ML20100B828
| ML20100B828 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 01/04/1996 |
| From: | Fleck J BABCOCK & WILCOX CO. |
| To: | |
| Shared Package | |
| ML19311B930 | List: |
| References | |
| BAW-10204, BAW-10204-R02, BAW-10204-R2, NUDOCS 9601260237 | |
| Download: ML20100B828 (227) | |
Text
i BAW-10204 REVISION 02 JANUARY 1996 SOUTH TEXAS PROJECT TUBE REPAIR CRITERIA FOR ODSCC AT TUBE SUPPORT PLATES FTl Non-proprietary FRAMATOME TECHNOLOGIES, INC.
P.O. BOX 10935 LYNCHBURG,VA 24506-0935 je822;gggggg;gg;,
BWNT 20311 A-8 (4/90)
BSWNUCLEAR BWTECHNOLOGIES LICENSING DOCUMENT APPROVAL File Point:
Document
Title:
/+ 7 45 RF 66 [f'/'4/4 b/ re'/./4 FsAt GPSe%- M 'Ti/BC 4Ut/DK.~f AWGS Doc.No. N- I OM4 O V O E- I /4 /'t k Rev/No.'/Date' O PSAR O FSAR % Topical O Draft O Documented Report Tech. Spec. Response to NRC Questions Document Preparer #~ ' L L fi l let h- 1 A g/ Signat'ure 9 fatel Document Preparer's Manager /f' c N/hO 4. C#l /!'/ fle Signature Date '
Document Reviewer C Jeerur c. e> cow 3t f/qMe
( Signature ' 'Date For Topical Reports Only is a list of source references required? O Yes yo if yes, complete source references on reverse side of this form
/ ddC-
/ Preparer's Preparer's initials Manager's
. Initials
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This document is the non-proprietary version of the proprietary document BAW-10204P-02. In order for this document to meet the non-proprietary criteria, certain blocks of information were withheld. The basis for determining what information to withhold was based on the criteria listed below. Depending upon the application criteria, the criteria codes below represent the ,
withheld information.
b (c) The use of the information by a competitor would decrease his expenditures, in time or resources, in designing, l producing or marketing a similar product.
l (d) The information consists of test data or other similar data ~ !
concerning a process, method or component, the application !
of which results in a competitive advantage to FTI. !
(e) The information reveals special aspects of a process, i method, component or the like, the exclusive use of which results in a competitive advantage to FTI. !
[] H' The information contains data that is directly proprietary to PTI and the corresponding code from above is applied to the information as needed between the brackets. .
[] " The information contains data that is directly proprietary [
to EPRI and HL&P, as a member of EPRI has declared that this information is proprietary to EPRI and therefore was e removed.
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- TABLE OF CONTENTS 4
Pace ,
LIST OF TABLES' ii !
1 LIST OF FIGURES iii !
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e -LIST OF ABBREVIATIONS vi 1
l RECORD OF REVISIONS .viii l
1.0 INTRODUCTION
1-1 i
.2.0 EXECUTIVE
SUMMARY
2-1 I 2 ,
1
.3.0- GENERIC LETTER APPLICABILITY TO STP 3-1 ,
V l 4.0 GENERIC LETTER EXCEPTIONS FOR STP 4-1 l 5.0 STP STEAM GENERATOR DESIGN INFORMATION 5-1 '!
6.0 REPAIR LIMITS 6-1
- 7.0 NDE INSPECTION CRITERIA 7-1 l
l 8.0' TUBE REMOVAL AND EXAMINATION / TESTING 8-1 l 9.0 VOLTAGE DISTRIBUTIONS AND PROJECTIONS 9-1 !
10.0 PROBABILITY OF BURST 10-1 11.0 EVALUATION OF LEAKAGE 11-1 12.0 OPERATIONAL LEAKAGE LIMITS 12-1 ,
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? 13.0 REPORTING REQUIREMENTS 13-1 ;
1 14.0 EXCLUSION OF INTERSECTIONS 14-1 I
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15.0 CONCLUSION
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16.0 REFERENCES
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APPENDIX A - NDE DATA ACQUISITION AND ANALYSIS REQUIREMENTS A-1 FOR.ODSCC AT TSP ARC 1 i
- FRAMATOME TECHNOLOGIES, INC.
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LIST OF TABLES i Page l I
TABLE 5-1 W-E DESIGN AND OPERATING CHARACTERISTICS 5-3
- TABLE 6-1 STP-1 ARC REPAIR LIMITS TO SATISFY STRUCTURAL 6-4 REQUIREMENTS !
TABLE 8-1 RESULTS OF TUBE PULL EXAMINATIONS ON STP-1 8-6 '
(A-D) 1993 H/L TSP INTERSECTIONS l TABLE 8-2 RESULTS OF TUBE PULL EXAMINATIONS ON STP-1 8-10 (A,B) 1995 H/L TSP INTERS 2CTIONS TABLE 9-1 STP-1 FIELD BOBBIN CALLS AND RE-SIZED CALLS 9-9 t FOR DSIs AT H/L TSPs 1995 INSPECTION t TABLE 9-2 BOUNDING VOLTAGE GROWTH DISTRIBUTION FOR 9-40 !
STP UNIT 1 I l
TABLE 10-1 MATERIAL PROPERTIES FOR WESTINGHOUSE ALLOY 10-6 i 600 MILL ANNEALED 3/4" x 0.043" TUBING TABLE 10-2 STP-l'EOC-5 PROBABILITY OF BURST RESULTS 10-8 !
