ML18022B001
| ML18022B001 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 02/27/1997 |
| From: | Robinson W CAROLINA POWER & LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML18012A538 | List: |
| References | |
| HNP-97-043, HNP-97-43, NUDOCS 9703040391 | |
| Download: ML18022B001 (209) | |
Text
CAMZCORV a 9 y, REGULAT, INFORMA ION DISTRIBUTIO TEM (RIDS)
ACCESSION NBR:9703040391 DOC.C(ATE: 97/02/27 NOTARIZED: YES 'OCKET ¹ FACIL:50-400 Shearon Harris Nuclear Power Plant, Unit 1, Carolina 05000400 AUTH. NAME ROBINSON,W.R.
'UTHOR Carolina AFFILIATION Power & Light Co.
RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
J
SUBJECT:
Application for amend to license NPF-63,amending TS 3/4.4.5, "SGs," & associated Bases, will add sleeve installation as alternative to tube plugging for repairing degraded ST tubes.
DISTRIBUTION CODE: APOID TITLE: Proprietary Review COFIES RECEIVED:LTR Distribution 1 ENCL 3 SIZE:
Pre Operating License & Operating R NOTES:Application for permit renewal filed. 05000400 6
RECIPIENT COPIES RECIPIENT COPIES
~
ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-1 LA 1 1 PD2-1 PD 1 1 LE,N INTERNAL: ACRS 1 1 ILE CENTER 01 1 1 OGC/HDS2 1 0 EXTERNAL: NRC PDR p! I26f p! $
D 0
NOTE TO ALL "RIDS" RECIPIENTS:
PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM OWFN SD-5(EXT. 415-2083) TO ELIMINATE YOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!
lo TOTAL NUMBER OF COPIES REQUIRED: LTTR ~ ENCL
Carolina Power & Light Company William R. Robinson PO Box 165 Vice President New Hill NC 27562 Harris Nuclear Plant SERIAL: HNP-97-043 10 CFR 50.90 FEB 27 1997 United States Nuclear Regulatory Commission ATTENTION: Document Control Desk Washington, DC 20555 SHEARON HARRIS NUCLEAR POWER PLANT DOCKET NO. 50-400/LICENSE NO. NPF-63 REQUEST FOR LICENSE AMENDMENT STEAM GENERATOR TUBE SLEEVING
Dear Sir or Madam:
In accordance with the Code of Federal Regulations, Title 10, Part 50.90, Carolina Power 8'c Light Company (CP&L) requests a revision to the Technical Specifications (TS) for the Harris Nuclear Plant (HNP). The, proposed amendment to Technical Specification (TS) 3/4.4.5, "Steam Generators," and its associated Bases, will add sleeve installation as an alternative to tube plugging for repairing degraded steam generator tubes. provides a description of the proposed changes and the basis for the changes. details, in accordance with 10 CFR 50.91(a), the basis for the Company's determination that the proposed changes do not involve a significant hazards consideration. provides an environmental evaluation which demonstrates that the proposed amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Therefore, pursuant to 10 CFR 51.22(b), no environmental assessment needs to be prepared in connection with the issuance of the amendment. provides page change instructions for incorporating the proposed revisions.
I
) provides the proposed Technical Specification pages. contains Combustion Engineering Report, CEN-630-P (and CEN-630-NP), "Repair of 3/4 Inch O.D. Steam Generator Tubes Using Leak Tight Sleeves," Rev'ision 01, (Proprietary and Non-Proprietary, respectively) and related affidavit. As CEN-630-P contains information proprietary to Combustion Engineering, Inc., it is supported by an affidavit signed by Combustion Engineering, the owner of the information. The affidavit s ts fort t e basis on tt~llllllll)llll
~llJ3$>llll5llllillllllI State Road 1134 New Hill NC Tel 919 362-2502
'/0,( I'W, Fax 919 362-2095 ivJ/o ~~
Document Control Desk HNP-97-043 / Page 2 which the information may be withheld from public disclosure by the Commission and addresses with specificity the considerations listed in paragraph (b) (4) of Section 2.790 of the Commission's regulations. Accordingly, it is respectfully requested that the information which is proprietary to Combustion Engineering, Inc., be withheld from public disclosure in accordance with 10 CFR 2.790. Correspondence regarding the proprietary aspects of the items listed above or the supporting Combustion Engineering, Inc., affidavit should reference CEN-630-P and should be addressed to I. C. Rickard, Director, Operations Licensing, Combustion Engineering, P. O. Box 500, Windsor Connecticut, 06095-0500.
In accordance with 10 CFR 50.91(b), CP &L is providing the State of North Carolina with a copy of the proposed license amendment.
CP&L requests that the proposed amendment be issued such that implementation will occur within 60 days of issuance to allow time for procedure revision and orderly incorporation into copies of the Technical Specifications.
Please refer any questions regarding this submittal to Ms. D. B. Alexander at (919) 362-3190.
Sincerely, W. R. Robinson JHE/jhe
Enclosures:
- 1. Basis for Change Request
- 2. 10 CFR 50.92 Evaluation
- 3. Environmental Considerations
- 4. Page Change Instructions
- 5. Technical Specification Pages
- 6. CEN-630-P and CEN-630-NP W. R. Robinson, having been first duly sworn, did depose and say that the information contained herein is true and correct to the best of his information, knowledge and belief; and the'sources of his information are employees, contractors, and agents of Carolina Power & Light Company.
zo rvE No/%6 $ ~ )
My commission expires: $ . Vgq ~~r gQtAHy +o~~
~0BU<
COQV
+II)rc Sa4<~
Document Control Desk HNP-97-043 / Page 3 Mr. J. B. Brady, NRC Sr. Resident Inspector Mr. Mel Fry, N.C. DEHNR Mr. L. A. Reyes, NRC Regional Administrator Mr. N. B. Le, NRC Project Manager
Document Control Desk HNP-97-043 / Page 4 bc: Ms. P. B. Brannan Mr. R. D. Martin Mr. R. K. Buckles (LIS) Mr. W. S. Orser Mr. H. Chernoff (RNP) Mr. G. A. Rolfson Mr. B. H. Clark Mr. R. S. Stancil Mr. G. W. Davis Mr. R. F. Saunders Mr. J. W. Donahue Mr. D. L. Tibbitts Ms. S. F. Flynn Mr. M. A. Turkal (BNP)
Mr. H. W. Habermeyer, Jr. Mr. T. D. Walt Mr. W. J. Hindman Nuclear Records Ms. W. C. Langston (PE&RAS File) Harris Licensing File File: H-X-0511
I
~ .
i t k
ENCLOSURE TO SERIAL: HNP-97-043 ENCLOSURE 1 SHEARON HARRIS NUCLEAR POWER PLANT NRC DOCKET NO. 50-400/LICENSE NO. NPF-63 REQUEST FOR LICENSE AMENDMENT STEAM GENERATOR TUBE SLEEVING The steam generators (S/G) at the Harris Plant are Westinghouse Model D heat exchangers. The primary function of the steam generators is to transfer heat from the reactor coolant loop to the feedwater to generate steam for the turbine generator. Steam generator tubes are constructed of Inconel-600, a nickel-chromium-iron alloy, and are susceptible to degradation caused by corrosion. Eddy current examinations are performed periodically to measure steam generator tube degradation. The current Technical Specifications establish an allowable degradation limit of 40 percent (%) of the nominal tube wall thickness at which the steam generator tube must be removed from service. Historically, the corrective action taken when steam generator tube wall degradation exceeds the established limit has been to install plugs at the inlet and outlet of the steam generator tube. The proposed license amendment allows the use of tube sleeves to repair degraded steam generator tubes as an alternative to tube plugging. The tube sleeve spans the degraded area of the tube and provides a leak tight replacement pressure boundary to reestablish the structural integrity of the tube. The proposed change would permit the use of two types of leak tight steam generator (S/G) tube sleeves designed by Combustion Engineering, Inc. The two proposed sleeve types are a tube sheet sleeve and a tube support plate sleeve. A tube sheet sleeve is designed to restore the portion of a tube in the vicinity of the top of the S/G tube sheet. This sleeve is welded near the upper end and hard rolled into the tube within the S/G tube sheet. The second sleeve type, a tube support sleeve, spans the section of a S/G tube that passes through a tube support plate. This sleeve is welded to the S/G tube near each end of the sleeve. The use of these sleeves as an acceptable repair technique is described in the attached Combustion Engineering, Inc., Report, CEN-630-P, "Repair of 3/4 Inch O.D. Steam Generator Tubes Using Leak Tight Sleeves," Revision 01, (Enclosure 6),
The proposed amendment to Technical Specification (TS) 3/4.4.5, Steam Generators, will add sleeve installation as an alternative to tube plugging for repairing degraded steam generator tubes.
Technical Specification 3/4.4.5, currently requires that degraded tubes be plugged. This request proposes the use of tube sleeves for the repair of degraded steam generator (S/G) tubes. Sleeving Page El-1
.~
l l'
ENCLOSURE TO SERIAL: HNP-97-043 has been demonstrated to be a safe and effective method of repair for degraded steam generator tubes. Sleeve repairs will reduce the number of steam generator tubes that must be removed from service by plugging. Installed steam generator tube plugs remove the heat transfer surface of the plugged tube from service and reduces primary coolant flow rate available for core cooling. Installation of welded and/or welded and hard rolled steam generator sleeves does not significantly affect the heat transfer removal capability of the repaired tube. A large number of sleeves can be installed without significantly affecting primary core flow rate.
The sleeve dimensions, materials and joints were designed to the applicable ASME Boiler and Pressure Vessel (B&PV) Code. An extensive analysis and test program was undertaken to prove the adequacy of both the welded and welded/hard rolled sleeve. This program determined the effect of normal operating and postulated accident conditions on the sleeve-tube assembly, as well as the adequacy of the assembly to perform its intended function. The proposed sleeving is essentially a substitution in kind for a portion of a steam generator tube. Design criteria were established prior to performing the analysis and test program which, ifmet, would prove that these sleeve types are an acceptable repair technique. These criteria conformed to the stress limits and margins of safety of Section III of the ASME BEcPV Code. The safety factors of 3 for normal operating conditions and 1.5 for accident conditions were applied. Evaluation of the sleeved tubes indicates no detrimental effects on the sleeve-tube assembly resulting from reactor system flow, coolant chemistries, or thermal and pressure conditions. Structural analyses of the sleeve-tube assembly, using the applied margins of safety, have established its integrity under normal and accident conditions. The structural analyses for different sleeve types and lengths are provided in the attached report, CEN-630-P. Mechanical testing using ASME code stress allowables has been performed to support the analyses. Corrosion tests of typical sleeve-tube assemblies have been completed and reveal no evidence of sleeve or tube corrosion considered detrimental under anticipated service conditions. Based on analytical and test program results, the sleeves fulfilltheir intended function as leak tight structural members and meet or exceed the established design criteria.
Sleeving willresult in a slight reduction in heat transfer capability of the steam generator and a small increase in the primary side pressure drop. The number of steam generator tube sleeves is limited by pre-established tube plugging limits which are an integral part of each fuel reload analysis (performed for each refueling). The tube plugging limits ensure that the resulting configuration remains within the envelope of the reload analysis. As discussed in the attached report, CEN-630-P, the hydraulic equivalency of plugs and installed sleeves (sleeve/plug ratio) has been established and will be used when applying the tube plugging limit to the installation of tube sleeves. The FSAR accident analyses for overcooling events assume increased feedwater flow which increases heat removal by the steam generator. Thus, for overcooling events, any reduction in heat transfer due to the installation of sleeves is conservative. For overheating events in the FSAR, the heat transfer area of the steam generator remains constant. The available heat transfer area is defined as the steam generator design heat transfer area minus the tube plugging margin. Therefore, overheating events are bounded by tube plugging margin assumptions. Other analyzed FSAR events which do not involve overheating or overcooling are not affected by the proposed amendment.
Page E1-2
V~
U "I
h
ENCLOSURE TO SERIAL: HNP-97-043 Following the guidelines of Regulatory Guide 1.121 for tube degradation limits, the proposed license change incorporates a maximum allowable degradation of 40 % through wall as the plugging limit for sleeves. This plugging limit incorporates an allowance for eddy current uncertainties and additional degradation gr'owth. Eddy current techniques are available to perform necessary sleeve/tube inspections as needed to detect future defects. Other tests as described in CEN-630-P verify proper installation of the sleeve.
Q~l~ii ~
Sleeving has been demonstrated to be a safe and effective method of repair for degraded steam generator tubes. The use of sleeve repairs will reduce the number of steam generator tubes that must be removed from service by plugging. Based upon the testing and analyses performed, the proposed sleeves do not result in a significant increase in the probability of occurrence or consequence of an accident previously evaluated, create the possibility for a new or different kind of accident, or result in a significant reduction in a margin of safety.
Page El-3
ENCLOSURE TO SERIAL: HNP-97-043 ENCLOSURE2 SHEARON HARRIS NUCLEAR POWER PLANT NRC DOCKET NO. 50-400/LICENSE NO. NPF-63 REQUEST FOR LICENSE AMENDMENT STEAM GENERATOR TUBE SLEEVING The Commission has provided standards in 10 CFR 50.92(c) for determining whether a significant hazards consideration exists. A proposed amendment to an operating license for a facility involves no significant hazards consideration ifoperation of the facility in accordance with the proposed amendment would not: (1) involve a significant increase in the probability or consequences of an accident previously evaluated, (2) create the possibility of a new or different kind of accident from any accident previously evaluated, or (3) involve a significant reduction in a margin of safety. Carolina Power Ec Light Company has reviewed this proposed license amendment request and determined that its adoption would not involve a significant hazards determination. The bases for this determination are as follows:
The proposed amendment to Technical Specification (TS) 3/4.4.5, Steam Generators, will add sleeve installation as an alternative to tube plugging for repairing degraded steam generator tubes.
This change does not involve a significant hazards consideration for the following reasons:
The proposed amendment does not involve a significant increase in the probability or consequences of an accident previously evaluated.
The only equipment affected by sleeving is the steam generator tubes. The most severe malfunction of a steam generator tube is a tube rupture. The consequences of a ruptured sleeve are no greater than the consequences of a ruptured tube. Sleeving does not increase the probability of a steam generator tube failure because the sleeved tube has been shown to have a significant safety factor for burst and collapse pressures as well as demonstrated acceptable resistance to corrosion and fatigue loading. Thus, a steam generator with sleeved tubes would perform in the same manner as one without sleeved tubes.
A sleeved tube is functionally equivalent to an unsleeved tube except for less effective heat transfer due to the air gap and a slightly higher pressure drop due to the primary flow restriction. These differences are bounded by the current tube plugging limits.
Page E2-1
4 ENCLOSURE TO SERIAL: HNP-97-043 Analysis and testing have demonstrated that the sleeves are structurally adequate to withstand the load existing within the steam generator tubes whether the original tube is still intact or is breeched.
There is no increase in the possibility for increased fatigue loadings. There is no possibility for the sleeve to become dislodged from its plugging location and enter the RCS flow path.
The plant safety analysis for tube plugging bounds tube sleeving.
The proposed change has no significant effect on the configuration of the plant. The proposed change does not affect the way in which the plant is operated. Therefore, there would be no increase in the probability or consequences of an accident previously evaluated.
The proposed amendment does not create the possibility of a new or different kind of accident from any accident previously evaluated.
