ML20211N492
| ML20211N492 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 09/30/1997 |
| From: | STRUCTURAL INTEGRITY ASSOCIATES, INC. |
| To: | |
| Shared Package | |
| ML20211N489 | List: |
| References | |
| SIR-94-080-A, SIR-94-080-A-R01, SIR-94-80-A, SIR-94-80-A-R1, NUDOCS 9710160170 | |
| Download: ML20211N492 (178) | |
Text
{{#Wiki_filter:h 4 4 Relaxation of Reactor Coolant Pump FlywheelInspection Requirements ( StructuralIntegrity Associates, Inc. 3315 Atmaden Expressway
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- San Jose, CA 95118 'l557 PHONE: 408 978 8200 FAX: 408 978 8964 1
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l Repon No.: SIR 94 080 A Resisjon No.: 1 Project No.: CEOG 01Q File No.: CEOG.01Q 401 September 1997 Relanstion of Reactor Coolant Pump Flywheellaspection Requirements Prepared for: Consumers Power Company Fhrida Power & Light Company Entergy Operations Northeast Utilities Service Company Prepared by: Structurallntegrity Associates,Inc. 1
4 St Quality Procedure SIOP-013 Resisjon 0 October 1989 Page 10 of 10 REVISION CONTRO1. SHEET Document Numben SIR 94 080, Rev.1
Title:
Relaxation of Reactor Coolant Pump Flywheel Inspection Requirements Client: Consumers Power Company Florida Power & Light Company Entergy Operations Northeast Utilities Senice Company SI Project Numben CEOG 010-401 Section Pages Revision Date Comments 6.0 66 1 3/22/95 Addressed LOCA overspeed 8.0 8-1 1 3/22/95 Revised Refererce 5 a .~ h StructuralIntegrity Associates. Inc.
#"% RECE VED lt UNITE 3 STATES ]["
g f ,} NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. aoMHooi g 4 9997
"% , , . May 21, 1997 At40 UCD C S i
6c0A$5Ml8 Mr. Dwight C. Hims. Director Nuclear Safety Division Entergy Operations, Inc. 1448 SR 333 Russellville, Arkansas 72901
SUBJECT:
ACCEPTANCE FOR REFERENCING OF TOPICAL REPORT SIR-94-080,
" RELAXATION REqu!REMENTS" OF REACTOR COOLANT PUMP FLYWHEEL INSPECTION
Dear Mr. Hims:
We have completed our review of the subject topical report submitted in a letter dated April 4; 1995 by Entergy Operations, Inc. (Entergy) for Arkansas Nuclear One (ANO) -l'& -2 as lead plants. The report is acceptable for referencing in license amendment applications to the extent specified and under the limitations delineated in the report and the enclosed safety evaluation SE). could he len(gthened from the current 3 years to 10 years for the plantsTh identified in the SER. Total elimination of flywheel inspections is not justified. We do not intend to repeat our review of the matters described in the report when the report ap) ears as a reference in license amendment applications, except to ensure t1at the material presented is applicable to the specific plant involved as indicated in the conclusion section of the SE. Our acceptance applies only to the matters described in the report. In accordance with procedures established in NUREG-0390, it is requested that Entergy coordinate with the ABB Combustion Engineering Owners Group and publish this report within three months of receipt of this letter. The final version shall incorporate this letter, the enclosed evaluation, and Entergy's response dated December 9,1996 to the NRC request for additional information, between the title page and the abstract. The final version shall include an
-A (designating accepted) following the report identification symbol.
Licensees for ANO-2, Palisades Millstone 2, Waterford 3, and St. Lucie 1 & 2 need to verify the reference temperature RT, for their reactor coolant pump (RCP) flywheels and demonstrate, with plant-specific test results if possible,
- Dwight C. Mims values are equivalent to those that theincorresponding reported the topical report. fracture ANO-1,whicbatoughness (K ')lready has a 10-year in interval for its flywheels, will not be affected. The to)ical report indicated that flywheels for Waterford 3 could lose shrinc fit at the accident speed.
basis. The staff will pursue this issue with Waterford 3 on a plant-specific 1 Sincerely, 2m
- d. R fd AJ4%
Brian W. Sheron Director Division of Engineering Office of Nuclear Reactor Regulation i
ENCLOSURE SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION TOPICAL REPORT ON RELAXATION OF REACTOR C00LANf PUMP FLYWHEEL INSPECTION REQUIREMENTS
. ARKANSALNUCLEAR ONE 1 & 2 MATERIALS AND CHEMICAL ENGINEERING BRANCH DIVISION OF ENGINEEfLMA
1.0 INTRODUCTION
On April 4, 1995 Entergy Operations Inc. (Entergy), the '.icensee for
-l & -2, submitted a topical report SIR-94-080 (1),
Arkansas Nuclear
" Relaxation o# Roac. torOne Coo (ANO)lant Pump flys. heel Inspection RaqJivemer.ta," for N review. This report, which provides an engineering analysis based on fracture mechanics, is intended to eliminate reactor coolant pump (RCP) flywheel inservice inspection (ISI) requirements for five operating ABB Combustion
, Engineering Owners Group (CEOG l St. Lucie 1 & 2, and Waterford)3. plants: ANO-1 Presently, 1 -2, Millstone ANO-1 2 Palisades. is the only, plant with l Technical Specifications (TS) requiring its RCP flywheel inspection be i performed in 10-year intervals. All remaining plants have their flywheel . inspections performed in accordsnee with their licensing commitments to Regulatery Guide (RG) 1.14 (2). The regulatory position of RG 1.14 calls for an in-place ultrasonic volumetric examination of the areas of higher stress concentration at the bore and keyway at approximately 3-year intervals and a surface examination of all exposed surfaces and complete ultrasonic volumetric examination at approximately 10-year intervals. The flywheel inspection schedule is to coincide with the individual plant's ISI schedule as required by Section XI of the ASME Code.
2.0 BACKGROUND
The function of the RCP in the reactor coolant system (RCS) of a pressurized water reactor plant is to maintain an adequate cooling flow rate by circulating a large volume of primary coolant water at high temperature and pressure through the RCS. A concern over overspeed of the RCP and the potential for failure of its flywheel led to the issuance of RG 1.14 in 1971. Operating power plants have been inspecting their flywheels for over twenty years, and no flaws have been identified which affect flywheel integrity. This inspection record, plus the licensee's concern over inspection costs and personnel radiation exposure, prompted it to submit this topical report to demonstrate through fracture mechanics analysis that flywheel inspections can be eliminated without impairing plant safety, m _
2 A similar topical re) ort [3] for Westinghouse plants and for some Babcock and Wilcox plants was su)mitted on January 24, 1996, and a staff safety evaluation report (SER) [4] relaxing the RCP flywheel inspection interval from approximately 3 years to ten years was issued on September 12, 1996. In that report, the RCP flywheels were evaluated to criteria specified in IWB-3612 of
' Section XI of the ASME Code, except that the crack initiation fracture toughness (K ,) was used in the analyses for normal and upset conditions ins",eadoftbecrackarrestfracturetoughness(K i IWB-3612 specifies acceptance criteria based on the applied stress in\)e. nsity factor for analytical evaluation of flaws in ferritic steel components 4(applied K) inches and 3
greater in thickness. IWB-3612 specifies that fo applied K should be less than K divided by 10 faulted conditions, the applied N should be l(ess)p/pormal
,andforemergencyag than K divided by (2) .
conditio r ThemodifiedIWB-3612criteriawe,eacceptedbythestafY[4), 3.0 EVALUATION AND VERIFICATION The primary regulatory position of RG 1.14 regarding flywheel design concerns three critical speeds: (a) the critical speed for ductile fracture, (b) the critical speed for nonductile fracture, and (c) the critical speed for excessive defortnation of the flywheel. This regulatory position specifies, as a design criterion, that the nonnal speed of the flywheel should be less than one-half of the lowest of these three critical speeds. 3.1 MATERIAL INFORMATION The reference temperature RT , along with the operating temperature of the flywheels, determines the frEture toughness Ki , needed in the fracture mechanics analyses. Therefore, all licensees seeking application of this report their RCP to their plants Also, flywheels. need since to verify thethe K reference temperature RT, for v.s. (T-RT curve in Appe.1 dix A of Section XI of the ASME Code was develope,*d for vessel *,m)aterials such as SA 533 B and SA 508, licensees with flywheels made of different materials need to values. In both cases, if justify there aretheir use oftest plant-specific thisresults curve to are which derive the K *directly or indirectly rela to fracture toughness of the RCP flywheel material, they should be reported. 3.2 ANALYSIS FOR CRITICAL CRACK DEPTHS BASED ON NONDUCI M FRACTUE 3.2.1 Lif M SEES' EVALUATION RG 1.14 addresses both ductile and nonductile fracture of the flywheel. However, the topical report only provided the critical crack depths based on linear elastic fracture mechanics (LEFM) analysis to address nonductile fracture. The LEFM analysis in the topical report used a radial full-depth crack emanating from the bore of a rotating disk to calculate the applied K for the larger bore flywheels (ANO-1. Palisades, and St. Lucie 1 & 2). Fortbe smaller bore flywheels consisting of a crack em(ANO-2, M111 stone-2, and Waterford 3), a model anating from a hole in an infinite plate was used. In
3 a response (5) to the staff's request for additional information (RAI), the licensee demonstrated that the former appioach is conservative and the latter is slightly less conservative in the app 18.ed K i calculation. This point will be considered by the staff in the subsequent evaluation. The fracture resistance for the flywheels was obtained from the lower bound K curve of Section XI of the ASME Code. Use of K i was suggested by RG 1.14. u The load used in calculating the applied K, for ,each flywheel was from the normal speed, which is 900 rpm for ANO-2, Millstone 2, Palisades, and St. Lucie 1 & 2 and 1200 rpm for ANO-1 and Waterford 3. The bounding value of 150% of the normal speed was defined as the accident speed for each plant. Since RG 1.14 does not contain fracture mechanics criteria for evaluating the period of time between inspections, the licensees used the same criteria as that in the )reviously approved Westinghouse topical resort (6) in the fracture mec1anics analysis for their RCP flywheels. Tie licensees used 3.0 for normal conditions and 1.4 for emergency and faulted conditionr. In the original submittal, the effect due to centrifugal stresses and shrink-fit stresses were considered separately. The argument was that the maximum stress due to centrifugal forces occurred at the highest rpm, but the maximum stress due to shrink-fit ocrurred at zero rpm. In reality, the combined stress at the normal speed may exceed either of the two maximum stresses due to the centrifugal and the shrink-fit effect even though each individual contributor of the combined stresses is less than the maximum of its respective stresses. To respond to this concern, the licensee revised Figures 6-3 to 6-8 {l) by combining the shrink-fit stresses and the centrifugal stresses, and presented the updated applied K and fracture toughness v.s. In combinin crack stresses, depth a margin forofall 1.0flywheels was applied in shrin 5).7 to,12 (k-fit Figures to the andstresses, a margin g the i I of 3.0 was applied to the centrifugal stresses. The resulting critical crack depths were summarized in Table 3 of Reference 5, and it showed that the smallest allowable flaw size is 0.43 inches for Waterford 3 flywheels. Fatigue crack growth was determined from the growth rate formula in A)pendix A of Section XI. The topical report assumed an initial postulated crac( depth of 0.25 inches. This size crack represents the maximum flaw size that could have been missed during ultrasonic testing (UT) inspections, and was based u3on CEOG's judgement. This report assumed 4000 cycles of RCP startups and slutdowns, about eight times the design cycles for plant life. The crack growth aftst 4000 cycles is tabJl&ted in Table 6-3 of 513-94-030 for various flywheels. The largest growth is for Waterford 3 with a crack growth of 0.0186 inch. Based on the small fatigue crack growth in flywheels, and the finding that the smallest allowable flaw size from the LEFM analysis is greater than can be detected by ISI examinations, the licensees concluded that all flywheels meet the modified criteria of IWB-3612, 3.2.2 STAFF'S EVALUATION The staff agrees that if applied correctly, the LEFH is an acceptable methodology. Further, the staff determined that performing an elastic-plastic fracture mechanics (EPFM) analysis is not necessary because LEFH analysis is
4 appropriate for the thickness of the f1 eel and its operating temperature (about 100'F). The staff also agrees that meeting the margin based on fromIW8-3612isequivalent[o]meetingthemarginonthecritical applied speed spec K,ified in RG 1.14 for nonductile fracture of the flywheel. The staff disaprees with the licensee's approach of applying a margin of 1.0
' to the shrink fit stresses in its LEFM analyses because plastic co lapse is not the anticipated failure mechanism for the ferritic material at the flywheel op) rating temperature of 100*F. The cited precedence for using the 4 ex ' Evaluation of marginof1.0forpihin$na'pansionstressfromAppendixC flaws in Auatenitic ip of the A5ME Code is not applicable here, in the realm of LEFM, there 4 ni distinction between the nature of the shrink-fit and centrifug( .u w a n the a calculation, therefore the same l
margin should ce spoliat c both.pplied In the K, Westinghouse topical re, margin of ? ads app 1td tc Soth the centrifugal and shrink-fit stresses. port,-the ! Also str< M irtt W post' .teri crack depth of 0.25 inches has r.ot t'een substant ed, W mff un .he initial postulated crack depth of 0.33 inch and a 1( year t.% enth v .013 inch from Reference 4 in this evaluation. The i' 41 PMi.WW cran depth of 0.33 inch was based on industry expt . ente with M1 tr.swed'on of ferritic components with short metal paths. Reft f)y h m t in4 w Winted y v wethatm ;it is missed unlikely that any defect that could challenge by the inspections.
- riying b:. narem of ?.0 to both the centrifugal and the shrink-fit tre w:n uir staff (ot.id that only ANO-1 and Palisades flywheels meet the nqW ahut , M EM . .. The margin for flywheels was 2.65 for St. Lucie 1 &
- 4. LJr rm. AN04 R ') for Millstone 2, and 2.68 for Waterford 3. It was wntwhei [t] thnt ',ne infinite plate model of ANO-2, Millstone 2 and 6tefne 31s Wg..tly less conservative. The staff estimated from Figures s 5. min 6 c f ' lerence 5 that the applied K for ANO-2, Millstone 2, and tai vft N 3 f'fwheels might be 5% higher. Thkswouldreducethemarginfor A M to C.'o sfrom 2.82), the margin for Millstone 2 to 2.45 (from 2.57),- and the . 'r$ Nr Waterford 3 to 2.55 (from 2.68).
Margin is used to account for uncertainties in the LEFM analyses, e.g. the applied loadig. the stres s anal defects, the assunisd fit.w size, ysis, the existence of undetected fabrication and unaccounted for stresses such as residual stresses. key input The staff determined that, except for the assumed flaw size, all Therefore, parameters a mar to the LEFM can be estimated with high certainty. determined that' gin arouno 2.5 is adequate for this pplication. The staff the flywheels will have adequate fracture toughness during the service period for RCP flywheels of all plants listed in this topical report, and a 10-year inspection period appears reasonable. The analytical results for emergency and faulted conditions were provided in Figures 6-gto6-14[1?. From these figures and from considering the significant decrease of the shrink-fit stresses at a much higher speed, the staff determined that the .tomal and upset conditions are controlling for the flywheels. This is consistent with the finding in Reference 4 for the Westinghouse topical report on this issue. 4
5 Finally the staff wants to clarif that IWB-3612 is for cracks discovered duringInserviceinspections. App ying IW8-3612 to postulated cracks in the LEFM analysis for the RCP flywheel is conservative because so far no flaws which affect flywheel integrity have been reported from the industry. Therefore, using the criteria from IWS-3612 but with a safety factor of 2.5
. for the normal and upset conditions provides acceptable fracture toughness for flywheels.
3.3 COMPLIANCE WITH THE EXCESSIVE DEFORMATION FAILURE CRITERI0h The primary concern of RG 1.14 over excessive deformation is the enlargement of the bore that could cause a separation of the flywheel from the shaft or could cause an imbalance of the flywheel leading to structural failure. The main concern is the loss of shrink-fit at high speed, if a loss of shrink fit , occurred displacem,ent betwu n the whal and the shaft.the keys on the flywheels may not be a Table 4 of Reference 5 summarized the remaining shrink-fit for accident conditions for all flywheels. This remaining shrink-fit was calculated by subtracting the centrifugal displacement at accident conditions from the initial shrink-fit. When the remaining shrink-fit is zero, a total loss of shrink-fit occurs. Reference 5 reported that the largest remaining shrink-fit is 0.006 inch Based on these(St. Lucie 1 & 2), and the smallest is 0.0 inch (Waterford 3). reported values, the staff concludes that, except for the flywheels for Waterford 3, all flywheels satisfy the excessive defermation failure criterion. The staff will pursue the issue of the loss of shrink-fit of flywheels at the accident speed with Waterford 3 on a plant-specific basis.
4.0 CONCLUSION
S The Matr M ais and Chemical Engineering Branch has completed its review of the-licensu s submittals and has determined that the evaluation methodology in the reports is appropriate and the criteria meet the intent of the design criteria of RG 1.14. For the RG criteria on the critical speeds which affect flywheel integrity, the staff concluded that (1) all flywheels meet the proposed nonductile fracture criteria, and will have adequate fracture toughness during their service periods, and (2) all flywhuls except those for Waterford 3 satisfy the excessive deformation criterion of RG 1.14. This report requests complete elimination of flywheel inspections. The staff believes that even for flywheels meeting all the design criteria of RG 1.14, as modified in this SER, inspections should not be completely eliminated, inspections are performed in part to protect against events or degradation that is not anticipated and has not been considered in the analysis. This philosophy is consistent with the requirements in the ASME Code for successive inspections for flaws evaluated to the Section XI acceptance criteria. Therefore, the staff will not accept total elimination of flywheel inspection. However, considering that flywheel inspections can be conducted when RCP motor maintenance is required (about every 8 years from a limited survey [6)), the staff concluded:
6 (1) Licensees for ANO-2, Palisades, Millstone 2, Waterford 3, and St. Lucie 1
- & 2 who plan to submit a plant-specific application of this topical report need to verify the reference temperature RT., for their RCP flywheels. Also, if these licensees have flywheels made of materials other than SA 533 8 and SA 508, they need to justify the use of the K v.s. T-RT curve in A of Section XI of the ASME Code to derive tEsir res(pectfv,e)K i
, values.ppendix In both cases, they should report any existing plant-specific test results which are directly or indirectly related to fracture toughness of the RCP flywheel i
material. (2) Since ANO-1 already has a uoique flywheel inspection program of 10-year tntervals, this SER does not affect its status regarding flywheel inspections. Licensees meeting (1) above should either conduct a qualified in-place UT
! examination over the volume from the inner bore of the flywheel to the circle i
of one-half the outer radius or conduct a surface examination (HT and/or PT) of exposed surfaces defined by the volume of the disassembled fivwheels once every 10 years. The staff considers this 10-year inspection requirement not i burdensome when the flywheel inspection is conducted during scheduled ISI l inspection ce RCP motor maintenance. This would provide an appropriate level of defence in depth. The staff will pursue the issue of the loss of shrink-fit of flyWels at the accident speed with Waterford 3 on a plant-specific basis.
5.0 REFERENCES
1.0 Entergy Operations, Inc., letter from J. W. Yelverton (Entergy) to USNRC Document Control Desk with enclosed report, SIR-94-080, " Relaxation of Reactor Coolant Pump Flywheel Inspection Requirements," April 4, 1905, 2.0 USNRC, Regulatory Guide 1.14. " Reactor Coolant Pump Flywheel Integrity," 1971; Revision 1. August 1975. 3.0 Duquesne Light Co., letter from George S. Thomas (DLC) to USNRC Document Control Desk with enclosed report, WCAP-14F15. " Topical Report on i Reactor Coolant Pump Flywheel Inspection E.imination," January 24, 1996. 4.0 USNRC, letter from Brian W. Sheron (USNRC) to Sushil C. Jain (DLC) with enclosed SER, " Acceptance for Referencing of Topical Report WCAP-14535,
- Topical Report on Reactor Coolant Pump flywheel Inspection Elimination,
" September 12, 1996.
5.0 Entergy Operations, Inc., letter from Dwight C. Hims (Enteroy) to USNRC Document Control Desk, " Response to Questions Related to Rrn axation of Reactor Coolant Pump Flywheel Inspection Requirements," Decmoer 9, 1:5. 6.0 Duquesne Light Co., letter from Sushil C. Jain (DLC) to USNRC Document Control Desk, " Response to Request for Additional Information Concerning WCAP-14535; RAI Dated July 24, 1996" August, 2, 1996.