TABLE 10-3 VOLTAGE-BURST-LEAK RATE PROBABILITY'OF LEAK 10-13 DATA TABLE j i
TABLE 10-4 BASIS FOR EXCLUDING DATA FROM THE 3/4 INCH 10-19 i BURST CORRELATION (
i TABLE 11-1 PROJECTED EOC-6 LEAK RATES 11-7 TABLE 11-2 PROBABILITY OF LEAKAGE PARAMETERS 11-9 TABLE 11-3 BASIS FOR EXCLUDING INDICATIONS FROM 11-15 I 3/4" PROBABILITY OF LEAK CORRELATION TABLE 11-4 BASIS FOR EXCLUDING INDICATIONS FROM 11-16 3/4" LEAK RATE CORRELATION i TABLE 14-1
SUMMARY
OF TUBES TO BE EXCLUDED FROM ARC 14-17 k
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i LIST OF FIGURES 6 Page FIGURE 1
SUMMARY
OF THE MAJOR ASPECTS OF THE STP 1-3 ALTERNATE REPAIR CRITERIA '
i FIGURE 5-1 W-E RSG GENERAL ARRANGEMENT 5-4 '
FIGURE 9-1 STP-1 C S/G BOC 6 VOLTAGE DISTRIBUTION 9-41 FIGURE 9-2 -STP-1 BOUNDING VOLTAGE GROWTH DISTRIBUTION 9-42 i
(FROM TABLE 9-2) ;
a i FIGURE 9-3 STP-1 C S/G EOC 6 PREDICTED VOLTAGE 9-43 :
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DISTRIBUTION i FIGURE 10-1 BURST PRESSURE vs. BOBBIN AMPLITUDE FOR 3/4 10-20 INCH ALLOY 600 S/G TUBE MODEL BOILER AND FIELD DATA i l 1 FIGURE 10-2 BURST PRESSURE vs. BOBBIN AMPLITUDE 10-21 RESIDUALS vs. PREDICTED VALUES FIGURE 10-3 BURST PRESSURE vs. BOBBIN AMPLITUDE ACTUAL 10-22 2 vs. EXPECTED CUMULATIVE PROBABILITY '
FIGURE 11-1 2560 PSI MSLB LEAK RATE vs. BOBBIN 11-17 l i AMPLITUDE 3/4" TUBES, MODEL BOILER '
- AND FIELD DATA i FIGURE 11-2 RESIDUALS vs. PREL!CTED LOG OF LEAK RATES 11-18
- 3/4" TUBES, MODEL BOILER AND FIELD DATA FIGURE 11-3 CUMULATIVE PROBABILITY OF RESIDUAL LEAK 11-19 ;
2 RATES '
FIGURE 14-1 TSP MODEL 14-7 FIGURE 14-2 MODEL ELEMENTS 32 DEGREE WEDGE LOCATION 14-8 i
FIGURE 14-3 MODEL ELEMENTS 16 DEGREE WEDGE LOCATION 14-9 f j FIGURE 14-4 TUBE BUNDLE SHOWING TSP ELEVATIONS FOR 14-10 i IDENTIFYING WEDGE GROUPS FIGURE 14-5 WEDGE GROUP LOCATIONS: TSPs 1-11 14-11 '
j FIGURE 14-6 WEDGE GROUP LOCATIONS: TSP 12 14-12 i
j FIGURE 14-7 EXCLUDED TUBE REGION: TSPs 1-11 (NOZZLE SIDE) 14-13 FIGURE 14-8 EXCLUDED TUBE REGION: TSPs 1-11(MANWAY SIDE) 14-14 FRAMATOME TECHNOLOGIES, INC. '
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LIST OF FIGURES (CONT.)
Pace FIGURE 14-9 EXCLUDED. TUBE REGION: TSP 12 (NOZZLE SIDE) 14-15 FIGURE 14-10 EXCLUDED TUBE REGION: TSP 12 (MANWAY SIDE) 14-16 FIGURE A-1 PROBE WEAR STANDARD' SCHEMATIC A-27 FIGURE A-2 BOBBIN COIL AMPLITUDE ANALYSIS OF ODSCC A-28 AT TSP FIGURE A-3 BOBBIN COIL AMPLITUDE ANALYSIS OF ODSCC A-29 INDICATION AT TSP-IMPROPER-IDENTIFICATION OF FULL FLAW SEGMENT RESULTING IN REDUCED VOLTAGE MEASUREMENT WHEN COMPARED WITH FIGURE A-2 FIGURE A-4 BOBBIN COIL AMPLITUDE ANALYSIS OF ODSCC A-30 INDICATION AT TSP-IMPROPER IDENTIFICATION OF FULL FLAW SEGMENT RESULTING IN REDUCED VOLTAGE MEASUREMENT WHEN COMPARED TO FIGURE A-2 FIGURE A-5 CORRECT PLACEMENT OF VOLTAGE SET POINTS ON A-31 MIX 1 LISSAJOUS TRACES FOR R18C103 FIGURE A-6 CORRECT PLACEMENT OF VECTOR DOTS ON MIX 1 A-32 LISSAJOUS TRACES FOR R22C40 FIGURE A-7 INCORRECT PLACEMENT OF VECTOR DOTS ON MIX 1 A-33 LISSAJOUS TRACES FOR R18C103 FIGURE A-8 INCORRECT PLACEMENT OF VECTOR DOTS ON MIX 1 A-34 LISSAJOUS TRACES FOR R22C40 FIGURE A-9 INCORRECT MAXIMUM VOLTAGE DERIVED FROM A-35 PLACEMENT OF VECTOR DOTS ON TRANSITION REGION OF 550 kHz RAW FREQUENCY DATA LISSAJOUS TRACE FOR R42C44 FIGURE A-10 CORRECT PLACEMENT OF VECTOR DOTS ON MIX 1 A-36 LISSAJOUS FIGURE FOR R42C44 FIGURE A-11 PLACEMENT OF VECTOR DOTS BASED SOLELY ON A-37 MIX 1 LISSAJOUS FIGURE (NO SIGNIFICANT SHARP TRANSITIONS IN ANY OF THE RAW FREQUENCIES) -
R10C44 FIGURE A-12 PLACEMENT OF DOTS MARKING MIX 1 LISSAJOUS A-38 FIGURE FOR R16C26 FRAMATOME TECHNOLOGIES, INC.
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LIST OF FIGURES ( CONT _.j_
Page FIGURE A-13 INCORRECT PLACEMENT OF VECTOR DOTS MARKING A-39 MIX 1 LISSAJOUS FIGURE FOR R30C74 FIGURE A-14 CORRECT PLACEMENT OF DOTS TO EFFECT MAXIMUM A-40 VOLTAGE - R30C74 FIGURE A-15 EXAMPLE OF BOBBIN COIL FIELD DATA - MIX A-41 RESIDUAL DUE TO ALLOY CHANGE FIGURE A-16 EXAMPLE OF MRPC DATA FOR SINGLE AXIAL A-42 INDICATION (SAI) ATTRIBUTED TO ODSCC PLANT S FIGURE A-17 MRPC DATA FOR SINGLE AXIAL ODSCC A-43 INDICATION (SAI) - PLANT S FIGURE A-18 MRPC DATA FOR MULTIPLE AXIAL ODSCC A-44 INDICATIONS (MAI) - PLANT S FIGURE A-19 MRPC DATA FOR CIRCUMFERENTIAL ODSCC A-45 INDICATIONS AT DENTED UPPER AND LOWER TSP EDGES FIGURE A-20 EXAMPLE OF BOBBIN COIL FIELD DATA- A-46 FLAW SIGNALS FOR ODSCC AT DENTED TSP INTERSECTION FROM PLANT A FIGURE A-21 EXAMPLE OF BOBBIN COIL FIELD DATA - A-47 FLAW SIGNALS FOR ODSCC AT DENTED TSP INTERSECTION FROM PLANT A FIGURE A-22 EXAMPLE OF BOBBIN COIL FIELD DATA - A-48 FLAW SIGNALS FOR ODSCC AT DENTED TSP INTERSECTION FROM PLANT A FIGURE A-23 EXAMPLE OF BOBBIN COIL FIELD DATA - A-49 FLAW SIGNALS FOR ODSCC AT DENTED TSP INTERSECTION FROM PLANT A FIGURE A-24 EXAMPLE OF BOBBIN COIL FIELD DATA - A-50 FLAW SIGNALS FOR ODSCC AT DENTED TSP INTERSECTION FROM PLANT A 4
FIGURE A-25 EXAMPLE OF BOBBIN COIL FIELD DATA - A-51 FLAW SIGNALS FOR ODSCC AT DENTED TSP INTERSECTION FROM PLANT A FIGURE A-26 LOCATION OF ONE END OF AN INDICATION A-52 USING AN RPC PROBE FRAMATOME TECHNOLOGIES, INC.