A sleeved tube is functionally equivalent to an unsleeved tube except for less effective heat transfer due to the air gap and a slightly higher pressure drop due to the primary flow restriction. These differences are bounded by the current tube plugging limits.
The sleeved tube has been shown to have a significant safety factor for burst and collapse pressures as well as demonstrated acceptable resistance to corrosion and fatigue loading.
Thus, a steam generator with sleeved tubes would perform in the same manner as one without sleeved tubes.
The proposed change has no significant effect on the configuration of the plant. The proposed change does not affect the way in which the plant is operated. Therefore, the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.
The proposed amendment does not involve a significant reduction in the margin of safety.
The proposed revision to permit the installation of tube sleeves does not reduce the margin of safety as presently defined in Technical Specification BASES section 3/4.4.5.
This margin of safety includes primary to secondary leakage limits and tube plugging limits which are not changed by the proposed amendment. The analyses and testing of the proposed sleeve design demonstrates that the structural integrity of the RCS is maintained. Design of the tube sleeve considers mechanical/structural aspects, water chemistry and metallurgical aspects as well as thermal/hydraulic considerations.
P Therefore, the proposed change does not involve a significant reduction in the margin of safety.
Page E2-2
ENCLOSURE TO SERIAL: HNP-97-043 ENCLOSURE3 SHEARON HARRIS NUCLEAR POWER PLANT NRC DOCKET NO. 50-400/LICENSE NO. NPF-63 REQUEST FOR LICENSE AMENDMENT STEAM GENERATOR TUBE SLEEVING 10 CFR 51.22(c)(9) provides criterion for and identification of licensing and regulatory actions eligible for categorical exclusion from performing an environmental assessment. A proposed amendment to an operating license for a facility requires no environmental assessment if operation of the facility in accordance with the proposed amendment would not: (1) involve a significant hazards consideration; (2) result in a significant change in the types or significant increase in the amounts of any effluents that may be released offsite; (3) result in a significant increase in individual or cumulative occupational radiation exposure. Carolina Power & Light Company has reviewed this request and determined that the proposed amendment meets the eligibilitycriteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment needs to be prepared in connection with the issuance of the amendment. The basis for this determination follows:
The proposed amendment to Technical Specification (TS) 3/4.4.5, Steam Generators, will add sleeve installation as an alternative to tube plugging for repairing degraded steam generator tubes.
The change meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9) for the following reasons:
As demonstrated in Enclosure 2, the proposed amendment does not involve a significant hazards consideration.
The proposed amendment does not result in a significant change in the types or significant increase in the amounts of any effluents that may be released offsite.
Addition of the sleeving repair technique to Technical Specification 3/4.4.5 and the use of sleeves for repairing degraded steam generator tubes will not impact the type or quantities of radioactive materials produced by the facility. In addition, the TS allowable specific activity of the Secondary Coolant System remains unchanged. As such, the change can not affect the types or amounts of any effluents that may be released offsite.
Page E3-1
ENCLOSURE TO SERIAL: HNP-97-043 The proposed amendment does not result in a significant increase in individual or cumulative occupational radiation exposure.
The steam generator repair operation is designed to minimize personnel exposure during installation of sleeves through the use of robotics and remote operation of tools. Dose associated with steam generator inspections are not expected to increase. In addition, the TS allowable specific activity of the Secondary Coolant System remains unchanged.
Therefore, the amendment does not result in a significant increase in either individual or cumulative occupational radiation exposure.
Page E3-2
ENCLOSURE TO SERIAL: HNP-97-043 ENCLOSURE4 SHEARON HARRIS NUCLEAR POWER PLANT NRC DOCKET NO. 50-400/LICENSE NO. NPF-63 REQUEST FOR LICENSE AMENDMENT STEAM GENERATOR TUBE SLEEVING 3/4 4-13 3/4 4-13 3/4 4-14 3/4 4-14 3/4 4-16 3/4 4-16 3/4 4-16a 3/4 4-16a 3/4 4-17 3/4 4-17 3/4 4-19 3/4 4-19 3/4 4-20 3/4 4-20 B 3/4 4-3 B 3/4 4-3
NON-PROPRIETARY CEN-630-NP Revision 01 COMBUSTION ENGINEERING, INC.
November, 1996 R~eair f 3/4" OD team Generator Tubes sin Leak Ti t Sleeves FINALREPORT Combustion Engineering, Inc.
Nuclear Operations Windsor, Connecticut
LEGAL NOTICE THIS REPORT WAS PREPARED AS AN ACCOUNT OF WORK SPONSORED BY ABB COMBUSTION ENGINEERING. NEITHER ABB COMBUSTION ENGINEERING NOR ANY PERSON ACTING ON ITS BEHALF:
A. MAKES ANY WARRANTYOR REPRESENTATION, EXPRESS OR IMPLIED INCLUDINGTHE WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE OR MERCHANTABILITY,WITH RESPECT TO THE ACCURACY, COMPLETENESS,,OR USEFULNESS OF THE INFORMATION CONTAINED IN THIS REPORT, OR THAT THE USE OF ANY INFORMATION, APPARATUS, METHOD, OR PROCESS DISCLOSED IN THIS REPORT MAY NOT INFRINGE PRIVATELYOWNED RIGHTS; OR B. ASSUMES ANY LIABILITIESWITH RESPECT TO THE USE OR FOR DAMAGES RESULTING FROM THE USE OF, ANY INFORMATION, APPARATUS, METHOD OR PROCESS DISCLOSED IN THIS REPORT.
ABSTRACT A technique is presented for repairing degraded steam generator tubes in pressurized water reactor Nuclear Steam Supply Systems (NSSS). The technique described alleviates the need for plugging steam generator tubes which have become corroded or are otherwise considered to have lost structural capability. The technique consists of installing a thermally treated Alloy 690 sleeve which spans the section or sections of the original steam generator tube which requires repair. The sleeve is welded to the tube near each end of the sleeve for repairs at the tube support plates or welded at the upper end and lower end or welded at the upper end and hard rolled at the lower end for repairs to the steam generator tube in the tube sheet region.
This report details analyses and testing performed to verify the adequacy of repair sleeves for installation in a 3/4 inch O.D. nuclear steam generator tube. These verifications show tube sleeving to be an acceptable repair technique.
TABLE OF CONTENTS Section Title ~Pa e
1.0 INTRODUCTION
PURPOSE
1.2 BACKGROUND
1-2 ACRONYMS 1-2 2.0
SUMMARY
AND CONCLUSIONS 2-1 3.0 ACCEPTANCE CRITERIA 3-1 4.0 DESIGN DESCRIPTION OF SLEEVES AND INSTALLATION EQUIPMENT 4-1 4.1 SLEEVE DESIGN DESCRIPTION 4-1
~ SLEEVE MATERIALSELECTION 4-1 4.3 SLEEVE-TUBE ASSEMBLY 4-2 4.4 PLUGGING OF A DEFECTIVE SLEEVED TUBE 4-3 4.5 SLEEVE INSTALLATIONEQUIPMENT 4-3 4.5.1 Remote Controlled Mani ulator 4-4 4.5.2 Tool Deliver E ui ment 44 4.5.3 Tube Brushin - Cleanin E ui ment 4-5 4.5.4 Tube Rollin E ui ment 4-5 4.5.5 Sleeve Ex ansion E ui ment 4-6 4.5.6 Sleeve Weldin E ui ment 4-6 4.5.7 Nondestructive Examination 4-7
TABLE OF CONTENTS (Continued)
Section Title ~Pa e 4.5.8 Post-Weld Heat Treatment E ui ment 4-7 4.5.9 Sleeve Rollin E ui ment 4-7 4.6 ALARACONSIDERATIONS 4-8
4.7 REFERENCES
TO SECTION 4.0 4-9 5.0 SLEEVE EXAMINATIONPROGRAM 5-1 5.1 ULTRASONIC INSPECTION 5-2 5.1.1 Summar and Conclusions 5-2 5.1.2 Ultrasonic Evaluation 5-3 5.1.3 TUTEE 5-3 5.2 EDDY CURRENT INSPECTION 54 5.2.1 ~Back round 5-4 5.2.2 Plus Point Probe uglification Stud 5-5 5.3 VISUAL INSPECTION 5-6 5.3.1 Summar and Conclusions 5-6 5.3.2 Cleanin Ins ection 5-7 5.3.3 Weld Examination 5-7 54 REFERENCES 5-7 3.3. 2.
TABLE OF CONTENTS (Continued)
Section Title ~Pa e 6.0 SLEEVE-TUBE CORROSION TEST PROGRAM 6-1 6.1
SUMMARY
AND CONCLUSIONS 6-1 6.2 TEST DESCRIPTION AND RESULTS 6-1 6.2.1 ~Pi Sd 6-1 6.2.1.1 Pure Water Stress Corrosion Cracking Tests 6-3 6.2.1.2 Above the Tubesheet (ATS) Weld Capsule Tests 6-3 6.2.1.3 TSP Sleeve Weld Capsule Tests 6-4 6.2.1.4 Summary-Primary Coolant Corrosion Performance 6-5 6.2.2 6-6 6.2.2.1 Modified Huey Tests 6-6 6.2.2.2 Capsule Tests 6-7 6.2.2.3 Sodium Hydroxide Fault Autoclave Tests 6-8 6.2.2.4 Summary 6-9
6.3 REFERENCES
FOR SECTION 6.0 6-10
TABLE OF CONTENTS (Continued)
Section Title ~Pa e 7BO MECHANICALTESTS OF SLEEVED STEAM GENERATOR 7-1 TUBES 7.1
SUMMARY
AND CONCLUSIONS 7-1 7.2 CONDITIONS TESTED 7-1 7.3 WELDED SLEEVE TEST PARAMETERS AND RESULTS 7-1 7.3.1 Axial Pull Tests 7-1 7.3.2 Colla se Testin 7-2 7.3.3 B~T 7-3 7.3B4 Load C clin Tests 7-3
l'-8 STRUCTURAL ANALYSIS OF SLEEVE-TUBE ASSEMBLY 8-1 8.1
SUMMARY
AND CONCLUSIONS 8-1 8.1.1 ~DN* 8-1 8.1.2 Detailed Anal sis Summar 8-1 8.2 LOADINGS CONSIDERED 8-7 8.2.1 U er Tube Weld Pull-Out Load 8-7 8.2.2 Lower Sleeve Rolled Section Push-Out Load 8.2.3 W~ld 8-8
TABLE OF CONTENTS (continued)
SECTION TITLE PA E EVALUATIONFOR ALLOWABLESLEEVE WALL 8-8 DEGRADATION USING REGULATORY GUIDE 1.121 8.3.1 Normal 0 eration Safet Mar ins 8-8 8.3.2 Postulated Pi e Ru ture Accidents 8-10 8.3.3 Avera e Minimum Weld Hei ht Re uirements 8-11 8.4 EFFECTS OF TUBE LOCK-UP ON SLEEVE LOADING 8-13 8.4.1 Sleeved Tube in "Worst" Case ABB/CE Plant Free at E Crate 8-13 8.4.2 Sleeved Tube in "Worst" Case Westin house Plant Free at Su ort Plate 8-14 8.4.3 Sleeved Tube in "Worst" Case ABB/CE Plant 8-15 Lock-u at First E Crate 8.4.4 Sleeved Tube in "Worst" ase Westin house Plant 8-15 Lock-u at First Su ort 8.4.5 Effect of Tube Prestress Prior to Sleevin 8-22 8.4.6 Lower Sleeve Rolled or Weld Section Pushout 8-22 Due to Restrained Thermal Ex ansion 8.5 SLEEVED TUBE VIBRATION CONSIDERATIONS 8-23 8.5.1 Effects of Increased Stiffness 8-23 8.5.2 Effect of Severed Tube 8-23 8.5.3 Seismic Evaluation 8-25 8.6 STRUCTURAL ANALYSIS FOR NORMAL OPERATION 8-27 8.6.1 Fati ue Evaluation of U er Sleeve/Tube Weld 8-27 8.6.2 Fati ue Evaluation of Lower Sleeve Rolled Section 8-31
TABLE OF CONTENTS (Continued)
SE TION TITLE PAGE
8.7 REFERENCES
FOR SECTION 8.0 8-34 8A FATIGUE EVALUATIONOF UPPER TUBE/SLEEVE WELD 8A-1 8B SLEEVE HISTORY DATA 8B-1 9.0 SLEEVE INSTALLATIONVERIFICATION 9-1 9.1
SUMMARY
AND CONCLUSIONS 9-1 9.2 SLEEVE-TUBE INSTALLATIONSEQUENCE 9-1 Ex ansion/Roll Transition Zone Sleeve With Rolled Lower Join 9-1 9.2.2 Tube Su ort Sleeve 9-2 9.3 WELD INTEGRITY 9-2 9.3.1 Cleanin uglification 9-2 9.3.2 Ex ansion uglification 9-3 9.3.3 Weld uglification 9-3 9.3.4 Ultrasonic Testin ual ification 94 9.3.5 Post Weld Heat Treat uglification 94 9.3.6 ~Sammar 9-6
TABLE OF CONTENTS (Continued)
SECTION TITLE PAGE 9.4 ROLLED JOINT INTEGRITY 9-7 9.5 COMMERCIALSLEEVE INSTALLATION
9.6 REFERENCES
FOR SECTION 9.0 9-7 EFFECT OF SLEEVING ON OPERATION
LIST F TABLES TABLE N TABLE PAGE ACRONYMS USED IN REPORT 1-3 2-1 INSTALLATIONSOF ABB-CENO WELDED SLEEVE 2-3 3-1 REPAIR SLEEVING CRITERIA 3-2 5-1 ACRONYMS USED IN ET ANALYSIS 5-8 6-1 STEAM GENERATOR TUBE SLEEVE CORROSION TESTS 6-2 6-2 SLEEVE/TUBE CAPSULE SCC TESTS 6-4 6-3 SECONDARY SIDE STEAM GENERATOR TUBE SLEEVE 6-8 CAPSULE TESTS SLEEVE-TUBE ASSEMBLY MECHANICALTESTING 7-5 RESULTS 8-1
SUMMARY
OF SLEEVE AND WELD ANALYSIS RESULTS 8-4 8-2
SUMMARY
OF LOWER JOINT (WELDED AND ROLLED)
DESIGN, ANALYSIS,ANDTEST RESULTS 8-6 8-3A 26 INCH SLEEVE AXIALMEMBER PHYSICAL PROPERTIES FOR "WORST" CASE ABB/CE PLANT 8-16 8-3B 26 INCH SLEEVE AXIALMEMBER PHYSICAL PROPERTIES FOR "WORST" CASE WESTINGHOUSE PLANT 8-17 8-4A AXIALLOADS IN SLEEVE WITH TUBE NOT LOCKED INTO EGG CRATE FOR "WORST" CASE ABB/CE PLANT 8-18 8-4B AXIALLOADS IN SLEEVE WITH TUBE NOT LOCKED INTO TUBE SUPPORT FOR "WORST" CASE WESTINGHOUSE 8-19 PLANT
LIST F TABLES TABLE NO. TABLE PA E 8-5A AXIALLOADS IN SLEEVE WITH TUBE LOCKED INTO EGG CRATE FOR "WORST" CASE ABB/CE PLANT 8-20 8-5B AXIALLOADS IN SLEEVE WITH TUBE ~LCKED INTO TUBE SUPPORT FOR "WORST" CASE ENVELOPMENT 8-21 8-6 UPPER SLEEVE WELD-TRANSIENTS CONSIDERED 8-29 FOR AN ABB/CE PLANT 8-7 UPPER SLEEVE WELD-TRANSIENTS CONSIDERED 8-30 FOR A WESTINGHOUSE PLANT 8-8 LOWER SLEEVE SECTION-TRANSIENTS CONSIDERED 8-32 FOR AN ABB/CE PLANT 8-9 LOWER SLEEVE SECTION-TRANSIENTS CONSIDERED 8-33 FOR A WESTINGHOUSE PLANT 8A-1A STRESS RESULTS, 100% STEADY STATE 8A-4 8A-1B STRESS RESULTS, 15% STEADY STATE 8A-5 8A-1C STRESS RESULTS, 0% STEADY STATE 8A-6 8A-1C STRESS RESULTS FEEDWATER CYCLING 8A-7 8A-2A RANGE OF STRESS AT WORST LOCATION 8A-8 8A-2B FATIGUE EVALUATIONAT WORST LOCATION 8A-9 8A-3A STRESS RESULTS, 100% STEADY STATE (0.020" Weld) 8A-11 8A-3B STRESS RESULTS, 15% STEADY STATE (0.020" Weld) 8A-12 8A-3C STRESS RESULTS, 0% STEADY STATE (0.020" Weld) 8A-13 8A-3D STRESS RESULTS FEEDWATER CYCLING (0.020" Weld) 8A-14 8A-4A RANGE OF STRESS AT WORST LOCATIONS (0.020" Weld) 8A-15
LIST OF TABLES TABLE NO. TABLE PAGE 8A-4B FATIGUE EVALUATIONAT WORST LOCATIONS (0.020" Weld) 8A-16 9-1 0.875 O.D. SLEEVED TUBE PWHT DATA 9-9 9-2 0.750" O.D. SLEEVED TUBE PWHT DATA, TUBES LOCKED AT ALLSUPPORTS 9-10 9-3 ABB CENO S/G SLEEVE OPERATING HISTORY 9-11 10-1 HYDRAULICEQUIVALENCE RATIOS 10-2