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December 9,1996 OCAN129601 U. S. Nuclear Regulatory Commission Document Control Dest Mail Station Pl.137 Washington, DC 20555
Subject:
Arkansas Nuclear One Units 1 and 2 Docket Nos. 50-313 and 50-368 License Nos. DPR 51 and NPF-6 Add.:tional Information Regarding Technical SpeciScations Change Request to Delete Reactor Coolant Pump Flywheel Inspections Gentlemen: By letter dated Apdl 4,1995 (OCAN049504), Entergy Operations requested changes to the Arkansas Nuclear One, Units 1 and 2 (ANO-1 and 2) Technical Specifications. The changes were to delete the requirements fr- inservice inspections of reactor coolsnt pump (RCP) flywheels. ANO submitted the it posed changes as a lead plant for the Combustion Engineering Owners Group. The o'ther affected plants are Millstone 2, Palisades, St. Lucie Units 1 and 2, and Waterford 3. The staffinformed ANO that the generic implications of the total deletion of the flywheel inspections could not be resolved prior to ANO's next scheduled flywheel inspection (ANO 2 refueling outage 2R11). In order to obtain relief for the next inspection, Entergy Operations submitted a revised Technical Specification Change Request (TSCR) on August 25, 1995 (2CAN089505). The NRC granted the reliefin a letter to ANO dated September 22,1995 (2CNA099507). Entergy Operations submitted a similar revised TSCR for ANO-1 on August 23, 1996 (ICAN089602), since ANO was informed by the NRC that the generic implications of the total deletion of the flywheel inspections could not be resolved prior to ANO-l's next scheduled flywheel inspection (refueling outage IR13). This request for relief was withdrawn via correspondence to the NRC dated October 9,1996 (ICAN099602). The flywheels were inspected during refueling outage IR13. The results of these inspections indicated no flaws or cracks. The results were provided to the NRC staffin a letter dated November 20,1996 (ICAN119603), to provide further data in support of the original (April 5,1995) TSCR to completely eliminate RCP flywheel inspections. C-RONOLOGCA' ni e
U.S.NRC December 9,1996 0CAN129601 Page 2 l in a letter dated October 2,1996 (OCNA109601), the NRC staff requested additional 1 information in order to complete their review of the original TSCR. The additions] information is provided in the attachment, Should you have further questions, please contact me. _Very truly yours, - C* W Dwight C. Mims Director, Nuclear Safety DCM/awb Attachment cc: Mr. Leonard J. Callan Regional Administrator U. S. Nuclear Regulatory Commission
. RegionIV 611 Ryan Plan Drive, Suite 400 Arlington, TX 76011-8064 NRC Senior Realdent inspector Arkansas Nuclear One P.O. Box 310 London, AR 72847 .
Mr. George Kalman NRR Project Manager Region IV/ANO 1 & 2 U. S. Nuclear Regulatory Commission NRR Mail Stop 13-H 3 One White Flint North 11555 Rockville Pike Rockville, MD 20852 - l ____u
Attachment to OCAN129601 PageIcf25 Response to Questions Related to " Relaxation of Reactor Coolant Pump Flywheel Inspection Requirements"
- 1. Section 3.0, Previous laspection Results for RCP [ Reactor Coolant Pump)
Flywheels, Pgs. 31 to 312t Provide additional information if the ultratonic (UT) examinations at the Combustion Engineering Owners Group (CEOG) member plants were quallned relative to laspection of RCP nywheels. Regardless whether a formal qualincation was performed, please include in your-response the following: Note: Inspection related questions 1 and 2 are answered from the perspective of the lead CEOG plant, Arkansas Nuclear One, Units 1 and 2 (ANO 1 and 2). The flywhed inspection program at ANO is considered representative of the inspection programs in existence at the other CEOG member plants. -
- m. Any informatism supporting quallAcation of the examinations of RCP l nywheels.
At this time, there has not been any " formal" quali6 cation of the ultr:uonic (UT) techniques used for examination of the RCP flywheels at ANO. The techniques utilized at ANO are consistent with the techniques used at other plants throughout the industry. The techniques generally consists of using a calibrated metal path to detect the keyway in the flywheel or a notch in a block, adding gain, and scanning for the appearance of any uncharacteristic reflectors that are not indicative of the geometry of the bore / keyway or holes in the flywheel,
- b. Any information supporting qualincation of the personnel performing the examinations of RCP nywheels.
Ultrasome examination personnel that have performed the RCP flywheel examinations were all certified to Level II or Level IH. Some of the examination personnel also held EPRI Intergranular Stress Corrosion Cracking (IGSCC) or Performance
- Demonstration Initiative (PDI) detection certifications. Examination personnel utilized in the past have not been speci6cally quali6ed to examine RCP flywheels via a performance demonstration. -
c, . Any information regarding the degree of uncertainty in UT measurements based on the procedures and personnel qualification basis. At this time, it is uncertain how capable any of the examination techniques currently used would be for sizing an indication after detection. The techniques can provide confirmation of the absence or presence of flaws but may not be effective for measuring dimensions of a detected flaw.
Attachment to 0CAN129601 Page 2 ef 25
- 2. Secties 3.0, Previous laspection Results for RCP Plywheels, Pgs. 3-1 to 3-12:
The fatigue analysis is dependent on the premise that UT equipment used for eaaminations of RCP Aywboels at these faculties is capable of securately detecting and slalog a 0.25-ineb long near-surface Raw. Provide your basis supporting the probability of detection (POD) for the eamminations performed. Provide details on how the POD values were detennh ed, quallned, sad used in concluding the' assumed size of the laitial Asw. Also, provide a demonstration of the CEOG asomber plaats' UT detection capsbuity la act missing a Asw size of 0.25 lach. As stated in response to question 1 above, there has been no formal qualification of the UT procedures on known er " mock" flaws. The procedures were based on generic , UT principion. 1 Previous ultrasonic technique quali6 cations for probability of detection of a given flaw l was considered in determining the 0.25 inch minimum detectable size flaw. The flaw size generally agreed upon by the participating utilities as being reasonably detectable was 0.25 inch. Guidance was also taken fkom the ANO-1 Safety Analysis Repon, which references ASME Section III (Class A N 321 and N 322) requirements that state that the smallest radial crack that could exist in a plate having passed an angle beam UT examination would be less than 0.24 inch based on a plate thickness of eight inches and a three percent notch. Even though a detectable flaw size minimum has not been proven by mock-up performance demonstrations, ANO has conducted an evaluation of detectability on known notches in a calibration block. ANO calibration block UT-99 is a 6.125 inches thick block that has several mock keyways that are 1 inch deep by either 1 inch or 3 inches in width. There are a series of machined notches in the keyways that are either 0.100 inch or 0.400 inch in depth. An exercise was conducted using the ultrasonic tecimiques used to examine the flywheels at ANO-1 and 2. Using each technique separately, both the 0.100 inch and 0.400 inch notches were detectable in at least one direction of scanning. The 0.100 inch notch was difBcult to separate from the keyway comer signal, but could be sorn as a moving signal directly in front of the upper corner signal. The 0.400 inch notch was readily detectable with all techniques used. Even though this exercise does not define an absolute minimum ,letectable value, it does bound a detectable flaw size value between 0.100 inch and 0.400 inch. Based on this, it would seem reasonable that an 0.25 inch flaw would have a good probability of detection, depending on the oristation of the flaw and the direction of the scan. Furthermore, en evaluation was perfonned to determine the acceptable initial flaw size that can be tolerated by the flywheels with consideration of crack growth. In this
Attachment to DCAN129601 Page 3 cf 25 crack growth evaluation,4000 cycles were assumed (eight times the 500 cycles for plant life de6ned in the plants' technical speci6 cations). A summary of this evaluation is presented below in Table 1 for all Sywheels. Fu the most limiting case, the acceptable initial Saw size is more than double the originally assumed 0.25 inch. This effectively renders the detection capability of a 0.25 inch flaw moot. The question now becomes, can a Saw greater than 0.5 inch be reliably detected? If the NRC believes a performance demonstration of this capability is still warranted, the CEOG will gladly comply, but will nrW to address me issues, e.g., flaw size, - implanted fatigue crack or electrodischarge mehlaias (EDM) notch, with the staff before a mockup is fabricated for this purpose. Table 1 Acceptable Initial Flow Sises Plant Name Allowable Plaw Sise Acceptable Initial Flaw Size Considering Crack Growth ANO1 1.16 1.148 ANO-2 >2 >2 Millstone-2 >2 >2
. Palisades >2 >2 St. Lucie 1 & 2 >2 >2 Waterford 3 0.58 0.579
- 3. Section 6.1.1, Centrifugal Stresses, Pg. 61: It was stated s curve-fitting the stress distribution that a radial distance of 2 laches from the keyway was considered in order to obtain an accurate fit. Did you only consider the stress distribution within this 2-inch range in the fracture mechanics analysis or did you exclude this part of stress distribution in your analysis?
Only the stress distribution within the 2 inch radial distance from the keyway was used for the curve St and thus considered in the fracture mechanics evaluation. As can be seen from Figures 6-3 through 614 in the subject report, the stress intensity factor was only calculated within this 2-inch distance, This approach is consistent with current ASME Sectioni XI evaluation methodology (1992 Edition) which specifies curve St over the crack depth.
Attachment to OCAN129601 Page 4 cf 25
- 4. Section 6.1.1, Centrifugal Stresses, Pg. 6 !: The finite element method (FEM) was employed in the stress analysis, but not in the fracture mechanics analyses.
Support your fracture mechanics results by modifying the FEM model to include the postulated crack sad then input the crack face pressure using the complete tangential stress distributions for the critical keyway regions in Figures 5-28
, through 5-33 or demonstrate that the simplified models used are conservative.
In the subject report, a model consisting of a longitudinal crack in the cylinder with t/R = 1.2 (t: thickness and R: inside radius) was chosen for the large-bore flywheels at ANO-1, Palisades, and St. Lucie Units 1 and 2. For the smaller bore flywheels at ANO-2, Millstone-2, and Waterford-3, a model consining of a crack emanating from a hole in an infmite plate was chosen. To show the adequacy in the use of these models, sensitivity studies were performed to determine the effect of the geometric parameter, t/R, rar.ging from 0.1 to infmity. This was achieved by using various models Srom the pc-CRACK software library. The analysis was performed for all the large-bore and small-bore flywheels for the plats considered in the subject report. The results of the evaluation in terms of stress intensity factor, K, versus crack length are presented in Figures 1 through 6 For the large-bore flywheels of ANO-1, Palisades, r.nd St. Lucie 1 and 2, the K variation with flaw length does not change significantly between the various t/R ratios l for crack lengths up to about 1 inch as shown in Figures 1 through 3. The actual t/R ratios for these flywineels varies from 1.22 to 1.37, as shown in Table 2. In the subject report, a t/R ratio of 1.2 was used to perform the evaluation which, for analysis purposes, is slightly more conservative than the actual t/R values for these large-bore i flywheels shown in Table 2. Hence, the results presented in the subject report are conservative. The K versus flaw size distributions for t!'e small-bore flywheels are shown in Figures 4 through 6 for ANO-2, Millstone-2, ard Waterford-3. The actual t/R ratios for these flywheels vary from 4.46 to 4.93 as rhown in Table 2. In the evaluation in the subject report, a crack emanating from a hde in an infinite plate with t/R ofinfinity was used. This model, although slightly less conservative than the actual t/R values for the flywheels for crack lengths greater than 0.75 inches, is acceptable considering the relatively large t/R ratios of th:se flywheels. To determine the sensitivity of the t/R ratio, the allowable flaw sizes were calculated itsing both models with t/R values of 1.2 and infinity, as explained in Item 5 below, even though it is believed that the t/R ratio : ofinfmity more closely rt. presents these small-bore flywheels. Both models yielded acceptable results.
Attachment 15 0CAN129601 Pago 5 cf 25 Table 2 - Geometric Data and t/R Ratios for Mywheels j Plant Name Bore Outside Thickness Inside g Diameter Diameter t Radius (R) (in.) (in.) (in.) (I"*) ANO-1 30.4 72.0 20.80 15.2 1.37 l ANO-2 13.74 81.5 33.88 6.87 4.93 Millstom-2 13.74 75.0 30.63 6.87 4.46 Palisades 33.0 72.0 19.50 15.5 1.25 St. Lucie 1 & 2 32.5 72.0 19.75 16.25 1.22 Waterford-3 13.75 78.0 32.125 6.875 4.67 l
OCAN129601 Page 6 of 25 LEFM Model Comparison Large Bore- ANO-1(Centrifugal) 45000 " t/R = 0.1 and O. 40000 - . t/R = 1 and 1. , 35000 -- E
;} 30000 --
$ Nd t/R = Infimty
. 25000 --
b
'ci
$c
'j 20000 --
bi , Actualt/R equals 1.37 l 15000 -- ' d 10000 -jj 5000 0.00 0.50 1.00 1.50 2.00 Crack Depth (in.) Figure 1. Comparison of Stress Intensity Factors for Various R/t Ratios - ANO-1
Attachment to OCAN129601-Page 7 of 25 LEFM Model Comparison . Large Bore- PALISADES (Centrifugal) l 30000 4 25000 -- t/R = 0.1 and 0.2 I g t/R = 1 and 1. , c 3 20000 -- W m E
.5 15000 . t/R = Minity E
$5
. Actualt/R equals 1.25 l 10000 --
I 5000 I . 0.00 0.50 1.00 1.50 2.00 Crack Depth (in.) Figure 2. Comparison of Stress Intensity Factors for Various R/t Rations - Palisades
Attachment to OCAN129601 Page 8 of 25 l LEFM Model Comparison Large Bore- ST. LUCIE (Centrifugal)
.30000 t/R = 0.1 and 0.2 i 25000 --
t/R = 1 and 1.2
- - r
-::: r g ,
4 20000 -- W
,$ t/R = Infinity N
l .5 15000 -- 0 55
/
Actualt R equals 1.22 l 10000 -- I 5000 . 0.00 0.50 1.00 1.50 2.00 Crack Depth (in.) Figure 3. Comparison of Stress Intensity Factors for Various R/t Ratios- St. Lucie 1 and 2
At1&Cnment to OCAN129601 Page 9 ef 25 ( LEFM Model Comparison small Bore - ANO-2 (Centrifugal) 35000 t/R = 0.1 and O. ' - 30000 -- t/R = 1 and 1.2 6 25000 -- *
*ii
*T m .
O _ ;::n:-::" l
. 20000 -- t/R = Infinity 6
i
.s O
M 15000 -- ActualtIR equals 4.93 i 10000 -- - st 5000 0.00 0.50 1.00 1.50 2.00 Crack Depth (in.) Figure 4. Comparison of Stress Intensity Factors for Various R/t Ratios - ANO-2
Attachment to OCAN129601 Page 10 cf 25 LEFM Model Comparison Small Bore -(Centrifugal) MILLSTONE l 30000 t/R = 0.1 and 0.2 l 25000 -- d a r
'g 20000 --
g _ : :;rr-g t/R = Infini c; E
.5 15000 --
E 3 Actualt/R equals 4.46 l 10000 -- 5000 0.00 0.50 1.00 1.50 2.00 Crack Depth (in.) Figure 5. Comparison of Stress Intensity Factors for Various R/t Ratios - Millstone-2 )
Attachment to OCAN129601 Page 11 ef 25
.LEFM Model Comparison Small Bore-(Centrifugal) l WATERFORD l 50000 i
t/R = 0.1 and 0.2s 45000 -- t t/R = 1 and 1.2 40000 -
$ 35000 -- .
5u S 30000 -~ t/R = Infinity h4 j 25000 -- E a 20000 -- Actualt/R equals 4.67 l 15000 -- 10000 -- 5000 ' O.00 0.50 1.00 1.50 2.00 Crack Depth (in.) Figure 6. Comparison of Stress Intensity Factors for Various R/t Ratios - Waterford-3
OCAN129601 Page 12 cf 25
- 5. Section 6.3, Allowable Flaw Size Determination, Pg. 6-6: It was stated that the stress intensity distribution for.the centrifugal and the shrink-fit stresses are compared separately with the allowable fracture toughness to determine the 4 allowable flaw sizes. Under normal operating conditions, the staff believes that contributions from both centrifugal and shrink-fit stresses to the applied stress
' intens!ty factors are comparable and should be combined. Figures 6-3 through 6-8 indicate that when the combined effect is considered the ASME Code criteria may not be met even for the faltlal crack size of 0.25 inch. Clarify this. Also, provide a revised copy of Figures 6-3 and 6-14 by adding the stress latensity due to shrink fit at the proper speed to the stress intensity due to centrifugal load.
In the subject report, the centrifugal and the shrink-fit stresses were treated separately to detennine the allowable sizes since the maximum stresses for these two loads do not occur at the same time. This approach was considered reasonable since very ' conservative shrink-fit values were used in the analysis (5.2 mils for the small-bore flywheels and 12.5 mils for the large-bore flywheels). In addition, the shrink-St stresses are seconduy (displacement type) stresses whose contribution to fracture is not as significant as the primary centrifugal stresses. It is expected that because of the very conservative initial shrink-fit values assumed in the analysis, that some amount of shrink-6t will still be present at the normal operating speed of the flywheel. To determine the residual shrink-fit values at normal operating speed, the finite element analysis performed in support of the subject report was reviewed to determine the relative displacement (initial shrink-fit minus centrifugal displacement) at normal operating speed. This relative displacement was used to calculate the residual shrink-fit stresses at normal operating speed. Stress intensity factors calculated for the centrifugal and residual shnnk fit stresses at normal operating speed are shown in Figures 7 through 15 for all the flywheels that were evaluated in the subject report. For the large-bore flywheels, a model with t/R ratio of 1.2 was used to deulate the applied stress intensity factor and is shown in Figures 7 through 9. For the small-bore flywheels, stress intensity factors were calculated using t/R ratios of 1.2 and infinity as shown in Figures 10 through 15. To determine the allowable flaw size, a safety factor of 3, consistent with ASME Code Section XI, was applied to the centrifugal stresses since these are primary stresses. A safety factor of I was applied to the shrink-fit stresses since these are displacement type stresses which do not contribute to the fracture of the ductile noterials. All the flywheels operate in the upper shelf region and are therefore expected to exhibit very ductile behavior. Precedent for the use of a safety factor of I for secondary stresses has been established in ASME Code, Section XI, Appendix C for materials that exhibit clastic-plastic fracture behavior. The comparison of the total f actored applied str:ss intensity factors with the fracture toughness for the flywheels are shown in Figurcs 7 through 15. The allowable flaw sizes resulting from these corr.parisons are shown in Table 3.
OCAN12%01 Page 13 cf25 It can be seen that these allowable flaw sizes are greater than the final flaw sizes for the assumed initial flaws of 0.25 inches in the flywh6els, even when the conservative shrink fit stresses are considered in the evaluation and, even if a conservative model with t/R = 1.2 is used for the small-bore flywheels. This demonstrates that the conclusions of the subject report are not changed by inclusion of the secondary shrink-
. fit stresses in the determination of the allowable flaw sizes.
Table 3 Allowable Flaw Sizes Centrifugal + Shrink-Fit Stresses Plant Name Allowable Flaw Size t/R = 1.2 t/R == ANO-1 1.16 N/A ANO-2 1.60 >2 Millstone-2 1.48 >2 Palisades >2 N/A St. Luc.c ' & 2 >2 N/A . Waterford 3 0.43 0.58
Attachment to OCAN129601 Page 14 cf25 Allowable Flaw Evaluation Normal Operating Conditions Large Bore Case- ANO-1
, 140000 Total 120000 - -
,/
%,./
100000 - - / S n
.5 .
a' k . S 3o000 .
/
,/ 3 x Centrifugal h4 . /
. /
b -
/
1 m . / l 5 / y 60000 - -
/
. t y .
I 2: / cn '
/
' I 40000 - I CmM&g
.I -
I
'I 20000 - -
Shrink Fi 0 ; ' 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Crack Depth (in.) Figure 7. Determination of Allowable Flaw Size (t/R = 1.2) - ANO-1 . l
Attachment to OCAN129601 Page 15 Cf 25 Allowable Flaw Evaluation Normal Operating Conditions , PALISADES 120000 - 100000 - - h U p 80000 - - 75 m . b . W - 60000 - - b < m . 6
.u E , 3 x Centrifu m
e ' 40000 - -
/
s'
. /
/
[f Centrifu
/
20000 --/ -- I
~
Shrink Fit O
^
l- ; ;- ; 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Crack Depth (in.) Figure 8. Determination of Allowable Flaw Size (t/R = 1.2) - Palisades
OCAN129601 - Page 16 cf 25 Allowable Flaw Evaluation Normal Operating Conditions ST. LUCIE 120000 100000 - -
~
p 80000 - . Total e . r b l & '
'p e" l .
60000 -- b m 5 3
- 3 x Cmdfu U .
b / M 40000 - - l / t
/
/
/
/ Centrifug
. /
/
20000 -
'I **............,22' ' ' ' ' ~ '
f Shrink Fit 0 ';' : ; : : ' : : ': ': - 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Crack Depth (in.) Figure 9. Determination of Allowable Flaw Size (t/R = 1.2) - St. Lucie 1 and 2
Attachment t3 OCAN129601 Page 17 cf25 Allowable Flaw Size Evaluation Normal Operating Conditions Small Bore - ANO-2 120000 100000 - -- h Total p 80000 - - y
.!!! 1
.f .
- --~~~~..
W
. 60000 - -
b ' i j
/
/ 3 x Centrifug 1.!.! .
/
N '
/
t! / Gi 40000 - -
/
t
' I
.I C a d fu
. ,I --
20000 - -
, . .,' Shrink Fit O ; ; ; ; ; ;
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Crack Depth (in.) Figure 10. Determination of Allowable Flaw Size (t/R = m)- ANO-2
Attachment to OCAN129601 Page 18 cf25 Allowable Flaw Size Evaluation Normal Operating Conditions { j MILLSTONE 100000 90000 - f Q Total I 80000 - - 70000 - - n C2 e .
"{" 60000 - -
I
. 50000 - - /
,b -
3 x Centrifug a -
,/
h
~
/
i
.E 40000 . /
g; . / u I y
. /
- /
30000 -
-li Centrifug I
20000 -
; ,.- Shrink Fi 10000 --/
O ; ; ; ; ; ; ; ; ; 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Crack Depth (in.) Figure 11. Determination of Allowable Flaw Size (t/R = m) - Millstone-2
Attachment t3 OCAN129601 Page 19 cf 25 Allowable Maw Size Evaluation Normal Operating Conditions WATERFORD 140000 120000 - -
. Total
/ ' ,
100000 - - h - j ,,. - c . 7 .
/
5 80000 -.-
/
/
l . 3 x Centrifugal
- d .