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i, LIST OF ABBREVIATIONS ARC Alternate Repair Criteria ASME American Society of Mechanical Engineers
! BC Bobbin Coil l BOC Beginning of Cycle EWNT B&W Nuclear Technologies C/L Cold Leg EC Eddy Current ECT Eddy Current Testing EDM Electric Discharge Machining EFPM- Effective Full Power Month EFPY Effcctive Full Power Year EOC- End of Cycle EPRI- Electric Power Research Institute F Fahrenheit FSAR Final Safety Analysis Report GDC General Design Criteria GL Generic Letter GPD Gallons per Day GPM Gallons per Minute H/1 Hot Leg HL&P Houston Lighting and Power Company l ID Inside Diameter IGA Intergranular Attack IN/SEC Inch per Second kHz Kilo-Hertz LBB Leak Before Break LB/HR Pounds per Hour L/HR Liter per Hoar l
LOCA Loss-of-Coolant Accident l
LTL Lower Tolerance Limit MB Model Boiler MRPC Motorized Rotating Pancake Coil MSLB Main Steam Line Break NDD No Detectable Degradation NDE Non-Destructive Examination NRC Nuclear Regulatory Commission OD Outside Diameter ODSCC Outside Diameter Stress Corrosion Cracking PCT Peak Clad Temperature POD Probability of Detection POL Probability of Leakage PPM Parts per Million PSI Pounds per Square Inch PSIA Pounds per Square Inch Atmospheric PSID Pounds per Square Inch Differential PWR Pressurized Water Reactor RCS Reactor Coolant System RG Regulatory Guide RHR Residual Heat Removal RL Repair Limit FRAMATOME TECHNOLOGIES, INC.
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LIST OF ABBREVIATIONS (CONT.)
RSG Recirculating Steam Generator S/G Steam Generator SG Steam Generator SRSS Square Root of the_ Sum of the Squares l SSE Safe Shutdown Earthquake l STP South Texas Project l STP-1 South Texas Project Unit 1 STP-2 South Texas Project Unit 2 SU Ultimate Tensile Stress SY Yield Stress TS Technical Specifications l TSP Tube Support Plate TYP Typical UT Ultrasonic Testing Vst Voltage Structural Limit i Vat Voltage Repair Limit i Vuon NDE Voltage Measurement Error Veo Voltage Growth Anticipated Between Cycles 1RE04 Refueling Outage 4 1RE05 Refueling Outage 5 1RE06 Refueling Outage 6 l
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RECORD OF REVISIONS _
l Pace i
REVISION 02 !
All Sections Changed all BWNT to Framatome Technologies, Inc, All' j j
t All Sections Removed all references to STP Unit 2. All Table of Added, deleted and renumbered Tables, 11 Contents where applicable. ,
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1.1 Revised paragraph to reflect the changes from 1-1 :
Generic Letter 95-05. _j l
2.2 Revised bullet items to' reflect changes from 2-1,2 l GL 95-05. I t
3.1 Reworded phrasing of third paragraph. 3-1 ,
i 3.2 (2) Revised section to reflect changes from 3-2 GL 95-05. !
3.2.1 Changed number of ODSCC TSP flaws to 602 3-3 l from 1REOS. !
i 4.1 Revised section to reflect changes from 4-1,-2 )
GL 95-05. j i
5.2. Renamed section and added ' Enclosure l'. 5-1,-2 i Removed reference to Unit 2 TSP. l Table 5-1 Changed MSLB pressure to 2560 psid. 5-3 i
6.2 Revised section to reflect changes from 6-1 !
GL 95-05. i 6.2.1 Added reference 27, added 2560 psid, 6-2,-3 !
changed faulted pressure to 3661 psid, j and changed %Vuog and %Veo to reflect values in j GL 95-05, i
Table 6-1 Revised STP-1 ARC Repair limit to 2.85 volts 6-4 '
and Structural limit to 4.70 volts based on {
the new Burst Pressure Correlation and GL 95-05 i requirements. 'j 7.3.2 Revised sections to reflect changes from 7-2 7.3.3 GL 95-05.
}
7.3.4 }
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RECORD OF REVISIONS Page 7.4.2 Revised sections to reflect changes from 7-3,-4 7.4.3 GL 95-05.
7.4.4 7.4.5 7.4.6 7.4.7 8.2 Updated sections to reflect GL 95-05 8-1,-2,-3 l 8.3 requirements and to discuss tube pulls j 8.4 performed at STP-1 during 1REOS.
8.5 Revised database reference to incorporate 8-4
! Westinghouse pulled tube data Table 8-2 Added new Table showing the results of 8-10,-11 tube pull examinations performed during 1REOS.
9.2 Revised section to reflect changes 9-1,-2 from GL 95-05.
I 9.3 Revised section to reflect that an STP-1 9-3,-4 specific growth rate is being utilized, in lieu of the EPRI generic growth rate.
( 9.4 Reworded discussion on Analyst and 9-4,-5 Acquisition Errors.
9.5 Reworded e. 1re section to better explain 9-5 to the Monte Carlo process of determining the 9-7
( Projected EOC Voltage Distribution.
Table 9-1 Revised to include the DSI population 9-9 to -39 l from 1995 Bobbin Coil inspection.
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Table 9-2 Deleted STP-2 Data and replaced with 9-40 STP-1 bounding Voltage Growth Distribution.
Table 9-3 Deleted EPRI Growth Distribution Table; 9-41 Replaced with Table 9-2.
Figure 9-1 Updated to reflect changes from STP-1 9-41 Figure 9-2 DSI voltage distribution BOC 6. 9-42 l Figure 9-3 9-43 l 10 Revised entire section to include more 10-1 thru details on the POB model, statistical 10-22 methods utilized, equations used in the Monte Carlo simulation and updated )
correlations and figures based on new Industry Database.
FRAMATOME TECHNOLOGIES, INC. ix
FECORD OF REVISIONS Pane Table 10-3 Updated to correspond with new Industry 10-13,-19 Table 10-4 database.
l 11 Revised entire section to include more 11-1 thru details on the POL ar.d leak rate models, 11-19 l
statistical methods utilized, equations used in the Monte Carlo simulation, and i updated correlations and figures based on new Industry Dat. abase l 13.2 Revised section to incorporate changes 13-1,-2 from GL 95-05.
13.3 Revised section to incorporate changes 13-3,-4 from GL 95-05.
. 13.3.1 Revised section to incorporate changes 13-4 l from GL 95-05.
14.0 Revised section to incorporate changes 14-1 from GL 95-05.
15 Revised section to include updated results 15-1 to from the simulations. -3 16.0 Changed Reference 1 to GL 95-05. 16-1,-3 i Added References 26, 27, 28, 29, 30, 31,32. -4 l l
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1.0. INTRODUCTION I'
1.1' Purcose-I l_ The purpose of . this document is to provide a. technical justification to implement an alternate steam generator tube repair criteria.for outer diameter stress corrosion cracking (ODSCC) 'at the tube-to-tube support plate intersections in the South Texas Project Unit 1 steam generators, t This justification addresses the criteria and guidance contained in NRC Generic Letter 95-05: Voltage-Based Repair l Criteria'for the Repair of Westinghouse Steam Generator Tubes Affected by Outside Diameter Stress Corrosion Cracking (August 1995)[1].
