ Qualification Rept for Class 1E Equipment for Shoreham Nuclear Power Station Unit 1 Lilco ML20072K0141983-06-27027 June 1983 Rev 1 to Independent Design Review,Shoreham Nuclear Power Plant ML20076M0861983-06-27027 June 1983 Rev 5 to Environ Qualification Rept for Class IE Equipment for Shoreham Nuclear Power Station Unit 1 ML20072F2401983-06-22022 June 1983 Element-By-Element Review of Lilco Transition Module of Shoreham Nuclear Power Station Offsite Radiological Emergency Response Plan ML20079R7351983-05-31031 May 1983 Shoreham Common Sensors Failures Evaluation Rept ML20073L5911983-04-30030 April 1983 Cable Separation Analysis Rept 1994-01-24
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML20140G4481997-05-0101 May 1997 Part 21 Rept Re Potential Defect in Component of Dsrv & Dsr Enterprise Standby Diesel Generator Sys.Recommends That Springs Be Inspected on Periodic Basis,Such as During Refueling Outages ML20135D8011996-11-26026 November 1996 Part 21 Rept Re Two Safety Related Valves Supplied by Velan Valve Corp Were Not in Compliance W/Originally Supplied QA Documentation.Returned Valves to Velan in May 1996 & on 961120 Velan Advised That Valves Had Been Misplaced ML20080G4691995-01-26026 January 1995 Record of Telcon W/Nrc & Licensees 950126 to Clarify Position Re Dispositioning of Exempt Sources Listed in Section 6.3.3 of Shoreham Termination Survey Final Rept Dtd Oct 1994 ML20069F0001994-01-24024 January 1994 Vols 1-4 to Shoreham Decommissioning Project Termination Survey Final Rept ML20058K3841993-12-0909 December 1993 Part 21 Rept Re Potential Defect in Component of Dsrv & Dsr Enterprise Standby DG Sys,Regarding Potential Problem W/ Subcover Assembled Atop Power Head ML20057F2261993-09-30030 September 1993 Safety Evaluation Supporting Exemption Request from Requirements of 10CFR50.54(q) for License NPF-82 ML20056C7181993-07-14014 July 1993 SE Supporting Amend 10 to License NPF-82 ML20045B3551993-06-11011 June 1993 LER 93-001-00:on 930429,refueling Jib Crane Moved in Vicinity of Spent Fuel Pool Using vendor-supplied Lifting Eye in Violation of NUREG-0612.Caused by Failure to Identify Crane as Heavy Load.Meetings held.W/930611 Ltr ML20045C8881993-06-0808 June 1993 Vols 1 & 2 to Refueling Jib Crane 1T31-CRN-008A Incident Root Cause Analysis. W/One Oversize Encl ML20044C1181993-02-28028 February 1993 Shoreham Nuclear Power Station Updated Decommissioning Plan. ML20128P6451993-02-28028 February 1993 Snps Decommissioning Project Termination Survey Final Rept for Steam Turbine Sys (N31) ML20128P7431993-02-19019 February 1993 Rev 3 to 93X027, Nuclear QA Surveillance Rept ML20127H2301993-01-15015 January 1993 Part 21 Rept Re Potential Defeat in Component of Dsrv & Dsr Enterprise Standby DG Sys.Starting Air Distributor Housing Assemblies Installed as Replacement Parts at Listed Sites ML20126B0421992-12-17017 December 1992 Final Part 21 Rept Re Potential Problem W/Steel Cylinder Heads.Initially Reported on 921125.Caused by Inadequate Cast Wall Thickness at 3/4-inch-10 Bolt Hole.Stud at Location Indicated on Encl Sketch Should Be Removed ML20125C7161992-12-0707 December 1992 Part 21 Rept Re Possibility for Malfunction of Declutching Mechanisms in SMB/SB-000 & SMB/SB/SBD-00 Actuators. Malfunction Only Occurs During Seismic Event.Balanced Levers May Be Purchased from Vendor.List of Affected Utils Encl ML20127P5861992-11-23023 November 1992 Followup to 921005 Part 21 Rept Re Potential Defect in SB/SBD-1 Housing Cover Screws.Procedure Re Replacement of SBD-1 Spring Cover Bolts Encl.All Fasteners Should Be Loosened & Removed.List of Affected Utils Encl ML20128B9641992-10-31031 October 1992 Rev 0 to Shoreham Decommissioning Project