/
g . t r,; . /
$ 60000 - -
f i
.5 . p '
1 E . I E .I M
.I Centrifug -
40000 --4 20000 - Shrink Fit 0 l : ; ; ; 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Crack Depth (in.) Figure 12. Determination of Allowable Flaw Size (t/R = m) - Waterford.3
Attachment to OCAN129601 Page 20 cf 25 Allowable Flaw Size Evaluation Normal Lperating Conditions Small Bore- ANO-2 4 120000 100000 - Q G 80000 - - 3 . L . b
. 60000 -
/
/ 3 x Centrifu
'v; *
/
1 8 . I c '
*~ -
/
m / y ~
/
r.n 40000 - - I I
'I 1 C m d fu I
I 20000 - -
- ,.. ~~. -
ShrinkFit O ; ; ; ; ; ; ; ; ; 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Crack Depth (in.) Figure 13. Detennination ofAllowable Flaw Size (t/R = 1.2)- ANO-2
Attachment to OCAN129601 Page 21 cf 25 Allowable Flaw Size Evaluation Normal Operating Conditions MILLSTONE 100000 90000 :- g 80000 - f f Total - 70000 - - c a : /
' ' ~
lI 60000 - -
+
E
- 4 .- -
- 3 x Centrifugal
. 50000 - - '
b a .- l 5 : /
,5 40000 - ,-
y . / f g . I
-/
30000 7 ,1 Shrink Fit 20000 ;t - 2 .' Centrifugal 10000 --/ O ; ; ; ; ; ; ; ; ; 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Crack Depth (in.) Figure 14. Determination of Allowable Flaw Size (t/R = 1.2) - Millstone-2
Attachment to OCAN129601 Page 22 cf 25 Allowable Flaw Size Evaluation Normal Operating Conditions WATERFORD 160000 I 140000 - f . Total # 120000 - -
,/
q 3 x Centrifugal
.] 100000 -@ ,,, } ,
g . /
. 80000 - .
f b . t .
'E .
f h . /
.E . /
E 60000 - e
,t i Centrifugal 40000 f; 20000 Shrink Fit f
... l 0 ; ; ; ;- ; ; ; ; ;
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Crack Depth (in.) Figure 15. Determination of Allowable Flaw Size (t/R = 1.2) - Waterford-3
Attachment 13 OCAN129601 Page 23 er25
- 6. Provide information on the remaining shrink fit for accident conditions for all Hywheels. -
The estimated remaining shrink-fit for accident conditions for all flywheels is shown in Table 4. These were calculated by determining the centrifugal displacement at accident conditions and subtracting it from the initial shrink-fit. Table 4 Remaining Shrink-fit at Accident Conditiom Plant Name Initial Centrifugal Remaining Shrink-Fit Displacement Shrink-Fit (in) (in) (in) ANO-1 0.0125 0.0108984 0.00160 ANO-2 0.0052 0.003777 0.00142 Millstone-2 0.0052 0.003134 0.00207 Palisades 0.0125 0.006527 0.00597 St. Lucie 1 & 2 0.0125 0.006439 0.00606 l Waterford 3 0.0052 0.005844 0.00000 ? .
- 7. Provide past RCP Hywheel maintenance records in terms of maintenance frequency and level of disassembly involved.
Complete access to'the flywheels allowing for a more thorough inspection is made possible dudng reactor coolant pump motor replacement evolutions. The historical motor replacements that have occurred at ANO are provided in Table 5 below. Table 5 Historical Reactor Coolant Pump Motor Replacements at ANO ANO Unit Pump Type of Motor Outage Date 1 P32B New 1R12 Spring 1995 2 2P32A New 2R9 Fall 1992 2 2P32B Refurbished 2R10 Spring 1994
OCAN129601 Page 24 of25 The tentative ANO schedule for future reactor coolant pump motor replacements is provided in Table 6 below. Table 6 l Planned Future Reactor Coolant Pump Motor Replacements ANO Unit Pump Type of Motor ' Outage Date 1 P32C or P32D Refurbished IR14 Spring 1998 1 P32C or P32D Refurbished IRIS Spring 2000 1 P32A Refurbished IR16 Spring 2002 2 2P32C Refurbished 2R12 Spring 1997 2 2P32D Refurbished 2R13 Spring 1999
- 8. Discuss the test results from the initial examination on Arkansas Nuclear One, Unit l's RFP Dywheels in terms of detection and sizing capability of the acoustic emission methodology used and the future inspection plan for these nywheels.
Acoustic-emission inspection involves the detection of released strain initially stored in a strain Beld. Detection forms the basis for analyzing the integrity of the material or structure. If a discontinuity is unstab!s and is affected by loading, the discontinuity will emit acoustical energy, which will reveal its presence. If the discontinuity is not affected by loading, it will not be an active emitter; that is, it is in a s*able condition and will not affect the structural integrity of the material being tested. In January 1983, acoustic emission' tests were performed on reactor coolant pump motor flywheels P32A, P22B, P32C, and P32D at ANO-1. The evaluations of the four flywheels were accomplisi ed in accordance with ANO test procedures. The acoustic emission inspection system provided two independent analysis routines. Real-time Source Display (RSD) analyzes all emission intensities on a video screen which contains a geometricallayout of the structure being inspected. Source analysis computer (SAC) processes and analyzes emission data using criteria that selects only the predominantly (non-random) sources to analyze for structural location and significance. - The flywheel inspections were divided into two tests (Test I and Test 2). The inspection portions of Test I and Test 2 utilized the two independent analysis routines, RSD and SAC. ~
GWmimm m OCAN129601 Page 25 ef25 During Test 1, all flywheels showed random emissions during the RSD analysis. The random emissions were pdmarily in the region of the highest expected stress of the Bywheels. Ali four Bywheels released energy at a constant rate and at a low value indicating no_ Grade A sources (sources were insigni5 cant to stmetural integrity). Neither predominant nor persistent emitters were detected on any of the four Sywheels. To con 6rm and correlate the results of the RSD analysis, post-test statistical computer analysis was conducted, ne post test analysis revealed bw. one to three areas of - sourcs location correlation beres. transducer sets or stress increments. However, the data from these correlated areas did not meet the minimum grading criteria as ~ de6ned in AEI-82-154, Rev.1, Section 7.4 of Appendix A. Because the minimum grading requirements were not met, all of the identi6ed areas of sources locations were classi3ed as either innocuous, or minor and m* aigni6 cant to structural integrity. Test 2 of Sywheels P32A, P32B, P32C, and P32D from the RSD revealed no predominant nor persistent emitters. On P32A, P32B and P32D only random emissions were detected from the regions of highest stress. On P32C mostly random emissions were displayed coming from the regions of highest stress and from the shaft and spoke region. The four flywheels had energy release rates that remained low, and no gradable sources were revealed in the post-test statistical computer analysis. The most significant sources of emissions of the flywheel %+2 ions were determined to be paint-to-metal interface, metal-to-metal interface of the flywheel, and bolted counterweight below the flywheel. The acoustic emission system is sensitive to sound both on and within the structure being tested. The majority of sounds transmitted during the two tests were of long duration such as those generated by structural interfaces moving with respect to each other, whereas, crack generation emissions are characteristic of short duration. The flywheel ima~*lons did not reveal any indications of significance. All flywheels analyzed were of good integrity under the conditions imposed during the acoustic emission tests. Acoustic emission crack detection is dependent on crack growth and deformation time. 4 Acoustic emission is capable of dMag microcracks in the size range 4 of 10 to 10 inches as they are formed. Ir.c ..ents ofmacrogrowth of the same dimension can also be detected. Crack growth that === a motion in the sensor of 10a2 inches can be detected, assuming the deformation time is 20 microseconds or less. The sensitivity of the acoustic emission system can range from gross deformations, which caus'e audible sound, to micro-occurrences, such as movement of dislocations. Acoustic emission is no longer utilized for the flywheelm' spections at ANO-1. All four flywheels have been ultrasonically examined since the performance of the acoustic emission i=Flon. Future flywheel inspections at ANO-1 will continue to utilize ultrasonic techniques as the primary means of examination.
EXECUTIVE
SUMMARY
The inspection requirements for reactor coolant pump (RCP) flywheels are specified in Regulatory Guide 1.14 (RG 1.14), Revision- 1 issued by the U.S. Nuclear Regulatory Commission. In addition to mandated preservice inspections, RG 1.14 requires the following inservice inspection plan: a) An in. place ultrasonic volumetric examination is to be performed on the areas of higher stress concentration at the bore and keyway. This should occur at approximately 3 year intervals, during the refueling or maintenance shutdown, ' coinciding with the ISI schedule, as required by Section XI of the ASME , Code. l b) A surface examination of all exposed surfaces and complete ultrasonic volumetric examination shall be performed at approximately 10-year intervals, during the plant shutdown, coinciding with the ISI schedule, as required by Section XI of the ASME Code. To date, plants that are committed to RG 1.14, have complied with its in service inspection uquirements, while most plants that are not committed to RG 1.14 have taken guidance from its inspection requirements. rhis has resulted in many examinations of the flywheel as part of the normalISI program. The inspections have never revealed a condition which could lead to the failure of the flywheel. While severalinstances have been recorded in the ' literature where the reactor coolant pump shaft has been subjected to cracking, no reported instance of flywheel service induced degradation or cracking has been reported. The flywheel inspections, both at 3 year and 10-year intervals, result in significant outage time, man rem exposure and cost to utilities which may be minimized by use of a more carefully designed inspection program. This program should account for the failure history of the flywheels, potentialin service degradation mechanisms and applicable locations, prior inspection results, and an evaluation of the failure propensity of the entire coolant pump motor to determine if failure of a flywheel between inspections is a credible event. This report presents analyses of flywheel integrity performed by Structural Integrity
- Associates (SI) for four utilities in the Combustion Engineering (CE) Owners Group to justify relaxation of the RG 1.14 in service inspection requirements. The four utilities are Consumers Power (Palisades), Entergy Operations (Arkansas Nuclear Units 1/2 and Waterford Unit 3), Florida Power & Light (St. Lucie Units 1/2) and Northeast Utilities (Millstone Unit 2). ANO-1 is not covered by RG 1.14 but is included in this study to determine if their current inspection plan can also be relaxed. Flywheels at these plants have been used in a study to determine alternate inspection requirements for the RCP flywheels. This evaluation includes a detailed review of past ultrasonic data of the affected plints, an industry-wide survey of other plants, the determination of degradation mechanisms -which may affect the flywheel, stress analyses and fracture mechanics evaluations.
SIR-94-080, Rev. O i { Structors!IntegrityAssociates,Inc.
The evaluations have demonstrated that for the plants considered in this study, the inspection of the RCP flywheels as mandated by Regulatory Guide 1.14 and incorporated in the Plants' Technical S;iecifications can be eliminated without compromising safety. This conclusion is supported by several observations made during the evaluations presented in this report and summarized below, e Inspections that have been performed to date at all seven plants have never revealed l _ the presence of any service induced flaws. The inspections have spanned several l years and have been performed using both ultrasonic and surface examination i methods. 4 o A survey of several other plants was also performed to determine if any flaws have been reported during flywheel inspections. The survey revealed that to date, no flaws have been reported in any of the plants that were contacted. e Various mechanisms that cotad potentially degrade the flywheel materials during
. service were evaluated. It was concluded that other than fatigue crack growth, there are no other mechanisms that can affect the service performance of the flywheel.
Fatigue crack growth analyses were performed to show that crack growth, assuming a conservative initial flaw at the worst location, is negligibly small. Flaw tolerance evaluations performed using conservative linear clastic fracture mechanics principles and considering the critical location of the flywheel indicated that the flywheels do not present a safety concern for current plant life and life exterision. These evaluations were performed using lower bound fracture toughness values at the most highly stressed locations. A conservative flaw size of 0.25 inch was assumed to be present, due to UT detection uncertainty. Fatigue crack growth
- analyses using the ASME Section XI crack growth law showed that this initial flaw propagated to less than 0.3 inch following 4000 startup/ shutdown cycles (about eight times those estimated for the plant life). This final flaw size is significantly below the -
ASME Code allowable flaw size for any of the flywheels examined in this study. SIR-94-080, Rev. O ii f StructuralIntegrityAssociates,Inc. _.______J
0. Table of Contents Section ' EASC
- 1.0
- I NTRODU CTI ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1.1: Ba ckgro und . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1.2 - Objective and Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
2.0 DESCRIPTION
OF FLYWHEElJ!i ............................. 2.1 21 Arkansas Nuclear One Unit 1 (ANO-1) . . . . . . . . . . . . . . . . . . . . . . 2-2 2.2 Arkansas Nuclear One Unit 2 (ANO-2) . . . . . . . . . . . . . . . . . . . . . . 2-3 2.3 2.4 Millstone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Palisades . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4 2.5 S t. Lu cie . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ........
............... 2-5 2.6 Wa te rford-3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .........
........ 2-5 3.0 PREVIOUS INSPECTION RESULTS FOR RCP FLYWHEEL 3 . . . . . . 3-1 .
3.1 Plant Specific Results ......................... 3-2 3.2 Industry-wide Survey . . . . . . . . . . . . . . . . . . . . . . . . . . .......... l-3-2 !' 4.0 l POTENTIAL FLYWHEEL DEGRADATION MECHANISMS . . . . . . . . 4-1 L 5.0 - ' STRESS ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1 5.1 Centrifugal Loads Due to Pump Speed . . . . . . . . . . . . . . . . . . . . . . 5-1 5.2 - Stresses -Due to Shrink-Fit . . . . . . . . . . . . . . . . . . . . . . 5 5.3
- Seismic Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5 t
5.4 . Vibrational Loa ds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....... ....... 5-5 5.5 Key I.cading Due to Shaft Torque . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5 6.0 FRACTURE 6.1 Fracture MECHANICS EVALUATION . . . . . . . . . . . . . . . . . . . . . .61 . Mechanics Models and Stress Factor
- Determination . . . . . . . . . . . . . . . . . . . . . . ...... . . . Intensity 6.2 6-1 Fracture Toughness . . . . . . . . . . . . . . . . . . . . . . . . . . . ..........
.......... 63 6.3 6.4 Allowable Flaw Size Determination . . . . . . . . . . . . . . . . . . . . . . . . 6. -4 Crack Growth Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6. -6 7.0 -
SUMMARY
AND CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1 .. 8.0 - REFEREN CES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 ....
' APPENDIX A RCP FlywheelInspection Survey Results ................... A-1 SIR-94-080, Rev. O iii f StructurallategrityAssociates,Inc.
List of Tables 21 Flywheel Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6 31 Inspection Summary for ANO-1 RCP Mywhech . . . . . . . . . . . . . . . . . . . . . 3-4 32 Inspection Summary for ANO 2 RCP Mywheek . . . . . . . . . . . . . . . . . . . . . 3-5 33 Inspection Summary for Millstone Unit 2 RCP Mywheek . . . . . . . . . . . . . . 37 3-4 Inspection Summary for Palisades Mywheek . . . . . . . . . . . . . . . . . . . . . . . . 3-8 35 Inspection Summary for St. Lucie Units 1 and 2 . . . . . . . . . . . . . . . . . . . . . 3-10 3-6 Inspection Summary for Waterford 3 Flywheek . . . . . . . . . . . . . . . . . . . . . 3-12 6-1 Fracture Toughness Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 6-2 Allowable Flaw Size s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-8 6 Crack Growth Evaluation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 SIR 94-080, Rev. 0 - iv f SimcturalintegrityAssociates,Inc.
t i List of Figures g 21; Typical RCP Motor Assembly with Large Bore Flywheel . . . . . . . . . . . . . . - 2-7 2-2 Critical Area of Flywheel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8 51 Flywheel Stress Distribution Due to Centrifugal Force . . . . . . . . . . . . . . . . 5-6
-52 Finite Element Model for large Bore Flywheel . . . . . . . . . . . . . . . . . . . . . 57 53 Finite Element Model for Small Bore Flywheel . . . . . . . . . . . . . . . . . . . . . 5-8 4 Overall Tangential Stress Distribution Due to Centrifugal Force (ANO-1) . . 5-9 5-5 Details af Tangential Stress Distribution in Keyway Region Due to Centrifugal Force (ANO-1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 10 5-6 Overall Radial Stren Distribution Due to Centrifugal Force (ANO-1) . . . . .- 5-11 5-7 - Details of Radial Stress Distribution in Keyway Region Due to Centrifugal Force ( ANO 1 ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 12 5-8 Overall Tangential Stress Distribution Due to Centrifugal Force (ANO-2) . 5-13 59 Details of Tangential Stress Distribution in Keyway Region Due to Centrifugal Force ( ANO 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 14 510L Overall Radial Stress Distribution Due to Centrifugal Force (ANO-2) . . . . 5 5-11_ Details of Radial Stress Distribution in Keyway Region Due to Centrifugal Force ( ANO 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-16 5-12 Overall Tangential Stress Distribution Due to Centrifugal Force (Millstone-2) .5-17 -5 13 Details of Tangential Stress Distribution in Keyway Region Due to Centrifugal Force (Millstone-2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-18 5 14: Overall Radial Stress Distribution Due to Centrifugal Force (Millstone-2) . 5-19 5-15 -Details of Radial Stress Distribution in Keyway Region Due to Centrifugal Force (Millstone-2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-20 SIR-94-080, Rev. O _ v
{ StructurallategrityAssociates,Inc.
O List of Figures (continued) Eisma East 5016 Overall Tangential Stress Distribution Due to Centrifugal Force (Palisades) 5 21 5 17 Details of Tangential Stress Distribution in Keywa Force (Palisades) . . . . . . . . . . . . . . . . . ......................
. . . . .y Region Due to Centrifugal 5-22 So18 Overall Radial Stress Distribution Due to Centrifugal Force (Palisades) . . 5-23 5019 Details of Radial Stress Distribution in Keyway Region Due to Centrifugal Force (Palisades) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-24 5 20 Overall Tangential Stress Distribution Due to Centrifugal Force (St. Lucie) 5-25 5 21 Details of Tangential Stress Distribution in Ke Force (St. Lucie) . . . . . . . . . . . . . . . . ........................
. . . .yway Region Due to Centrifugal 5 26 5-22 Overall Radial Stress Distribution Due to Centrifugal Force (St. Lucie) . . 5-27 5 23 Details of Radial Stress Distribution in Keywa Force (St. Lucie) . . . . . . . . . . . . . . . . ........................
. . . .y Region Due to Centrifugal 5-28 l 5 24 Overall Tangential Stress Distribution Due to Centrifugal Force (Wa te rford 3 ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , 5 29 5-25 Details of Tangential Stress Distribution in Keyway Re Force (Waterford 3) . . . . . . . . . . . . , . . . . . ................... . . . . gion Due to Centrifugal 5-30 So26 Overall Radial Stress Distribution Due to Centrifugal Force (Waterford-3) . 5-31 5 27 Details of Radial Stress Distribution in Ke Force (Waterford 3) . . . . . . . . . . . . . . . yway Region Due to Centrifugal
.......................... 5-32 5-28 Tangential and Radial Stress Distribution from Bore to Outside Diameter
( AN O 1 ) ' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-33 5 29 Tangential and Radial Stress Distribution from Bore to Outside Diameter ( AN O-2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-34 5 30 Tangential and Radial Stress Distribution from Bore to Outside Diameter (Millsto ne -2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-35 SIR 94-080, Rev. O vi f StructuralIntegrityAssociates,Inc.
i List of Figures
., (continued) 5 31 Tangential and Radial Stress Distribution from Bore to Outside Diameter
( (Palisa de s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 .3 6 5 32 Tangential and Radial Stress Distribution from Bore to Outside Diameter [ (S t. Lucie) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5. 3. 7. 5 33 Tangential and Radial Stress Distribution from Bore to Outside Diameter (Wa te rford.3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 38 5 34 Comparison of Finite E!cment Results for Centrifu Results (ANO 1) . . . . . . . . . . . . . . . . . . . . . . . . gal Force With Theoretical
.................... 5 39 5 35 Comparison of Finite Element Results for Centrifu Results (ANO 2) . . . . . . . . . . . . . . . . . . . . . . . . gal Force With Theoretical
.................... 5 40 5 36 Comparison of Finite Element Results for Centrifu l
Results (Millstone 2) . . . . . . . . . . . . . . . . . . . . . gal Force With Theoretical
.................... 5-41 5 37 Comparison of Finite Element Results for Centri Results (Palisades) . . . . . . . . . . . . . . . . . . . . . fugal Force With Theoretical
...................... 5-42 5 38 Comparison of Finite Element Results for Centrifu Results (St. Lucie) . . . . . . . . . . . . . . . . . . . . . . . gal Force With Theoretical
.................... 5-43 5 39 Comparison of Finite Element Results for Centrifu Results (Waterford 3) . . . . . . . . . . . . . . . . . . . . gal Force With Theoretical
.................... 5-44 5-40 Overall Tangential Stress Distribution Due to Shrink Fit Force (ANO 1) . .5-45 .
5-41 Details of Tangential Stress Distribution in Ke Force (ANO 1) . . . . . . . . . . . . . . . . . . . . .yway Region Due to Shrink Fit
....................... 5-46 5-42 Overall Radial Stress Distribution Due to Shrink Fit Force5-47 (ANO-1) . . . . .
5-43 Details of Radial Stress Distribution in Ke Force (ANO 1) . . . . . . . . . . . . . . . . . . . yway Region Due to Shrink Fit
.......................... 5-48 5-44 Overall Tangential Stress Distribution Due to Shrink Fit Force (ANO 2) 5-49 ...
SIR 94-080, Rev. O vii { StructuralIntegrityAssociates,Inc.