This justification relies on the industry's recommended l approach and methodologies, as developed by the Committee for Alternate Repair Limits for ODSCC at TSPs through the Electric Power Research Institute (EPRI) . This recommended approach is defined in EPRI Technical Reports TR-100407, Revision 2A, "PWR Steam Generator Tube Repair. Limits -
Technical Support Document for Outside Diameter Streas Corrosion Cracking at Tube Support Plates (6), NP-7480-L " Steam Generator Tubing Outside Diameter Stress Corrosion Cracking at Tube Support Plates - Database for Alternate Repair Criteria, Volume 2: 3/4 Inch Diameter Tubing" (3) and WCAP-14277 NON-PROPRIETARY CLASS 3 (SG-95-01-007), SLB Leak Rate and Tube Burst Probability Analysis Methods for ODSCC at TSP Intersections (26) .
1.2 Backaround Stress corrosion cracking initiating on the outer diameter of Alloy 600 steam generator tubes has been diagnosed in the tube support plate (TSP) region of the South Texas Project Unit 1 steam generators, as well as at many other pressurized water reactor (PWR) steam generators throughout the world. If existing tube plugging limits based on crack depth were applied, many tubes would require repair that is unnecessary from either a safety or reliability standpoint.
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To address this issue, the PWR industry, working through EPRI, has developed an approach to define an alternate repair criterion (ARC) that does not set limits on depth of cracks to ensure tube integrity. Instead, this criterion relies on l correlating the eddy current voltage amplitude from a bobbin coil probe with the more specific measuiement of burst pressure and leak rate. In turn, these items are related to assuring the structural integrity of the tubes and the safe operation of the plant.
Allowing tubes with axial ODSCC to remain in service can be justified based on a combination of enhanced in-service inspection, a repair limit based on eddy current testing voltage, a limit on the number of ARC tubes remaining in service (determined by leakage limits for faulted loads), and l a reduced primary-to-secondary allowable leak rate at normal operating conditions.
1.3 Oroanization of Reoort Each section of this report addresses a different NRC Generic Letter requirement as specified in Reference 1. The l
requirements are listed and then STP's compliance with that particular requirement is presented in a manner as to justify the STP results and position on the requirement. Section 4 l
contains a Table that summarizes STP's differences with the l requirements specified in Reference 1.
Figure 1-1 depicts the major steps involved in developing the ARC for the South Texas Project. The major requirements for the implementation of the voltage-based repair criteria are f
l shown in this figure and the related section of this report is referenced for each.
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FIGURE 1-1
SUMMARY
OF THE MAJOR ASPECTS OF THE STP
(- ALTERNATE REPAIR CRITERIA
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2.0 EXECUTIVE
SUMMARY
, This report documents the technical justification for an Alternate Repair Criteria (ARC) for Outer Diameter Stress Corrosion Cracking (ODSCC) indications at Tube Support Plates (TSP) for South Texas Project Unit i steam generators. This assessment demonstrates that a correlation relating tube burst pressure to bobbin voltage and main
. steam line break (MSLB) leakage to bobbin voltage can be
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used to conservatively satisfy the Reg Guide 1.121 l guidelines for tube integrity at South Texas' Project Unit 1.
l 3.1 Overall Conclusions The South Texas Project Unit 1 pulled tubes (1993 and 1995 outage) show that the degradation morphology for indications at TSPs can be described as axial ODSCC within the TSP length. The burst. test behavior of these indications is consistent with the data base supporting the repair limits of this report. Application of the generic ODSCC ARC methodology developed through EPRI is appropriate for South Texas Unit 1 ODSCC flaws, satisfies the NRC Generic Letter on ODSCC ARC, and is consistent with other approved ODSCC ARC methodologies.
2.2 Recuirements for Imolementation of ARC The following requirements for South Texas Project ARC conservatively satisfy Reg Guide 1.121 guidelines for tube integrity: !
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o Indications less than the lower voltage repair limit (1 ;
volt), as measured by bobbin coil, may remain in j service. 1 i
o Indications greater than the lower limit (1 volt) and less than or equal to the upper voltage repair limit as !
. measured by bobbin coil, can remain in service if RPC inspections do not confirm the indications.
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o Indications greater than the lower limit (1 volt) and less than or equal to the upper voltage repair limit, as measured by bobbin coil, that are confirmed by RPC, and indications greater than the upper voltage repair limit, as measured by bobbin coil must be repaired.
o Projected leakage for a postulated steam line break event at end of cycle (EOC) conditions shall be less than the bounding leakage necessary to remain within applicable dose limits (10 CFR 100, NUREG 0800, and GDC 19).
o Projected tube burst probability for a postulated steam line break at EOC conditions shall be calculated and compared to a threshold value of 1 percent (1. 0 x 10")
for the most limiting steam generator.
o Tubes identified as subject to significant deformation (as discussed in Section 14.0 of this report) at a TSP under a postulated LOCA + SSE event shall be excluded from application of the ARC at that TSP location.
Inspection Requirements o The inspection shall include 100% bobbin coil inspection of all hot leg intersections and cold leg intersections down to the lowest TSP for which the ARC is to be applied. ,
o Bobbin coil flaw indications above 1.0 volt and below the upper' voltage repair limit shall be inspected by MRPC to evaluate for detectable MRPC indications and to support ODSCC as the degradation mechanism.
o Eddy current analysis guidelines shall be equivalent to the requirements given in Appendix A.
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Operating Leak Rate Limit o The normal operating leak rate requiring plant shutdown shall be limited to 150 gpd per steam generator.
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3.0 GENERIC LETTER APPLICABILITY TO STP 3.1 Introduction In the Generic Letter, the NRC describes the information necessary to justify the use of an ARC for ODSCC at TSP intersections. Voltage-based repair criteria are considered applicable only to indications at support plate intersections where the degradation mechanism is dominantly axial ODSCC with no significant cracks extending outside the thickness of the support plate.
For the purposes of the Generic Letter, ODSCC refers to degradation whose dominant morphology consists of axial stress corrosion cracks which occur either singularly or in networks of multiple cracks, sometimes with limited patches of general intergranular attack (IGA). Circumferential cracks may sometimes occur in the IGA affected regions resulting in a grid-like pattern of axial and circumferential cracks, termed cellular corrosion. Cellular corrosion is assumed to be relatively shallow (based on available data from tube specimens removed from the field), transitioning to dominantly axial cracks as the cracking progresses in depth. The circumferential cracks are assumed (based on available data) not to be of suf ficient size to produce a discrete, crack-like circumferential indications during field nondestructive examinations (NDE) inspections. Thus, the failure mode of ODSCC is axial and the burst pressure is controlled by the geometry of the most limiting axial crack or array of axial l cracks.
For purposes of the Generic Letter, ODSCC is confined to within the thickness of the tube support plate, based on available data from tube specimens removed from the field.
Very shallow microcracks are sometimes observed on these specimens that initiate at locations slightly outside the thickness of the tube support plate; however, these microcracks are small compared to the cracks within the thickness of the support plate and are too small to produce an eddy current response.