Termination Survey Plan ML20118B4391992-09-11011 September 1992 Part 21 Rept Re Degradation in Abb Type 27N Undervoltage Relays Used in Electrical Switchgear.Recommends That Users Review Applications Requiring Exposures Greater than 1E03 Rads TID W/Time Delay Function Option ML20099H5781992-07-31031 July 1992 Rev 4 to Shoreham Defueled Sar ML20114A6311992-07-28028 July 1992 Shoreham Decommissioning Plan ML20101K5791992-06-25025 June 1992 Long Island Power Authority Shoreham Decommissioning Project,Shoreham Nuclear Power Station,Technical Rept on Water Processing & Water Mgt Activities for Reactor Pressure Vessel & Wet Cutting Station ML20094L1271992-03-13013 March 1992 Amend 1 to Part 21 Rept 159 Re Potential Defect in Power Cylinder Liner.Initially Reported on 920115.Caused by Liner/ Block Fit & Localized Matl Microstructure.All Drawings & Specs Revised to Address Matl Design Requirements ML20082M5081991-08-26026 August 1991 Rev 3 to Shoreham Defueled Sar PM-91-125, Monthly Operating Rept for Jul 1991 for Shoreham Nuclear Power Station1991-07-31031 July 1991 Monthly Operating Rept for Jul 1991 for Shoreham Nuclear Power Station PM-91-112, Monthly Operating Rept for Jun 1991 for Shoreham Nuclear Power Station1991-06-30030 June 1991 Monthly Operating Rept for Jun 1991 for Shoreham Nuclear Power Station PM-91-075, Monthly Operating Rept for Apr 1991 for Shoreham Nuclear Power Station1991-04-30030 April 1991 Monthly Operating Rept for Apr 1991 for Shoreham Nuclear Power Station ML20024G7171991-04-22022 April 1991 LER 91-001-00:on 910324,RB Normal Ventilation Sys (Rbnvs) Outboard Exhaust Valve Closed for No Apparent Reason.Cause Inconclusive.Sys Restored to Normal Lineup & Rbnvs Outboard Valve Will Be Stroked on Routine basis.W/910422 Ltr SNRC-1806, Revised Pages 2 & 6 to Encl a of 10CFR50.59 Annual Rept for 19901991-04-15015 April 1991 Revised Pages 2 & 6 to Encl a of 10CFR50.59 Annual Rept for 1990 PM-91-058, Monthly Operating Rept for Mar 1991 for Shoreham Nuclear Power Station1991-03-31031 March 1991 Monthly Operating Rept for Mar 1991 for Shoreham Nuclear Power Station PM-91-037, Monthly Operating Rept for Feb 1991 for Shoreham Nuclear Power Station1991-02-28028 February 1991 Monthly Operating Rept for Feb 1991 for Shoreham Nuclear Power Station PM-91-016, Monthly Operating Rept for Jan 1991 for Shoreham Nuclear Power Station1991-01-31031 January 1991 Monthly Operating Rept for Jan 1991 for Shoreham Nuclear Power Station SNRC-1797, 10CFR 50.59 Annual Rept of Facility Changes,Procedure Changes,Tests & Experiments for Jan-Dec 19901990-12-31031 December 1990 10CFR 50.59 Annual Rept of Facility Changes,Procedure Changes,Tests & Experiments for Jan-Dec 1990 SNRC-1794, Shoreham Nuclear Power Station Annual Operating Rept,19901990-12-31031 December 1990 Shoreham Nuclear Power Station Annual Operating Rept,1990 SNRC-1799, Lilco 1990 Annual Rept1990-12-31031 December 1990 Lilco 1990 Annual Rept ML20069Q3901990-12-31031 December 1990 Shoreham Nuclear Power Station Decommissioning Plan. (Filed in Category P) ML20028H0231990-09-28028 September 1990 LER 90-007-00:on 900907,unplanned Actuation of ESF Sys Occurred During I&C Surveillance Test.Caused by Inadequate procedure.SP44.650.16 Revised to Require That Leads Lifted & Individually separated.W/900928 Ltr ML20056A2001990-07-31031 July 1990 Safety Evaluation Supporting Amend 6 to License NPF-82 PM-90-097, Monthly Operating Rept for June 1990 for Shoreham Nuclear Power Station1990-06-30030 June 1990 Monthly Operating Rept for June 1990 for Shoreham Nuclear Power Station ML20055E3911990-06-25025 June 1990 Safety Evaluation Supporting Amend 5 to License NPF-82 PM-90-083, Monthly Operating Rept