\\
0 List of Figures (continued) . Egms P.agt 5 45 Details of Tangential Stren Distribution in Keyway Region Due to Shrink Fit For ce (AN O 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 50 5 46 Overall Radial Streu Distribution Due to Shrink Fit Force (ANO 2) . . . . . . 5 51 l 5 47 Details of Radial Stress Distribution in Keyway Region Due to Sitrink Fit Force ( ANO 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 552 l l 5-48 Overall Tangential Stress Distribution Due to Shrink Fit Force (M illstone 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 53 5 49 Details of Tangential Stress Distribution in Keyway Region Due to Shrink Fit Force (M111 stone 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 54 5 50 Overall Radial Stress Distnbution Due to Shrink Fit Force (Millstone 2) . . 5 55 5 51 Details of Radial Stress Distribution in Keyway Region Due to Shrink Fit Force (Millstone 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 56 5 52 Overall Tangential Stress Distribution Due to Shrink Fit Force (Palisades) . 5 57 5 53 Detads of Tangential Stress Distribution in Keyway Region Due to Shrink Fit For ce (Palisa de s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 58 5 54 5 59 Overall Radial Stress Distribution Due to Shrink Fit Force (Palisades) . . . 5 55 Details of Radial Stress Distribution in Keyway Region Due to Shrink Fit Force (Palisades) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-60 5 56 Overall Tangential Stress Distribution Due to Shrink Fit Force (St. Lucie) . 5 61 5 57 Details of Tangential Stress Distribution in Keyway Region Due to Shrink Fit Force (St. Lucie ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 62 5 58 5-63 Overall Radial Stress Distribution Due to Shrink Fit Force (St. Lucie) . . . 5 59 Details of Radial Stress Distribution in Keyway Region Due to Shrink Fit
, Force (St. Lucie) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-64 SIR 94-080, Rev. O viii f StructurnilategrityAssociates,Inc.
4
0 IJst of Figures (continued) Egura
, M 5 60 Overall Tangential Stress Distribution Due to S Force (Watetford 3) . . . . . . . . . . . . . . . . . . . . ............ . . . . . . . . . . 545 . . .hrink Fit 541 Details of Tangential Stress Distribution in Ke Force (Waterford 3) . . . . . . . . . . . . . . . . . .yway Region Due to Shrink Fit
....................... 546 542 Overall Radial Stress Distribution Due to Shrink Fit Force (Waterford 547 3) .
543 Details of Radial Streu Distribution in Ke ! Force (Waterford 3) . . . . . . . . . . . . . . . yway Region Due to Shrink Fit
.......................... 548 61 LEFM Crack Model H from pe. CRACK 1.on (t/R = 1.2) . . . . . . . . . . . . . . . . . . . . . . . . . .gitudinal Crack in Cylinder
. . . . . . . . . . . . . . . . . . . . . . - 6 10 62 LEFM _ Crack ModelI from pc CRACK Crack Emanatin Infinite Plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .g from Hole in an
.............. 6 11 63 Comparison of Applied Stress Intensity Factor Versus Allowable Stress Intensity Factor for Normal Operating Conditions (ANO.1) . . . . . . . . . . . . 6 17 6-4 Comparison of Applied Stress Intensity Factor Versus Allowable Stress Intensity Factor for Normal Operating Conditions (ANO.2) . . . . . . . . . . . . 6 13 65 Comparison of Applied Stress Intensity Factor Versus Allowable Stress Intensity Factor for Normal Operating Conditions (Millstone 2) . . . . . . . . . 6 14 64 - Comparison of Applied Stress Intensity Factor Versus Allowable Stress Intensity Factor for Normal Operating Conditions (Palisades) . . . . . . . . . . . 6 15 6-7 Comparison of Applied Streu Intensity Factor Versus Allowable Stress Intensity Factor for Normal Operating Conditions (St. Lucie) . . . . . . . . . . . 6 16 6-8 Comparison of Applied Stress Intensity Factor Versus Allowable Stress
. Intensity Factor for Normal Operating Conditions (Waterford 3) . . . . . . . . 6 17 6-9 Comparison for Applied Stress Intensity Factor Versus Allowable Stress Intensity Factor for Accident Conditions (ANO 1) . . . . . . . . . . . . . . . . . . . 6 18 6 10 Comparison for Applied Streu Intensity Factor Versus Allowable Stress Intensity Factor for Accident Conditions (ANO 2) . . . . . . . . . . . . . . . . . . . 6 19 SIR 094-080, Rev. O ix f StructurallategrityAssociates,Inc.
List of Figures
, (concluded)
G11 Comparison for Applied Streu Intensity Factor Venus Allowable Stress Intensity Factor for Accident Conditions (Millstone 2) . . . . . . . . . . . . . . . . G20 6 12 Comparison for Applied Stress Intensity Factor Versus Allowable Stress intensity Factor for Accident Conditions (Palisades) . . . . . . . . . . . . . . . . . . G21 613 Comparison for Applied Stress Intensity Factor Versus Allowable Stress Intensity Factor for Accident Conditions (St. Lucle) . . . . . . . . . . . . . . . . . . 6 22 6 14 Comparison for Applied Stress Intensity Factor Versus Allowable Streu Intensity Factor for Accident Conditions (Waterford 3) . . . . . . . . . . . . . . . . 6 23 SIR.94-080, Rev. 0 - x { StructuralIntegrityAssociates,Inc.
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1.0 INTRODUCTION
1.1 Background
Reactor coolant pump (RCP) flywheels operate at speeds such that in the very unlikely event of a failure during operation, they present a potential safety concern to the reactor coolant system, the containment and other equipment of systems important to safety as a result of the effects of missile impact. Regulatory Guide 1.14 (RG 1.14), Revision 1, issued by the U.S. Nuclear Regulatory Commission (NRC), presents a methodology for minimir.ing the potential for failure of RCP Dywheels in light water cooled reactors [1]. Included within the requirements of RG 1.14 are the material, fabrication, design, testing and inspection requirements necessary to assure the f:ywheel is placed into service in compliance with the Guide, and the ASME Boiler and Pressure Vessel Code, providing a high quality component for plant operation. Most utilities added surveillance requirements to conduct Dywheel inspection according to RG 1.14 in order to resolve Systematic Evaluation Program (SEP) Topic III 10.B, " Pump Flywheel Integrity." This requirement was subsequently incorporated into the Technical Specifications of the plants as a result of Standard Review Plan (SRP) Section 5.4.1.1 [2] which was identified under NRC Staff SEP Topic V-7, " Reactor Coolant Pump Overspeed." It was expected that a generic review on SEP Topic V 7 would be conducted by the NRC. However, the isruance of NUREG 0933 [3), made this rt: view unnecessary since it was concluded from this NUREG that there is a very low risk associated with Dywheel failure. In spite of this, utilities still continue to spend considerable resources on the inspection of the Dywheels per the requirements of RG 1.14.
' Subsequent to initial plant operation, RG 1.14 mandates in service inspection (ISI) to be performed at specific intervals to assure that the structural integrity of the Dywheel is maintained. The inspection requirements, as specified within RG 1.14, require that a spin test be performed prior to initial operation at the design speed of the Dywheel. Then, the SIR 94-080, Rev. 0 1-1 h StructuralIntegrity Associates. Inc.
finished flywheel is subjected to a check of critical dimensions and a nondestructive
- examination (NDE) which includes the following:
- 1. Inspection of areas of higher stress concentration for surface defects in accordance with Section III of the ASME Code with acceptance criteria in accordance with paragraph NB 2500 of the Code.
! l l 2. Ultrasonic volumetric examination of 100% of each finished Dywheel as l l speel6ed in paragraph NB 2500 of the Code. , Following introduction into service, the ISI program for the Dywheel is to be performed for each Dywheel in accordance with the following paragraphs: a) An in place ultrasonic volumetric examination is to be performed on the areas of higher stress concentration at the bore and keyway. This should occur at approximately 3 year intervals, during the refueling or maintenance shutdown, coinciding with the ISI schedule, as required by Section XI of the ASME Code, b) A surface examination of all exposed surfaces and complete ultrasonic volumetric examination shall be performed at approximately 10-year intervals, during the plant shutdown, coinciding with the ISI schedule, as required by Section XI of the ASME Code. To date, plants that are committed to RG 1.14, have complied with its in service inspection requirements, while most plants that are not committed to RG 1.14 have taken guidance from its inspection requirements. This has resulted in many examinations of the Dywheel as part of the normal ISI program. The inspections have never revealed a condition which could lead to the failure of the Dywheel. While several instances have been recorded in the SIR 94-080, Rev. 0 12 { StructuralirrtegrityAssociates,Inc.
literature where the reactor coolant pump shaft has been subjected to cracking, no reported instance of Dywheel servi'c e induced degradation or cracking has been reported. The flywheel inspections, both at 3 year and 10 year intervals, result in significant outage time, man rem exposure and cost to utilities which rnay be minimized by use of a more carefully designed inspection program. This program should account for the failure history of the Dywheels, potentialin service degradation mechanisms and applicable locations, prior inspection results, and an evaluation of the failure propensity of the entire coolant pump motor to determine if failure of a Dywheel between inspections is a credible event. Evaluations have been performed by the utilities participating in this study to demonstrate flaw tolerance of the Dywheels in the six plants in conformance with RG 1.14 requirements. The evaluations are documented in References 4 through 9. It was shown in these evaluations that the flywheel materials have adequate toughness and that the critical speeds of the Dywheels are significantly greater than their normal operating speeds, such that the probability of missiles resulting from the failure of a flywheel is extremely small. As part of this study: these evaluations were reviewed. In all cases,it was found that there is adequate safety margin against brittle and ductile fracture of the flywheel. Supplemental stress cnalyses and fracture mechanics evaluations were performed to demonstrate that at the most criticallocation of the hywheels, fracture is not a concern for the balance of plant life, such that current inspection requirements can be relaxed without compromising safety. This report documents the independent review and analyses of flywheelintegrity performed by Structural Integrity Associates (SI) for four utilities in the Combustion Engineering (CE) Owners Group to justify relaxation of the RG 1.14 in service inspection requirements. The four utilities are Consumers Power (Palisades), Entergy Operations (Arkansas Nuclear Units 1/2 and Waterford Unit 3), Florida Power & Light (St.= Lucie Units 1/2) and Northeast - Utilities (Millstone Unit 2). ANO 1 is not covered by RG 1.14 but is included in this study to determine if their current inspection plan can also be relaxed. Flywheels at these plants have been used in a study to determine alternate inspection requirements for the RCP SIR 94-080, Rev. O' 1-3 h StructurnilategrityAssociates,Inc.
flywheels. This evaluation includes a detailed review of past ultrasonic data of the affected
! plants, an industry wide survey of other plants, the determination of degradation mechanisms which may affect the Dywheel, stress analyses and fracture mechanics evaluations. i i
- 1.2 Objective and Organization i
j l The objective of this study is to perform a comprehensive evaluation of the Dywheel to j justify the relaxation of the inspection requirements of RG 1.14. This investigation examines j the Dywheel material properties, fabrication processes and design, reviews past operating
-history and inspection results for the Dywheel throughout the industry. The study then l postulates an initial flaw and performs a crack growth and stability analysis for the Dywneels ,
j under the most severe environmental and lading conditions for the component. In addition, l cll other failure mechanisms which can affect low alloy steels under the flywheel conditions are examined. This information can be utilized to develop a new recommended inspection schedule which will maintain safe performance of the RCP while reducing inspection costs
- and exposure.
l Section 2 of this report examines the flywheel geometry and material properties for each of the plants in the evaluation. Section 3 discusses previous inspection results of the plants
- analyzed in this study, as well as from the industry in general, where information is available.
Section 4 discusses the potential senice degradation mechanisms which may undermine the seniceability of the flywheel. Section 5 provides a finite element stress analysis of the l flywheel, examining locations of stress intensification under bounding loading conditions. Section 6 provides fracture mechanics analyses, postulating the maximum flaw that could be present, yet undetected during ultrasonic examination (UT), and propagating it using bounding crack growth rates for the flywheel operating conditions. ASME Section XI F cllowable flaw sizes are also calculated in this section and compared to the final flaw sizes, l considering potential crack growth. Recommendations are provided along with a summary cnd conclusions in Section 7. Section 8 lists the references used to support this study. i SIR 94-080, Rev. 0 14 { StructuralIntegrityAssociates,Inc. i
10 DESCRIPTION OF FLYWHEEL.S RCP Dywheels are large steel discs which are attached to the shafts of RCP motors. The function of the Dywheels is to maintain the rotationalinertia of the RCP motor, providing coast down and assuring a more gradualloss of main coolant flow to the core in the event that pump power is lost. In most cases, the Dywheels consist of two or more discs bolted together either at the top and/or at the bottom of the motor. Two basic types of flywheels are encountered in the plants under evaluation in this study. The first type is a " solid" Dywheel in which the Dywheel is directly attached to the shaft. These flywheels have relatively small bores; typically between 11 and 14 inches. They are shrunk fit to the shafts such that contact is maintained between the Dywheels cnd the shafts, even at maximum postulated overspeed conditions. There is at least one vertical keyway which key the flywheel to the shaft to provide continuity of the rotating assembly. Figure 21 shows a photograph of this type of Dywheel in the RCP motor assembly with details shown in Figure 2 2. The second type is a " hollow" Dywheel in which the flywheel is shrunk fit unto a spoke or spider arm arrangement. These spokes are welded to the shaft, extending about 10 to 12 inches radially from the shaft and also extend from the top to the bottom flywheels in the axial direction. A typical RCP motor assembly for this configuration is shown in Figure 2 3. In addition to the vertical keyway, these Dywheels also have a continuous circumferential groove which helps to prevent axial movement of the flywheels. The flywheels in most cases are fabricated from ferritic steel plates. As required by RG 1.14, the Dywheel materials are processed by vacuum melt and degassing processes. All flame cut surfaces are removed by machining to a depth of at least 1/2 inch below the Dame-cut surface. No welding is permitted in the finished Dywheel. The normal operating temperature of the flywheels is ambient containment temperature (100*F to 110*F) since they are not in contact with the retctor coolant. Normal operating speeds for the flywheels range between 900 and 1200 rpm with design overspeed being 25% greater than the normal operating speed. SIR 94-080, Rev. 0 2-1 { Structurn!IntegrityAssociates,Inc.
Table 21 provides specific information about the flywheels of the six plants considered in this evaluation, including materials, operating conditions and critical dimensions. The l Oywheels under consideration can be categorized into two types discussed above, with either a small or large bore. Flywheels at ANO 1, Palisades and St. Lucie are "bollow" and therefore have a large bore diameter (measuring approximately 30 inches). Flywheels at ANO 2, Millstone 2, and Waterford 3 are " solid" and therefore have a smaller bore diameter (m:asuring approximately 14 inches). The following provides a brief description of the flywheels at each of the plants. 2.1 i Arkansas Nuclear One Unit 1 (ANO 1) Each of the existing reactor coolant pump motors has two Dywheel assemblies, a large essembly at the upper end of the motor and a small assembly at the lower end. The flywheels are " hollow". Since the top assembly is much larger in diameter than the bottom ) assembly, ultrasonic testing is performed on the top assembly only. This top configuration l is judged to be critical and therefore, the only flywheel evaluated in this report. It has a i bore of 30.4 inches with an outside diameter of 72 inches. The keyway measures 0.75 inches in width, by 0.39 inches in depth. l l The material of the flywheelis ASTM A 516, Grade 65 (rolled plate). The minimum yield strength specified for this material is 35,000 psi. The nil ductility transition (NDT), as determined by the Charpy V Notch tests, is less than +10*F. The minimum fracture toughness of the Dywheel material was calculated in Reference 4 as 109.6 ksivTn The normal operating speed of the pump is 1,200 rpm. The motor is designed for a maximum overspeed of 125%. In the event that a double-ended rupture (a reactor cc,olant piping break in either the suction or discharge side of the pump) of the 28 inch pump discharge piping occurs at the same time as a loss of power to the pump motor, a speed of 1,800 rpm is predicted. It is anticipated that the RCP motor at ANO 1 will be replaced at a future date. The flywheel dimensions and material of the new motor are different from the existing flywheel, cs shown in Table 21. The new replacement Dywheel is " solid" and therefore has a smaller outside diameter and smalier bore than the existing Dywheel. The keyway dimensions of the SIR 94-080, Rev. 0 22 { StructuralIntegrityAssociates,Inc.
new replacement flywheel are, however, larger than the existing one. The new flywheel is fabricated from SA 533, Grade B while the existing Dywheelis fabricated from ASTM A 516, Grade 65. Operating speeds and overspeeds are the same for both flywheels. A comparative analysis performed between the existing and the new replacement flywheel using equations presented in Section 5 indicates that the stresses are lower in the replacement flywheel for the same speed. Also the fracture toughnen of the new Dywheel is judged to be better in the new flywheel than the existing one. In this report, a bounding evaluation will be performed for ANO 1 by considedng only the existing Dywheel. The results of this evaluation can be conservatively applied to the replacement flywheel. 2.2 Arkansas Nuclear One Unit 2 (ANO 2) The flywheel assembly at ANO 2 consists of two discs (6 inches thick each) of the solid disc type. Each disc is shrunk on and keyed to the motor shaft at a location between the upper motor bearing bracket and the rotor punchings. The material used for the flywheels is pressure vessel quality vacuum improved steel plate produced to ASTM A 533, Grade B, Cass 1 specification. The minimum fracture tougnness calculated in Reference 5 is 100 ksivTn. A replacement RCP motor has been ordered for ANO 2. The Oywheel material for the replacement motor is ASTM A 508, Class 5. The frccture toughness of this Dywheel material is 112 ksivTEwhich is bounded by that of the existing ASTM A-533 Grade B, Class 1 material. The normal operating speed is 900 rpm and the overspeed is 1125 rpm. The LOCA overspeed for the motor is 2359 rpm. 2.3 Millstone Unit 2 Each flywheel assembly cr.nsists of two solid discs bolted together, shrunk onto, and keyed to the shaft above the motor. The dimensions of each disc include an outer bore diameter of 75 inches, an inner bore diameter of 13.74 inches and thickness of 12 inches (two,6 inch slabs). The keyway measures 2.5 inches in width, by 1.062 inches in depth. SIR-94-080, Rev. 0 23 { StructuralIntegrityAssociates,Inc.
0 The flywheel is made of ASTM A 516, Grade 65 material, which is pressure vessel quality, vacuum improved steel plate. To improve the fracture toughness properties of the material, the flame cut discs, with a 1/2 inch allowance for machining, were heat treated as follows: heated to 1650*F f. 25'F and held for a minimum of 3.5 hours; water quenched to below 400'F; o tempered at 1140'F for 3 hours. This material exceeds the requirements of ASTM A 516, Grade 70. The nil ductility transition (NDT) is lower than the value of +10'F as specified in Reference 1. A conservative value of fracture toughness was estimated in Reference 6 to be 90 ksivTEat the operating temperature of 100*F. Considering the fact that a much lower NDT value was observed in Reference 6 than required in Reference 1, a higher fracture toughness value can be justified for the material of this Dywheel. During Pefueling Outage 12, the original General Electric motor on Pump B was replaced with a motor also manufactured by General Electric. The Dywheel for the replacement motor has the same dimensions as the original one except that it is one solid flywheel compared to the two discs bolted together for the original flywheel. The metert.: of the replacement flywheel is SA 508, Class 5 which is estimated to have fracture toughness which is at least equal to that of the original SA 516, Grade 70 material. The normal operating speed of the Dywheel is 900 rpm; the design overspeed (125% of operating speed)is 1125 rpm. 2.4 Palisades Each of the four flywheels at Palisades has a 72 inch outer diameter,34 inch inner bore diameter and are 7 inches thick. They are of the " hollow" type fitted over a spoked center section and bolted down to a separate bore lower Dywheel of a smaller diameter. Near the outer periphery is a row of 24 equally-spaced threaded blind holes for the purpos', of adding balancing weights, although these have not been used. Four larger diameter (3 inch) counterbored holes,11 inch from the outer periphery of the flywheel, allow for bolting to SIR 94-080, Rev. 0 24 { StructuralIntegrityAssociates,Inc.
b l the lower flywheel section. The keyway is relatively small, measuring 0.5 inch in width, by 0.25 inch in depth. . The flywheel is made from ASTM.A 108 (1017), low carbon steel with a minimum yield strength of 27,000 psi and tensile strength of 50,000 psi. The pump Oywheels are machined from cross rolled blanks. l The NDT of the Dywheel material is no higher than 40*F with an average Charpy % notch (CVN) energy of 100 ft lb observed at 70'F. Therefore, this material does not meet the NDT requirement of Reference 1 although the CVN requirement is met. The NDT was determined to be 40'F,30'T greater than 10'F speci6ed per the' requirements of RG 1.14. However, the operating temperature of 100'F is 60'F abose NDT. This margin coupled with a CVN energy at 70*F exceeds the required energy of 50 ft lbs, demonstrating cdequate fracture toughness for this material The fracture toughness was determined to be 100 ksVEin Reference 7. The normal operating speed is M0 rpm with design overspeed of 1125 rpm. 2.5 St. Lucie Units 1 and 2 4 i The flywheels at St. Lucie 1 and 2 are of the " hollow" type with the flywheels shrunk fit unto I
- a spoke arrangement. The top flywheel which is the critical one has an outside diameter of .
-7; inches, bore diameter of 32.5 inches and thickness of 7.785 inches. The vertical keyway i
1 has a width of 1 inch and 1/2 inch into the flywheel and 1/2 inch into the spider arm. The Dywheel material for Unit 1 meets the requirement of SA 516 Grade 70, while the ' material for Unit 2 is ASTM A 543 Class 1 Type B. The minimum fracture toughnen (K ic) [ for the Unit 1 flywheel is 90 ksVE at 100*F; Kje for Unit 2 is 100 ksVE at normal
- j. operating temperature [8].
i j The normal operating speed is 900 rpm with design overspeed of 1125 rpm. LOCA accident j speed is speci6ed as 265% of normal speed. However the LOCA overspeed is limited by speed for electrical breaking effects of the motor which is speci6ed as 105% of normal j spead, i SIR-94-080, Rev. 0 25 f StructuralIntegrityAssociates,Inc. t.__.. ,a._. . _ . _ . _ . . . , , . _ ,, _.--_ ,_ ._ _ _ _ __..,_._,.. . .. .,_ .__ _,. _ . _ _ _ . _ _ _ _
I 2.6 Waterford Unit 3 The Dywheel at Waterford 3 is of the solid type and has an outer diameter of 78 inches, an inner bore diameter of 13.75 inches and a thickness of 8.5 inches. The keyway measures 1.0 inch in length, by 0.531 inch in depth. The material used to manufacture the Dywheel is pressure vessel quality, prepared by the vacuum melt and degassing process, ASTM.A.543, Grade B, Class 1 steel plate. The lower bound fracture toughness is 100 ksif, as determined in Reference 9. The normal operating speed is 1200 rpm. The design overspeed is de6ned as 125% of normal operating speed (1500 rpm). A maximum speed of 1585 rpm is predicted during a pump discharge accident event. SIR 94-080, Rev. 0 2-6 { StructuralIntegrityAssociates,Inc.