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Confirmation that the degradation mechanism is dominantly axial ODSCC should be accomplished by per,iodically removing-tube specimens from the steam generators and by examining and testing these specimens as specified in Section 4 of the Generic Letter. The acceptance criteria should consist of demonstrating that the . dominant. degradation mechanism
! affecting the burst and leakage properties of the tube is axially oriented ODSCC. In addition, results-of inservice inspections with motorized rotating pancake coil (MRPC) probes would be evaluated in accordance with Section 3.b of the Generic Letter to confirm the absence of detectable crack-like circumferential indications and detectable ODSCC-indications extending outside the tube support plate thickness.
l 3.2 Generic Letter Acolicability The criteria in the Generic Letter are only applicable to ODSCC located'at the tube-to-tube support plate intersections in Westinghouse designed steam generators. These criteria are l not applicable to other forms of steam generator tube degradation, nor are they applicable to ODSCC that occurs at other locations within a steam generator. The voltage-based l repair criteria can be applied only under the following constraints:
l (1) The repair criteria of the Generic Letter apply only to l Westinghouse designed steam generators with 1.9 cm [3/4-inch] and 2.2 cm (7/8-inch] diameter tubes and drilled hole tube support plates, (2) The repair criteria of the Generic Letter apply only to predominantly axially oriented ODSCC confined within the tube-to-tube support plate intersection as discussed in Section 1.a of Enclosure 1 of the Generic Letter and, (3) Certain intersections are excluded from the application of the voltage-based repair criteria as discussed in Section 1.b of Enclosure 1 of the Generic Letter.
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Compliance with the Generic Letter Requirements 3.2.1 STP Generic Letter Applicability In compliance with Section 2 of the Generic Letter, STP has 4 Westinghouse Model E steam generators.
The tubes are 0.749" i 0.005" OD x 0.043" i 0.004" wall mill-annealed nickel-chromium-iron alloy UNS NO6600 tube per ASME material specification SB-163
[10].
In compliance with Section 2 of the Generic Letter, STP has confirmed, by pulling tubes from the STP-1 steam generators, that axially oriented ODSCC exists and is the dominate degradation mechanism within the tube-to-tube support plate intersections. During the last inspection outage for STP-1 in 1995, the unit had 602 ODSCC flaws.
In compliance with Section 2 of the Generic Letter, l certain intersections are excluded from the application of the voltage-based repair criteria as l discussed in Section 1.b of the Generic Letter.
Section 14.0 of this report discusses the l intersections excluded from application of ARC for l STP.
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l -4.0 GENERIC LETTER EXCEPTIONS FOR STP 4.1 Introduction-Generic Letter 95-05: " Voltage-Based Repair Criteria for the Repair of Westinghouse Steam Generator Tubes Affected by Outside Diameter Stress Corrosion Cracking" was issued on i
August 3,1995. There are no exceptions to the requirements addressed in. Generic Letter 95-05 for the STP-1 ARC submittal.
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5.O STP STEAM GENERATOR DESIGN INFORMATION 5.1 Introduction The ARC evaluation shall consider as a minimum, the design and operational loading conditions for South Texas Project as summarized in this section, including Figure 5-1 and Table 5-1.
STP-1 has 4, Westinghouse Model E steam generators. The steam generator tubes are 0.749" 0.005" OD x 0.043" 0.004" wall mill-annealed nickel-chromium-iron alloy UNS N06600 tube per ASME material specification SB-163 [10] .
The tubing in the "as-built" condition was not stress relieved in the regions of interest at the TSPs. At STP-1, the tubes are roller expanded into the tube sheet and the tube support plates are carbon steel with drilled holes.
5.2 Tube Exclusions Based on Analysis Considerations The analysis as required per the NRC Generic Letter, Section 1.b. of Enclosure 1, shall consider the effect of SSE and LOCA with respect to the maximum loads that may be generated in a TSP and reacted at the wedge locations. As specified in GDC-4 (52 FR 41288), with NRC acceptance, leak-before-break (LBB) has been evaluated at STP and thus may be used to determine support plate loads (18,19]. With LBB, the large primary pipe breaks are eliminated and the next largest branch pipe break in the primary system, not included in LBB, shall be considered. The bounding branch line LOCA break is a 12" Schedule 140 attachment line. The use of LBB at STP is also consistent with an NRC letter [12]
which says that LBB of primary piping is acceptable in evaluating internals for steam generator replacements, provided that an assumed break occurs in the branch piping.
With this in mind, the structural analysis to identify tube exclusion areas was performed with the following considerations:
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DESIGN AND OPERATING CHARACTERISTICS [10] i i~ [ t i
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FIGURE 5-1 W-E RSG GENERAL ARRANGEMENT
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6.0 REPAIR LIMITS l i
- 6.1. Introduction ,
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! The voltage-based repair limits of the Generic Letter were l l determined considering the entire range of design basis f
4 events that could challenge tube integrity. The voltage j
$ repair limits ensure structural integrity and leakage limits j
} for all postulated design basis events. The structural (
l criteria are intended to ensure that tubes subjected to the !
i voltage repair limits.will be able to withstand a pressure {
of 1.4 times the maximum possible main steam line break !
(MSLB) differential pressure postulated to occur at the end I l of the operating cycle, consistent with the criteria of I
! Regulatory Guide 1.121. The induced leakage under worst-f j case MSLB conditions calculated using licensing basis 4
f assumptions will not result in offsite dose releases that !
l exceed the applicable limits of 10 CFR 100. .f i
) 6.2 Voltace Recair Limits Der the Generic Letter l Per the Generic Letter, the voltage repair limits for 1.9 cm
[3/4 inch] diameter tubes are: !
i Indications less than the lower voltage repair j limit, as measured by bobbin coil, may remain in <
1 service. For 1.9 cm (3/4") diameter tubes, the '
i lower voltage repair limit is 1.0 volt. ,
l Indications greater than the lower limit and less l than or equal to the upper voltage limit, as i measured by bobbin coil, can remain in service if
, MRPC inspections do not confirm the indications. i l The methodology for calculating the upper voltage repair limit is specified in Section 2.a.2 and
, 2.a.3 of Enclosure 1 of the Generic Letter. <
Indications greater than the lower limit and less l l than or equal to the upper limit, as measured by i j bobbin coil, that are confirmed by MRPC, and
, indications greater than the upper repair limit, l as measured by bobbin coil, must be repaired. l 4 !
4 FRAMATOME TECHNOLOGIES, INC.
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BTP Compliance with Requirements 6.2.1 Voltage Repair Limit Methodology The Generic Letter states that the lower repair limit is fixed and not plant specific. However, the upper repair limit is plant specific and not fixed. In compliance with the Generic Letter, the tube repair limit methodology described in this report is conservatively developed to preclude free span tube burst. The correlation between burst pressure and bobbin voltage amplitude, discussed in Section 10 of this report, is derived from the combined model boiler and pulled tube specimens discussed in References 3 and 27. The burst pressure versus bobbin voltage correlation was adjusted to account for operating temperature and minimum material properties. To establish the voltage structural limit (Vn) that satisfies the RG 1.121 guidelines for margin against tube burst, the burst correlation must be evaluated at the .
higher of 1.43 times the faulted pressure or three l times the normal operating pressure differential.