for May 1990 for Shoreham Nuclear Power Station1990-05-31031 May 1990 Monthly Operating Rept for May 1990 for Shoreham Nuclear Power Station 05000322/LER-1988-0151990-05-16016 May 1990 LER 88-015-02:on 880916,seismic Monitoring Instrumentation, Including Peak Acceleration Recorders,Removed from Svc for More than 30 Days Due to Corrosion on Scratch Plates.Cover Gasket Replaced & Thermal Barrier Mount to Be Installed 05000322/LER-1986-0391990-05-16016 May 1990 LER 86-039-01:on 861006,unplanned Initiation of Reactor Bldg Standby Ventilation Sys Occurred W/All Rods Inserted in Core.Caused by Faulty Design of Retaining Device.Warning Signs Attached to Valve Actuator & Valve Mod Initiated 05000322/LER-1986-0321990-05-16016 May 1990 LER 86-032-01:on 860728,RWCU Isolated on High Differential Flow Sensed by Steam Leak Detection Sys While Placing Filter Demineralizers in Operation.Cause Not Determined. Operating Procedures Revised to Monitor RWCU Sys 05000322/LER-1987-0091990-05-16016 May 1990 LER 87-009-01:on 870203,full Reactor Trip Occurred Due to Perturbation in Ref Leg.Caused by Spurious Low Level Reactor Pressure Vessel Water Level Signal.Existing Level & Pressure Transmitters Replaced W/Newer Models 05000322/LER-1987-0221990-05-16016 May 1990 LER 87-022-01:on 870604,HPCI Test Valve to Condensate Storage Tank,Globe Valve & Hpci/Rcic Test Valve to Condensate Storage Tank Failed to Close Against Sys Operating Pressure.Disc of motor-operated Valve 37 Modified 05000322/LER-1989-0051990-05-16016 May 1990 LER 89-005-01:on 890321,results of Local Leak Rate Test of Core Spray Suction Valve a Determined That Leakage,When Combined W/All Type B & C Penetration Leakages,Exceeded Tech Spec Limit.Caused by Normal Valve Degradation 05000322/LER-1989-0031990-05-16016 May 1990 LER 89-003-01:on 890310,emergency Diesel Generator (EDG) 102 Manually Shutdown During 18-month Surveillance Test Due to Failure of EDG Output Breaker.Cause Not Determined. Replacement Breaker Installed in Cubicle 102-8 05000322/LER-1985-0591990-05-16016 May 1990 LER 85-059-01:on 851219,half Reactor Trip,Full NSSS Shutoff Sys Isolation & Reactor Bldg Standby Ventilation Sys Initiation Occurred Due to Loss of Power to Reactor Protection Sys Bus B.Assembly Breaker Reset 05000322/LER-1987-0351990-05-16016 May 1990 LER 87-035-02:on 871221,880106 & 0330,high Energy Line Break Logic Isolations of RWCU & Main Steam Line Drain Valves Occurred.Caused by Problems W/Temp Monitoring Units. Grounding Scheme Changed & Transformers Rewired 05000322/LER-1988-0031990-05-16016 May 1990 LER 88-003-01:on 880322,unplanned Automatic Initiation of Reactor Bldg Standby Ventilation Sys Side a Occurred During Deenergization of Relay.Caused by Close Placement of Relay Terminals.Wiring Inside Electrical Panels Reworked 1997-05-01
[Table view] |
Text
_ _ . . . . _ .
Failum ENGINEERING AND METALLURG. CAL CONSULTANTS 2225 EAST BAv5HOAE ACAO PO box 51470 FaAA-83-12-9 PALO ALTO. CALtFORNIA 94303 :415 8564400 TELE 8 7042?6 M&T3/7396
)
l
)
l ANALYSIS OF THE REPLACEMENT CONNECTING ROD BEARINGS FOR EMERGENCY DIESEL GENERATORS, FATIGUE LIFE PREDICTION j SHOREHAM M) CLEAR POWER STATION
)
Prepared by Failure Analysis Associates
) 2225 East Bayshore Road Palo Alto, California 94303
)
)
December 15, 1983
)
)
8401030243 831216 PDR ADOCK 05000322 S PDR
) PALO ALTO + LOS ANGELES
l b
)
1.0 Stm ARY AND CONCLUSIONS Four upper connecting rod bearing snells in two Transamerica Delaval
)
Incorporated (TDI) Enterprise ciesel engines at the Shoreham Nuclear Power Station (SNPS) were found to be cracked after about 250 hours0.00289 days <br />0.0694 hours <br />4.133598e-4 weeks <br />9.5125e-5 months <br /> of full load operation.