Flywheel Specific:tions
- c 6
A , so. of Des tgre Desigre more j Plant Pisup Isoter Ipe. of Flyisheels flytecel Overspeegt etster Keyamy Ecyuey Diam. aperating Diasm. Whictnese Width 1 same maruefactesrer seetors per tester meteriet (rge) scyth me. of
- Speed (in.) (in.) (in.) (in.) (in.) seyueye
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(rm) N
* . Asso-1 Allis- 4 2* A5fM-A-516, 1500 1200 30.4 72.0 Chalmers Gr. 65 8.0 0.75 0.39 1 1 AIBO- 1 Jessiont i 1 1 ASTM A-533, 1500 1200 Shnalder 11.61 6T.87 6.496 2.165 0.83&6 ] crede 3, Ct. 1 eruf 3 i 4
11.55 l Asso-2 Generet 4 1'D A$1M-A-533, 1125 900 13.74 81.5 11.75 2.5 Electric Gr. 8. Ct. 1 1.062 1 Asso-2 Generei 1 1 ASTM-A-508 1125 900 13.74 81.5 11.75 2.5 1.062 1 Electric Ct. 5 Millstone-2 Generat 4 1" 8 A$fM-A-516, 1125 900 13.74 Electric T5.0 12.0 2.5 1.062 1 ! Gr. TO , 2 Milistone-2 Generel 1 1 ASTM-A-508 1125 900 13.74 Electric 75.0 12.0 2.5 1.062 1 4 Ct. 5 4 Petisodes Attis- 4 2* A STM- A - 1('9 1125 900 33.0 72.0 T.0 0.5 Chelmers 0.25 1 St. Lucle-1 Allis- 4 2* ASTM-A-516 1125 900 Chelmers 32.5 T2.0 T.785 1.0 0.50 1 Gr. TO , ! St. Lucle-2 Attis- 4 2* AsfM A-543. 1125 900 32.5 72.0 T.785 1.0 0.50 j Ch.i rs Cr. s. Ci. 1 1 i j Waterford-3 General 4 1* A STM- A-563, 1500 1200 13.75 78.0 8.5 Electric 1.0 0.531 1 { Gr. s, Ct. 1 4 I Notes ' 0s I k I) Top flywheel consists of three plates imited together. Bottom flywheel consists of one plate. [ 2) Omsists of two plates holted together. j
- 3) Top flywheel consists of two plates imited together. Bottom flywheel consists of one plate.
o
$=- 4) Top and bottom flywheels consist of one plate each.
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3.0 PREVIOUS INSPECTION RESUL'IS FOR RCP FLYWHEELS Since the issuance of RG 1.14, most utilities have performed inspections of the RCP Dywheels per the requirements of the document. Many plants have performed both the , 3 year interval UT examination and surface examinations as well as complete UT cxaminations during the 10 year interval using procedures recommended in RG 1.14. , UT procedures require the use of a couplant for sound transmission between the search unit - (which transmits and receives ultrasound) and the surface of the Dywheel Straight beam examination (longitudinal) is used to detect laminar type discontinuities which interfere with the angle beam examination. Angle beam examination (shear wave) is used to detect
- l. discontinuities and cracking which are detrimental to the service life or operation of the Dywheel.
I.amellar discontinuities frequently occur in rolled plate and are revealed during ultrasonic inspections. They are usually elongated non metallic inclusions (such as sulfides and silicates) and their distribution is seldom uniform ber.ause it depends on factors such as rolling practice and impurity segregation la the ingot. When their orientation is parallel to the design tensile stresses and their existence is not evidenced by lamellar tearing during fabrication, their existence is ignored during ultrasonic examinations.1.aminar indications are also revealed during ultrasonic inspections. These discontinuities are caused during manufacturing, where air is trapped in the steel and rolled out. Typically they lie within a 10' band parallel to the top and bottom surface of the flywheel and are in a plane parallel to the top and bottom surfaces. These laminations do not pose any structural integrity concerns for the flywheel since they are not oriented in the plane of the stresses. Inspection results considered in this study from plant operation were examined to determine if any flaws have been identified during the RG 1.14 mandated inspections. In addition, a survey of other plants was performed to determine if there are any plants that have identi5ed flaws during the inspections. SIR 94-080, Rev. 0 31
- f StructuralIntegrityAssociates,Inc.
- 3.1 Plant Specific Results The inspection results for the plants under evaluation are presented in Tables 31 through 3 6. As can be seen from these tables, the Dywheels have been inspected on numerous occasions. As explained previously, ANO 1 is not covered specifically by the requirements
^
of RG 1.14, therefore, the flywheel inspection program is conducted every ten years. From ' Tables 31 through 3-6, it can be seen that no cracks have ever been reported during these
- inspections. Only geometric reDectors and laminar indications which typically occur during l fabrication have ber,n identi6ed. As explained earlier, these indications do not present any structural integrity concerns for the flywheels since they are not oriented in the plane of the stresses.
3.2 Industry wide Survey Personnel from over 30 plants were contacted to assess their inspectior history and inspection results associated with the performance of their RCP Dywheels. A letailed set of questions were presented. Highlights of the survey are as follows: All plants conduct ISI of the flywheel component using manual ultrasonic inspection techniques. A wide range of costs are associated with in situ ultrasonic examination of the - flywheels, dependant upon a variety of factors including the presence of qualified on-site personnel and access to the flywheel. Some ph.us have incorporated inspection requirements into their plant specific technical specification document or final safety analysis report (FSAR). Some plants have coordinated the 10 year (complete) inspection to coincide with motor overhaul,
- 4 reducing the amount of maintenance effort.
SIR-94-080, Rev. 0 , 32 h StructuralIntegrityAssociates,Inc.
Most plants have reported that obtaining access for inspection is difficult and, in most cases, very costly. ' In some cases plant personnel are pted to some level of radiation exposure during the inspections. ' L Industry experience related to RCP Dywheel performance has identi6ed no reportable - indications from ISI of Dywheels (other than laminations and other non structurally significant fabrication defects). No service induced cracking or other defects which would increase the probability of Dywheel failure have been identified as a result of this investigation. l
.am SIR 94-080, Rev. 0 33 ,,
{ StructurniIntegrityAssociates,Inc.
Table 31 Inspection Summary for ANO 1 RCP Flywheels Areas of RCP Year Inspection Examination Flaws / Creeks - Flywheel No. Examined Volume or Area Methods Used Identined ABCD 1983 100 % Acoustic None l Examination of Emission - each Dywheel D 1992 100 % UT & MT None i w The ANO 1 f1' wheels for each RCP motor consist of two assemblies, one at the top of the moto. m J or.: at the bottom. Since the top assembly is larger in diameter than the bottom assembly, the plant Technical Specifications (4.2.6) only address the top assembly. The results above refer to the top flywheel assembly only. No cracks have ever been identified on any of the RCP flywheels. SIR 94-080, Rev. 0 3-4 { StructuralIntegrityAssociates,Inc.
Table 3 2 Inspection Summary for ANO.2 RCP Flywheels Refueling Outage ' RCP & Year inspection Volume Examination Methods Used Indications Flywheel No. Examined or Area Detected 2P32A 2R2 1982 Bore & Kesway Volumetric . UT 10' Geometric 2R4 1985 Bore & Keyway Volumetric . UT 10' Geometric 2R5 1986 Bore & Ke3way Volumetric UT 10' None Accessible Surfaces Volumetric UT O' None 2R7 1989 Bore & Keyway Volumetric . UT 10' None Accessible Surfaces Volumetric . UT O' None 2R8 1991 Bore & Ke3way Volumetrie . UT 45' None Accessible Surfaces Volumetric. UT 08,450 & Surface ECT None Post 2R9 1993 Bore & Kesway Volumetrie . UT 45' None Accessible Surfaces Volumetric UT 08,45' & Surface MT 12minations 2P32B 2R2 1982 Bore & Keyway Volumetric . UT 10' Geometric 2R4 1985 Bore & Keyway Volumetric . UT 10' Geometrie 2R5 1986 Bore & Kesway Volumetric . UT 10' None Accessible Surfaces Volumetric . UT O' Lamlution 2R7 1989 Bore & Keway Volumetric . UT ?O' None - Accessible Surfaces Volumetric . UT O' None 2R8 1991 Bore & Keway Volumetric UT 45' None Accessible Surfaces Volumetric . UT 08,450 & Surface ECT None Post 2R10 1994 Bore & Kesway Volumetric . UT 45' None Accessible Surfaces Volumetric . UT O*. 450 & Surface MT laminations 2P32C 2R2 1982 Bore & Keyway Volumptr8 . UT 100 Geometric 2R4 1985 Bore & Keyway V .w . .. ic . UT 100 Geometric 2RS .1986 Bore & Keway Volumetric . UT 10' None Accessible Surfaces Volumetric . UT O' None 2R7 1989 Bore & Keyway Volumetric UT 10'
, None Accessible Su .ces Volumetric . UT O' None 2R8 1991 Bore & Keway Volumetric . UT 45' None Accessible Surfaces Volumetric . UT 08,45' & Surface.ECT None 2R10 1994 Bore & Keyway Volumetric . UT 45' None SIR.94 080, Rev. 0 35 4
h StructuralIntegrity As sociates, Inc.
Table 302 (concluded) Refueling Outage RCP & Yest inspection Volume Enamination Methods Used' ladications Flywheel No. Enemined or Area wg 2P32D 2R2 1982 Bore & Keyway Volumetrk . UT 10* Geometric 2R4 1985 Bore & Keyway Volumetrk . UT 10' Oeometrk 2R$ .1986 Bore & Keyway Volumetrk . UT 10' None Acussible Surfaces Volumetric . UT O' None 2R7 1989 Bore & Keyway Volumetric . UT 10' None Accessible Surfaces Volumetric . UT O' None 2R8 1991 Bore & Keyway Volumetrk . UT 45' None Accessible Surfaces Volumetrk . UT O',45' & Surface ECT None 2R101994 Bore & Keyway Volumetrie . UT 45' None l l SIR.94-080, Rev. 0 36 h StructuralIntegrity Associates, Inc.-
Table 3o3 Inspection Summary for Millstone Unit 2 RCP Flywheels RCP F1pheet Inspection Exasalnation hiethods Indications No. Year Examined Volume or Ares Used Detected RP 40 A 1978 Bore & Keyway Volumetrie . UT 10' L No , 1982 Bore & Keyway Volumetric . UT 10' L Geometric 1985 Bore & Keyway Volumetric . UT 10' L Geometric 1985 Surface 1.imited Scan Eddy Current Surface Scratches 1992 Bore & Keyway Volumetric . UT 10' L No RP.40 B 1978 Bore & Keyway Volumetric . UT 10' L No 1980 Bore & Keyway Volumetric . UT 10' L No 1985 Bore & Keyway Volumetric . UT 100 L Geometric 1985 Surface Limited Scan Eddy Current No 1989 Bore & Keyway Volumetric UT 10' L No 1992 Bore & Kepsy Volumetric . UT 10' L No RP 40-C 1978 Bore & Keyway Volumetric . UT 10' L No 1982 Bore & Keyway Volumetric . UT 10' L Geometric 1985 Bore & Keyway Volumetric . UT 10' L Geometric 1985 Surface Limited Scan Eddy Current No 1989 Bore & Kenav Volumetric . UT 10' L No 1992 Bore & Keway Volumetric . UT 10' L No RP 40 D 1978 Bore & Keyway Volumetric . UT 10' L No 1980 Bore & Keyway Volumetric . UT 10' L No 1985 Bore & Keyway Volumetric . UT 10' L Geometric 1985 Surface Limited Scan Eddy Current No 1989 Bore & Keyway Volumetric . UT 100 L No 199.' Bore & Keyway Volumetric . UT 10' L No SIR 94-080, Rev. 0 37 { StructuralIntegrity Associates, Inc.
Table 3-4 Inspection Summary for Palisades Flywheels RCP Flptwel Irapection Examination
- Methods Indications No. Year Examined Volurne or Aree Used Detected PCS 72 RCL 1A 1970 Upper Surface Volumetric . UT 100% None 1973 Upper Surface Volumetric . UT 100% None 1976 Upper Surface Volumetric . UT 100% None 1978 Upper Surface Volumetric . UT 100% _ Geometric 1979 Upper Surface Volumetric . UT 100% None 1981 Upper Surface Volumetric UT 100% None 1983 Upper Surface Volumetric . UT 100% Lamination 198_6 _ Upper Surface Volumetric UT 100% Geometric 1991 Upper Surface Volumetric . UT 100% Lamination 1992 Upper Surface Volumetric . UT 1004 Lamination 1993 Upper Surface Volumetric . UT 100% lamination PCS 72.RCL 1B 1970 Upper Surface Volumetric . UT 100% Lamination l
1973 Upper Surface Volumetric LTT 100% None 1976 Uppe Surface Volumetric . UT 100% None 1978 Upper Surface Volumetric . UT 100% Geometric 1979 Upper Surface Volumetric UT 100% Geometric 1981 Upper Surface Volumetric . UT 100% None 1983 Upper Surface Volumetric . UT 100% Lamination 1986 Upper Surface Volumetnc UT 100% Geometric j 1991 Upper Surface Volumetric UT 100% Lamination 1992 Upper Surface Volumetric . UT 1p% Lamination 1993 Upper Surface Volumetric . UT 100% 12mination PCS 72-RCL 2A 1970 Upper Surface Volumetric . UT 100% Lamination 1973 Upper Surface Volumetric . UT 100% None 1976 Upper Surface Volumetrie . UT 100% None 1978 Upper surface Volumetric . UT 100% Lamination 1979 Upper Surface Volumetric . UT 100% Lamination 1981 Upper Surface Volumetric . UT 100% None 1983 Upper Surface Volumetric . UT 100% Lamination 1986 Upper Surface Volumetric . UT 100% None 1991 Upper Surface Volumetric . UT 100% Lamination 1992 Upper Surface Volumetric . UT 100% Lamination 1993 Upper Surface Volumetric . UT 100% Lamination SIR 94 080, Rev. 0 3-8 Structural Integrity Associates, Inc.
Table 3 4 (concluded) MCP T1pheel lasportlos Emmeninadon' Methods Indicadens No. Year Esannined Volusse or Area Used Detected PCS 72 RCL 2B 1970 Upper surface Volumetrie . UT 10;>i lamination 1973 Upper Surface Volumetrie . UT 10tr% None 1976 Upper Surface Volumetric . UT 100% None 1978 Upper Surface Volumetrie . UT 100% Lamination 1979 Upper Surface Volumetric . UT 100% None 1981 Upper Surface Volumetric . UT 100% Geometric 1983 Upper Surface Volumetrie . UT 100% 12mination 1986 Upper Surface Volumetric . LTT 100% Geometric 1991 Upper Surface Volumetric . UT 100% 12mination 1992 Upper Surface Volumetric . UT 100% Lamination 1993 Upper Surface Volumetric . U f 100% 12mination l l
' All examinations are straight beam examinations.
I SIR.94-080, Rev. 0 39 Structural Integrity Associates, Inc.
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. RCP Flywheel , inspection Veleme Examiesties Metimds Indicati es No.3 Year Examined er Area 8 Used3 Detected
- 1Al 1993 A UT None IA2 A UT None th! A UT None 1B2 A UT None
-2Al 1994 A UT None 2A2 A UT None
'B1 A UT None 2B2 A UT None Notes:
- 1) RCP Pump Flywheel identification per unit:
SL Lucie Unit 1 St. Lucse Unit 2 lAl 2A1 1A2 2A2 181 2B1 IB2 2B2
- 2) Inspection Method / Area Requirements:
A = 100% Volumetric of Bore and Keyway Areas B = 100% Volumetric of Flywheel C = Par'ial Volumetric of Flywhcci Surface
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E q 3) Examination Methods Used: ! 5 UT = Volumetric (Ultrasonic Examination)
$' PE = Surface (Patrial Ultrasonic Surface Wave)
E M k 8 B iit 5 SIR-94-080, Rev. 0 3-11
Table 3-6 , Inspection Summary for Waterford 3 Flywheels RCP Refueling Outage Inspection Examination Indication Flywheel No. & Date Examined Volume or Area Methods Used Detected RCP 1A RF01 - 04/28/88 Bore & Keyway Volumetric - UT 10* None RF04 - 03/27/91 Bore & Keyway Volumetric - UT 9* None RCPIB RF02 - 05/04/88 Bore & Keyway Volumetric - UT 10' None RF04 - 03/27 91 Bore & Keyway Volumetric - UT 9* None RCP 2A Rf 02 - 05/04/88 Bore & Keyway Volumetric - UT 10* None RF04 - 05/06/91 Bore & Keyway Volumetric - UT 9' None RCP 2B RF02 - 05/04/88 Bore & Keyway Volumetric - UT 10* None RF04 - 05/06/91 Bore & Keyway Volumetric - UT 10* None SIR-94-080, Rev. 0 3-12 f StructuralIntegrityAssociates,Inc.
- 4.0 POTENTIAL FLYWHEEL DEGRADATION MECHANISMS The typical RCP flywheel is exposed to a dry air environment at a nominal operating temperature of approximately mM10*F. Consequently, under normal operating conditions, no water related degradation mechanisms would be expected to be operative. However, a potential seal leak in the RCP housing could produce the potential for a water spray, injecting a mist of primary PWR water in the Dywheel vicinity. As a result of this po,tential ' . event, environmentally-related degradation mechanisms are addressed as potentially active .
for the RCP flywheel.
- A comprehensive review of the material degradation mechanisms potentially affecting low alloy steel components in light water reactor environments is presented in Reference 10.
They are classified under the following general categories: Corrosion Fabrication Defects Embrittlement
. Mechanical / Thermal Fatigue The mechanisms are reviewed for their relevance to RCP flywheels in the following paragraphs.
Corrosion At low temperatures, (below 200*F), the environmentally-related degradation mechanisms are typically not as prominent as at higher temperatures for most materials. However, some corrosion mechanisms are active for low alloy steels, such as pitting and hydrogen embrittlement which are prominent low temperature degradation mechanisms. Examining SIR-94-080, Rev. 0 4-1 . f StructuralIntegrityAssociates,Inc.
- the corrosion mechanisms in Reference 10, one observes that because of the temperature, the active mechanisms which must be considered are the following:
General Corrosion or Wastage
- Crevice Corrosion ,
- Pitting
- Hydrogen Embrittlement Microbiologically Influenced Corrosion (MIC)
- - General Corrosion or Was.tAgt Although the flywheel environment is normally dry air, potential seal leaks in the RCP can produce conditions where primary PWR water may be directed at the flywheel. Under this condition, boric acid corrosion is possible. Particularly since the flywheel is open to air (an oxidizing environment),it is possible that the boric acid could concentrate thereby producing a condition in which accelerated general corrosion or wastage is possible. However, the flywheel operating temperature is so low that no concentrating mechanism is readily apparent. Therefore, it is believed that boric acid wastage is not a likely degradation mechanism for the flywheel.
On the other hand, general corrosion or_ impingement corrosion _is possible if sufficient coolant were to leak from a faulty seal.-- Under these circumstances, it is likely that the leakage would be readily detected prior to significant corrosion occurring as a result of normal plant operation. In addition, the flywheels are typically painted with corrosion resistant paints to mitigate any general corrosion concerns. Crevice Corrosion Depending upon the design of the flywheel assembly,it is possible for ::revices to be present
-which may give rise to the possibility of crevice corrosion. However, since this component SIR-94-080, Rev. 0 -
4-2 { StructuralIntegrityAssociates,Inc.
we is in a low temperature region of the system and there are no obvious concentrating mechanisms for crevice corrosion, it is expected that crevice corrosion will not be a likely degradation mechanism for the RCP Dywheel. Pitting and MIC Pitting and MIC can be combined as potentially operative degradation mechanisms for the' flywheel, but only during extended downtime, particularly when stagnant, low temperature water is present. This is not a normal condition for the flywheet However, it is possible that this may occur and should be addressed in an appropriate maintenance / inspection plan. Clearly, without a specific operating event which exposes the low temperature primary PWR l water to the Dywheel, and since the Dywheel is nominally in dry air during operation and downtime, pitting and/or MIC should not be problems for the RCP flywheel. Hydrogen Embrittlement One mechanism which can produce significant deterioration to a flywheel is hydrogen embrittlement. This mechanism requires that the component be exposed to an aqueous environment, at or near room temperature and the component must have been heat treated (or mis heat treated) so that the materialis in an untempered, very hard condition. For this class of alloys, the fabrication specifications require that suitable post weld heat treatment be performed following any thermal operations so that the likelihood for hydrogen embrittlement is minimized. . Additionally, this phenomenon is likely to occur early in plant life, or even before plant operation if the component is exposed to ambient moist air. Consequently,if prior inspections have not revealed evidence of hydrogen embrittlement damage, and if no further thermal treatments are performed, e.g., weld repair, or severe grinding; hydrogen embrittlement should not be a concern. SIR-94-080, Rev. 0 4-3 - { StructuralIntegrityAssociates,Inc.