- For STP, this value is 1.43 times the faulted ,
pressure of ( ]c". The '
voltage structural limit must be reduced to allow l for NDE measurement error and ODSCC growth between i steam generator tube inspections.
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The voltage repair limit provides margins against 4
tube rupture, consistent with RG 1.121 guidelines,
. including allowances for NDE measurement error and defect growth, and can be expressed as follows:
[ l EP Eq. 6-1
[6]
or EP
[ J where: Vu = voltage limit for tube repair, Vmys = NDE voltage measurement error, v3 a = voltage growth anticipated between inspections, and ,
Vst = voltage structural limit from the burst pressure and bobbin voltage correlation (volts)
The value for %Vm3s has been determined from available data and is provided in Reference 1 for the industry standard. As discussed in Reference 1, the %VWoe = 20 with the use of a transfer
- standard. The value for %Vaa has been determined in Reference 1 for the industry standard and is
%Vco= 30/EFPY. Therefore, for a cycle length of 1.5 EFPY, %Veo 45. The distributions for NDE uncertainty and voltage growth are utilized during a Monte Carlo simulation, in order to project an EOC voltage distribution that is used to determine the probability of burst and leak rate during MSLB conditions.
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HL&P plans to implement the 1.0 volt criterion at l STP as the lower repair limit and a [ ] dFP volt criterion as the upper repair limit. Table 6-1 summarizes the development of the ARC repair limit based on reducing the structural voltage limit of
[ ]dF P volts by allowances for growth and NDE ;
uncertainties at STP. At the lower 95% prediction interval, a bobbin voltage of [ ]dFP volts .
?
establishes the structural requirement for 1.43
]d FP tube burst Capability faulted pressure [
as shown on Figure 10-1. After adjusting the ;
structural limit voltage by the allowances for growth and NDE uncertainties, the resulting equivalent ARC repair limit is [ ]d FP volts.
! The ARC repair limit is used to define an upper ,
bobbin voltage limit for leaving unconfirmed ,
bobbin indications in service.
l TABLE 6-1 l STP-1 ARC REPAIR LIMITS TO SATISFY STRUCTURAL REQUIREMENTS I
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l l FRAMATOME TECHNOLOGIES, INC.
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4 7.0- NDE INSPECTION CRITERIA-1 7.1 Introduction
- In order to apply the ARC to the applicable tube support 3 plate (TSP) intersections, the Generic Letter (GL) requires
- that the bobbin coil inspection guidelines listed below be implemented. These guidelines ensure that the techniques i used to inspect the steam generators are consistent with the j techniques used in the development of the voltage-based l repair limit methodology.
7.2 Bobbin Coil Insoection Scone and Samolina 4
'The bobbin coil inspection should include 100% of the hot-leg TSP intersections and cold-leg intersections down to the
! lowest cold-leg TSP with known ODSCC. The determination of TSPs having ODSCC should be based on the performance of at ;
least a 20% random sampling of tubes inspected full length.
STP Compliance with Requirement For Unit 1, Cycle 6, implementation of the TSP ARC requires !
l 100% bobbin coil inspection for all of the H/L TSP l intersections and all cold leg intersections down to the f lowest C/L support plate with ODSCC indications. The i determination of the TSP intersections having ODSCC l indications shall be based on the performance of at least a ,
20% random sampling of tubes inspected over their full length.
7.3 Motorized Rotatina Pancake Coil (MRPC) Insoection j MRPC inspections should be conducted as specified in the GL for the purposes of obtaining additional characterization of the ODSCC flaws found with the bobbin coil inspection and to further inspect intersections with significant bobbin i
- interference signals which may influence the bobbin coil
- measurement or impair the detectablility of an ODSCC flaw,
, One of the main reasons for performing MRPC inspections is FRAMATOME TECHNOLOGIES, INC.
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to ensure the absence of detectable crack-like circumferential1 indications and detectable indications extending beyond the boundary of the TSP. The voltage-based -
repair criteria are not applicable to TSP intersections containing these types of indications, and special reporting requirements pertaining to the discovery of such indications are described in Section 6-of the Generic Letter.
7.3.1 MRPC inspection.should be performed for all indications exceeding 1.0 volts as measured by bobbin coil, for 3/4 inch tubing.
t 7.3.2 All intersections with interfering signals from copper deposits should be inspected with MRPC.
Any indications found at such intersections with MRPC should cause the tube to be repaired.
7.3.3 All intersections with dent signals greater than 5 volts should be inspected with MRPC. Any indication found at such intersections with MRPC should cause the tube to be repaired. If circumferential cracking or primary water stress corrosion cracking indications are detected, it may be necessary to expand the MRPC sampling plan to include dents less than~5.0 volts.
7.3.4 All intersections with large mixed residuals should also be inspected with MRPC. Large mixed residuals are those that could cause a 1.0 volt -
bobbin signal to be misread or missed. Any indication found by MRPC at such an intersection should cause the tube to be repaired.
STP Compliance with Requirement HL&P will address each of the requirements listed above, and specified in the Generic Letter, during steam generator j inspection outages when ARC will be implemented. The i specific requirements for the MRPC inspection scope are
-contained in Appendix A of this report.
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7.4 Data Acauisition and Analysis These inspection guidelines are intended to maintain a level of consistency for all plants utilizing an alternate repair criteria. They ensure that the inspection techniques used by the plants are consistent with those used in the i development of the tube integrity methodologies for the voltage-based repair limits.
7.4.1 The bobbin coil calibration standard should be calibrated against the reference standard used in the laboratory in the development of the voltage-based approach by direct testing or through the use of a transfer standard.
7.4.2 Once the probe has been calibrated on the 20%
through-wall holes, the voltage response of new .
bobbin coil probes for the 40-100% ASME through-wall holes should not differ from the nominal (
voltage by more than 1 10%.
7.4.3 Probe wear should be monitored by an in-line measuring device or through the use of periodic wear measurement. When utilizing the periodic wear ;
measurement approach, if a probe is found to be out of specification, all tubes inspected since the last successful calibration should be reinspected with the new calibrated probe. ,
] Alternatives to this approach, which provide i equivalent detection and sizing and are consistent with the tube integrity analyses discussed in Section 2 of Enclosure 1 of the Generic Letter, l 4
may be permitted subject to NRC approval.
7.4.4 Data analysts should be trained and qualified in the use of the guidelines and procedures. Analyst performance should be consistent with the i assumptions made for analyst measurement variability in Section 2.b.2 (1) of Enclosure 1 of the Generic Letter and used in the tube integrity ,
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analysis. (Section 9 of this report) .
i 7.4.5 Quantitative noise criteria, that which results !'
from electrical noise, tube noise, or calibration standard noise, should be included in the data {
analysis guidelines. Data that fails to meet the' !
criteria should be rejected and the tube '{
reinspected. !
7.4.6 Data analysts should review the mixed residuals on i the standard itself and take action as necessary !
to minimize these residuals. l 7.4.7 Smaller diameter probes can be used to inspect f tubes where it is impractical to utilize a full j sized probe, provided that the probes and procedures have been demonstrated on a statistical l basis to give equivalent voltage response and ,
detection capability when compared to a full size l
l probe.