) An earlier Failure Analysis Associates (FaAA) report [1] has been issued analyzing the cracking in qualitative terms. That report cited high peak oil film pressure, lack of bearing shell support at connecting rod cham-fers, concentration of load at bearing ends, and voids 0.5m to 0.7m in
) diameter as contributing to the cracking.
Along with new crankshafts of modified design, new connecting rods and new connecting rod bearings have been installed in the the SNPS diesel en-
) gines. The new connecting rods have a smaller bore chamfer, eliminating the unsupported bearing ends. The increase in crankpin diameter from 11 inch to 12 inch was shown to reduce peak oil film pressure from 29,745 psi to 26,780 psi. This pressure is slightly above an industry-accepted guideline for peak
) value and suggests the need for fatigue lifetime calculations.
Subsequent finite element method (FEM) stress analysis and a fracture mechanics analysis of the satigue cracking of the bearings have shown that the tensile stress in the bearirgs, that caused cracking in the original bearings,
)
is reduced by 50.5% in the new bearings. The predicted fatigue life of the new bearings is 513,000,000 stress cycl es , or 38,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> at full load, despite the fact that the peak oil film pressure is slightly above an industry guideline [3]. These industry guidelines are not absolute maximum allowable
)
val ues . Some engine manufacturers successfully operate engine sleeve bearings above industry guidelines in specific applications, by exerci sing careful control of engine component design, manufacturing, and operating conditions.
- LILC0 appears to be exercising the degree of control necessary for successful
)
Falure tes
)
operation at 26,780 psi peak all film pressure. In addition, the FEM and
) fracture mechanics analysis of the co.inecting re,d bearings, performed by FaAA, is a much more detailed analysis than is performed by engine builders and bearing suppliers in the course of normal applications engineering. This detailed analysis provides the basis for the calculated bearing fatigue life.
}
Thi; expected fatigue life is conservatively calculated in that it does not include any reduction in edge loading of the bearings obtaining from the increased pin diameter and concomitant reduction in torsional yawing of the crankshat s ,7ir:.
The expected fatigue life is approx imately an order of magnitude greater than the total anticipated full-load test time during the 40 year life of $NPS. Also, the routine maintenance procedures planned by LILC0 req 3 ire
) periodic inspection of all the surfaces, including nondestructive examination for flaws and bearing thickness measurement, each scheduled plant outage.
2.0 INTRODUCTION
) An earlier report by Failure Analysis Associates (FaAA) [1] identified the primary causes of damage of some of the connecting rod bearing shells in ,
the TDI Enterprise diesel engines at SNPS. Records indicate that after approximately 250 hours0.00289 days <br />0.0694 hours <br />4.133598e-4 weeks <br />9.5125e-5 months <br /> of operation, at or above 100*. power, four of the
) twenty-four upper connecting rod bearing shells hao cracked about S/ 8-inch from one end. These cracks extended radially through the thickcess of the.
bearing and circumferentially to a length of approximately 4 inches.
Four factors contributing to the cracking were identi fied in the 4
g earlier report. First, the peak oil film pressure in the hydrodynamic oil film separating the crankshaft and the bearing exceeded the guidelines of a y major independent su? plier of engine bearings by 14%, [2, 3]. Second, the geometry of the conne. ting rod bore left the end of the bearing unsupported,
)
inducing ca'ntilever bending. Fig'ure 1 shows the configuration of the connect-ing rod relative to toe bearing. Third, the contact ',atterns in the electro-plated babbitt overlay on the bearing inner diameter showed that the cracted bearings had been subjected to edge loading, or a concentration of load on the
)
c Fadure ArWym
' Mtes
)
l '
1 bearing enas due to lack of parallelism between the crankshaft journal and the bearing surface. The fourth cause was thougnt to be the presence of voids ranging in size from 0.5m to 0.7mm.
i
, The failure analysis of the connecting rod bearing shells indicated that voids in the size range of 0.5m to 0.7m were the initiation sites for
') the cracks that formed. However, analysis since issuance of the initial .
report showd that these voids are not atypical of cast aluminum bearings, and in the absence of abnormally high stresses world not normally be detrimental .
to bearing life. .
- ~
The compu';ations described in thic, report were performed in order to ,
develop a conservative estimate of the expected life of the new connecting rod bearings in the TDI Enterprise diesel engines. Along with the new crank- _
) shaf ts, new bearings and new connecting rods have been put into the engines.