LIST OF FI URES FIGURE NO. TITLE PAGE 4-1 EXPANSION/ROLL TRANSITION ZONE SLEEVE 4-10 4-2 TUBE SUPPORT SLEEVE 4-11 4-3 EXPANSION/ROLL TRANSITION ZONE 4-12 SLEEVE INSTALLATION 4-4 TUBE SUPPORT SLEEVE INSTALLATION 4-13 4-5 MANIPULATORAND TOOL DELIVERY SYSTEM 4-14 4-6 TOOL DELIVERY EQUIPMENT 4-15 47 TUBE CLEANING EQUIPMENT 4-16 4-8 SLEEVE EXPANSION EQUIPMENT 4-17 4-9 SLEEVE WELDING HEAD ASSEMBLY 4-18 4-10 SLEEVE WELDING HEAD POWER SUPPLY UNIT 4-19 4-11 ULTRASONIC TEST EQUIPMENT 4-20 4 12 VISUALTEST EQUIPMENT 4-21 4-13 POST WELD HEAT TREAT EQUIPMENT 4-22 4-14 SLEEVE ROLLING EQUIPMENT - STRAIGHT 4-23 4-15 SLEEVE ROLLING EQUIPMENT - CURVED 4-24
i 0
LIST OF FIGURES (Continued)
FI URE NO. TITLE PAGE 5-1 NDE PROCESS FLOW CHART 5-9 5-2 ET PROCESS FLOW CHART 5-10 5-3 UT B SCAN - ACCEPTABLE 5-11 5-4 UT B SCAN - REJECTABLE 5-12 5-5 UT PROBE 5-13 5-6 UT CALIBRATIONSTANDARD 5-14 6-1 PURE WATER CORROSION TEST SPECIMEN 6-11 6-2 ATS WELD CAPSULE TEST SPECIMEN 6-12
~s TSP WELD CAPSULE TEST SPECIMEN 6-13 6-4 CAUSTIC CORROSION AUTOCLAVETEST SPECIMEN 6-14 8-1 WELDED SLEEVE/TUBE ASSEMBLY 8-35 8-2 SYSTEM SCHEMATIC FOR "WORST" CASE ABB/CE PLANT 8-36 8-3 SYSTEM SCHEMATIC FOR "WORST" CASE WESTINGHOUSE 8-37 PLANT 8-4 STIFFNESS MODEL OF SLEEVE AND LOWER TUBE 8-38 8-5 STIFFNESS MODEL OF UPPER TUBE AND SURROUNDING TUBE 8-39 8-6 FINITE ELEMENT MODEL OF UPPER TUBE WELD 8-40
LIST DF FIIIURSS (C I" d)
FIG RE NO. TITLE PA E 8A-1 NODE AND STRESS CUT IDENTIFICATION 8A-3 8A-2 NODE AND STRESS CUT IDENTIFICATIONFOR 20 MILWELD 8A-10 9-1 POST HEAT TREAT-BRUSHED SECTION 9-12 9-2 0.875 O.D. LOCKED TUBE TEST 9-13 9-3 0.875 O.D. LOCKED TUBE TEST, TEMPERATURE AND AXIALLOAD PROFILE 9-14 94 , 0.750 O.D. LOCKED TUBE MOCKUP 9-5 0.750 O. D. TYPICAL TEMPERATURE PROFILES 9-16
LIST F APPENDICES APPENDIX NO. NO. OF PAGES PROCESS AND WELD OPERAT R ALIFICATION A-1 A.1 SLEEVE WELDING AND SLEEVE WELDER A-1 QUALIFICATION A.2 REFERENCES TO APPENDIX A A-1 XV
- l. INTRODUCTION 1.1 PURPOSE The purpose of this report is to provide information sufficient to support a technical specification change allowing installation of repair sleeves in 3/4" O.D. tube steam generators including; ABB CENO designed steam generators and Westinghouse designed Series D and E steam generators. This report demonstrates that reactor operation with sleeves installed in the steam generator tubes will not increase the probability or consequence of a postulated accident condition previously evaluated. Also it will not create the possibility of a new or different kind of accident and will not reduce the existing margin of safety.
ABB Combustion Engineering (ABB-CE) provides two types of leak tight sleeves for repair of 3/4 inch O.D. steam generator tubes with full depth rolled or expanded tubesheet joints. The first type of sleeve spans the parent steam generator tube at the top of the tubesheet. This sleeve is welded near the upper end and hard rolled into the tube within the steam generator tubesheet. The steam generator tube with the installed sleeve meets the structural requirements of tubes which are not degraded.
The second type of sleeve spans degraded areas of the steam generator tube at a tube support or in a free span section of tube. This leak tight sleeve is welded to the steam generator tube near each end of the sleeve. The steam generator tube with the installed welded sleeve meets the structural requirements of tubes which are not degraded.
Design criteria for all types of sleeves were prepared to ensure that all design and licensing requirements are considered. Extensive analyses and testing have been performed on the sleeve and sleeve to tube joints to demonstrate that the design criteria are met.
The effect of sleeve installation on steam generator heat removal capability and system flow rate are discussed in this report. Heat removal capability and system flow rate was considered for installation of one to three sleeves in a steam generator tube.
Plugs will be installed if sleeve installation is not successful or if there is unacceptable degradation of a sleeve or sleeved steam generator tube. Standard steam generator tube plugs may be used to take a sleeved tube out of service.
1-1
1.2 BACKGROUND
The operation of Pressurized Water Reactor (PWR) steam generators has in some instances, resulted in localized corrosive attack on the inside (primary side) or outside (secondary side) of the steam generator tubing. This corrosive attack results in a reduction in steam generator tube wall thickness. Steam generator tubing has been designed with considerable margin between the actual wall thickness and the wall thickness required to meet structural requirements. Thus it has not been necessary to take corrective action unless structural limits were being approached.
Historically, the corrective action taken when steam generator tube wall degradation has been severe has been to install plugs at the inlet and outlet of the steam generator tube when the reduction in wall thickness reached a calculated value referred to as a plugging criteria. Eddy current (ET) examination has been used to measure steam generator tubing degradation and the tube plugging criteria accounts for ET measurement uncertainty.
Installation of steam generator tube plugs removes the heat transfer surface of the plugged tube from service and leads to a reduction in the primary coolant flow rate available for core cooling. Installation of welded and/or welded and hard rolled steam generator sleeves does not significantly affect the heat transfer removal capability of the tube being sleeved and a large number of sleeves can be installed without significantly affecting primary flow rate 1.3 ACRONYMS Table 1-1 (along with Table 5-1) contains a list of the acronyms used throughout this report.
1-2
TABLE 1-1 ACRONYM USED IN REPORT
+ POINT: + Point ~
ATS: Above the Tubesheet EFPH: Effective Full Power Hours EPPY: Effective Full Power Years ET: Eddy Current Testing ETZ: Expansion/Roll Transition Zone LOF: Lack of Fusion PWHT: Post Weld Heat Treatment TS: Tube Support UT: Ultrasonic Testing VT: Visual Testing 1-3
SUMMARY
AND CONCLUSIONS The sleeve dimensions, materials and joints were designed to the applicable ASME Boiler and Pressure Vessel Code. An extensive analysis and test program was undertaken to prove the adequacy of both the welded and welded-hard rolled sleeve.
This program determined the effect of normal operating and postulated accident conditions on the sleeve-tube assembly, as well as the adequacy of the assembly to perform its intended function. The proposed sleeving provides for a substitution in kind for a portion of a steam generator tube. The proposed change has no significant effect on the configuration of the plant, and the change does not affect the way in which the plant is operated. Design criteria were established prior to performing the analysis and test program which, if met, would prove that these sleeve types are an acceptable repair technique. These criteria conformed to the stress limits and margins of safety of Section III of the ASME BkPV Code. The safety factors of 3 for normal operating conditions and 1.5 for accident conditions were applied. Based upon the results of the analytical and test programs described in this report these sleeve types fulfilltheir intended function as leak tight structural members and meet or exceed all the established design criteria.
Evaluation of the sleeved tubes indicates no detrimental effects on the sleeve-tube assembly resulting from reactor system flow, coolant chemistries, or thermal and pressure conditions. Structural analyses of the sleeve-tube assembly, using the demonstrated margins of safety, have established its integrity under normal and accident conditions. The structural analyses have been performed for sleeves which span the tube to a maximum length of [ j inches, sleeves which span a tube support or free span length of tube with a length of t ] inches and a combination of the sleeve types. The structural analyses performed are applicable to shorter tubesheet and tube support sleeves. The analyses for the different sleeve types and lengths are given in Section 8.
Mechanical testing using ASME code stress allowables has been performed to support the analyses. Corrosion tests of typical sleeve-tube assemblies have been completed and reveal no evidence of sleeve or tube corrosion considered detrimental under anticipated service conditions.
Based upon the testing and analyses performed, the proposed sleeves do not result in a significant increase in the probability of occurrence or consequence of an accident previously evaluated, create the possibility for a new or different kind of accident, or result in a significant reduction in a margin of safety.
Welding development has been performed on clean tubing, dirty tubing which has been taken from pot boiler tests and contaminated tubing taken from a number of steam generators. ABB-CE installed their first welded sleeves in a demonstration program at 2-1
Ringhals Unit 2 in May 1984. ABB-CE's sleeving history is shown in Table 2-1.
The success rate for all installed sleeves is 98%. Since 1985, no sleeve which has been accepted based on NDE has been removed from service due to service induced degradation.
Ifa steam generator tube which has been sleeved is found to require plugging to remove it from service, a standard steam generator tube plug can be installed.
No discussion or evaluation of the standard tube plug is provided as part of this document.
In conclusion, steam generator tube repair by installation of any of the two types of sleeves described herein is established as an acceptable method.
2-2
TABLE 2-1 INSTALLATIONSOF ABB-CENO WELDED SLEEVE INSTALLED PLANT DATE UANTITY TYPE*
KRSKO 6/96 273 TS 188 ETZ Byron 1 4/96 3527 ETZ Prairie Island 1 2/96 253 . WTS ANO 2 10/95 711 ETZ Zion 1 10/95 911 WTS Zion 2 1/95 162 WTS KRSKO 6/93 160 ETZ 14 TS Ginna 4/93 51 Zion 2 12/92 172 WTS Prairie Island 1 11/92 158 WTS Ginna 4/92 175 63 Curved WTS Zion 1 4/92 124 Kewaunee 3/92 16 Curved WTS Ringhals 3 7/91 46 ETZ 22 TS Ginna 4/90 192 48 Curved WTS Zion 2 4/90 82 WTS Prairie Island 1 1/90 63 WTS Zion 1 9/89 445 WTS Ginna 4/89 395 WTS 107 Curved WTS Prairie Island 1 9/88 74 WTS 2-3
TABLE 2-1 (cont.)
INSTALLATIONSOF ABB-CENO WELDED SLEEVE INSTALLED PLANT DATE QUANTITY TYPU Ringhals 2 5/87 571 WTS Prairie Island 1 4/87 27 WTS Ginna 2/87 105 WTS Zion 1 10/86 128 WTS Ringhals 2 5/86 599 WTS Ginna 2/86 36 WTS Ringhals 2 5/85 59 WTS Ringhals 2 5/84 18 WTS Straight sleeves unless otherwise noted 2-4
- 3. ACCEPTANCE CRITERIA The objectives of installing sleeves in steam generator tubes are twofold. The sleeve must maintain structural integrity of the steam generator tube during normal operating and postulated accident conditions. Additionally, the sleeve must prevent leakage in the event of a through-wall defect in the steam generator tube. Numerous tests and analyses were performed to demonstrate the capability of the sleeves to perform these functions under normal operating and postulated accident conditions.
Operating conditions used to bound the CE steam generators are defined as:
(Pressure and temperature ~difference were considered in determining bounding conditions)
Primary Side: 611'F (operating) 2250 psig (operating)
(Hot Side)
Secondary Side: 506'F (100% load) 815 psig (100% load)
Operating conditions used to bound the W steam generators are defined as:
(Pressure and temperature differences were considered in determining bounding conditions)
Primary Side: 620'F (operating) 2250 psig (operating)
(Hot Side)
Secondary Side: 526.5'F (100% load) 815 psig (100% load)
Table 3-1 provides a summary of the criteria established for sleeving in order to demonstrate the acceptability of the sleeving techniques. Justification for each of the criterion is provided. Results indicating the minimum level with which the sleeves sur-passed the criteria are tabulated. The section of this report describing tests or analyses which verify the characteristics for a particular criterion is referenced in the table.
3-1
TABLE 3-1 REPAIR SLEEVING CRITERIA Criterion Justification Results Section
- 1. Sleeve is leak tight Leakage between 4.0 primary and secondary side is prevented.
- 2. Sleeve-tube assembly Sleeve tube assembly 8.0 functional integrity must meets applicable ASME be maintained. Code requirements.
- 3. Axial load cycle without Bounds cycle loading 7.0 weld joint or rolled joint from normal operating failure. and transient cycling.
- 4. Pressurization of annulus Prevention of sleeve 7.0 between sleeve and tube failure for through wall does not collapse sleeve at defect in tube wall.
1500 psig.
- 5. Pressurize sleeve (without Factor of safety of three 7.0 tube) to 4800 psig without for N.O. conditions.
bursting.
Exposure of sleeve-tube Sleeve-tube assembly 6.0 assembly to various required to function primary and secondary under coolant chemistries without loss chemistries of functional integrity.