}
Fabrication Defects Among the fabrication defects which may affect structural material components, the prine! pal defects potentially affecting the Dywheel are casting and forming defects [10]. The flywheel is most often produced from plate formed material, and as such is a high quality i component,with few fabrication defects. Appropriate volumetric inspections on the finished component assure that fabrication defects are not present which can have a deleterious cffect on the performance of the flywheel. Overspeed testing of the component provides additional confidence in the quality and structural reliability of the flywheel. Consequently, for a flywheel which has undergone proof testing and has been in service, fabrication defects should have a minimal effect on future performance. Embrittlement Embrittlement is an inactive mechanism for low alloy steel components at low temperatures (10). Mechanical / Thermal Processes Among the mechanical or thermal processes affecting low alloy steel performance at low l temperatures, only fretting and mechanical wear are potentially active mechanisms. These mechanisms are potentially active for the flywheel. However, normal operational procedures checking flywheel balance and Dywheel operational monitoring will detect evidence of significant fretting and wear. This mechanism need not be addressed since it will be addressed as part of the normal operational procedures and monitoring, for example, vibrational analysis and motor current monitoring. SIR-94-080, Rev. 0 4-4 h StructuralIntegrityAssociates,Inc.
Fatigue Fatigue is a potentially signi6 cant degradation mechanism for the low alloy steel ACP flywheel in PWRs. In general, the degradation is the result of mechanical fatigue, genently high cycle. This mechanism cnd its potential effect on the operation and inspection of tl.e Dywheel is addressed analytically in later sections of this report. i SIR-94-080, Rev. 0 4-5 . f StructurnilategrityAssociates,Inc.
5.0 STRESS ANALYSIS Stress analyses have been performed for the flywheels under consideratiori to determine stresses to be used in the fracture mechanics analyses in the next section. Potentialloadings for the Dywheels include the following: centrifugal loads due to pump speed
- shrink-fit loads
- seismic loads
! - vibrationalloads
- key loading due to t. haft torque l
l Of these loads, the most significant are centrifugal and shrink-fit loads. The other loads are considered small enough that they will not contribute significantly to flaw growth or fracture during the life of the flywheel. 5.1 Centrifugal Loads Due to Pump Speed Without consideration of geometric discontinuities such as the keyway and bolt holes in the Dywheel, the flywheel can be considered to be an annular rotating disc. The radial and tangential stresses in such a case can be calculated using the following equations from References 11 and 12: g, , 3+y,pd. a 232_aY -r 2 (5-1) 8 8 r; 9 o,=3+p,pd, 8 g a232 a322 _1+3 r2 (5-2) r 2 3+M . sir-94-080, Rev. 0 5-1 h StructuralIntegrityAssociates,Inc.
4 where: a, = ' radial stress'(psi) a, = tangential stress (psi) ' a = bore radius (in)_. .
-b-= outer radius (in)
-p -
mass density (lb-sec2 /md ), for steel = 0.283/386 = 0.00073 lb-sec2 /ind , w= rotational speed rad /sec, (rad 2rr)/60 - p = Poisson's ratio (in/in), for mild steel = 0.3 in/in These equations have generally been used by most utilities to determine the flywheel centrifugal stresses for the RG 1.14 evaluation. The stress distribution from the inner bore to the outer bore, using Equations 51 and 5 2, is shown in Figure 5-1. Although the magnitude of the stresses will vary with angular velocity and specific flywheel dimensions, the overall shape of the stress distribution remains essentially the same at all speeds. For a radial crack emanating from the inner bore, the tangential stress will be the component contributing to crack growth. It can be noted from Figure 51 that the tangential stress is essentially linear over 90% of the flywheel with a sharp peaking effect due to the stress concentration at the bore. This peaking effect will be even more significant if the keyway is considered in the analysis. To account for geometric discontinuities introduced by the keyway, Snite element models were developed for the flywheels considered in this study. The bolt holes were not modeled because the stress concentration introduced by the keyway is more significant than that caused by the bolt. holes. Moreover, the maximum tangential stress, responsible for propagating cracks, occurs near the inner bore where the keyway is located. The bolt holes are remote from this critical region. For the hollow flywheel, the circumferential keyway was also not modeled since it is_ parallel to the tangential stresses and therefore the stress concentration effect is not critical compared to the vertical keyways. l
' SIR 94-080, Rev. 0 5-2 StructuralIntegrity Associates, Inc.
The ANSYS computer program [13) was used to develop thd models. Each flywheel was i modeled using the geometric and material info mation provided in Table 2-1. Two-dimensional isoparametric elements were used to develop a plane strain model for the flywheels. A plane strain model is justified for these analyses since the flywheels are relatively thick. The keyway for each of the Dywheels was explicitly modeled in order to determine the stress concentration effect in this region, with adequate refinement of the finite element models in the keyway region in order to determine the peak stress. A typical finite element model for the large bore flywheels is shown in Figure 5-2 while a typ! cal smaller bore flywheel finite element modelis shown in Figure 5-3. A total number of 2472 elements were used for the large diameter models, while 2944 elements were used for the smaller diameter models. The analyses were performed under normal operating speeds of the motor for each plant. i Results for other speeds can be determined by factoring the results obtained for the normal operating speeds by the square of the speed ratio. The ANSYS computer program allows , l for a rotational centrifugal force to be applied to the model, using the speed as input. To prevent rigid body motion, the nodal points on the outer bore,180' from the keyway location, were restrained. Local stresses at these restrained locations are therefore fictitious and should be ignored. Figures 5-4 through 5-27 present the tangential and radial stress distributions under
- centrifugal loading for all six flywheels considered in the evaluation. Four figures are presented for the flywheel of each plant. The first two figures for each plant depict the overall stress distribution and detailed keyway region stresses in the tangential direction.
The third and fourth figures provide the overall stress distribution and detailed keyway
' stresses in the radial direction.
The stress distributions from the inner to the outer bore in the tangential and radial directions due to the centrifugal force are presented in Figures 5-28 through 5-33 for the six flywheels. In these figures, the stresses are plotted separately for the keyway region and SIR-94-080, Rev. 0 5-3 h StructuralIntegrityAssociates,Inc.
locations remote from the keyway region. As can be seen from these figures, there is a significant difference between the stress distribution in the vicinity of the keyway and remote from the keyway region. There is a very signi5 cant increase in stresses in the keyway region relative to thi remote locations. However, these peak stresses are localized and after a short distance from the keyway, the stress distributions become identical. Figures 5 34 through 5-39 provide a comparison between the results of the finite element' l enalyses stress distributions (remote locations away from keyway) and the distributions , determined using Equations 51 and 5-2. It can be seen that the comparisons are very good for all Dywheels analyzed, thus providing added assurance of the validity of the finite element results. 5.2 Stresses Due to Shrink-Fit The flywheels are shrunk-fit onto the RCP pump rotor assemblies to prevent the flywheel from rotating relative to the shaft Even though it could not be verified that shrink-fit was applied to all the plants considered in this evaluation, the stresses associated with shrink-fit were analyzed for all the flywheels. The physical effect of shrink-fit is to increase the size of the inner bore of the flywheel by a very small amount. This effect was modeled in the ANSYS finite element model developed for the flywheels and described above. A unit displacement of 0.001 inches was applied radially to all nodes on the inner bore to simulate the shrink-fit. The stresses associated with this displacement have been scaled by the actual shrink-fit for the various flywheels. Although actual shrink-fit values were not available for all the flywheels considered in this evaluation, a value of 0.0052 inches was obtained for the flywheel at two of the plants for the small-bore flywheels and was used for these flywheels. Hence, the analysis results for these plants should be scaled by 5.2. A value of 0.0125 inches was reported for one of the larger bore Dywheels. This value, even though it was judged to be conservative but_was used for the evaluation of these flywheels. Results of this analysis for the larger bore flywheels should be scaled by 12.5 to obtain actual shrink-fit stresses. SIR-94-080, Rev. 0 5-4 - f StructurallategrityAssociates,Inc.
l The results of the 1 mil shrink fit analysis are shown in Figures 5-40 through 5-63 for the five flywheels. As before, plots are presented for the tangential and radial stresses for both the overall flywheel stress distributions and for the detailed stress distributions in the keyway region. As can be seen from these figures, especially in the detailcd keyway region, both the tangential and radial stresses are tensile in the keyway region. 5.3 Seismic Loads Because the stresses from the dead weight of the flywheel are very small, the stre:ses resulting from seismic loads on the flywheel are also small. Furthermore, seismic loads on the RCP motor, RCP pump or the attached piping are not transmitted to the flywheel. 5.4 Vibrational Loads Flywheels are continuously monitored to limit the amount of vibration. As such, vibrational loads are relatively small and for the purpose of this evaluation will not be considered. 5.5 Key Loading Due to Shaft Torque Key loading becomes important when the shrink-fit between the flywheel and the shaft is lost. This occurs at relatisely high speeds. However, at normal operating speeds and design overspeeds, there is adequate shrink-fit such that key loading is not a concern. This loading scenario will therefore not be considered in this evaluation. SIR-94-080, Rev. 0 5-5 h StrucibralIntegrityAssociates,Inc.
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i -n C M n N' n M M n rl o rl F l1 ABYS-PC 4.01 s OCI 25 1994 7:24:16 cn POSTI STRESS 5 STEP:1 6 ITER:1
-e t SV (AYC) 8; CSYS:1 i M :9.919646 E'
5-SMN :-1182 SMMB -5588 SMX :27396
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E 8398 8 11564 3--X E 14731 P E 17897
- O 21964 E 24239 E 27396 Flyu'neel Evaluation, AliO-1 (Centrifugal Force - Tangential Stress)
Figure 5-4. Overall Tangential Stress Distribution Due to Centrifugal Force (ANO-1)
em , a m wm em u cn rm c; AEYS-PC 4.01 OCT 25 1994 e 5:56:29 , Ei POSTi STRESS I
. 6 STEP:1 l
- ITER:1 h SV (AUG)
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M :9.810646 S W :-1192
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, E 11564 E 14731 E 17897 O 21964 E 24239 E 27316 Flywheel Evaluation, AH0-1 (Centrifugal force - faasential Stress)
Figure 5-5. Details of Tangential Stress Distribution in Keyway Region Due to Centrifugal Force (ANO-1)
m , i n n rm e n n n u n n wul ri
'l AffSYS-PC 4.4A1 OCT 25 1994 7:21:38 POSTI STRESS M STD:1 ? ITER:1 y SX CSts:1 (AYC) o ?, DMX :9.919646 SNN :-992.375
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y SNMB -7695 e f j SNX :7485 i E SNXB:14399 2U :1 DIST:39.6
-992.375 E -59.493 E 891.389 i' E 1833 E 2775 Z__)( g 3717 9 E 4659 C
E 5691 lE 65437485 Figulfel Evaluation, ANO-1 (Centrifugal Force - Radial Stress) Figure 5-6. Overall Radial Stress Distribution Due to Centrifugal Force (ANO-1) L_
MM M M M W M W 1 rn-_r' L_r0 r'T r'T c'T r~T r1 ANSft-PC 4.01 2 OCT 25 1994 l
? 5:48:52 !
2 POST 1 STRESS g STEP:1 5 ITER:1
'n SX (AUC) .
j
-q CSYS:1 1 M :9.919646 i S M :-992.375 SMB:-7685 SNX :7485 SNXB-14399 2Y :1
*DIST:5.588
*XF :9.066362 M F :14.762
-992.375 u E -58.493 a
E 891.389 1833 E 2775 E 3717 E 4659 5601 E 6543 E 7485 Fipheel Evaluation, ANO-1 (Centrifugal Force - Radial Stress) Figure 5-7. Details of Radial Stress Distribution in Keyway Region Due to Centrifugal Force (ANO-1) L . _ _ _ _
L- Jm rm rm M rm U rm rm r0 cm c' 1 rO TO r0 r' ' I r1 11 ANSYS-PC 4.4A1 50 OCT 25 1998
? 6:12:39 POSTI STRESS i
6 STEP:1 jis ITER-1 SY (AUC) x CSYS:1 g
;., DMX :9.964488 SMN :-415.994 Sl99 -4125 SMX :29957 SMXB:26942 2U :1 DIST:44.825
-415.994 E 1968 o E 4334 v.
2 E E 6799 a 9984
" U E 11458 E 13833 O 16298 E 18582 E 20957 Flpheel Enisnfien, ANO-2 (Centrifugal force - Tan 9ential Stress)
Figure 5-8. Overall Tangential Stress Distribution Due to Centrifugal Force (ANO-2) C .-- .. .
,_ u e em e nn n n o n _o r 1_r 1 r1 o n ANSYS-PC 4.4A1 OCT 25 1994 : to 7:14:51 1 5 POST 1 STRESS STEP:1 l 6 P ITER:1 SY (AUG) -
@ CSYS:1 ,
F DMX :9.994488
-< S W :-415.994 o $196 -4125 SNX :29957 SNXB:26942 2U :1
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*Vf :6.826
-415.994 E 1969 E 4334 P E E 6799
% E Agg4 E 11458 E 13833 O 16298 E 18582 E 29957 Figuheel Evaluation, ANO-2 (Centrifugal Force - Tangential Stress) Figure 5-9. Details of Tangential Stress Distribution in Keyway Region Due to Centrifugal Force (ANO-2)
. e _a_c, , , c <- cm e e e e e cu, m ea o ex e, m 1 AMSTS-PC 4.4A1 m OCT 25 1994 l 5 6:98:53 l 6 POST 1 STRESS i
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-* DMX :9.994488 Ss;:-611.222 SMNB -5784 SMX :8321 SMXB-13891 ZU :1 DIST:44.825
-611.222 E 381.296 i
E 1374 E 2366 5 E 3358
" Z- X E 4351 N 5343 O 6336 E 7328 E 8321 Figulwel Evaluation, AHO-2 (Centrifugal Force - Radial Stress)
Figure 5-10. Overall Radial Stress Distribution Due to Centrifugal Force (ANO-2) E------
ANSYS-PC 4,4A1 OCT 25 1994 6:87:12 POSTI STRESS S STEP:1
? IIER:1 2 SX (AUG) -
M CSYS:1
.o DMX :9.994488
- n SMN :-611.222
.a SMNB -5784 e SNX :8321 SMXB:13891 ZU :1
*DIST:5.657
*XF :9.874G37 W F :9.925
-611.222 E 381.296 E 1374 E 2366 u E 3358 N E 4351 E 5343 0
E 6336 E 7328 8321
, Flywheel Evaluation, AH0-2 (Centrifugal Force - Radial Stress)
Figure 5-11. Details of Radial Stress Distribution in Keyway Region Due to Centrifugal Force (ANO-2)
FT c'T c'-( 1 ANSYS-PC 4.Q 1 c' J Vl OCT 25 1994 22 19:28:48
? POSTI SIRESS 2 SIEP:1 A IfER:1 5 SV (AYC)
;c CSYS:1 Q DMX :9.90353 6 SMN :-352.992 SMMB -3481 SMX :17939 SNXB:23369 ZY :1 DIST:41.25
-352.9?2 E 1679 E 3712 Y E 5744 u E 7777 A
" U 9899 O 11842 13874 E 15997 E 17939 Flywheel Evaluation, Hillstone (Centeifugs1 Force - Tangential Stress)
Figure 5-12. Overall Tangential Stress Distribution Due to Centrifugal Force (Millstone-2) 1
t___rm m r t rm rm u u w 'L__r1 rm c L _r L- r1 AMSYS-PC 4.0 1 OCT 25 1994 m 19:15:00
; E POSTI STRESS 6 STEP:1
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DMX :9.90353 = -* S W :-352.992 5106 -3481
,; SMX :17939 SMXB:23369 MX 2Y :1
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*XF :9.199989 MVF :6.925
= - 1:n S$2 E 3712 Y E 5744
- E 7777 E 9899 8 11842 C 13874 l
E 15987 I E 17939 Flywheel Evaluation, Millstone (Centrifugal Force - Tangential Stress) Figure 5-13. Details of Tangential Stress Distribution in Keyway Region Due to Centrifugal Force (Millstone-
.i :- -
m , . e m 1 - r u w rm rn_f- 1 r l1 ANSYS-PC 4.C 1 l OCT 25 1994 9:48:31 POSTI STRESS
$ STEP:1 % ITER:1 g SX (AUG) -
6 CSYS:1 8 DMX :9.99353 'n S M :-521.961 -g S MB -5386 SMX 27195 SMXB:11964 ZU :1 DIST:41.25
-521.961 E 326.399 E 1174 Y
E 2821 E 2868 Z- X E 3716 m 8 4563 A C 5411 E 6258 E 7195 Flywheel Evaluation, Millstone (Centrifugal Force - Radial Stress) Figure 514. Overall Radial Stress Distribution Due to Centrifugal Force (Millstone-2)
M M m M U rML_r' L r' 1 r' U I r' L-_r' L_f AltSYS-PC 4.01 OCT 25 1994 22 , 19:19:95
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ITER:1 - 8 -
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SX (MG) ha . CSYS:1 DMX:9.98353 Sitt:-521.961
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. -521.961 E 326.399 u, E 1174 t' >
- r M 2921 E 2868 E 3716 7
Flpheel Evaluation, Millstone (Centrifugal Force - Radial Stress) Figure 5-15. Details of Radial Stress Distribution in Keyway Region Due to Centrifugal Force (Millstone-2)
w c- em r t__r t__rm__rm rm_xrm m e a r t_ r 1 r ANSYS-PC 4.01 l1 OCT 25 1994 8:59:34 POSTI STRESS m STEP:1 jii IIER:1 6 SV (AVC) '
? CSYS:1 NIX :9.996364 S W :-787.277 F S MB -3492
-< SitX :15318 o E SMXB-19936 20 :1 DIST:39.6
-787.277 E 1973 E 2854 Y E 4634 E 6415 U E 8196 E 9976
$ 0 11757 - E 13537 E 15318 Figuheel Evaluation, Palisades (Centrifugal Force - Tangential Stress) Figure 5-16. Overall Tangential Stress Distribution Due to Centrifugal Force (Palisades)
~WWWMMMWE3E"WWWWW A sis-PC 4 C1 m CCI 25 1994 g B:56:38 s FOSTI STRESS e STEP:J 8 1T0:1 S7 (aK: - % CSYS:1 ? NtX:9.906364
. .o S!GI:-787.277 Sit 1B -3492 SitX :15318 SilKB:19636 2 11 : 1 WIST:2.445 E GT :9.911834 W F :16.127
-787.277 1873 P 2854 0 4634 E 6415 81 %
9976 O 11757 E 13537 E 15318 Flyd. eel Evaluation, Palisades (Centrittsal Force - Tangentiat stress) Figure 5-17. Details of Tangential Stress Distribution in Keyway Region Due to Centrifugal Force (Palisades)
w > > r- L r t rm m rm u m w n rm n r 11 AMSYS-PC 4.C1 OCT 25 1994 B:47:15 POSTI STRESS ; 5 SIIP:1
? ITER:1 2 SX (AYO - @ CSYS:1 .o DitX :9.996364
- o Slet :-645.235 "E Sl01B -4328 o SMX 23551 E SMXB-7815 ZL1 :1 MST:39.6
-645.235
-178.946
.,, E 287.344 E 753.633 E 1229 3 X 1586 y E 2153
" 2619 E 3385 E 3551 Flywheel Evaluation, Palisades (Centrifugal Force - Radial Stress) Figure 5-18. Overall Radial Stress Distribution Due to Centrifugal Force (Palisades)
- m rm w rm s' AllSYS-PC 4.G 1 w OCT 25 1994 g 9:04:41 6 POSTI SIRES e SID=1 8 1I5:1 SX (AVC) - N CSYS:1 9 NEX:9.006364 o SIM :-645.235 5195 -4328 SitX :3551 SitXB-7911 2U :!
*DISI:4.6M MXF :-9.966263 MVF :17.E3
-645.235
-178.946
? 287.344
% E E 753.633 1229 E 1686 E 2153 2611 3885 E 3551 Flywheel Evaluation, Palisades (Centrifugal Force - Radial Stress)
Figure 5-19. Details of Radial Stress Distribution in Keyway Region Due to Centrifugal Force (Palisades)
L 1 1 1 L._ m- zS.mm.