Two of the causes of the bearing cracking have thereby been addressed: the unsupported bearing ends have been eliminated with the new components, as .
shown in Figure 2, and the calculated peak oil film pressure has been reduced to 26,780 psi in the new connecting rod bearings [2]. Through finite element stress analysis and fracture mecharics calculation of fatigue crack growth, the fatigue lifetime of the new configuration can be estimated to determine a suitable inspection or replacement interval for the connecting rod bearings.
) '
J 3.0 BEARING STRESS ANALYSIS Finite elemant analysis of both the original and replacement connecting rod bearings was performed using the ANSYS code. The results of the journal orbit analysis [2] were used as the basis for the apolied loads on the bear-ing. Since the journal orbit analysic assnes perfect parallelism between the bearing and the journai [4], the pressure distribution was skewed toward the N
end of the bearing to correlate with the centact patterns in the babbitt. The loading was skewed so that 82.67, of the applied load is carried on the outer
)
28.2% of the bearing length. Both the cast aluminum bearing shell and the 7 forged steel connecting rod were included in the finite element model . In . .
addition, the compressive preload on the bearing resulting from the inter- ,
ference fit of the bearing in the connecting rod was included in the model .
)
i t m I
)
) The maximum tensile stress was found to occur in the longitudinal direction, at the inner surface of the bearing shell, at a node 0.879 inch from the end of the bearing. The values of these stresses are listed in Table 1.
)
Table 1 Maximum Tensile Stress:
) Longitudinal direction, on bearing inner diameter Original bearings,11 inch diameter crankpins:
tensile stress - 10,931 psi New bearings, 12 inch diameter crankpir.s:
)
tensile stress - 5,412 psi The maximum tensile stress in the new bearings is predicted to be only half the stress in the original bearings that cracked after about 250 hours0.00289 days <br />0.0694 hours <br />4.133598e-4 weeks <br />9.5125e-5 months <br /> of full-load operation. About one-fifth of the reduction in stress results from a reduction in the calculated peak oil film pressure, a direct consequence of the larger journal diameter. The remaining four-fifths of tne reduction in stress is directly attributable to the elimination of the unsupported bearing ends via reduction of the bore chamfer in the new connecting rods.
4.0 BEARING LIFE PREDICTION The known behavior of aluminum in response to cyclic stressing can be used to predict the fatigue life of the new bearings installed in the TDI Enterprise diesel engines. In the elastic strain, high-cycle-fatigue region (number of cycles greater than 106), the behavior of aluminum can be described by the equation [5]:
)
Fadure A res
5
=
a of(2N)b where aa = stress amplitude oy= fatigue strength coefficient N = number of cycles
)
b = fatigue strength exponent.
The stress amplitude for the connecting rod bearings is one-half of the maximum tensile stress computed by the FEM analysis described in Section
) 3.0. The coefficient of has not been determined for the B850 aluminum bearing alloy, but in using the ratio of the stress amplitudes to compute the ratio of the number of cycl es to failure, the coefficient drops out of the expression. The fatigue strength exponent, b, also has not been determined
) for the B850 alloy, but from work on a wide variety of metals and aluminum alloys, it has been determined that the value for b is in the range of -0.06 to -0.14. The most conservative computation is to use b = -0.14, which yields the smallest change in N for a given change in oa* -
)
- * " -0 M o 0 a ng = .495 =c) (2N (New bearing))
-U "
op (2N (Old bearing))
~
)
N (New bearing) = 152 N (Old bearing)
This calculation predicts that the new bearings shculd not fail by fatigue j until they have experienced 152 times the number of cycles that failed the original bearings.
The connecting rod bearings are subjected to one stress cycle ir. every two rotations of the crankshaft, or 225 cycles per minute. The original bear-
)
ings were cracked after approximately 250 hours0.00289 days <br />0.0694 hours <br />4.133598e-4 weeks <br />9.5125e-5 months <br />, or 3,375,000 cycles. The new bearings would not be expected to begin to exhibit cracking until after 513,000,000 cycles, or 38,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> of full-load operation have occured.
)
Fadure Assors s
1 5.0 DISCUSSION
) Calculations have demonstrated that the major contributor to the crack-ing of the original connecting rod bearings in' the TDI Enterprise diesel engines was the unsupported bearing end, the result of a 0.25 inch chamfer in the connecting rod bore.