Non-destructive Periodic examination of 5.0 examination of tube and tubes and sleeves sleeve to levels of required to verify detectability required to structural adequacy show structural adequacy.
- 8. Welded sleeve installation Sleeve repair should not 10.0 does not significantly reduce power removal affect system flow rate or capability of reactor or heat transfer capability of steam generator below the steam generator. rated value.
3-2
DESIGN DESCRIPTION OF SLEEVES AND INSTALLATIONEQUIPMENT 4.1 SLEEVE DESIGN DESCRIPTION There are two (2) types of sleeves which may be installed in various combinations within a steam generator tube. These sleeves are shown in Figures 4-1, and 4-2. Each sleeve type has a nominal outside diameter of [ ] inches and a nominal wall thickness of [ ] inches. The sleeve material is thermally treated Alloy 690.
Each of the sleeve types include a chamfer at both ends to prevent hang-up of equipment used to install the sleeve and to facilitate the inspection of the steam generator tube and sleeve.
The first type of sleeve, shown in Figure 4-1, spans the expansion transition or roll transition at the top of the tubesheet. This Expansion/Roll Transition Zone (ETZ) sleeve is up to [ ] inches long and includes a [band of nickel and a band of metal oxide on one end. The nickel band improves sealing of the sleeve when the lower end is hard rolled into the expanded or rolled portion of the parent tube while the rough surface of the metal oxide provides a strong mechanical joint. ]
The second type of sleeve, shown in Figure 4-2, spans a tube support or egg crate support plate. This Tube Support (TS) sleeve is [ ] inches in length. The sleeve spans a support plate elevation or can be used on a free span section of the tube.
SLEEVE MATERIALSELECTION The thermally treated Alloy 690 tubing, from which the sleeves are fabricated, is procured to the requirements of the ASME Boiler and Pressure Vessel Code,Section II SB-163, Code Case N-20. Additional requirements are applied including a limit on Carbon content of 0.015 - 0.025% and a minimum annealing temperature of 1940'F (1060'C) for a minimum of two minutes. The thermal treatment is specified at 1300'F (704'C) for a minimum of five hours to impart greater corrosion resistance in potential faulted secondary side environments; The enhanced corrosion resistance is achieved in the thermal treatment by insuring the presence of grain boundary carbides and by reducing the residual stress level in the tubing.
The principal selection criterion for the sleeve material was its resistance to stress corrosion cracking (SCC) in primary and caustic faulted secondary PWR environments. ABB-CE's justification for selection of this material and condition is based on the data contained in Reference 4.7.1.
4-1
4.3 SLEEVE-TUBE ASSEMBLY The installed sleeves are shown in Figures 4-3 and 4-4. The Expansion Transion Zone (ETZ) sleeve spans the expansion/roll transition zone at the top of the tubesheet. If defects exist at a tube support or egg crate support plate, as well as, at the top of the tubesheet, an ETZ sleeve and a Tube Support (TS) sleeve may be used.
The ETZ sleeve, shown in Figure 4-3, is [ ] inches in length or shorter. The bottom of the sleeve is located near the neutral axis of the tubesheet. [
The TS sleeve shown in Figure 4-4 is [ ] inches in length. It is approximately centered ata supportplate. [
4-2
When it is considered to be of benefit (based on steam generator primary and secondary side conditons), a post weld heat treatment of the sleeve weld will be added to the sleeve installation process. After the sleeve has been welded into the tube, the weld joint is heated in the range of [ ] As described in Reference 4.7.5, this time and temperature combination is sufficient to reduce the level of residual stress in Alloy 600 while minimizing detrimental effects such as grain growth or sensitization. This treatment is similar to that utilized in some operating units to heat treat the tight radius U-bends.
Qualification of the sleeve welding process is in accordance with the procedure described. in Appendix A.
4.4 PLUGGING OF A DEFECTIVE SLEEVED TUBE If a sleeve or sleeved tube is found to have an unrepairable defect, the tube can be taken out of service with standard steam generator tube plugs installed at both ends of the tube using approved methods.
4.5 SLEEVE INSTALLATIONPROCESS AND EQUIPMENT The equipment used for remote installation of sleeves in a steam generator is made up of the following basic systems. These systems are:
- 1. Remote Controlled Manipulator 4-3
These systems, when used together, allow installation of the sleeves without personnel entering the steam generator. In this way, personnel exposure to radiation is held to a minimum.
The tooling and methods described in the following sections represent the present technology for leak tight sleeve installation. As technological advances are made in sleeve installation, the new tooling and/or processes may be utilized after they have been laboratory-verified to provide improved sleeve installation methods.
Remote Controlled Mani ulator The remote controlled manipulator (Figure 4-5) serves as a transport vehicle for inspection or repair equipment inside a steam generator primary head. The manipulator consists of two major components; the manipulator leg and manipulator arm. The manipulator leg is installed between the tube sheet and bottom of the primary head and provides axial (vertical) movement of the arm. The manipulator arm is divided into the head arm, probe arm and a swivel arm. Each arm is moved independently with encoder position controlled electric motors. The swivel arm allows motion 'for tool alignment in both square pitch and triangular pitch tube arrays.
Computer control of the manipulator allows the operator to move sleeving tools from outside the manway and accurately position them against the tube sheet.
Tool Deliver E ui ment The purpose of the tool delivery equipment is to support and vertically position the various tools required for the sleeving operation and to provide controlled rotation to some of the tools. Two different delivery systems may be used for the tool delivery.
The probe driver is a modified Zetec probe pusher or equivalent unit located outside the manway of the steam generator. A flexible conduit extending from the probe driver to an adaptor on the manipulator arm provides the guide path for the tools. The guide path adaptor is attached to the end of the manipulator arm by a dovetail fitting and manual lock. The drive wheels of the probe driver deliver the tools to the required elevations within the tube. Where positioning is critical, a hardstop attached to the tool shaft locates the tool relative to the steam generator tube end.
The tool delivery system for controlled tool rotation consists of two major components;
[ ], Figure 4-6. The tool mounting plate is attached to the end of the manipulator arm by a dovetail flitting and manual lock. One or two sets of pneumatically operated fingers are used to draw-up and lock the tool mounting plate to the tube sheet. Proper alignment of the tool mounting plate to the
mounting plate to the tube sheet. Proper alignment of the tool mounting plate to the tube sheet is assured through the actuation of three switches against the tube sheet. A spring loaded, air pressure release, quick change mount is provided on the face of the tool mounting platform for quick mounting of the probe pusher or the rolling tool elevator.
The probe pusher attaches to the tool mounting platform with the quick change mount.
The probe pusher includes two double sets of drive wheels and two idler wheels. The drive wheels are powered by electric motors to insert and remove the various sleeving tools and the sleeve into the steam generator tube. Vertical positioning of the tools is accomplished by hardstops and/or verified by visual means. Controlled rotation of the weld and non-destructive examination (NDE) tools is provided by an electric motor which rotates the probe pusher relative to the tool mounting platform.
4.5.3 Tube Brushin -Cleanin E ui ment 4.5.4 Tube Rollin E ui men
4.5.5 Sleeve Ex ansion E ui ment 4.5.6 Sleeve Weldin E ui ment 4-6
i Three types of nondestructive examination equipment are used during the sleeving process. They are as follows: eddy current test (ET) equipment, ultrasonic test (UT) equipment (Figure 4-11) and visual test (VT) equipment (Figure 4-12).
The ET inspection will be performed using the most recently developed eddy current probes and techniques for sleeving inspection. The eddy current probe presently being used is the new advanced +point rotating probe. Future probe designs may be used after suitable qualification demonstration has been performed. The ET fixture, with conduit, is used on the manipulator arm to position the probe.
Ultrasonic testing using an immersion technique with demineralized water as a couplant is used to inspect the tube to sleeve weld. A one-quarter inch diameter focusing transducer is positioned in the weld area and rotated by the probe pusher to scan the weld. A digital imaging system is used to acquire and store the inspection data.
Visual inspection of the steam generator tube to sleeve weld is accomplished with the use of a boroscope or micro camera system delivered and rotated by the probe pusher.
Inspection data is stored on video tape.
4.5.8 Post-Weld Heat Treatment E ui ment 4.5.9 Sleeve Rollin E ui ment The sleeve rolling equipment is used to expand the lower end of the ETZ into contact with the steam generator tube within the tubesheet, forming a strong leak tight joint.
The rolling tool is mounted on the manipulator and positioned within the tube by a hard stop on the roll tool shaft seating against the tube sheet. The rolling tool includes a dovetail attachment for quick mounting on the manipulator. The rolling tool mounted on the manipulator, [ ] may be used in the central tubesheet region 4-7
while a curved elevator [ ] is used for the periphery. Although the curved elevator is used specifically for the periphery, it may be used at any tube location.
The rolling equipment consists of the air motor, tube expander, torque read-out, strip chart recorder and a torque calibration unit. The torque read-out and settings of the rolling tool are verified on the torque calibration unit prior to rolling of the sleeves.
The rolling tool is located by a hardstop on the tool shaft. The hardstop positions the upper end of the tube expander within the portion of the sleeve which was hydraulically expanded during sleeve installation. The approximately 1-1/4 inch long roll is located at the nickel and metal oxide bands on the lower end of the ETZ sleeve.
The sleeve is expanded to a torque which has been demonstrated by testing to provide a leak tight joint. A record of the rolling tool torque is made for further evaluation of the rolling process on the individual sleeves. A rolled joint which fails to meet the acceptance criteria may be re-rolled.
4.6 ALARACONSIDERATIONS The steam generator repair operation is designed to minimize personnel exposure during installation of sleeves. The manipulator is installed from the manway without entering the steam generator. It is operated remotely from a control station outside the containment building. The positioning accuracy of the manipulator is such that it can be remotely positioned without having to install templates in the steam generator.
The tool delivery equipment is designed so that the dovetail fitting quickly attaches to the manipulator. The probe pusher is designed to quickly engage the individual sleeving tools. The tools are simple in design and all sleeving operations are performed remotely using tools held by the manipulator. Each tool can be changed at the manway in 10-15 seconds. A tool operation is performed on several sleeves rather than performing each tool operation on the same sleeve before proceeding to the next sleeve. This reduces the number of tool changes which are required. Spare tools are provided so that tool repair at the manway is not required. If tool repair is necessary, the tool is removed and sleeve operation continues using a spare tool. The tool may or may not be repaired during the outage but repair is performed in an area which does not have significant radiation.
Air, water and electrical supply lines for the tooling are designed and maintained so that they do not become entangled during operation. This minimizes personnel exposure outside the steam generator All equipment is operated from outside the containment. The welding power source and programmer is stationed about a hundred feet from the steam generator in a low radiation area.
Lead lined manway shield doors, both primary side and secondary (ventilation) side, are also employed to reduce radiation exposure.
4-8
4.7 REFERENCES
TO SECTION 4.0 4.7.1 Allo 690 for Steam Generator Tubin A lications, EPRI Report NP-6997, October 1990.
4.7.2 Sedricks, A. J., Schultz, J. W., and Cordovi, M. A., "Inconel Alloy 690- A New Corrosion Resistant Material", Ja an Societ of Corrosion En ineerin, 28, 2 (1979).
4.7.3 Airey, G. P., "Optimization of Metallurgical Variables to Improve the Stress Corrosion Resistance of Inconel 600", Electric Power Research Institute
, Research Program RP1708-1 (1982).
4.7.4 Airey, G. P., Vaia, A. R., and Aspden, R. G., "A Stress Corrosion Cracking Evaluation of Inconel 690 for Steam Generator Tubing Applications", Nuclear
~Tecboolo, 55, (November, 1981) 436.
4.7.5 Hunt, E.S. and Gorman, J.A., S ecifications for In-Situ Stress Relief of PWR Steam Generator Tube U-bends and Roll Transition, EPRI Report NP-4364-LD, Electric Power Research Institute, Palo Alto, CA, December 1985.
4.7.6 Krupowicz, J. J., Scott, D. B., and Fink, G. C., "Corrosion Performance of Alternate Steam Generator Materials and Designs Vol. 2: Post Test Examinations of a Seawater Faulted Alternative Materials Model Steam Generator," EPM-NP-3044, July 1983.
4.7.7 G. Santarini et al, Recent Corrosion Results - Alloy 690, EPRI Alloy 690 Workshop, New Orleans, LA, April 12-14, 1989.
FIGURE 4-1 EXPANSION/ROLL TRANSITION ZONE SLEEVE 4-10
FIGURE 4-2 TUBE SUPPORT SLEEVE 4-11
FIGURE 4-3 EXPANSION/ROLL TRANSITION ZONE SLEEVE INSTALLATION 4-12
FIGURE 4-4 TUBE SUPPORT SLEEVE INSTALLATION 4-13
FIGURE 4-5 MANIPULATORAND TOOL DELIVERY SYSTEM 4-14
8 FIGURE 4-6 TOOL DELIVERY E UIPMENT 4-15
FIGURE 4-7 TUBE CLEANING E UIPMENT 4-16
FIGURE 4-8 SLEEVE EXPANSION E UIPMENT 4-17
FIGURE 4-9 SLEEVE WELDING HEAD ASSEMBLY 4-18
FIGURE 4-10 SLEEVE WELDING HEAD POWER SUPPLY UNIT 4-19
FIGURE 4-11 ULTRASONIC TEST E UIPMENT 4-20
FIGURE 4-12 VISUALTEST E UIPMENT 4-21
FIGURE 4-13 POST WELD HEAT TREAT E UIPMENT 4-22
FIGURE 4-14 SLEEVE ROLLING E UIPMENT 4-23
FIGURE 4-15 SLEEVE ROLLING E UIPMENT - CURVED 4-24
'LEEVE EXAMINATIONPROGRAM During the installation process, the sleeves are examined using a combination of visual testing (VT), ultrasonic testing (UT) and eddy current testing (ET) at different stages of the installation process. The general process is described in the flow charts presented in Figures 5-1 and 5-2, which are described below.
After the description of the inspection process, the individual inspection methods will be described in additional detail.
After completion of the brush cleaning step, the first inspection is a VT process on tubes to be sleeved to confirm adequate cleaning to proceed with the welding process.
Parent tube cleanliness has been identified as a critical feature of the overall welding process. A VT after cleaning is performed with a miniature remote camera inserted into the tube up to the elevation where the welding will be performed. The VT inspectors are trained using images of examples of acceptable and inadequate cleaning.
In simplest terms, the cleanliness requirement is the presence of "bright, shiny metal" in the region of the tube where welding will take place. If adequate cleaning is not confirmed by the remote VT, then the cleaning process is repeated until a suitable cleanliness is achieved. The extent of this inspection program is presently 100% of tubes to be sleeved. At such time that process control is demonstrated to assure cleaning efficiency, a sampling program may be used.
Upon confirmation of cleaning, the sleeve is inserted, expanded and welded. The next inspection is performed on the ATS weld by UT to confirm a leak tight bond has been achieved by the welding process. The weld height is not measured by the UT method, but rather is controlled by the welding process qualification. A confirmation of 360 degrees of weld bond is the acceptance criteria for the UT inspection. If a lack of fusion (LOF) through the weld height is detected, then the sleeve may be identified for rewelding or plugged. After a reweld, the UT is repeated to confirm a leak tight weld. An 'acceptable UT result is required for any ATS weld left in service.