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-6 % .473 1886
- v. 2872 i E 4656 6441 E 8225 8 19089 C 11734 13578 l E 15362 CE0G Flywheel Evaluation, St. Lucie (Centrifugal Terce) m,.r,- ei n,.e n. nr Ton .;oi c. . n: +.,w. ~ : v . o.- n.-- .-. c - - -- - - - . c__- u,. . . . _ _ ,
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w - u m m ww m m m m eu1 e 1 AlEYS-K 4.01 JAN 19 1995 m ; g 19:27:57 POSIl STRESS ! 6 e STEP:1 l
@ ITER:1
- SX (AUG) W CSYS:1 9 DMX :9.182M o Sitt:-589.318 S198 -5199 SMX :4315
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E SMXB:8627 TJ =1 MSI:39.6
-688.318 E -116.367 E 447.584
> l M 1g12 h M 1575 Z-__X W 2131 G 2793 U 3267 E 3831 E 4395 CE00 Tipheel Evaluation, St. Lucie (Centrifugal Force) Ficure 5-22. Overall Radial Stress Distribution Due to Centrifnaal Form (St. Incie)
1 m m u m m x .- n 'm m , r, m ,r1 m st s1 /1 ANSYS-PC 4.C1 JAN 19 1995 E! 19:48:M i
? POSTI STRESS STEP:1 l
i E 6 ITER:1 - 8 Sx (wc) CSYS:1 x a NtX :9.18294
' SIGf:-688.318 4 519E -5119 I SitX :4395 I SitXB-8655 2U :1 E 41ST:19.M3 dXF :9.917783 MF :13.665
-6 0 .318
, -116.367 m
g, 447.584
- E 1812 1575 2139 2793 C 3267 3831 E 4395 CEOG Flywheel Evaluation, St. Lucie (Centrifugal Force)
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C . rm r em v v w rm m rm rn__r- Ju t c II A EYS-PC 4.01 I OCT 25 1994 5:13:0 POSTI SIFES STEP:1 5 ITER:1
? SY (ac)
E CSYS:1 g NIX :9.99696
.o S!tt:-784.598
- c Sles -2945 0 SIIX 235256 o 510G-43731 ZU :1 MST:42.9
-784.598 E 3228 v^ E 7224 E 11229 E 15234 U E 19238 u
E 23243
@, h27247 31252 E 35256 Fisuheel Evaluation, Waterfont (Centrifunl Force - Tangential Stress)
Figure 5 '24. Overall Tangential Stress Distribution Due to Centrifugal Force (Waterford-3)
w w rm rm v rm rm rm rm u n mv M L__r AMSYS-PC 4.01 OCT 25 1994 5:22:45 m POSTI STRESS g SIEP:1 6 IIER:1 e SY (MG) - Pn CSYS:1 DMX :9.99696 F SIO(:-784.598
- 510E -2945 o SitX 35256 SitXB-43711 2U :1 gg *DiSI:4.378 iWF :9.997976
*VF :6.328 1g -784.599 E 3220 E 7224 E 11229
? E 15234
$ E 19238 E 23243 O 27247 E 31252 E 35256 Flywheel Evaluation, Naterford (Centrifugal Force - Tangential Stress)
Figure 5-25. Details of Tangential Stress Distribution in Keyway Region Due to Centrifugal Force (Waterford-3) L---
- - e em e, cu u 1 AMSYS-PC 4.0 1 OCT 25 1994 5 5:18:37 ? POST 1 STRISS 2 SIIP:1 N ITER:1 .o SX (AVC) x CSYS:1 2 M :9.996%
o SIM :-799.59 S198:-6255 1 SMX :19173 1 SMXB:18452 2 11 : 1 DIST:42.9
-799.5?
E 499.56 E 1799 E E 2918 u 4127 0
~
% X E 5336 U 6545 U
E 7754 8964 E 19173 [FIguheel Evaluation, liaterford (Centrifugal Force - Radial Stress) Figure 5-26. Overall Radial Stress Distribution Due to Centrifugal Force (Waterford-3) _ _ _ _ _ \
~
ggg uuu OCT 25 1994 %. A 5:39:36 5 POST 1 STRBS 2 STEP:1 h ITU:1 6 SX (49C) . p CSYS:1 g DieC :9.996%
- 510(:-799.59 Sl98 -6255 SICC :19173 SitG-18452 2U :1
*DIST:4.79
*XF :9.011977 NVE :6.233
-799.59 E 499.56
- v. E 1799 E 2918 E 4127 E 5336 E 6545 O
E 77548964 E 19173 Figuheel Fvaluation, Waterford (Centrifugal Force - Radial Stass) Figure 5-27. Details of Radial Stress Distribution in Keyway Region Due to Centrifugal Force (Waterford-3) ( --
l in W* e f
.b Jt W
a
< F;, ".;;: Dimensions:
h 25000 Bore Diameter: 30.4* i Outer Diametec 72" Keywey Dimensions: 2 : Length: .75" ! 20000 Depth: .39" Operating Speed:1200 rpm 15000 1
'^
i
" 10000 t 5000-A...... . . l g
;r ..
20 25
= =
30 35 41 i g i i 5 to 15 O
=
E E
*d
-5000 namenn tene. '
2: g l--+-awi.t o-t.3 -e-reti. o-t.3 -+-awi.t can=ri -*-r==.nti.t cen=r> l : ar s
-[ Figure 5-28. Tangential and Radial Stress Distribution from Bore to Outside Diameter (ANO-1)
=
9 .
li! 1 1lI ' 5 4
)
2-
=
0 4 O N A ( r e l m p
)
y t s "8 : s r e w e n3 y m io71 . "5n s3 8 o i 0 0 5 K ( e i a _ n1 r : s n "5. 6"2: 3 3 t D e.e r e 2 0. d s met e i e
- 1 e t d
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. 2 I
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23
? .
j e _ x W y 16000 C Flywheel Dimensions: 14000 Bore Diameter: 13.7415' Outer Diameter: 75" Keyway Dimensions: g Length: 2.5' Depth: 1.062" Operating Speed: 900 rpm 1 c,- 10000 a , Y a e, sooo 4000 S W^ ^ ^ ^ G 2~ m
- 'N . ..
2 zoco . jL
= =
z o to 15 zo 25 so 35 to 0 s 4 n.di. oe.t c. tion w l+Redial (Remote) Tangentlet (Remote) --e--Redf ot (Keywey) -M-Tenearttist (reywey]_ h
$ Figure 5-30. Tangential and Radial Stress Distribution from Bore to Outside Diameter (Millstone-2) 5 9
.M N
h. . n W Flywheel Dimensions: Q l'" Bore Diameter: 32.S" O Outer Diameter: 72" Keyway Di.mnsions: 12000 Length: 0.5" Depth: 0.25" Operating Speed: 900 rpm 10000 e :: % g.8000 h E m0 4000
~
i
. 0 y ::
k..... - .
=
~.
35 to 20 25 30 to
$ 0 5 15 n=es:os.1.ac.(ia)
{ iw i-.-.... _ ,. 1 - ,.i . _ ,.,-.-. . . - ,_ -, - ,.i . - >i
- Figure 5-31. Tangential and Radial Stress Distribution from Bore to Outside Diameter (Pa n
lllll il 1 il lfll \ l 3 4
- l
)
y a y w
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p K (
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- 5. "2 s
^
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)
y r e o uy a e e 3 w t r p B Oe K e p y e K e m O ; ( a t i l d e D 2 R a e d i t s 1 ^ 5 u 2 ) e O o _ t
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)
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]
J g t c t a s R - R e i _ T N ( D E 5 t e s 1 s C l d e r a t R S l i a l d a R d o n t a l i a t n e g n a T 5 2 3-5 e r u g i F i 0 0 0 0 0 0 0 3 0 0 0 6 1 0 4 1 0 2 1 m i 0 0 a 0 0 M 4 - 0 0 2 i e. 3?eth WE 0 ?$ g ::aQ214hh r Ea*. E
O m
'O e' !
40000
*A Flywheel Dimensions:
N " o 35000- Bore Diameter = 13.75" l Outer Deemeter = 78" Keyway Dimensions: Length = 1.0" 3cono Depth 0.831" operating speed:1200 rpm 25000 c-E . m 20 m ' h 3
.b .,
15C00 10000 t 4
- " ^ " ^
5000- 0 - p _
~
N E . - g - 4 E D 30 35 40 ! 9 0 5 to 15 20 25 [ RamelINotence M x : N o l-+-Redlet (Remote) --G--Teneentist (Reuete) tedist (Keyway) -M-Tengentlet (Keyway)l g- i _w g Figure 5-33. Tangential and Radial Stress Distribution from Bore to Outside Diameter (Waterford-3) ,
. j I
1ll1 1I! } l i l 1 4
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)
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=
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g 0.9 i 0.8 o 0 0.7 i _ 0.6
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. : i I w !
I b ' 0.2 j m 0.1 R l h 0 - - 2 C 5 to 15 20 25 30 35 su E - 4q -0.1 l kM RamalDhtace M t o l-+-Redlet (Cetc) -#-f angentist (Calc) --a-Redlet (meSYS3 -M-Tengentist (MtSTs)l l ar w '
-" Figure 5-36. Comparison of Finite Element Results for Centrifugal Force With Theoretical Results (Millstone-2) i s
D L t
53 lc o.9 l l
. 0.8 Oc ,
a O 0.7 R
. 0.6 w
a 3 o.5 8 j 0.4 1,sm o L 4 ' N Y
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$ Figure 5-37. Comparison of Finite Element Results for 7.entrifugal Force With Theoretical Results (Palisades)
Er 9
FIGURE 10 50 x 6 St. Lucie Centrifugal Force
,. 0.9 N i E
C 0.8 0.7 C
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[w nesses oiseena. M l
$ l-+-Rodf at (Celc)-5-Tergentlet (Cele.) -*-Redlet (ANSTS) +Tengentell (ANSTS)l 6 E-a g Figure 5-38. Comparison of Finite Element Results for Centrifugal Force With Theoretical Results (St. Lucie) i
23
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e 1
, 0.9 S
o 0.s t y 0.7 . i kO.6 i
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==
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& Radhi(Notence M f
g I-+-adiat (cate> +T=wentet (cate) -*-awi.i cansys> -*-.r nce.t cansys3 l Figure 5-39. Comparison of Finite Element Results for Centrifugal Force With Theoretical Resuits (Waterford-3) j Er 9 e
~- - m w w w r m ct__r I l1_ AfttfS-PC 4.C1 A!!G 231994 2:13:55 5 POSTI STRESS ? SIEP:1 2 ITER:1 6 SY (NC) $ CSYS:1 Dftf:9. NIM 1
- o
'ei e i Sitt:-61.622 510E -1836
- Sitt -3781 l MX S!IKB-4343 2U :1 DIST:39.6 B1.622 E 23.981 a E 451.659 2
E 927.299 E 183 u 3 X M 1373 l 3 E 3306 E 3781 = 1 l CEOC Figuleel Evaluation, ANO thit 1 (Shrink Fit force) Figure 5-40. Overall Tangential Stress Distribution Due to Shrink-Fit Force (ANO-1)
1 1- rm rm rm m u rm rm rm u t ra c' J 1 ra n r ARTS-PC 4.C1 co ABC 231994 si 2:11:M 6 POSTI S M S$ t STEP:1 IID:1 -@ SY (NC) R CSYS:1 -< DISC :9.051001 o Sitt :-491.622 5108:-1836 S W =3781 E SletB:4341 2U :1 4I5T:9.055 E T :-8.147314 iWF :11.114 491.622 E 23.981 P E 451.659 A E 927.299 E 1483 E 1871 0 2354 O 2830 E 3306 E 3781 CEOG Figsheel Evaluation, AND Enit 1 (Shrink fit Terce) Figure 5-41. Details of Tangential Stress Distribution in Keyway Region Due to Shrink-Fit Force (ANO-1)
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-2485
-1806 1126 E 447.999 E 232.296 CIOC FIguheel Evaluation, AND Enit 1 (Shrink Fit Force)
Figure 5-43. Details of Radial Stress Distribution in Keyway Region Due to Shrink-Fit Force (ANO-1) a 8 _ _ i
- 9 i 1 3 5 39 C. 4 3r 98 49 9 R
)
G 99.4 1 69943 5 99.9 2 5 C11T P 1S M 3683 9.4119 8. 3 5 328486284 4498N529741 647148
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" 3249 E 3976 E C 4712 E 5448 E 6184 CEOG F19 wheel Evaluation, ANO linit 2, Shrink Fit Force ,
Figure 5-45. Details of Tangential Stress Distribution in Keyway Region Due to Shrint ' x (ANO-2)
, r c em- u ." c 1 l AMSYS-PC 4.C1 l AUG 23 1994 3:58:31 i m POSTI STRESS 5 STEP:1 IfER:1 6
SX (tYG) CSfS:1
-8 DMX:9.901833 i f SIM :-12173
-* Sitk-13516 SitX :172.898 S1021922 ZU :1 DIST:44.825 12173 E 19801 E 9429 Y E -8857 E -6686 U E -5314 5i E -3942
~ C -2571
! E -1199 I E 172.898 CEGG Figwieel Eeatuation, ANO Unit 2, Shriek Fit Force I
Figure 5-46. Overall Radial Stress Distribution Due to Shrink-Fit Force (ANO-2)
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' -451.372
; E 293.712 Y
m f7$ E 2529 0 W E 3274 E 4819 C 4764 E 5589 E 6254 CE0G Fign=ct realuatian, Millstone, (Shrink Fit Force) Figure 5-48. Overall Tangential Stress Distribution Due to Shrink-Fit Force (Millstone-2)
AMSYS-PC 4.4A1 M AllC 23 1994
? 5:59:26 A POSTI STRESS g SIEP:1 ITER:1 ,
z SY (MG) j 2 CSYS:1 6 DIOC :8.901933 S E :-451.372 Sl96 -1728 SP0t:6254 S10CB:8872 2U :1
#DIST:6.166 iGF :9.342495 MVF :8.174
-451.372 u E 293.712 f7 E 2529 E 3274 E 4819 5
E 6254
. CEOG Figuheel Evatustion, Hillster.e, (Sheink Tit Fose)
Figure 5-49. Details of Tangential Stress Distribution in Keyway Region Due to Shrink-Fit Force (Millstone-2)
, em n c- e e r- r e-m rm, rm rm m cm rm o uw r; il ANSYS-PC 4.441 '
RI!G 231994 1 m 5:47:26 35 POSTI STRESS 6 STEP:1
$ ITER:1 '
8 SX (WC) i CSYS:1 F DMX :9.001833
-< 5101:-12421 SitG:-13791 SMX :213.45 ,
SMXB:2831 2U :1 DIST:41.25
-12421
-11817 E -9614
? M -8218
. EIE -6896
$ L__X E"' -5482
" -3998
-2594
-1199 I E 213.45 CEOG Figsheel Evaluation, Hillstons, (Sleink Fit force)
Figure 5-50. Overall Radial Stress Distribution Due to Shrink Fit Force (Millstone-2)
- - - -- - - - - - -, -,,,c, ,, ,_,
AMSYS- K 4.Q1 52 AllC 231994 5:56:30 :
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- POSTI STRESS l
$- STEP:1 i
8 ITER:1 (NC) ka SX CSFS:1 l l
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CEOG FIpial Evaluation, Hillst6ne, (Sheink Fit Force) Figure 5-51. Details of Radial Stress Distribution in Keyway Region Due to Shrink-Fit Force (Millstone-2)
-u 1
ANCYS-Pc 4,c1 AllC 231994 cn 6:16:34 5 POSTI STRESS SID:1 y ITER:1 g - SY (Mc) p csrs=1
- o ; DNE :g,get Q S E :-571.937 6 Sles:-1568 SNK :3595 MR SNtB-4286 zu =1 DIST:39.6 g
~
571.937 118.995 g 333.947 E g 786.889 g 1248 P 3.___3 m 1693
$ gg 2146 g 2599 g 3852 m 3595 Lf[M II2WImel Evaluation, Palisaacs, (Shrink Tit Force)
Figure 5-52. Overall Tangential Stress Distribution Due to Shrink-Fit Force (Palisadesy
, w~w rm rm u, ca rw-w a1 m. wn ewt e AMSYS-PC 4.C 1 ;
a AUG 23 1994 i g 6:21:44 POSTI STRESS I c, g SIEP:1 IfER:1
-g SV (HC)
CSfS:1 l F DMX:9.001 ; o Sitt:-571.937 l S1018:-1568 SMX :3585 SMXB:4296 2U :1
;*DIST:3.783 MXF :9.0572
*VF :14.846
-571.937 E -118.995 P E 333.947 M E 786.889 E 1240 E 1693 E 2146 O 2599 E 3852 E 3585 CE0G D.pheel Evaluation, Palisades, (Shrink Fit Force) _
j Figure 5-53. Details of Tangential Stress Distribution in Keyway Region Due to Shrink-Fit Force (Palisades) L. _ ______ _
[ [ [c a sE E 2 -z=9 wass==- annomaEgs?S
- x. g-ag m.e a ,., sanas e g --. ggie i i iit i r-maa hM5kb
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6.0 FRACTURE MECHANICS EiALUATION All of the flywheels considered in this evaluation are ferritic steels fabrica*:d either from low alloy pressure vessel steel or carbon steel plate material. For the fe ritic steels, the traditional concept used for fracture mechanics analyses in the ASME Code is linear clastic fracture mechanics (LEFM)in which the toughness of the materialis assumed to be in the lower-shelf region and hence, the failure mode is brittle fracture. Even though it can be argued that the flywheels under consideration may be in the transition to the upper-shelf region which will justify the use of elastic-plastic fracture mechania (EFFM) analyses, LEFM principles are conservatively used in this section to determine allowave flaw sizes and crack growth for the various flywheels. These will then be used to establish safe operating periods which will serve as the basis for establishing alternate inspection intervals for the flywheels. 6.1 Fracture Mechanics Models and Stress Intensity Factor Determination 6.1.1 Centrifugal Stresses If' local discontinuities such as the keyway and the bolt holes are neglected, the stress intensity factor (Ki ) for a radial crack emanating from the bore of the flywheel can be calculated using the model of Williams and Isherwood [14), which assumes the flywheel to be a rotating disc. In this model, the expression for Ki is given by ta Kg = pteb, 50 0 ( ,h) (6-1) (1 -V") . SIR-94-080, Rev. 0 6-1 h StructuralIntegrityAssociates,Inc.
where:
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ct y gl 15 (6 2) where: a = bore ndius (in.) b = outer radius (in.) i i e = crack depth measured from the center of flywheel (in.) p = mass density (Ib/in3 ) w= rotational speed (rad /s) v = Poisson's ratio As explained in Reference 12, this model can be used for a crack emanating from a keyway except that in this case, the keyway depth is included as part of the total crack depth. It is also explained in Reference 12 that the above equations give an erroneous value of stress intensity for zero crack depth if the keyway depth is added to the crack depth. Moreover, as was seen in Section 4, the stresses at the keyway are considerably higher than the areas which are remote from the keyway. To accurately account for the effect of the keyway, other fracture mechanics models were considered for the evaluation using the stress distributions obtained in Section 5. For the
-larger bore flywheels of ANO-1, Palisades and St. Lucie 1 & 2, a model consisting of a longitudinal crack in a cylirah:r, as shown in Figure 6-1, was chosen. This model, though conservative in that it applies to infinitely long crackr, matches the t/R ratio for the SIR-94-080, Rev. 0 6-2 h StructuralIntegrity Associates, Inc.
i flywheels, as can be seen from Table 2-1. For the smaller bore flywheels of ANO 2, Millstone 2 and Waterford 3, which have considerably larger t/R ratios, a model consisting of a crack emanating from a hole in an infinite plate, shown in Figure 6 2, was chosen. Both l of these models are featured in the pc CRACK [15), computer program library and therefore l were readily available for use in the evaluation. l l It should be noted from Figures 61 and 6 2 that in order to use these. models, the stress distribution in the critical keyway region has to be establisbed. Hence, the tangential stress distributions obtained for the critical keyway region; in Figures 5-28 through 5-33 were curve-fit using pc CRACK to describe the stress distribution. In curve-fitting these stress distributions, a radia distance of 2 inches from the keyway was considered in order to obtain an accurate fit, since the allowable flaw size is expected to be limited to this value for all the flywheels. The resulting stress intensity factor distribution versus crack size from the keyway for the flywheels are shown in Figures 6-3 through 6-8. l 6.1.2 Shrink-fit Stresses The same models used for the determination of stress intensity factors for the centrifugal stresses were used to determine the stress intensity factors for the shrink fit stresses. Once again, the shrink-fit stresses determined in the previous section were curve-fit using the pc-CRACK software over a relatively short distance (about 2 inches) from the bore. Shrink-fit displacements have been determined to be 12.5 mils for the large bore diameter flywheels, (ANO-1, Palisades, St. Lucie 1 & 2) and 5.2 mils for the small-bore diameters (ANO-2, Millstone, Waterford). Therefore, the stresses have been scaled accordingly. The resulting stress intensity factor distribution versus crack size are shown in Figures 6-3 through 6-8 for all the flywheels. SIR-94-080, Rev. 0 6-3 h StructuralIntegrityAssociates,Inc.
6.2 Fracture Toughness The fracture toughness (Kje) values of the materials of the flywheels considered in this evaluation have been detailed extensively in References 4 through 9 and summarized in Table 6-1. These Kic values represent conservative minimum values from References 4 through 9. Some of these velues were obtained at values below the normal operating temperatures of 100 - 110*F for the flywheels, and represent extreme lower bounds of the material qualification test. Therefore, considerably higher toughness values than those shown in Table 6-1 can be justified. For the purpose of this study, a minimum K ei value of 100 ksipin will be conservatively used. 6.3 Allowable Flaw Size Determination Since the flywheels were all fabricated from ferritic plate material, the allowable flaw sizes can be determined using paragraph IWB-3610 of the ASME Code, Section XI [16]. The acceptance criteria can be determined based on flaw size or applied stress intensity. The acceptance criteria based on flaw size is given as: of < 0.1 a, (6-3) af < 0.5 ag where: af = the maximum size to which the detected flaw is calculated to grow in a specified time period, which can be the next scheduled inspection of the component, or until the end of vessel design lifetime, a, = the minimum critical flaw size of the flaw under normal operating conditions. af = the minimum critical flaw size of the flaw for initiation of non-arresting growth under postulated emergency and faulted conditions. SIR-94-080, Rev. 0 6-4 h StructuralIntegrityAssociates,Inc.
E J @'i W.
!M 1851 The acceptance criteria, based on stress intensity factor is provided separately for normal l. 3,{.1 operating and emergency / faulted conditions as follows: i g y;f<.
a) For normal conditions: h.bd x#. hn Kg < K, f / /10 (6-4) where: W K=f the maximum applied stress intensity factor for normal (including upset and . test) conditions for the Daw rize af, t Kj, = the avw:iable fracture toughness based on crack arrest for the corresponding crack tip temperature. ( l b) For emergency and faulted conditions: Ky<K,//2 f (6 5) where: D K= f the maximum applied stress intensity factor for the flaw size af under emergency and faulted conditions. K, f = the available fracture toughness based on fracture initiation for the -- corresponding crack tip temperature. In this evaluatien, the acceptance criteria, based on stress intensity represented by Equations 6-4 and 6-5 above are used. However, the safety margins on stress intensity factor of 3.0 and 1 A are used for normal operating and falted conditions, respectively, for consistency with g' the original Section III design margins for these loading conditions. At normal operating speed, the allowable criteria of Equation 6-4 is used while at accident speed, the criteria of . j Equation 6-5 is used. Accident speeds were not readily available for plants considered in this evaluation. A value of 150% of normal operating speed was selected as an upper bound , ul (25% greater than the design overspeed). This value is generally limited by other jl 1.1 SIR-94-080, Rev. 0 6-5 . { StructuralIntegrityAssociates,Inc. f I y ;-- . q ,y .g . . . [ -'7
._ g ; .; 7.. e . . ; (.3 w %;; , g.m. .g. ...