STP Compliance with Requirement i i
l HL&P will address each of the requirements listed above, and !
l specified in the Generic Letter, during steam generator ;
i
- inspection outages that ARC will be implemented. The specific requirements pertaining to the~ items listed above are contained in Appendix A of this report. I t
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'8.0- TUBE REMOVAL AND EXAMINATION / TESTING 8.1 -Introduction Implementation of voltage-based plugging criteria should include a program of tube removals for testing and examination as described below. The purpose of this program is to confirm axial ODSCC as the dominant degradation mechanism at the TSP intersections and to provide additional data to enhance the burst pressure, probability of leakage, and conditional leak rate correlations, as described in Sections 10 and 11.
8 .2 Number and Frecuency of Tube Pulls As stated in the Generic Letter, two pulled tube specimens with an objective of retrieving as many intersections as is practical (a minimum of four in*tersections) should be obtained for each plant either during the plant SG inspection outage that implements the voltage-based repair criteria or during an inspection outage preceding initial application of these criteria. On an ongoing basis, an additional (follow-up) pulled tube specimen with an objective of retrieving as many intersections as practical (minimum of two intersections) should be obtained at the refueling outage following accumulation of 34 effective full power months of operation or at a maximum interval or three refueling outages, whichever is shorter following the previous tube pull.
Alternatively, the request to acquire pulled tube specimens may be met by participating in an industry sponsored tube
- pull program endorsed by the NRC that meets the objectives E
of the Generic Letter.
STP Compliance with Rcquirement l
f- During the September, 1993, outage at STP-1 (2.9 EFPY), HL&P i
elected to pull four tubes from the Unit 1 steam generators (S/G). Three tubes were pulled from the 'D' S/G and one 4
FRAMATOME TECHNOLOGIES, INC.
8-1 l
from the 'C' S/G. Each of these tubes contained three hot leg TSP intersections, thus producing 12 TSP intersections for laboratory testing. HL&P has therefore met this requirement for STP-1, as specified. HL&P will continue to pull tubes from STP-1 in accordance with the requirements outlined in this report, during future inspection outages.
In addition, HL&P pulled two additional tubes from STP-1 S/G
'D' during the March, 1995 (3.9 EFPY), inspection outage to provide additional information about the flaw morphology at the TSPs.
8.3 Candidate Selection Criteria ;
l l
The selection of tubes as candidates for pulling should consider the following criteria:
i 1. Tubes with large voltage indications.
- 2. Tubes should cover a range of voltages, including intersections with no detectable degradation (NDD).
- 3. Selected tube intersections comprising the total data set should include at least a representative number of
, intersections with MRPC signatures indicative of a l single dominant crack as compared to intersections with MRPC signatures indicative of two or more dominant cracks about the circumference.
STP Compliance with Requirement The STP-1 1RE04 and 1RE05 pulled tubes met the requirements specified in the Generic Letter. During future outages at
( STP, HL&P will follow the guidelines listed above, and l specifically in Reference 1, for developing a list of tube pull candidates to support the voltage-based repair criteria for axial ODSCC at TSPs.
8.4 Examination and Testinq -
Removed tube intersections should be subjected to leak and burst test under simulated MSLB conditions to confirm that the failure mode and the leakage rates are consistent with l
l FRAMATOME TECHNOLOGIES, INC.
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that assumed in the development'of the voltage-based repair l
criteria. Additionally, these data may be used to enhance ]:
i the supporting data sets for the burst pressure and leakage l
] correlations subject to NRC review and approval. Subsequent i l to burst testing, the intersections should be destructively
] examined to confirm that the degradation morphology is i consistent with that assumed for ODSCC. t l I 1
l STP Compliance with Requirement i As previously stated, tubes were pulled from STP-1 during .
l the 1REO4 outage, 1 from the 'C' steam generator, and 3 from l i the 'D' steam generator. The tubes.that were pulled had l 2 i various types of defects confirmed through the laboratory i tests. However, only the tubes with axial-oriented ODSCC at ;
TSP intersections are pertinent for the purposes of the ARC l
- implementation.
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During future outages at STP, HL&P will follow the guidelines listed above, and specifically in Reference 1, i for developing a list of tube pull candidates to support the voltage-based repair criteria for axial ODSCC at TSPs.
8.5 General Criteria for Burst and Leakace Models and Succortina Test Data Only the use of NRC approved burst and leakage models and correlations are to be utilized; this includes the approval of the data that supports the models and correlations.
STP Compliance with Requirement The use of the EPRI burst and leak databases as contained in References 27 and 28 were utilized in the development of the data correlations for the STP ARC. Any modification performed on any of the data came only from NRC requirements on exclusion or inclusion of data points within the correlations [1]. These exclusions and inclusions of data FRAMATOME TECHNOLOGIES, INC.
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TABLE 8-1 (A)
RESULTS OF TUBE PULL EXAMINATIONS ON STP-1 1993 H/L TSP INTERSECTIONS t
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i RESULTS OF TUBE PULL EXAMINATIONS {
- ON STP-1 1993 H/L TSP INTERSECTIONS
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NDD = No detectable degradation ,
j SAI - Single Axial Indication i ;
SVI = Single Volumetric Indication l
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.f RESULTS OF TUBE PULL EXAMINATIONS }
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- N/A = Not Inspected
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{ SVI = Single Volumetric Indication 4 i I
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. RESULTS OF TUBE PULL EXAMINATIONS ON STP-1 1993 H/L TSP INTERSECTIONS f
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RESULTS OF TUBE PULL EXAMINATIONS .
ON STP-1 1995 H/L TSP INTERSECTIONS f
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N/A = Not Inspected NDD = No detectable degradation [
SAI = Single Axial Indication .
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RESULTS OF TUBE PULL EXAMINATIONS ;
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4 SVI - Single Volumetric Indication I l
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i 9.0 VOLTAGE DISTRIBUTIONS AND PROJECTIONS i
9.1 Introduction !
In order.to support the calculation of the conditional probability of burst and the total leak rate during MSLB conditions, the voltage distributions, beginning of cycle '
(BOC) and end of cycle (EOC), must both be developed as part l of the ARC evaluation'. l 9.2 Distribution of Bobbin Indications as a Function of Voltace I at BOC !
i i
As stated in the Generic Letter, the frequency distribution :
by voltage of bobbin indications actually found during :
inspection should be scaled upward by a factor of 1/ POD to account for non-detected cracks which could potentially leak or rupture during MSLB conditions during the next cycle of operation. The probability of detection (POD) reflects the I
ability of the inspection method to detect all of the ODSCC flaws that exist in the steam generator tubing. The I adjusted frequency distribution minus the detected flaws that.have been plugged or repaired constitutes, for the purposes of ARC tube integrity analysis, the assumed j frequency distribution of bobbin indications as a function of voltage at BOC. This can also be expressed as: j Ng= (1/ POD) x (NAsround)-NRphM Eq. 9-1 (1) i where i N,oc l
- assumed frequency distribution of bobbin indications at BOC i POD = probability of detection of ODSCC flaws I N6 roa = frequency distribution of indications detected during the inspection N',,y,,,, = frequency distribution of repaired :
indications !