Prior to the UT inspection, an optional VT-1 inspection of the ATS weld may be performed, but is not required. The VT-1, as defined in ASME Section XI, is suitable for detection of incomplete welds, blow holes and weld splatter geometric irregularities in the weld. Experience has shown that the UT and ET inspections are capable of detecting these conditions, so the VT is primarily useful to help resolve uncertainties in surface conditions detected by either the UT or ET inspections. If a 5-1
VT-I inspection is performed and a blow hole or other potentially deleterious condition (with the exception of an incomplete weld) is detected, then a noncomformance report (NCR) must be generated. Blow holes identified as within the pressure boundary portion of the weld must be repaired. Blow holes not within the pressure boundary portion of the weld are identified for additional evaluation by the ET and UT inspections.
The final inspection is performed on all installed sleeves using the ET method with a
+point probe. Ifpost weld heat treatment is performed, this inspection must be performed after the heat treatment due to the possibility of additional signals from permeability variations caused by the heat treatment process. The entire length of the pressure boundary, including the pressure boundary portion of the parent tube behind the sleeve is inspected with the ET method. The pressure boundary portion of the sleeve tube assembly is shown in Reference 5.4.3. The details of the ET inspection are described in Section 5.2 and Figure 5-2 with the associated definitions in Table 5-1.
The sleeve to tube weld joints are qualified by process control as described in Appendix A. Checks are made to ensure that the welds meet these design requirements. The welding current and voltage are recorded as the weld head rotates inside the sleeve.
The recordings are examined after the welding sequence has been completed to verify that the essential parameters given in Reference 1 to Appendix A are met.
These descriptions of inspection techniques and tooling represent the current state-of-the-art practices. As new technology becomes available, advanced techniques may be substituted after a suitable qualification program has demonstrated equivalent or superior performance.
ULTRASONIC INSPECTION Summar and onclusions An ultrasonic inspection is performed on each sleeve to tube ATS weld to confirm a leak tight fusion. The test is performed using an ultrasonic crystal with a resonant frequency of [ 15 ] MHz (physical construction of the probe will reduce the effective output frequency to [ 8- 12 ] MHz, typically. Actual output frequency is documented in the transducer certification package required by procedure.) The mechanical drive device performs a scan of the weld in 2 degree increments around 360 degrees with axial step increments of [ 0.020 ] inches; the scan path extends from above the weld so that the sleeve backwall is detected to below the weld until the backwall of the sleeve is detected. The inspection is demonstrated to detect a milled notch representing a weld lack of fusion (LOF) region of [ 0.030 ] inch or greater. The ultrasonic signal is 5-2
lack of fusion (LOF) region of [ ] inch or greater. The ultrasonic signal is digitized and stored in order to provide a permanent record of the individual A scans (lower presentation on Figure 5-4), which are used to display plan view C scans (upper presentation on Figure 5-4) of the weld as well as cross sectional views in the axial direction (B'cans) and cross sectional views (B scans). For each individual sleeve inspection, a calibration confirmation is available by monitoring the response to the sleeve back wall either above or below the weld zone.
ltrasonic Evaluati n The basis of the UT inspection is the detection of a reflective surface at the sleeve to tube interface to detect a condition indicative of a lack of fusion. Sound is transmitted from the sleeve inner surface through the weld to the tube outer surface. Although the reflection from the tube outer surface is typically discernible in the recorded data, this is a sufficient, but not necessary indication of fusion. Geometric distortions in the weld region may preclude detection of this tube back wall as a consistent indicator of weld fusion.,
In the data acquisition phase, a C scan is displayed for the operator with a [
] for monitoring reflections from the sleeve/tube interface. During analysis, both circumferential and axial cross sectional views of the ultrasonic reflectors are reviewed for evaluation of each weld. Detection of a[ ] reflection is an indication of a complete weld.
In the absence of this signal, axial and circumferential cross sections (B and B'cans) data reviews are conducted. Locally, reflectors are compared to 20% of the sleeve backwall signal amplitude for determination of a local LOF. Using the B'can axial cross section, a LOF condition through the weld height is discernible. Using a combination of laboratory samples and removed tubes (Prairie Island, February, 1996),
unbonds as narrow as 10 degrees are detectable using this B scan analysis techniques, as reported in References 5.4.1 and 5.4.2. Sample outputs from the UT results for an acceptable weld and unacceptable LOF condition are provided in Figures 5-3 (acceptable) and 5-4 (rejectable).
Te E ui men The test equipment for the ultrasonic inspection comprises the following:
- 1. IntraSpect Ultrasonic Imaging System
- 2. Sleeve Weld UT Inspection Probe, 15 MHz, 0.250 diameter crystal, sized for sleeve ID, as depicted in Figure 5-5 5-3
- 3. Couplant supply system, integral with the probe and driver system
/
- 4. Position device for rotational and translational motion, include encoder feedback for each axis
- 5. Calibration standard with machined notches for initial set up, as depicted in Figure 5-6.
5.2 EDDY CURRENT INSPECTION 5.2.1 Back~round For the initial installation of sleeves, each sleeve will be inspected for a baseline and for acceptance. Over the years, the eddy current probe technology has evolved with ever increasing sensitivity in the probe response. Early sleeving programs used a cross wound bobbin coil design, which was later replaced by the I coil design and ultimately by the plus point probe design. The current practice uses the plus point probe design with the option of adopting future probe designs after suitable qualification demonstration has been performed. The description below discusses the most recent plus point probe design, which was extensively qualified for sleeve inspections in a program that exceeded the requirements of the EPRI Steam Generator Inspection Guidelines, Appendix H in effect at this writing, as described in reference 5.4.3. This qualification used a detection threshold of 40% degradation of the sleeve wall thickness rather than the 60% allowed by Appendix H to add conservatism to the process.
The ET method is used to inspect the entire sleeve region pressure boundary which has four distinct regions:
I) the sleeve between the upper weld and lower joint (either roll or weld, depending on sleeve type)
- 2) the pressure boundary region of the steam generator tube behind the sleeve
- 3) the steam generator tube below the lower rolled joint for an ETZ sleeve
- 4) the unsleeved portion of the steam generator tube The first three regions are the subject of this discussion, the fourth region is handled as part of the normal tube inspection using the prevailing methods. If post weld heat treating is pe'rformed on the weld zone, the ET inspection is performed after the heat treatment.
5-4
Plus Point Probe uglification Stud The plus point ET technique was extensively qualified for each of the regions identified above using laboratory samples with EDM notches and laboratory produced weld imperfections. The details of the inspection samples and results for the weld zone indications are provided in references 5.4.1 and 5.4.2 and the Appendix H qualification report is provided in reference 5.4.3. The Appendix H qualification report provides the details for both the acquisition (ACTS) and analysis (ANTS) of the inspection data.
Site specific analysis guidelines have been developed and analysts are trained and tested on the specifics of the technique. In summary, the plus point technique was demonstrated to be able to detect relevant flaw mechanisms 40% throughwall and greater in each of the regions identified above.
Particular attention was paid to the ATS weld region of the sleeve. The detailed process for the initial installation inspection is shown in the flow chart in Figure 5-2 with the companion list of acronyms in Table 5-1. For the subsequent inservice inspections, reviews of previous inspection results may be used in lieu of the VT and UT reviews mentioned in the flow chart. Either the standard +point probe or the magnetically biased style may be used for the inspection. Experience has shown that one of the most common interfering signal sources in the weld region is caused by local permeability variations, which are greatly reduced by the partial magnetic saturation provided by the magnetically biased probe.
The ET indications are separated into two broad categories, surface and subsurface.
Surface indications are caused by minor weld sag which produces a signal classified as GEO for geometric. Local irregularities in the weld surface are classified as weld surface indications (WSI). In extreme cases, the WSI source could be a blow hole in the weld. Additional VT reviews are used to evaluate surface related indications prior to acceptance. With the aid of the VT data, WSI signals are resolved as blow holes outside or within the pressure boundary portion of the weld (BHA or BHB) or nondeleterious surface irregularities (WSS). If no surface condition is observed, then the signal is considered as a subsurface weld zone indication (WZI) and evaluated accordingly. For blow holes, the location relative to the pressure boundary is determined using a combination of the VT and UT results. Accordingly, the BHA (blow hole outside pressure boundary portion of the weld) condition is acceptable for service while the BHB (blow hole within the pressure boundary portion of the weld) is not.
The WZI signals may be caused by oxide inclusions in the weld or a partial void caused by a gas pocket during the welding process. Metallographic work, as reported in reference 5.4.1, has shown that these conditions occur at either the upper or lower edge 5-s
of the ATS weld on the sleeve outer surface. The oxide inclusion condition is generally precluded by proper cleaning, which is verified using VT before installing the sleeve. Minor voids may occur in a small percentage of welds even with proper cleaning, but generally are very shallow. No attempt is made to distinguish inclusions from voids, nor is there an attempt to measure depth or circumferential extent for these conditions. The only acceptance criteria is based on the location relative to the pressure boundary with indications outside the pressure boundary portion of the weld (WZA) acceptable for service and indications within the pressure boundary portion of the weld (WZB) not acceptable for service. The ability to determine the true location of indications relative to the pressure boundary portion of the weld was demonstrated in the Appendix H qualification study and is reported in references 5.4.2 and 5.4.3.
Various other anomalous conditions may be reported by the ET analyst that would trigger an nonconformance report (NCR) and additional evaluation.
The sleeve plugging criteria stated above provides at least a 9% margin with respect to growth and ECT uncertainity. This is consistent with the minimum allowable sleeve thickness determined in Section 8.0, an appropriate growth factor for Alloy 690 (given its excellent corrosion resistance in primary and secondary environments), and the success rate in detecting indications of 40% or greater (Reference 5.4.3).
The other area of particular interest is the expansion transition zone above the weld.
Here the parent tube constitutes the pressure boundary. The ability to detect 40%
through wall flaws was demonstrated using EDM notches and is detailed in reference 5.4.3.
5.3 VISUALINSPECTION 5.3.1 Su and Conclusions There are two visual inspections associated with the sleeving process. The first inspection is performed after the brush cleaning process for the weld region. Tubes are inspected for cleanliness prior to sleeve installation. The second, optional inspection is performed after completion of the ATS weld and is conducted as a VT-1 inspection per Section XI of the ASME Code. The VT-1 inspection is performed when needed to resolve surface indications identified by the ET or UT inspections. The VT-1 inspection is also performed for rewelds.
The VT is performed remotely by means of a miniature CCD camera inserted into the tube with the results recorded on video tape. Visual aids are provided for the inspectors for evaluation of cleaning and weld quality. A training tape with examples of weld irregularities is provided and reviewed by the VT-1 inspectors. Conditions of interest include blow holes, incomplete welds, splatter, pits and burn through.
5-6
k 3.3.2
~ ~ ~33 ~ '
After the cleaning operation, the parent tube in the region where the weld will be made is inspected for adequacy of cleaning. Approximately a two inch long zone is cleaned and inspected. The acceptance criteria is bright, shiny metal to assure that there is no remaining oxide on the tube surface that could affect the weld quality by producing inclusions. This process verification step is identified in the site specific traveller. The extent of this inspection program is presently 100% of tubes to be sleeved. At such time that process control is demonstrated to assure cleaning efficiency, a sampling program may be used.
3.3.3 ~l The primary inspection methods for ATS weld and sleeve acceptance are the UT and ET methods described above. An additional VT-1 inspection of the weld is optional, unless required by the site procedure for specific situations, such as repair welds. The VT-1 is also used as a supplemental technique to aid in the analysis of surface conditions reported in either the UT or ET results.
The CCD camera and right angle viewing mirror is inserted into the sleeve. The camera system is checked using a 1/32" black line on an 18% neutral gray card. Also, a sleeve sample with a 0.020" diameter through hole is used to scale the image. The VT-1 results are recorded on video tape for permanent storage.
5.4 REFERENCES
5.4.1 ABB CENO CEN-628-P Rev 01-P, "Verification of the Structural Integrity of the ABB CENO Steam Generator Welded Sleeve, March, 1996 (PROPRIETARY) 5.4.2 ABB CENO 96-3-9038T Rev 01, "POD Assessment for NDE of Sleeves",
June 14, 1996 5.4.3 ABB CENO 96-OSW-003, "EPRI Steam Generator Examination Guidelines Appendix H Qualification for Eddy Current Plus-Point ProbeExamination of ABB CENO Welded Sleeves", April 27, 1996 (PROPRIETARY) 5-7
TABLE 5-1 ACRONYMS USED IN ET ANALYSIS BHA: Blow Hole Outside Pressure Boundary BHB: Blow Hole Within Pressure Boundary GEO: Geometric signal LOF: Lack Of Fusion NCR: NonConformance Report NDD: No Detectable Degradation PID: Positive ID retest RMB: Retest with Magnetically Biased probe UT: Ultrasonic Test VT-1: Visual Test, Type 1 per ASME Code, Section XI VT: Visual Test WEE: Weld at Edge of Expansion WOE: Weld Outside Expansion region WSI: Weld Surface Indication WSS: Weld Surface Signal WZA: Weld Zone indication Outside Pressure Boundary WZB: Weld Zone indication Within Pressure Boundary WZI: Weld Zone Indication-subsurface or indeterminant 5-8
AtJECT ACCt AT NC~CTt AtJCCT WELO ACCTJT ttEltCT ACCTPT CC'T SEE CHART TTo. 2 FIGURE 5-1 NDE PROCESS FLOW CHART 5-9
SLEEVE NOE RMB PROCESS FLOW CHART 2 LITICIL 08$ CIWATNNf ACCCT'TALC ACCC AT ATAC AC Ctt TATAC ACCTPTATILC ACCCA TACLC ACCtATAALC FIGURE 5-2 ET PROCESS FLOW CHART 5-10
File Channel Gate C-Scan B-Scan A-Scan Tools Settings Help File; PIR5C484 Kxoe Dote.'&21/96 'Tloel 17:Co 17t'lo Chonnel: 1 Cot<<: IFACC Hodo: Thresh Video Hoa ~ 1 Off Video Flttee: 8 coin: 74.0 oB Deo: CFF offostt 0.0 do Pulsee Volcote: 400 X Axlsi 321.000, Y Axis: 0,020 FHP; 782 TOF: 12.320 uo dS: 5 8 HP: 1.418 in D th: 1.418 0 1/2 V Y
0.2 TOF 12oo f (us>
x -0 0
X Axle I
50 i
100 321 000 I
150 I
200 Y Axle 250 0.020 300 350 DTOF1 0.320 us Heos: HA
~r 12:6~-j 13.2+-
13 ~
X 845 Axis xSX Axts: 321,000 SY Axle'. 0. 020
&Pi 122k TOFi 12 320 us HPi 1.418 ln Dpthi 0.582 8 2/2 V 0.4 -0.3 0 -0,1 0.0 0t I 012 03 0)4 1
12.0
\'2.
5 13.0 T
0 F
13.5 u
. 15.0 120 110 100-90-00-70 60-50.