)
Eliminating this unsupported end, along with lowering peak oil film pressure by 10%, results in a predicted fatigue life of 38,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> at full- ,
load. This life is approximately a factor of 10 greater than Lhe expected time of full-load operation during the life of the plant. Consequently, FaAA is able to conclude that the connecting rod bearings have adequate design fatigue 1ifetime without the need for replacement during normal plant operation despite the fact that the oil film pressure is still slightly above an industry guideline for peak value [3].
a The fatigue life of the new bearings has been conservatively calculated in that no reduction in yawing of the crankpin journals relative to the bear-ings has been assumed; such reduction is expected as a consequence of the
~
) increased torsional stiffness of the new crankshaf t. This yawing contributes to the edge loading that was evident on every cracked bearing.
No change in materials properties or structure was assumed. The 33,000
)
hour predicted life for Me new bearings is in the presence of the 0.5mm to 0.7mm voids found in the old bearings. As a check on the influence of the voids, the stress fetensity factor range, AK, was computed for these voids and the stresses computed by FEM analysis. For the original bearings, AK = 1.8
)
ksi V in. For the new bearings, AK = 0.9 ksi V in. The threshold value of AK for growth of a pre-existing void in fatigue is not known precisely for this alloy, but in comparison to other aluminum alloys, is estimated to be approxi-ma t.ely [5] AKth = 2.0 ksi / in. [5]. The. efc. a, since the M value fc- the new bearings is below the threshold value for growth of pre-existing voids, this presence of 0.5m to 0.7mm voids will not have an impact on fatigue cracking.
t Fadure tes
~
The state of stress in the old bearings is close to that required to cause the voids to initiate cracks, wnile the state of stress in the new bear-ings is well below that necessary to initiate fatigue cracks at the voids.
) The inspection procedure at Shoreham planned by LILC0 calls for inspec-tion of all surfaces of the connecting rod bearings, including nondestructive inspection for flaws and measurement of the thickness in six places, including the ends subjected to edge loading, during every scheduled refueling outage.
)
)
)
)
)-
)
)
Fadure Assomtes
)
REFERENCES
- 1. Failure Analysis Associates " Emergency Diesel Generator Connecting Rod Bearing Failure Investigation, Shoreham Nuclear Power Station, Pal o Al to ,
California, October 31, 1983.
- 2. Journal Orbit Analyses of TDI Enterprise R-48 Diesel Engine performed by Imperial Clevite Inc. for Failure Analysis Associates, October 6,1983.
- 3. W. A. Yahraus (Manager of Product Analysis, Imperial Clevite Inc., Engine Parts Division), private communication with L. A. Swanger (FaAA), October 4, 1983.
- 4. Ross , J. M. and R. R. Slaymaker, " Journal Center Orbits in Piston Engine Bearings, " SAE Paper 690114, Society of Automotive Engineers, Warrendale, Pennsyl vania, 1969.
- 5. H. O. Fuchs and R. I. Stephens, Metal Fatigue in Engineering, John Wiley &
Sons, New York, 1980, p. 78.
i 4
I Falure Anxares
o
!$ e$ e$ EI, g*. aR e
r j
( \ /
s x 84 x 28
"* , 'N s*
gr N
x
as /
c
~E
-n /
=
y x
"% o x / o. T N 8" 5 N 07"* % s' m ;; 's io @ s sn - x8 m -'
x 28 E sa a3 n I N rn <E F =M r= 'N o e o x 0 o S kOo h1
'\N
'l 5 o
8 2:
a\
m z
8
.a
=
a nan)
,N n
8 n'
2 s
a E
o
'N x
$ U \ 2 8 o 2
& N\ C. s " \
? 5. i 'x N G S. x a
E j'N\- > -=
'q i <
a
N O TE: drawing at .74 of original l, ' / .-
/ // / / / / / /
/ / ,/ / /
' Connecting rod /
ch mfer_ ,/ l ,/ l ,/ , j '
1/16" '
chamfor Connecting rod bearing inner surface
'iiE
, . - ~
g UNSUPPORTED END Figure 1. Bearing: Connecting rod configuration with original 11" Journals.
%- //
,,,,. / _,j/ Connecting rod chamfers / / / / .
[.
Connecting rod bearing
\ COfAPLETELY SUPPORTCD END ~
Figure 2. Bearing: Connecting rod configuration with replacement 12" journals. -
FaAA-83-12-9
- . _ _ _ _ _ _ _ _ _ . _ _ - _ _