. . . . . : r . ., . . . . .
.s .c,~ n~ w , . mw
considerations such as the speed for electrical breaking effects of the motor which for one plant is specified as 105% of normal speed. Because the stresses and the stress intensity factors increase by the square of the speed, all the stress intensity factors determined for the normal operating conditions were factored by 2.25 to determine those for the accident condition. In addition, the critical flaw size for the most conservative LOCA overspeed case (2359 rpm at ANO 2) will be calculated and compared to the predicted balance of plant life flaw size to ensure that even for this severe and unlikely scenario, the flywheel integrity is d maintained. To determine the ailowable flaw size, it should be noted that the maximum centrifugal stresses occur at maximum speed when the shrink fit stresses are minimum and Use to zero. The shrink fit stresses are maximum at zero speed when the centrifugal stresses are tero. Therefore, the stress intensity distribution for the centrifugal and the shrink fit stresses are compared separately with the allowable fracture toughness to determine the allowable flaw sizes. The minimum of the two is chosen as the allowable flaw size. The comparisons of the stress intensity factor distribution for normal operating speed with the allowable fracture toughness are shown in Figures 6-3 through 6-8 while the comparison for the accident case is shown in Figures 6-9 through 614. The allowable flaw size corresponds to the intersection of the stress intensity curve with the allowable fracture toughness curve. The minimum of either the centrifugal or the shrink-fit is chosen as the allowable flaw size. The allowable flaw sizes for the various flywheels are summarized in Table 6-2 for both normal and accident speeds. It can be seen from this table that for all the flywheels considered in this evaluation, the minimum allowable flaw size is 1.0 inch. It can be seen from Figures 6 3 through 6-14 that if the actual fracture toughness is considered, there is a very considerable margin before actual fracture will occur. When the most conse..vative LOCA overspeed case (ANO-2) is considered, the critical flaw site is about 0.8 inch, which is consistent with what was obtained in the study presented in Reference 5. 6.4 Crack Grewth Evaluation As discussed in Section 4, there are no other degradation mechanisms which will result in the propagation of existing cracks in the flywheel, other than fatigue. Hence,in this sec. tion, a fatigue crack growth evaluation is performed to determine the gro vth of pre-existing cracks. The flywheels are remote from the reactor coolant water and therefore the SIR 94-080, Rev.1 6-6 h StructuralInk]rity Associates, Inc.
emironment is air. As such, the fatigue growth law for air environment in ASME Code Section XI Appendix A for ferritic steels is used. This law is given as,
= C,(M')"
where: n = 3.07 C, = 1.99 x 10-10 S S = 25.72 (2.88 R).3.07 R = K,g/K m,x 0 5. R < 1 E' = range of applied stress intensity factor In performing fatigue crack growth analysis, the initial flaw size is an important input parameter. As can be seen from Tables 3-1 through 3-6, no flaw indications have been identified to date ia any of the flywheels as a result of the RG 1.14 mandated inspections and, therefore, the initial flaw size was based on the maximum flaw size that could have been missed during these inspections. This, in turn, is dependent on the sensitivity and accuracy of the UT transducers used during the inspections. Discussions with several participants in this program produced varying maximum flaw sizes that could possibly have been missed during these inspections. A conservative value of 0.25 inches was used as initial fla'w size in the evaluations. The design number of startup/ shutdown cycles for the RCP motor is no more than 500 for plant life. However, for this evaluation, a conservative 4000 cycles were considered to determine the crack growth. The results of the analysis are summarized in Table 6-3 and - show that crack growth is very insignificant. The initial flaw size of 0.25 inches grew to, at most,0.27 inches after 4000 cycles. This final crack size is significantly below the allowable flaw sizes calculeted previously in this section. This demonstrates that fatigue crack growth is not a concern in the assessment of the structural integrity of the flywheels. Considering the maximum flaw size that could have been missed during previous inspections, the flywheels can operate for a significant number cf cycles beyond plant life without concern for their structural integrity. SIR-94-080, Rev. 0 6-7 h StructuralIntegrityAssociatss,Inc.
Table 6-1 Fracture Toughness Values Minimum Plant Name Flywheel Material Fracture Reference Toughness (Kie) ksi/in ANO-1 ASTM A-516 Cir. 65 109.6 4 ANO2 ASTM A-533 Gr. B, O. I 100 5 Millstone-2 ASTM-A 516 Gr. 70 90 6 Palisades AS'1%A 108 100 7 St. Lucie 1 ASTM-A-516, Gr. 70 90 8 St. Lucie 2 ASTM A-543 Gr. B, C1. 100 8 Waterford-3 ASTM-A-543 Gr. B, Q. I 100 9 Table 6-2 Allowable Flaw Sizes Allow 3ble Flaw Size (in) Plant Name Normal Operating Speed Accident Speed ANO1 1.24 1.00 ANO-2 > 2.00 > 2.00 Millstone 2 1.64 > 2.00 Palisades > 2.00 > 2.00 St. Lucie 1 > 2.00 > 2.00 St. Lucie 2 > 2.00 > 2.00 Waterford-3 1.24 1.00 SIR-94-080, Rev. 0 6-8 h StructuralIntegrity Associates, Inc.
Table 6-3 Creek Growth Evaluation Results . Plant Name Initial Flaw Size Final Flawl ggge (in.) (in.) ANO1 0.25 0.2605 ANO-2 0.25 0.2557-Millstone-2 0.25 0.2535 Palisades 0.25 0.2515 St. Lucie 1 0.25 0.2519 St. Lucie 2 0.25 0.2519 Waterford 3 0.25 0.2686 Note:
- 1. Based on 4000 startup/ shutdown cycles SIR-94-080, Rev. 0 6-9 h StructuralIntegrityAssociates,Inc.
f i , e Ce+Ci t+Cgt !+c3 3
~
A t Co: inner surface stress (x = 0) REQUIRED INPUTS: t: wall thickness a: crack depth (a.ax 5 0.8t) Figure 6-1. LEFM Crack Model H from pc-CRACK - Longitudinal Crack in Cylinder (t/R = 1.2) SIR-94-080, Rev. 0 6-10 h StructuralIntegrityAssociates,Inc.
\ .
/
1
\
cr =Co+C 1 X+C 2 x2+C 3 X3 i j s -X \ rz a l Co: surface stress (x = 0) REQUIRED INPUTS: R: hole radius a: crack depth (a.u 5 2.0R) Figure 6-2. LEFM Crack Model I from pc-CRACK - Crack Emanating from Hole in an Infinite Plate SIR-94-080, Rev. 0 6-13 StructuralIntegrity Associates, Inc.
l
,V_) l y.
120000 e Y o 00 P N n 100000 : : : : : : : : ::::: : : : : ::::: : : : : : : : : : : : : : : : : : : : : : : : : : : : \ 4 o 80000 W o 4 5 S l ~~ e i cn h to " - - 40000 .
,. -: h,
- : : : : : : ::::: 2 - " ' ' ' ": C^.==50 ____ "====Mr%% : :
========0 0;; E
_______._,n;==_____o, e : : ________;==_, g 20000 tr
- W n.
=
E
~.
ama
~
en 0
% 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 4
Y Crack Stre(in) h us y l-+-Centrifuget --M--Shrirt KIc/3 -Klc l O
=. .a% Figure 6-3. Comparison of Applied Stress Intensity Factor Versus Allowable Stress Er Intensity Factor for Normal Operating Conditions (ANO-1) 9
En s m [ 120000 O Nn 100000 : : : : : : : :::: ::::::::::::::::::::::::::::::::::::: O 80000 E Y 4 2 S M. 60000 I-v
- E tos as 40000
%%%%%%%%%%33EEEEEE6EEEEEEEEEEEEEEEE7%%333EEE322%%-
0 0 0 0 0- ,- .- ... g .;;; . .. .- --- ---
~
G n b
/
E R 0 0.8 1.2 1.4 1.6 1.8 2 0.4 0.6 Q 9 0 0.2 1 Crack Size (In) g m $ l-+-Centri fugal -*-Shritt -M-Kic/3 -e-Kic l n a-Er v> Figure 6-4. Comparison of Applied Stress Intensity Factor Versus Allowable Stress 's F' intensity Factor for Normal Operating Conditions (ANO-2)
in s-e W. 120000 1
- I f
O 1 x , Q 100000 MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM l o 40000 3 Y 4 1 U. 60000-b a
.T$ e A g -
e 40000
- L L L L L L L L _L L & L L L_ _L L L L_ L L L_ L_ L_ L_ L L_ L L_ L L_ L_ L L " " ", 2 : : : : : : : :
20000 : : : : : : : : : : : 0 0 0 - - - - - - - - - - m ,,,,, , E . a
==
an 5 0 Gir 0.2 0.4 0.6 0.8 1.2 1.4 1.6 1.8 2 Q 9 0 1 Crack Stre (In) 3 w
$ l-+-Centrifuget Shrink -e-KIc/3 -M--KIc l n
m-N Figure 6-5. Comparison of Applied Stress Intensity Factor Versus Allowable Stress g E Intensity Factor for Normal Operating Conditions (Millstone-2)
lli, 1 11 l] Ili!Il .ll tI
. 2
- L -: ',
- A _: -
8
- _:- 1
- : _ -: s s
= : = : e r
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e
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- - E ws o de
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l Aias l
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= L - s n k ni t
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n i n t ea r
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i ( e h r I nep z S
- : =. - 1 i
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= k el
=.- c a t r a
- : =. . C r t e
g Smr
- = .. f u de o
- : = :
i r iN l t n pr
- : : : 8 e po 0 C Afr ot o
- f
- : : : c l
na oF s
- : : - iy r t
- 6 ai
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- : _- : 6-
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- ~ .
u g i
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0 0 0 . 0 0 0 0 0 2 1 0 0 0 0 1 0 0 0 4 0 0 2 0 0 ct r .j5 e 1
%,g,EQ~5& Q Yhm$nw~E f vmW 6 b s Wo<.o T~u I1ll
.vs W.
e St. Lucie a 6 Normal Operating Conditions m
-O 120000 W
n 4 O I 100000 a i a a i a a a a a a a a i i a a i i a i i a a i a i a i i 1." iaaaiaaaai"1iaiii ! 80000 G Y T - { 60000 b a e
.I, 40000
-rZ5: Or __
r CC55
-r __
to- 20000 . . ,. .. . . - - -: 0- 0 0 0 0 - g -: .-,, -: ;.,,. n 2 Q E E 4:n 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
- 2.
Q creet sire en) w m m l-+-Centrlfuget -G--Shrinit Fit KIc KIc/10~0.i l o o e m
's Figure 6-7. Comparison of Applied Stress Intensity Factor Versus Allowable Stress 9 Intensity Factor for Normal Operating Conditions (St. Lucie Units 1 and 2)
U1 m W 120000 6 k1 100000 ::::::::::::::::::::::::::::::::::::::::::::::::: ' O 80000 E Y 4 1
- u. 60w0 b
5 i C \
. a b 95 40000 - - -
, , . . . : :^
^
AAAAAAAhi .
$ h....
& & & $. $ $ $ h h h -{ { { b $ $ A A A A -
20000 t.o. B R
=
Q E O 1.6 1.8 2 m:a 0.2 0.4 0.6 0.8 1 1.2 1.4
- 2, 0 Q Crack Stre (In) y m
$ l-+-Centrifuget -G-Shrink -e--Kic/10'0.5 --*-KIc l Q
R - a Comparison of Applied Stress Intensity Factor Versus Allowable Stress Figure 6-8. 39 Intensity Factor for Normal Operating Conditions (Waterford-3) . e
M
- I N
6 V o - p 120000 x a O 100000 : : : : : : : :: : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : =: : I> 80000
, _ =============- = M ====================
1 T sa c 03 j e i 40000-4 g 20000 < ~ E ' E c N
~
5
-- 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 4 Crack Stre (Irt) b l-4-Centri fuget -G-KIc/1.4 +Kic l =E $ Figure 6-9. Comparison for Applied Stress Intensity Factor Versus Allowable. Stress g Intensity Factor for Accident Conditions (ANO-1)
11l:i;illlli l
' 2
=m M 0
= M 0
= M -
= M -
8 s
= M .
1 s
= M .. e r
t
= M : S
= M : l e
= M ' b 6
a
= M .- w 1 o
= M .- l l
= M , - A s
= M ; u s
= M ; r 4 e
= M 1 V )2 -
= r
=
M ' l oO M ." i c t cN
= M ." K F( aA
= M .- = ys
= M 2 t n 1 4 i
s o
= M ,- 1 ni t
/ ei
= c t d M 0 i K
nn
= M 0
)
n I o
=
i ( X sC s M 0 e et r r n
= M 0 1 t
S l t
= k a
g Sed M 0 c u di c a f
= M 0 C
r i r i ec
= M 0 t
n l pA e pr Af o C
= M ^
= ; 8 0 M r r
= M ;
0 l f t oo
= M : nac
=
oF s M 4 i r yt
= M ; ai ps
= 6 n
=
M . 0 me ot M ,
= M ,
CI n
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= M -
6
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e
= M 8 0 r u
g
= M i
= M F
= M
= M 2 0
= M
= M
= M
= M 0
0 0 0 0 0 0 0 0 0 0 0 0 0 2 1 0 0 0 1 0 0 8 " 0 0 4 0 0 2 G 1 , m
)
UmW.eY - %a<~ O p#e t: e~GItE.5&$93wMonn&" 8 4 i! I
i, 4l1 tl!1 ! l! 1i4!i
~
2 M 1 : M : M : : x : :
= : : s.
1
= : :
x : : s s
= : - - e r
t M : _ - S , 6
= : _-
1 l e
% : _- b a
= : : w M : - l o
_ l M : .- A 4 s M : .- u) 1 s2 r - M : . - ee M : _ - Vn o _ M : , . l rt oi s _ M : - I c t c l i
- K f.
M : 2 a g 1 F( f M : -' M ys r t n x : .' 4 i s o ni t
= .- )
n 1
/
c ei d i ( t , t M " - e I K nn r I o sC t M ,- 1 s k s M : c et r n a r t t M : C e g S de u M [ f di c M L i r i ec [ 8 t c l pA - O M A ^ C pr
/f e 0
M ^ ' 0 r r M : *' oo l f t M M n oF ac ' s M : .- 6 i r yt 0 ai M : ps n M : 2 me ot M : 0 CI n M : - 1 M 4
- 1 0
% : 6 e
r 4 u
= : i g e M : F 2
M : 0 M : M : M : \ X 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 6 4 1 1 Cic* g1 N. E 3M 0 (n.W6fo0O Na$ O pu0 -$n.cD% E $=4bwMOnn&*. Sn
' ,I
en
'?
e 120000
? .a lc n 100000 : : : : : : : : : : : : : ::::::::::::::::::::::::::::::::::::
o soooo 9
- : : : : : ,a L : : : ::::::::" ::::::::::::::::::::::::::
1
#. 6o000 E
s P
- _ - : e*-+-"
N soooo
. 2. ~ -
G o E Q W g o ._ ._ ta o 0.2 0.4 o.6 L.4 1 1.2 1.4 1.6 1.8 2 u. 4 creet sir. M w c,3 . n f-4-Centriftts! IIc/1.4 --*-Klc l Er 5 Figure 6-12. Comparison for Applied Stress Intensity Factor Versus Allowable Stress E g Intensity Factor for Accident Conditions (Palisades) s )^ (
- Y . g
~
9 . e f
Fig.are 12 50
?
vs St. Lucie f- Accident condition 9 o Oo 120000 P N c O 100000 : : : : : : : : : : : ::::::::::::::::::::::::::::"::::::::: 80000 a h : : : : :==:======:::==========================' ' 1
, e .0000 U b a
* , , . . : : : 0 0 0 0 0 0 0 g.'
.f, 40000 I
~
20000 ii e / E E ' g 0 y 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 9 Crect Stre pi) h l-e-LIc -e--Centrifuget -G--Kic/2~0.5 l n ar [ Figu . ..13. Comparison for Applied Stress Intensity Factor Versus Allowable Stress 8 Intensity Factor for Accident Conditions (St. Lrtie Units 1 and 2)
. . , s FM m - _
U1 e-o N. c t 120000 8 o N n 4 o 100000 : : : : : : : : : : : :::::::::::::::::::::::::::::::::::::: I l 1 I 80000 E ii ^ 1iaaaa".A1a"."^^^^ ^ "
^0 icd 01Aiaa"1AiaOOOAiiAii s
t 60000 e u i - I 400Q g 20000
~
B It. t:: M
~
E g 0 1.6 1.8 7 y 0 0.2 0.4 0.6 0.8 1 1.2 1.4 N Crack Size Cin) h m 8 l--+-centrIfuget -e-Kic/2*0.5 -*--Kic l n Er E w
's Figure 6-14. Comparison for Applied Stress Intensity Factor Versus Allowable Stress 9 Intensity Factor for Accident Conditions (Waterford-3) y 6 a w ,, , p .
b r . S E. s s _s
7.0
SUMMARY
AND CONCLUSIONS The evaluations documented in this report have demonstrated that for the plants conridered in this study, the inspection of the RCP flywheels as mandated by Regulatory Guide 1.14 and , incorporated in the Plants' Technical Specifications can be eliminated without compromising' safety. This conclusion is supported by several observations made during the evaluations presented in this report and summari:ed below.
- Inspections that have been performed to date at all seven plants have never revealed the presence of any service induced flaws. The inspections have spanned several years and have been performed using both ultrasonic and surface examinations.
I e A survey of several other plants was also performed to determine if any flaws have been reported during flywheeli. :;pections. The survey revealed that to date, no flaws have been reported in any of the plants that were contacted. Various mechanisms that could potentially degrade the flywheel materiah during service were evaluated. It was concluded that other than fatigue crack growth, there are no other mechanisms that can affect the service performance of the flywheel. Fatigue crack growth analyses were performed to show that crack growth assuming a conservative initial flaw at the worst location is very small.
- Flaw tolerance evaluations performed using conservative linear elastic fracture mechanics principles and considering the critical location of the flywheel indicated that the flywheels do not present a safety concern for current plant life and life extension. These evaluations were performed using lower bound fracture toughness values at the most highly stressed locations. A conservative flaw size of 0.25 inch was assu ned to be present, due to UT detection uncertainty. Fatigue crack growth analyses using the ASME Section XI crack growth law showed that this initial flaw propagated to less than 0.3 inch following 4000 startup/ shutdown cycles (about eight SIR-94-080, Rev. 0 7-1 f StructuralIntegrityAssociates,Inc.
times the plant life). This final flaw size is significantly below the ASME Code allowable flaw size for any of the flywheels examined in this study.
- Economic and radiological exposure hardships are encountered during these flywheel inspections. Relaxation or elimination of the flywheel inspection requirements will reduce man rem exposure to plant personnel and the associated cost for the inspections.
i i SIR 94-080, Rev. 0 7-2 h StructuralIntegrityAssociates,Inc.
8.0 REFERENCES
L U.S. Nuclear Regulatory Commission, Regulatory Guide 1.14, " Reactor Coolant Pump Flywheel Integrity," Revision 1, August 1975.
- 2. Standard Review Plan Section 5.4.1.1 - Regarding General Design Criteria 4,
" Environmental Missile Design Bases," Appendix A of 10CFR50.
- 3. NUREG 0933, "A Prioritization of Generic Safety Issues," (Main Report and Supplements 1-12), July 1991.
- 4. Arkansas Nuclear One Unit 1 FSAR, Section IV, Amendment 11.
- 5. Combustion Engineering Interoffice Correspondence frort D. F. Steinz to F. M. A Stern, " Flywheel Overspeed", dated May 11,1973, with attached document CENPD- Ol 26 and Appendices A,B,C, and D.
- 6. Millstone Nuclear Power Station Unit 2 FSAR, Section 4, January 4,1990.
l 7. Letter from D. M. Crutchfield (USNRC) to D.P. Hoffman (Consumers Power l Company) with enclosure, ' Topic III'.10.B, Pump Flywheel Integrity (Palisades)," l Docket No. 50 255, LS05 81-029, dated May 15, 1981.
- 8. St. Lucie Plants, Unit 1 FSAR, Section 5.5 and Unit 2 FSAR, Section 5.4.
I
- 9. Waterford, Unit 3 FSAR, Section 5.4.1.4, Revision 3,
- 10. EPRI Report No. NP 5461, " Component Life Estimation: LWR Degradation Mechanisms." September 1987, Prepared by Structural Integrity Associates, Inc..
- 11. Shigley, J.E., " Mechanical Engineering Design," McGraw Hill Book Company,1963.
- 12.
- Riccardella, P.C., Bamford, W.H., " Reactor Coolant Pump Flywheel Overspeed Evaluation," Journal of Pressure Vessel Technology, November 1974.
- 13. ANSYS Finite Element Program, Version 4.4a.
- 14. Williams J.G., and Isherwood D.P.," Calculation of the Strain Energy Release Rules of Cracked Plates by an Approximate Method," Journal of Strain Analysis, Volume 3, No.1,1968, pp.17-22.
- 15. pc-CRACK Fracture Mechanics Software, Version 2.1, StructuralIntegrity Associates, Inc.
- 16. ASME Boiler & Pressure Vessel Code, Section XI 1989 Edition.
SIR-94-080, Rev.1 8-1}}