40 30 20-10-0 I I 12.0 13 0 13 5 14 0 15 0 15 5 16 0 C- TOF tuoeo>
Cspy laht (0) 1998 ABB AMOATA FIGURE 5-3 UT B S AN - ACCEPTABLE
File Channel Gate C-Scan B-Scen A-Scan Tools Settings File: PIRTC524 Expo Dote: 02/21@96 Tine: 17139 17:43 Channel: l Octal TFACK Hade: Thresh Video Hodol OFF Yodoo Filter; 8
'Cetnt 74.0 d8 Doo: oFF DFFsetl 0,0 db Pulsor voltozol 400 X Axlsi tC1,000 Y Axle: 0.060 AHpi 78Z TOF ~ 12.390 us de: 5.8 HP: 1.426 tn th; 1,426 8 4'2 V TOF <uo) 12 2u 12.4
- 12. 6 8
0.4 13.0 0.2 13e2 0.0 13.4 0.2 13.6 0.4 13,9 i 14. 0 50 300 X Axle X Axial 147.000 Y Axis: 0.060 DTOFi 0.390 us Heost HA SX Axle: 147,000 SY Axle: 0.060 FHPl 122Z TOFi 12.390 us HP: 1,426 in Dpthi 1,426 8 tr'2 V
-0.4 0.3 02 -0,1 003 013 02 03 3
04 12,0 x,. rxa
,sr
~ ~ n
- 13. 5
~" 4 0 is 14.0 14.5-we 120 110 100- '0-il 90- E 4 4 u 10 60 50-40- r 30-20" . ~
18-,
I I I 12.0 12. 5 13.0 13. 5 14. 0 14 5 15 0 15. 5 16 0 <- TOF <uooo>
,"Copyrlaht (0) 3115 A88 AMDATA FIGURE 5-4 UT B CA - REJECTABLE 5-12
FIGURE 5-5 UT PROBE 5-13
FIGURE 5-6 UT CALIBRATIONSTANDARD 5-14
- 6. SLEEVE-TUBE CORROSION TE 7 PROGRAM ABB-CE has conducted a number of bench and autoclave tests to evaluate the corrosion resistance of the welded sleeve joint. Of particular interest is the effect of the
- - mechanical expansion/weld residual stresses and the condition of the weld and weld heat affected zone. Tests have been performed on welded joints with and without a post-weld heat treatment. An outline of these tests is shown in Table 6-1. [As shown in the table some tests have been conducted with mill annealed Alloy 690 sleeves due primarily to material availability. For the environrrients being tested ABB-CE considers these to be conservative tests in that thermally treated material has been shown to perform as well or better than mill annealed material.]
6.1
SUMMARY
AND CONCLUSIONS 6.2 TEST DESCRIPTION AND RESULTS 6.2.1 Primary Side Tests 6-1
TABLE 6-1
.STEAM ENERATOR TUBE SLEEVE C RROS ION TESTS 6-2
6.2.1.1 Pure Water Stress Corrosion Crackin~ Tests 6.2.1.2 Above the Tubesheet (ATS) Weld Capsule Tests 6-3
TABLE 6-2 Sleeve/Tube Ca sule SCC Tests Sam le Condition Failure No. Failure Time Hrs 6.2.1.3 TSP Sleeve Weld Capsule Tests 6-4
6.2.1.4 Summary - Primary Coolant Corrosion Performance 6-s
6-s 6.2.2 Secondar Side Tests 6.2.2.1 Modified Huey Tests 6.2.2.2 Capsule Tests
TABLE 6-3 SECONDARY SIDE STEAM ENERATOR TUBE SLEEVE CAPSULE TESTS ENVIRONMENT EXPOSURE TIME RESULTS D.
6.2.~.3 Sodium Hydroxide Fault Autoclave Tests 6-s
6.2.2.4 Summary - Secondary Coolant Corrosion Performance 6-9
secondary fault environment. However, by the very nature of the weld joint in both an ETZ and TS sleeve, it must be located outside a region where fault species are capable of concentrating, ie. tube/support intersections. These environments would only exist in the area bridged by the sleeve and as such the structural integrity of the tube/sleeve assembly would not be degraded.
6.3 REFERENCES
FOR SECTION 6.0 6.3.1 Statistical Anal sis of Steam enerator Tube Degradation, EPRI Report NP-7493, September 1991.
6.3.2 Summary Report, Combustion Engineering Steam Generator Tube Sleeve Residual Stress Evaluation, TR-MCC-153, November 1989.
6.3.3 I. L. W. Wilson and R. G. Aspden, "Caustic Stress Corrosion Cracking of Iron-Nickel-Chromium Alloys." Stress Corrosion rackin~ and H dro~en Embrittlement of Iron Base Allo s, NACE,Houston, Texas, pp 1189-1204, 1977.
6.3.4 A. J. Sedriks, S. Floreen, and A. R. Mcllree, "The Effect of Nickel Content on the Stress Corrosion Resistance of Fe-Cr-Ni in an Elevated Temperature Caustic Environment". Corrosion,Vol. 32, No. 4, pp 157-158, April 1976.
6.3.5 F. W. Pement, I. L. W. Wilson and R. G. Aspden, "Stress Corrosion Cracking Studies of High Nickel Austenitic Alloys in Several High Temperature Aqueous Solutions." MaterialsPerformance, Vol. 19, pp 43-49, April 1980.
6.3.6 P. Berge and J. R. Donati, "Materials Requirements for Pressurized Water Reactor Steam Generator Tubing." NuclearTechnolo~, Vol. 55, pp 88-104, October 1981.
6.3.7 G. P. Airey, A. R. Vaia and R. G. Aspden, "A Stress Corrosion Cracking Evaluation of lnconel 690 for Steam Generator Tubing Applications." Nuclear
~Technolo, Vol. 55, pp 436-448, November 198 l.
6.3.8 J. R. Crum and R. C. Scarberry, "Corrosion Testing of Inconel Alloy 690 for PWR Steam Generators." Journal of Materials for Enero S stems, Vol. 4, No. 3, pp 125-130, December 1982.
6-io
FiGURE 6-1 P WATER RR I N TEST SPECIMEN
FIGURE 6-2 AT WELD CAPSULE T PECIMEN 6-12
FIGURE 6-3 T P WELD CAPS E TEST SPE IMEN 6-13
FIGURE 6-4 RTZ WELD CAPSULE TEST SPECIMEN
- 7. MECHANICALTESTS OF SLEEVED STEAM GENERATOR TUBES 7.1
SUMMARY
AND CONCLUSIONS Mechanical tests were performed on mockup steam generator tubes containing sleeves to provide qualified test data describing the basic properties of the completed assemblies. These tests determined axial load, collapse, burst and thermal cycling capability. A minimum of three tests of each type were performed.
7.2 CONDITIONS TESTED 7.3 WELDED SLEEVE TEST PARAMETERS AND RESULTS 7.3.1 Axial Pull Tests 7-1
7-2 7.3.3 7.3.4 Load C clin Tests 7-3
7-4 TABLE 7-1 SLEEVE-TUBE ASSEMBLY MECHANICALTESTING RESULTS"'OMPONENT AND TEST RESULT MAXIMUM RESULT MINIMUM Welded Joint Axial Load Capability Upward Direction Downward Direction Rolled Joint Axial Load Capability No slippage Welded Joint Cyclic Loading Rolled Joint Cyclic Loading Sleeve Burst Pressure Sleeve Collapse
- A minimum of three tests of each type were performed.
7-5
8.0 STRUCTURAL ANALYSISOF SLEEVE-TUBE ASSEMBLY This analysis establishes the structural adequacy of the sleeve-tube assembly. The methodology used is in accordance with the ASME Boiler and Pressure Vessel Code,Section III. The work was performed in accordance with 10CFR50 Appendix B and other applicable U.S. Nuclear Regulatory Commission requirements.
8.1
SUMMARY
AND CONCLUSIONS Based on the analytical evaluation contained in this section and the mechanical test data contained in Section 7.0, it is concluded that both the Expansion/rolled Transition Zone (ETZ) and Tube Support Plate (TS) sleeves described in this document, meet all the requirements stipulated in Section 8.0 with substantial additional margins. In performing the analytical evaluation on the tube sleeves, the operating and design conditions for all of the ABB/CE as well as the Westinghouse ~oeratin~ plants with 3/4 inch Inconel 600 tubes are considered (Reference 8.2).
8.1. 1 Design Sizino In accordance with ASME Code practice, the design requirements for tubing are covered by the specifications for the steam generator "vessel". The appropriate formula for calculating the minimum required tube or sleeve, thickness is found in Paragraph NB-3324.1, tentative pressure thickness for cylindrical shells (Reference 8.1). The following calculation uses this formula for the tube sleeve material which is Alloy 690 material with a specified minimum yield of 40.0 ksi.
i= 0.025 i<i. < i, = 0.030 in. (minimum sleeve ihiclaiess) Reference 8.10 Where t = Min. required wall thickness, in.
P = Design Tubesheet differential pressure, ksi (max. value for plants, Ref. 8.2)
R = Inside Radius of sleeve, in. (maximum value for plants considered)
S = Design Stress Intensity, S.l. @ 650'F maximum design (per Reference 8.16) 8.1.2 Detailed Anal sis Summ When properly installed and welded within specified tolerances, tlie ETZ sleeve and its upper weld and lower rolled joint, and the TSP sleeve and its two primary welds possess considerable margin against pull-out for all loading which can be postulated from operating, emergency, test, and faulted conditions.
8-1
8-2 The evaluation of the TS upper and lower welds shows that the stresses and loads calculated for the ETZ upper weld are bounding. Physically, the upper and lower welds of the TS sleeve are a duplicate of the ETZ upper weld. The ETZ sleeves at 26 inches are subjected to much higher loads than the shorter 9.0 inches or less TS sleeve, and therefore, the following analysis for the ETZ sleeves bounds the TS sleeves.
8-3
TABLE 8-1 SVMMARYOF SLEEVE AND WELD ANALYSIS RESULTS
- - The allowables listed in Table 8-1 are in accordance with the ASME Code (Refs. 8.1 and 8.16)
BDRMIIILABSDR DBAIEIIAIMEMBIDINEBIIIESIZB BDMMAIDZEDIN SAIIIE I-I (Note: All SI equations below are a derivation of the formula in Par. NB-3324.1 of Ref. 8.1.)
- 1. GENERAL PRIMARY MEMBRANESTRESS DESIGN TUBESHEET DELTA PRESSURE
- 2. MAINSTEAM LINE BREAK FOR ABB/CE PLANTS
- 3. FEEDWATER LINE BREAK FOR WESTINGHOUSE PLANTS
- 4. PRIMARY PIPE BREAK LOCA 8-5
TABLE 8-2 SQMIVIARYOF ROLLED JOINT DESIGN ANALYSIS AND TEST RESULTS 8-6
8.3.2 Postulated Pi e Ru ture Accidents NRC Regulatory Guide 1.121 requires the following:
"The margin of safety against tube failure under postulated accidents, such as a LOCA, steam line break, or feedwater line break concurrent with the safe shutdown earthquake (SSE),
should be consistent with the margin of safety determined by the stress limits specified in NB-3225 of Section III of the ASME Boiler and Pressure Vessel Code".
The above referenced ASME code paragraph deals with "faulted conditions", where for an elastic analysis of Inconel 690 sleeves, a general membrane stress of 0.7 S. = 0.7(80.0) =
56.0 ksi is allowed. In conjunction with the NRC Regulatory Guide 1.121, the following accidents are postulated:
8-10
S.2 LOADINGS CONSIDERED In this section a number of potential failure modes are examined to determine the relative safety margins for selected events. Failure loads are calculated based on minimum dimensions and compared with mechanical testing results from Section 7.0. Both calculated and measured loads are compared with the maximum postulated loads.
8.2.1 U r Tube Weld Pullout Load Assuming the parent tube is totally severed, the minimum load required to shear the upper tube weld is calculated. The force required to pull the expanded sleeve through the unexpanded tube is conservatively neglected.
In the event of a main steam line break (MSLB) for an ABB/CE plant, the secondary pressure would drop in a short time interval. Without rapid operator action, subsequent to the dryout of the faulted steam generator, continued Emergency Core Cooling System (ECCS) flow, combined with the heatup of the RCS from decay heat, a gradual repressurization of the RCS will result in a maximum value of 2520 psi (Reference 8.9). Postulating a main steam line break (MSLB) accident, the maximum available load would be In the event of a feedwater line break (FWLB) accident for a Westinghouse plant, the value of 2850 psi (Reference 8.4) is used. The maximum pullout load would be:
8-7
8.2.2 Lower Sleeve Rolled Section Pushout Load Assuming the parent tube is totally severed, the minimum load required to rupture the lower rolled section is calculated. The minimum measured test value for the pushout load is 2000 lbs., see Section 7. Postulating a loss of primary coolant accident (LOCA) during hot standby condition (0% Power), the maximum available load would be:
~ ~
Note that the LOCA pipe break accident is not controlling for this joint. See Section 8.4.6.
8.2.3 Weld Fatigue Since the factors of safety are quite high for loadings due to primary stress, the failure mechanism of greatest interest is the fatigue failure mode considering the variable axial loading of the sleeve during normal operating transients.
In Section 8.6.1, fatigue evaluations of the upper weld, which join the sleeve to the tube will be made. It is first necessary to determine the effects that tube lock-up within the tubesheet and tube supports have on the axial loads in the sleeve during normal operation. This subject is addressed in Section 8.4.
8.3 EVALUATIONFOR ALLOWABLESLEEVE WALLDEGRADATIONUSING REGULATORY GUIDE 1.V.1 NRC Regulatory Guide 1.121 (Reference 8.3) requires that a minimum acceptable tube (or sleeve) wall thickness be established to provide a basis for leaving a degraded tube in service.
For partial thru-wall attack from any source, the requirements fall into two categories, (a) normal operation safety margns, and (b) considerations related to postulated pipe rupture accidents.
8.3.1 Normal eration Safe Mar 'ns It is the general intent of these requirements to maintain the same factors of safety in evaluating degraded tubes as those which were contained in the original construction code, ASME Boiler and Pressure Vessel Code,Section III (Reference 8.1).
For Inconel Alloy 600 and 690 tube or sleeve materia! the controlling safety margin is:
"Tubes with partial thru-wall cracks, wastage, or combinations of these should have a factor of safety against failure by bursting under normal operating conditions of not less than 3 at any tube location".
8-8
From Reference 8.2, the normal operating conditions for the "worst" case envelopment of steam generators from both the ABB/CE and Westinghouse plants are:
Primary Pressure Pp. 2250 psi Secondary Pressure P = 815 psi Differential Pressure d,P = Ppri - Pace = 1435 psi Average Pressure P, = 0.5 (P~ + P ) = 1533 psi Assuming the parent tube is totally severed, the sleeve is required to carry the pressure loading. The following terms are used in this evaluation.
R = sleeve nominal inside radius Sy = minimum required yield strength (per U.S. NRC Reg. Guide 1.121, Ref. 8.3)
Sy~ = minimum yield strength of sleeve (Sy = 35.2 ksi min. at 650 'F, Ref. 8.16) 8-9
8-10 8.3.3 Minimum Weld Height Re uiremeat 8.3.3 Minimum Weld Height Re uiremeat Coat'd 8-12
8.4 EFFECTS OF TUBE LOCK-UP ON SLEEVE LOADING Objective: Conservatively determine the maximum axial loads on the sleeve (tension and compression) during normal operation.
General Assumptions: (See Figures 8-2 through 8-5).
8.4.1 Sleeved Tube in "Worst" Case ABB/CE Plant, Free at Eg~ Crate Su rt 8-13
The sleeve loads, Fi, are in Table 8-4A for the transient conditions shown in the same table.
8.4.2 Sleeved Tube in "Worst" Case Westin ouse Plant, Free at Tube Su rt 8-14
8.4.3 Sleeved Tube in "Worst" Case ABB/CE Plant, Lock-u at First Ea Crate Su ort 8.4.4 Sleeved Tube in "Worst" Case Westin ouse Plant, Lock-u at First Su rt 8-15
E 8-3A 26 1 I SLEEVE<
AXIALMEMBER PHYSICAL PROPERTIES FOR "WORST" CASE ABB/CE PLANT NOTE: 'ominal Dimensions for sleeve from Reference 8.10.
' and E for Inconel 690 from Ref. 8.13, Part D, Tables TM-4, TE-4 (same or more conservative than Ref. 8.12).
'ominal Dimensions for tubes from Reference 8.15.
' and E for Inconel 600 from Reference 8.13, Part D, Tables TM-4, TE-4.
' for Carbon Moly Steel from Reference 8.13, Part D, Table TE-1.
8-16
T E 8-38 26 INCH SLE<EVC<
AXI'ALMEMBER PIIYSICAI PROPERTIES FOR "WORST" CASE WESTINGHOUSE PLANT NOTE: 'ominal Dimensions for sleeve from Reference 8.10.
' and E for Inconel 690 from Ref. 8.13, Part D, Tables TM-4, TE-4 (same or more conservative tlian Ref. 8.12).
'ominal Dimensions for tubes from Reference 8.14.
' and E for Inconel 600 from Reference 8.13, Part D, Tables TM-4, TE-4.
' for Carbon Moly Steel from Reference 8.13, Part D, Table TE-I.
8-17
~ ~ ~ ~ ~ ~
~ ~
~ ~
TABLE 8MB AXIALLOADS IN SLEEVE WITH TUBE NOT LOCI<ED INTO TUBE SUPPORT FOR "WORST" CASE WESTINGIIOUSE PI.ANT
- NOTE: Due to small variation, E and a, value for normal operation, 100% power, are used.
8-19
TABLE 8-5A AXIALLOADS IN SLEEVE WITH TUBE LOCKED INTO EGG CRATE SUPPORT FOR "WORST" CASE ABB/CE PLANT
- NOTE: Due to small variation, E and a value for normal operation, 100% power are used.
8-20
TABLE 8-58 AXIALLOADS IN SLEEVE WITH TUBE LOCKED INTO TUBE SUPPORT FOR "WORST" CASE WESTINGHOUSE PLANT
- NOTE: Due to small variation, E and a value for normal operation, 100% power are used.
8-21
8.4.5 Effect of Tube Prestress Prior to Sleevin~
8.4.6 Lower Sleeve Rolled Section Pushout Due to Restrained Thermal Ex ansion 8-22
8.5 SLEEVED TUBE VIBRATIONCONSIDERATIONS The vibration behavior is reviewed since the installation of a sleeve in a tube could affect the dynamic response characteristics of the tube.
8.5.1 Effects of Increased Stiff'ness Stiff'ness and mass have opposing influences on tube vibration. While increased stiffness tends to raise the tube natural frequency, increased mass tends to lower it. ABB/CE's vibrational testing (Reference 8.6) demonstrated among other things, that a solid rod of the same O.D. as a tube will vibrate at nearly the same frequency. However, the displacements for the stiffer rod will be significantly less.
In addition, if any contact is made between the tube and sleeve along their length, the increased damping will absorb more ener~. The damping would have a significant effect onthe amplitude of vibration. In light of this damping effect and the other above mentioned effects resulting from a sleeve inside a tube, the vibration performance of the tobe/sleeve assembly is superior over the original tube.
8.5.2 Effect of Severed Tube 8-23
8-24 8.5.3 Seismic Evaluation The natural frequency of a sleeved tube for the span between the tubesheet and the first tube support for the "worst" case situation is:
f = (15.4/2zl') x (EIJW/I)" = 38.0 HZ, (Reference 8.5) where:
f~ = natural frequency, HZ l = span length = 47.75 in. (maximum value in Reference 8.2)
E = 28.78 x 10'si (minimum value for Inconel 600 tube at 573.3'F)
I = Tube Moment of Inertia = 0.0066 in.'
= Tube Weight + Weight of Primary Water in Tube &, Sleeve + Sleeve Weight +
Weight of Secondary Water Displaced W = 1.542 + 0.374 + 0.279 + 0.581 = 2.775 lb.
g = 386 in/sec"-
The natural frequency is based on a healthy tube span with an installed sleeve. Vibration test results of sleeved tubes (See Section 8.5.2) concluded that tube sleeves have negligible effect on the vibration characteristics of the tubes. Test results indicate a natural frequency for a completely severed tube somewhat below the healthy tube frequency, but above the seismic cut-off frequency of 33 HZ. Hence, the seismic evaluation is performed for the static equivalent load above 33 HZ.
The seismic load for a "worst" case situation, which more than envelopes the seismic curves in Reference 8.2 for loading above 33 HZ, is:
OBE = 2.25 g In the span between the tubesheet and support the OBE seismic load is:
woBE = (1.0 + 2.25) W/l = 0.189 lb./in.
For the fixed - pinned model the maximum moment is:
Moaz = 1/8 woeful"- = 53.8 in.-lb.
8-25
Considering the sleeve cross section:
Do 0.625 in.
Di = 0.562 in.
I = 0.0026 in.'
= Do/2 = 0.3125 in.
Stressoaa = MoaaC/I = (53.8)(0.3125)/(0.0026) = 6.5 ksi ( 1.5 S = 39.9 ksi It is concluded that a seismic event produces a small stress in the tube sleeve.
8-26
8.6 STRUCTURAL ANALYSIS FOR NORMAL OPERATION A static elastic analysis of the sleeved tube assembly was performed according to the requirements stipulated in NB-3220 Section III of the ASME Code Section. Section 8.6.1 describes the methods used to analyze the upper tube weld.
8.6.1 Fatigue Evaluation of U er Sleeve/Tube Weld 8-27
8-28 UPrza. SLZZvz mZLD - T~m~vrS CONSmzmm ZOR AW ma/Cz p~yr 8-29
TABLE 8-7 UPPER SLEEVE WELD - TRANSIENTS FOR A WESTINGHOUSE PLAÃZ 8-30
0 8.6.2 Evaluation of Lower Sleeve Rolled Section 8-31
LOWER SLEEVE SECTION - TRANSIENTS CONSIDERED I OR AN AHB/CE PLANT 8-32
E 8-9 LOWER SLEEVE SECTION - TRANSIENTS CONSIDERED FOR A WESTINGHOUSE PLANT 8-33
8.7 REFEEU<22'CES FOR SECTION 8.0 8.1 ASME Boiler and Prcssure Vessel Code,Section III for Nuclear Power Plant Canponents, 1989 editmm.
8.2 ABB/CE Letter Report No. CSE-96-116, "Tube Sleeve Kstory Data for 3/4 inch Steam Gaierator Tubes", May 07, 1996.
8.3 U.S. NRC Eb~iatory Guide 1.121, "Bases for Plugging Degraded PWR Steam Generator Tubes".
8.4 ABB/CE License Report CEN<24-P, Rev. 00, "Carolina Power 8h Light Shemon Hanis Steam Generator Tube Repair Using Leak Tight Sleeves", July 1995.
8.5 "Mechanical Vibrations", 4th Edition, by J.P. Hartog, McGraw+Bl Book Co., New York, New York, pg. 432.
8.6 "Vibration in Nuclear Heat Bcchingers Due to LMtuid and Two-Phase Flo," By WL Heiilm aud R.Q. Vmceat, Journal of Engiiieaing Sr Power, Vol. 103, Pages 358-366, April 1981 (REF 015).
8.7 "ANSYS" Finite Elanait Coinputer Code, Rev. 5.1, 1994, by Swans'nalysis Sys., Inc.
8.8 EPRI NP-1479, 'Ei5xt of Out+f-Plane Daiting Loads on the Structural Integrity of Steam Generator Internals," Coritiactor. Caiibustion Engineering, August 1980.
8.9 ABB/CE License Report CEN413-NP, Rev. 01, "Arizona Public Service Co. Palo Verde Steam Genaator Tube Repair Using Leak Tight Sleeves", January 1995.
8.10 ABB/CE Drawing No. D-SGNS-222401, Rev. 02, R'IZ Sleeve for 3/4" Dianieter Steam Gaierator Tubes".
8.11 ABB/CE Drawing No. D-SGNS-222402, Rev. 04, 'RTZ Sleeve Instalhtion".
8.12 Inconcl 690 Huntlogtcn Alloys, Inc., Hunttttgtou, W. Vugttna.
8.13 ASME Boiler and Pressure Vessel Code, Section 11, Materials, 1995 edition.
8.14 Westinghouse Steam GaMuator Standard Information Package, Jan. 04, 1982 (REF-96402).
- 8. 15 ABB/CE Drawing No. E-234622, Rev. 1, "Tube Details for SONGS II Steam Generator".
8.16 ASME Boiler and Pressure Vessel Code Case N-20-3, "SB-163 Nickel&hromium-Iron Tubing (Alloys 600 and 690) ... at Specdied Mimmm Yiehi Strength of 40.0 ksi ...,Section III, Division 1, Class 1", November 30, 1988.
8.17 ABB/CE Report No. TR-ESF 178, Rev. 1, "Palisades Steam Gaiaator Tube/Sleeve Viiion Tests", October 05, 1977 (REF-96403).
8-34
FIGURE 8-1 VKLDED SLEEVE/TUBE ASS~iLY 8-35
FIGURE 8-2 SYSTEMS SCHEMATIC FOR "WORST" CASE ABB/CE PLANT 8-36
FIGURE 8-3 SYSTEM SCHEblATIC FOR "WORST" CASE WESTINGHOUSE PLANT 8-37
FIGURE 84
. STIFFNESS MODEL OF SLEEVE ADD LOVER TUBE 8-38
X~MURK 8-v STIFFNESS MODEL OF UPPER TUBE AND SURROUiiDPfG TUBES 8-39
FPGTE ELEMENT MODEL OF UPPER TUBE WELD
APPENDIX 8A FATIGUE EVALUATIONOF UPPER SLEEVE/TUBE WELD 8A-1
INTRODUCTION The analysis presented in this appendix is discussed in detail in Section 8.6.1 of this Report. The results from the two (2) finite element models considered are presented in this Appendix. The model geometry is shown in Figure 8-6 of the report. The only difference in the two models is the weld height and the number of elements. The [ ] weld height model is based on the design geometry minimum dimension. The [ ] model is based on the minimum required axial weld length for operating and accident conditions. All stresses and usage factors for both configurations are satisfactory when compared to allowables.
GENERAL DISCUSSION The Finite Element Method (FEM) was incorporated in this analysis, using the ANSYS Computer Code (Reference 8.7). Figure 8-6 depicts the FEM model of the upper tube weld for both the ABB/CE and Westinghouse operating plants with Inconel 600 tubes. A tube thickness of .043 inches is conservatively used in the analysis. This will encompass the .048 inch tube design.
The lower end of the tube was assumed to be locked near the secondary side surface of the tubesheet.
From Section 8.4, it was found that the sleeve develops higher compressive loadings if the tube is free to slide through the first support . Therefore, sliding at the tube-to-support interface was conservatively assumed. The FEM model consists of 2-D isoparametric elements with an axisymmetric option. The ANSYS input and output data are included in Attachment 1.
The axial loads are conservatively determined from a thermal interaction for a [ ] inch sleeve length using the equations in Section 8.4. These axial loads are applied to the bottom of the sleeve finite lement model. The ABB-CE operating and transient conditions are used because they result in the highest temperature differences and highest axial loads. The transients were selected on the basis of the worst case combinations as explained in Section 8.6.1. The stresses resulting from the axial load cases are combined with the 100% steady state pressure case stresses. These combined stresses are combined with the thermal case stresses resulting from the radial thermal expansion for the transients considered.
A stress concentration factor of 4 is conservatively applied to the linearized membrane plus bending stresses for the axial, radial and shear stress components. The concentration factor is applied at the sleeve outside surface located below the weld, the top and bottom of the weld, and to the inside surface of the tube location above the weld.
The minimum required axial length of weld of [ ] inches was determined in Section 8.3.3. A fatigue analysis was performed using a conservative weld height of [ ] inches. The finite element model used for the [ ] inch weld design was modified by refining the element mesh as shown in Appendix 8A. For simplification purposes, the pressure stresses and stresses due to the radial thermal expansion were conservatively excluded. These pressure and thermal stresses result in tensile stresses which relieve the compressive stresses resulting from the axial loads.
The results of the analyses consist of the nodal stresses at the critical section, range of stress evaluation nd the calculation of the fatigue usage factor.
FIGURE SA-1 NODE AND STRESS CUT IDEÃI'XFICATION 8A-3
TABLE 8A-1A STRESS RESULTS 100Vo STEADY STATE 8A-4
TABLE SA-1B STRESS RESULTS 15'TEADY STATE 8A-5
TABLE SA-1C STRE~SS RESULTS 0% STEADY STATE 8A-6
TABLE SA-1D STRESS RESULTS FEED%'ATER CYCLING SA-7
TABLE SA-2A RANGE OF STRESS AT WORST LOCATION 8A-8
TABLE SA-2B FATIGUE EVALUATIONAT WORST LOCATION 8A-9
FIGURE 8A-2 NODE'Ai>D STRESS CUT IDEiiTII!ICATION FOR 20 iVIXL~LD 8A-10
TABLE SA-3A SMKSS RESULTS 100% STEADY STATE .02" Veld 8A-11
TABLE SA-33 STRESS RESULTS 15% STEADY STATE .02" Weld
TABLE SA-3C STRESS RESULTS 0% STEADY STATE .02" Weld) 8A-13
0 TABLE SA-3D STRESS RESULTS FKEDV'PATER CYCLING .02" Veld) 8A-14
TABLE SA-4A RANGE OF STRESS AT WORST LOCATIONS .02" Weld 8A-15
TABLE SA-48 FATIGUE EVALUATIONAT WORST LOCATIONS .D2" Weld 8A-16
TABLE SA-48 (Coat'd)
FATIGUE EVALUATIONAT WORST LOCATIONS .02" Weld 8A-17
APPENDIX SB TUBE SLEEVE HISTORY DATA 88-1
iL IS Ik PLQIF
@SEA BRQwN 9QVFRt Inter-Qfrice Correspondence To: W. R. Gahwiller May 07, 1996 44 Southeast Nuclear Service Center cc: D. P. Siska CSE-96-116/ Page 1 of 4 D. G. Stepnick T. M. Taylor
SUBJECT:
TUBE SLEEVE HISTORY DATA FOR 3/4 INCH STEAiH GENERATOR TUBES
REFERENCES:
(1) CENW1-P Rev. 0-P License Report, "Arkansas Nucl~ Oae Unit 2 Stmn Gmerator Tube Repair Using Leak Tight Sees" Juae 1992.
~
(2) CR-9417-CSE92-11194 Report, "Evaluaaoa of an ABB/CE Tube Sle=ve for Applicarion in Louisiana Power Ec Light Steam Generators Wat".;ord Unit 3, November 1992.
(3) CR-9417-CSE94-11194 R port, "Evaluarion of an ABB/CE Tube Sleeve for Applicarion in Maine Yankee Steam Genetatois", September 1994.
(4) CR-9417-CSE93-1 128-1 Report. "Evaluarioa of aa ABB/CE Tube Sle=ve for Applicarion in APS - Palo Verde Units 1, 2, 2 3 Steam Generator". January 1995.
(5) CR-941 KSE95-11194 Rcport, "Evaluarion of an ABB/Ci Tube Sle=ve for Applicarion in B.G.AE. Calvert CliffSeam C<neratots, Sept mber 1995.
(6) CENC-1272 2 1298 Reports, Aaalyrical R-ports for Southern California Edison San Oaofte Units 2 Ec 3 Smm generators", Sept"mber 1976 and September 1977.
(7) CEi%68-P Rev. 0-P Lie=use Report, "Florida Power k. Light Co. St. Lucie Units 1 dc 2 Steam Cinerator Tube Repair Using ~c Tight Sleeves', February 1988.
(8) CEN-337-P Rev. 0-P Licens Report, "V. C. Summer Stm Cinerator Tube Repair Using Leak Tight Sleeves", August 1986.
(9) CB -388-P Rev. 0-P Licnse Report, Houston Power 8c Light South Texas St=tm Geaerator Tube Remr Using Leak Tight Sleeves, April 1950.
(10) CEN-Nl-P R v. 0-P Licks- Report, Ringhals 3 Ec 'tun C-aerator Tube Repair Using Leak Tight S! eeves", October 1990.
(11) CEiildCO-P Rev. 1-P Lie=use Report, "ASCO 1 k, 2 Steam Cinerator Tube Repair Using I "ak Tight Sie=ves", June 1992.
(12) CR-9417-CSE93-1115-0 Report. Evaluation of an ABB/CE Tube Sleeve for Application in Krsko St am Generators", June 1993.
(13) CR-9451<SE95-1104-0 Rcport, Evaluanon of an ABB/CE Tube Sine for Application in CommoavMth Edison Byron k. Braidwcod Units 1 2 2 Steara Generators, April 1995.
(14) CR-9451<SE95-11114 Report, "Evaluation of an ABB/CE Tube Steeve for Applicarioa ia Carolina Power 8c Light Shearon Harris Steam C~aetators", July 1995.
Southeast Nuclear Service Cent r (SNSC) reviewed the past tube sleeve r ports for 3/4 inch steam generator tubes.
References 1 through 14 coataia the Section 8 structural analysis as part of the license reports. A review was also made of the other 3/4 inch steam generator tubes, primarily, the Wesaaghous- D2/D3/D4 Series steam generators to see if their parameters would produce a worst" case situation greater than those plants reviewed in References 1 through 14. Table 1 on pages 3 and 4 contain the necessary parameters from the fourteen references to develop a worst" cas= envelopment situarion for further suuctural analysis of 3/4 inch tube sleeves. Those "worst" case items
<<r operariag" plants with Incoael 600 steam generator tubes are noted ia Table 1 with an asterisk ( ).
CSE-96-116 / Page 2 of 4 For a "single" Westinghouse Plant smdy of all D2/D3/D4 steam generators with Inconel 600 mbes (including those plants not in thc fourt~ references), the ASCO 1 k 2 Plants (whose stcam generators are being replaced with ones containmg Alloy 800 tubes) had the largest axial load on the tube slecvc. However, the next largest axial load on the tube sHve is Ne CPS'hcaron Hams Plant which still has Inconel 600 mbes in Ne steam generator. This axial load calcularion is 939 lb. which is mainly du= to the maximum difference between the primary and secondary temperamres used in thc smtctural analysis (i.e. 93.5'F).
For a 'single" ABB/CF Plant study of all the stcam generators wiN Inconel 600 mbes (including Nose plants not in the fourteen references), the Waterford 3 and SONGS Plams will have the largest axial load on the tube sleeve, primarily, due to the maximum difference betwc=n the primary and s"condary temperatures in the peripheral tubes for the structural analysis being 105'F.
Sincerely, B. A. Bell V1DUFICATIONSTATUS: COMPLETE The Safety-R:lat d design iniotmarion contained in this document has be"n verincd to be correct by means of Design Review using Ch enlist in QP-3.4 of QP!vl-101.
Name Signature Indeed ut R mwer BAB:bab
~ ~
~ ~
I ~
~ ~
s l
~ (
~ ~
~ ~
- 9. SLEEVE INSTALLATI N VERIF~ICATI 9.1
SUMMARY
AND CONCLUSIONS The ABB-CENO welded sleeve installation process and sequence has been tested to ensure the installation of a sleeve which conforms to the design criteria described in Section 3. During this testing, actual steam generator conditions, such as the influence of tubes locked at tube supports, have been considered in assessing the acceptablity of the various processes and the sequence in which they are performed.
Actual sleeve operating history, as well as the qualification test program described within this report indicate that the ABB CENO steam generator tube sleeve is capable of performing as well as, if not longer than, the original tube in which it has been installed.
9.2 SLEEVE-TUBE INSTALLATIONSEQUENCE 9.2.1 Ex an i n Roll Tran i ion Zone leeve wi h Rolled Lower Joint The ETZ Sleeve with the rolled lower joint is described in Section 4.3 and Figure 4-3.
Installation is accomplished using the processes described in Section 4.5 in the following sequence:
9-1
9.2.2
~ ~ T~TI The TS Sleeve is described in Section 4.3 and Figure 4-4. Installation is accomplished using the processes described in Section 4.5 in the following sequence:
9.3 WELD INTEGRITY 9.3.1 A test program was conducted to establish the reduction of tube wall thickness after cleaning with the abrasive brush. Four oxidized tube samples were cleaned using a qualified brushing tool and process. It was determined that less than .0005 inches of metal was removed from each of the samples.
An additional test was conducted to determine whether the I.D. tube brushing would introduce noise interference on the bobbin coil eddy current test. A clean section of tubing was baseline tested to determine I.D. noise levels. The tubing was subsequently heat treated to produce an oxidation layer on the tube. One half of the tube section was then brushed to remove the oxide coating and the sample was retested with the bobbin coil. The results (Figure 9-1) show that the oxide does in fact generate a noise 9-2
component. However, after the tubing is brushed, the noise level returns to that of the baseline (pre-heat treat) data.
9.3.2 Ex ansion uglification An extensive test program was performed to qualify the bladder expansion tool and process, which provides a tight sleeve/tube fit up in preparation for welding. This program considered tubing with thick, thin and nominal walls as well as tubing with different heat treatments (yield strengths).
9-3
9.3.4 ltra nic Te in ualifica ion Ultrasonic (U.T.) techniques are employed to confirm the presence of weld fusion into the tube. A test program was completed by ABB-CE to qualify the Ultrasonic Examination of sleeve/tube upper welds. Fourteen sleeve/tube weld specimens were prepared for this qualification program. Each weld was ultrasonically inspected and then hydrostatically tested to confirm U.T. results. Test results indicate complete correlation between ultrasonic and hydrostatic testing.
9.3.5
~ ~ Po Weld He t Treat ualifcation The tubing used in some steam generators has been shown to be very susceptible to the effects of Primary Water Stress Corrosion Cracking (PWSCC). As a result, these utilities must minimize the residual stress induced in the steam generator tubing associated with any repair process. If sleeving is selected as the repair method, the sleeve to tube weld joint as well as the weld heat affected zone and primary pressure boundary portion of the tube expansion requires annealing to minimize residual stresses. The Electric Power Research Institute (EPRI) has documented (Reference 4.7.4 of Section 4.7) evidence in support of the annealing process. It was determined that a 3 to 5 minute soak time at a tube temperature of 1300'o 1425'F was required to maximize tube life.
9-4
9.3.5.1 Instrumented Analysis of Locked Tubes A plot of the temperature profile and the axial load measured are shown in Figure 9-3. The results of this test are shown in Table 9-3. Although no measurements were taken, no abrupt changes in the tube diameter were observed along the length of the tube. It was concluded that the deformation experienced by the tube would not be detrimental either to the installation process, i.e.. in preventing the tool from being removed, or to the long term performance of the sleeve/tube joint as described in Section 5.
A similar test was performed on a two by four array of .750 inch O.D. x .042 inch wall tubes arranged in a square pitch and supported as shown in Figure 9-4. This configuration replicates the first three hot leg supports of a typical Westinghouse D3 Series generator while conservatively simulating aspects of a CE unit. In addition, this configuration is conservative when compared to a Westinghouse Series 44/51 steam generator. Four of the 9-5
tubes were locked at their support (but not the FDB) location by tack welding in four locations. The other four were free from the tubesheet to Support Plate No. 8. Two Tube Support (TS) sleeves and a tubesheet sleeve were installed in each tube as shown in the figure. The tubes were instrumented with strain gages to determine the strain in the outer fibers. During the heat treatment of each sleeve the strain in the tube was recorded. A load cell was used to determine the total load in the upper most section of tube. In the case of this mockup, the heat treatment commenced at the upper most weld and proceeded toward the tubesheet. Both sleeve welds (where applicable) were treated prior to any strain gage measurements. A typical temperature/time plot is shown in Figure 9-5. The results of the test are shown in Table 9-2. As would be expected, the more times the tube segments experiences the heat treat cycle the greater the residual stress. Examination of the tube surfaces in the vicinity of the welds indicated [
9.3.6 ~ummar In summary, ABB-CE has conducted a comprehensive development and verification program to ensure weld integrity of its leak tight sleeves. Experience has shown that oxide layers as visually confirmed to exist on the steam generator secondary side do not affect weld parameters and the abrasive cleaning method described in the report is effective in preparing the tube for welding.
9-6
9.4 ROLLED JOINT INTEGRITY A development program was conducted to ensure the rolled joint of the ETZ sleeve was leak tight and capable of withstanding the design loads. The sleeves were rolled into mock-ups consisting of steam generator tubes which had been rolled into blocks simulating the tube sheet. The sleeves were then tested to confirm the rolled joint was leak tight both before and after cyclic load testing. Tests of the rolled joint were also conducted where process parameters such as torque, tube diameter and roll location relative to the [ ] were varied. A test matrix was used to verify the sleeve installation with sleeve rolling process parameter tolerances. The test program confirmed that the rolled joint integrity is acceptable within the allowable rolling process tolerances.
9.5 COMMERCIALSLEEVE. INSTALLATION ABB-CE's commercial sleeving experience is shown in Table 9-3. The success rate for all installed welded sleeves is 98%. Since 1985, no sleeve which has been accepted based on U.T. and V.T. has been removed from service due to service related degradation.
9.6 REFERENCES
FOR SECTION 9.0 9.6.1 Test Report on Steam Generator Tube Cleaning for Installation of Welded Sleeves, TR-MCM-126.
9.6.2 An Investigation of the Installation of Welded Sleeves in R.E. Ginna Tubing, TR-MSD-128.
9.6.3 Sleeving Centrifugal Wire Brush Development and Life Test Report, TR-ESE-705.
9.6.4 S.G. TSP/RTZ Sleeving-Tube I.D. Cleaning for 3/4 Inch O.D. X .042/.043 Wall Tubes, TR-ESE-860.
9.6.5 Steam Generator Sleeving - 3/4 inch Program, Bladder Expansion Pressure, TR-ES E-755.
9.6.6 Steam Generator Sleeving - 3/4 inch Program, Qualification of RTZ and TSP Sleeve Expansion Tools and Bladder Life Test, TR-ESE-809.
9.6.7 Ultrasonic Examination of 3/4 inch O.D. S.G. Tube to Sleeve Upper Welds, TR-400-001.
9-7
9.6.8 Qualification of the Post Weld Heat Treatment Tool for Westinghouse "D" Series Steam Generators, 00000-ESE-830.
9.6.9 Qualification of the Roll Transition Zone (RTZ) Sleeve Rolled Joint, 00000-ESE-826.
9-8
TABLE 9-1 0.875 O.D. SLEEVED TUBE PWHT DATA 9-9
TABLE 9-2 0.750" O.D. SLEEVED TUBE PWHT DATA TUBES LOCKED AT ALLSUPPORTS 9-10
TABLE 9-3 ABB CENO S/G SLEEVE OPERATING HISTORY 9-11
i FIGURE 9-1 POST HEAT TREAT - BRUSHED SECTION 9-12
FIGURE 9-2 0.875 O.D. LOCKED TUBE TEST 9-13
FIGURE 9-3 0.875 O.D. LOCKED TUBE TEST TEMPERATURE AND AXIALLOAD PROFILE 9-14
FIGURE 9-4 0.750 O.D. LOCKED TUBE MOCKUP 9-15
FIGURE 9-5 0.750 O.D. TYPICAL TEMPERATURE PROFILES 9-16
10.0 EFFECT OF SLEEVING ON OPERATION Multiple plant specific analyses have been performed to determine the effects of installation of varying lengths and combinations of ETZ and TS sleeves. Sleeve lengths and various combinations of installed sleeves were used to evaluate the effect of sleeving on the hydraulic characteristics and heat transfer capability of steam generators. Using the head and flow characteristics of the pumps, in conjunction with the primary system hydraulic resistances, system flow rates have been calculated as a function of the number of sleeved tubes and the types of sleeves installed. Similarly, curves are generated from calculations that show the percent reduction in system flowrate as a function of newly plugged tubes (per steam generator). These curves are derived from plant specific information based on the following steam generator conditions:
Number Of Open Tubes Per Steam Generator Number Of Tubes Sleeved Primary System Flowrate Primary Coolant Temperature This information has been used to generate tables, such as Table 10-1, that provide hydraulic equivalency of plugs and installed sleeves, or the sleeve/plug ratio. Table 10-1 is provided as an approximation only and is based on assumed operating parameters and sleeve types for steam generators with 3/4" O.D. tubes. It must be assumed that some variations in the sleeve/plug ratio will occur from plant to plant based on operating parameters and steam generator conditions.
The overall resistance to heat transfer between the primary and secondary side of the steam generator consists of primary side film resistance, the resistance to heat transfer through the tube wall, and the secondary side film resistance. Since the primary side film resistance is only a fraction of the total resistance and the change in flow rate is so small, the effect of this flow rate change on heat transfer is negligible.
When the sleeve is installed in the steam generator tube there is an annulus between the sleeve and tube except in the sleeve-tube weld regions. Hence, there is effectively little primary to secondary heat transfer in the region where the sleeve is installed. The loss in heat transfer area associated with sleeving is small when compared to the overall length of the tube.
In summary, installation of sleeves does not substantially affect the primary system flow rate or the heat transfer capability of the steam generators.
10-1
TABLE 10-1 TYPICAL SLEEVE TO PLUG E UIVALENCYRATIO CASE CONFIGURATION RATIO (Sleeve/Plug)*
1 ETZ (1) 2 ETZ (1) + TS (1) 3 ETZ(1) + TS (2)
"'his ratio should be considered approximate due to plant to plant variations.
10-2
APPENDIX A PROCESS AND WELD OPERATOR UALIFICATIONS A.1 SLEEVE WELDING AND SLEEVE WELDER UALIFICATION Sleeve welding is qualified using an approved test procedure (Reference 1). The sleeving test procedure is in compliance with applicable sections of the ASME Code. Sleeve welders are qualified using test records in accordance with applicable sections of the ASME Code.
The test procedure specifies the requirements for performing the welds, the conditions (or changes) which require requalification, the method for examining the welded test assemblies and the requirements for qualifying the welding operators. Sleeve welding is qualified by performing six consecutive welds of each type which meet specified design requirements. Welders are qualified by performing two consecutive successful welds of each type.
A.2 REFERENCES TO APPENDIX A
- 1. Welded Steam Generator Tube Sleeve Semi-Automatic Gas Tungsten Arc Detailed Welding Procedure Qualification, Test Procedure 00000-MCM-050.