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I POD should have an assumed value of 0.6, or as an f
alternative, an NRC approved POD function can be used if- !
< available.
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STP Contpliance with Requirement i a .
N The STP-1 beginning of cycle voltage distribution has been [
] determined from the 1REOS outage-bobbin voltage inspection l 1 data. Table 9-1 contains voltage calls for STP-1 1995 ,
i inspections. The total number of ODSCC flaws found in all
, 'STP-1 steam generators during the last inspection was j [ ]d". These previous inspections included 100% of the ;
i tube population in Unit 1. Evaluations for ARC probability j j of burst and leakage calculations, include separate analyses
{
l for each steam generator.
1
] The approach taken for determining the BOC voltage ,
- distribution is consistent with the method outlined above. i
) The "as-found" flaws were scaled upward by a factor of 1
1/ POD, to account for the undetected cracks potentially not l found during the ECT inspection. This scaling factor will !
have an assumed value of-0.6, per the Generic Letter, until j a more realistic value of POD has been approved for use. !
After scaling the "as-found" voltage distribution, the flaws that were removed from service were subtracted from scaled number, to give the assumed BOC voltage distribution, N,oc to [
2 be used in the burst and leakage analyses.
4 Note that Na r=w includes all flaw indications detected by }
4 bobbin coil, regardless ei MRPC confirmation. At the time ,
i of this submittal, HL;F does not have a plant specific l adjustment factor for excluding those bobbin calls that were '
j inspected with MRPC and were determined to have NDD. Per i
1 Section 2.b.1 of Enclosure 1 of the Generic Letter, a i methodology can be implemented upon review and approval by f
, the NRC where a fraction of bobbin indications at location
- - which have been inspected with MRPC probe, but where the i MRPC failed to confirm the bobbin indication, may be ;
excluded from Noroa . The BOC 6 voltage distribution of the i STP-1 'C' steam generator is shown in Figure 9-1. [
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9.3 Voltace Growth Due to Defect Prooression Potential voltage growth rates during the next inspection cycle should be based on growth rates observed during the last one or two inspection cycles. For a given inspection, previous results at TSP intersections currently exhibiting a bobbin indication should be re-evaluated consistent with the data analysis guidelines in Section 3 of of Enclosure 1 of the Generic Letter. In cases where data acquisition guidelines utilized during previous inspections differ from those in Section 3 of Enclosure 1 of the Generic Letter, adjustments to the previous data should be made to compensate for the differences. Voltage growth ratep should be evaluated for TSP intersections where bobbin indications can be identified at two successive outages.
The distribution of observed voltage growth rates should be determined for each of the last one or two inspection cycles. When the current or the current and the previous inspections employed data acquisition guidelines similar to those in Section 3 of Enclosure 1 of the Generic Letter, only the growth rate distribution for the previous cycle should be used to estimate the voltage growth rate expected for the next inspection cycle. If the Generic Letter, Section 3 of. Enclosure 1 guidelines were used in both of the two previous inspections, the most limiting of the two growth rates should be used to estimate the voltage growth for the next cycle. The two distributions should be combined if one or both is based on a minimal number of indications (i.e., < 200). Per the Generic Letter, if fewer than 200 ODSCC indications were present in prior inspections, the use of a bounding growth rate distribution based on experience at similarly designed and operating units is acceptable.
It is acceptable to use a statistical model fit of the observed growth rate distribution as part of the tube integrity analysis. It is also acceptable that the voltage growth distribution be in terms of A volts rather than percent A volts, as long as the conservatism of this FRAMATOME TECHNOLOGIES, INC.
9-3
approach is supported by operating experience. Negative growth rates should be included as zero growth rates in the assumed distribution.
STP Compliance with Requirement The above method for evaluating the voltage growth due to defect progression was utilized in the initial application of ARC at STP (EOC 6 projections). STP-1 bounding growth rate will be utilized for the purposes of ARC evaluations.
The STP-1 bounding growth rate cumulative distribution is presented in Table 9-2. The table is converted into a voltage growth distribution and is shown in Figure 9-2.
9.4 Eddy Current Voltace Measurement Uncertainty Uncertainty in eddy current voltage measurements stems primarily from two sources:
- 1. voltage response variability (test repeatability error) resulting from probe wear, and
- 2. voltage measurement variability among data analysts (measurement repeatability error) .
Each of these uncertainties should be quantified. An acceptable characterization of these uncertainties is contained in Reference 6, with the exception that no distribution cutoff should be applied to the voltage measurement variability distribution. The assumed 15%
cutoff for the voltage response variability distribution in Reference 6 is acceptable.
STP Compliance with Requirement Accuisition and Analyst Errors i For the purposes of the STP ARC analyses, the acquisition error that will be utilized will be sampled from[
FRAMATOME TECHNOLOGIES, INC.
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] EP as determined in Reference 6. [.
Je FP The analyst error is addressed in a similar fashion as the acquisition error. It is also represented by[
s]" suggested in Reference 6. [The Monte Carlo
. simulation also randomly samples from this normal distribution during the prediction of the EOC voltage distribution. But unlike that of the acquisition error,
.there is no cutoff limit.]e FP This method also meets the requirements specified in the Generic Letter.
9.5 Proiected End-of-Cycle (EOC) Voltace Distribution As discussed above, the EOC voltage distribution is required in order to calculate the conditional probability of burst and leakage during a postulated MSLB, 'In order to project an EOC voltage distribution from the BOC voltage distribution determined in Section 9.2, the effects of voltage growth to account for defect progression (presented i in 9.3), and eddy current voltage measurement uncertainty {
(presented in 9.4) must be considered. Monte Carlo !
techniques are an acceptable means for sampling EC l measurement uncertainty and voltage growth distribution to j determine the EOC voltage distribution. ,
l l
STP Compliance with Requirement In order to project an EOC distribution, a Monte Carlo ;
simulation was performed utilizing the BOC voltage !
distribution from Section 9.2, the voltage growth cumulative distribution table from Section 9.3, and the ECT uncertainties from Reference 7 and Section 9.4. These k
FRAMATOME TECHNObOGIES, INC.
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t values are consistent with EPRI Reference 6 and the Generic Letter [1] .
The first step in the Monte Carlo simulation is to combine the. eddy current uncertainties with the measured BOC voltages to obtain the 'true', but unknown, BOC voltages, j The method of accounting for these uncertainties assumes i that both the acquisition and analysis uncertainties are i distributed about the true voltage [26] . For the.
[ acquisition uncertainty, the deviation from the true voltage is given by:
acq"Eacq EOacq EVCrue Eq. 9-2 where Z,y = randomly selected value from the normal distribution 0 ,9 = standard deviation for acquisition uncertainty (0.070)
V, m - the true, .but unknown, BOC voltage For the analysis uncertainty, the deviation from the true voltage is given by:
A V ,n ,1= Z ,,,x o ,n ,,x V e ,,,
Eq. 9-3 where Z.,i = randomly selected value from the normal distribution amo = standard deviation for analysis uncertainty (0.103)
V, m - the true, but unknown, BOC voltage FRAMATOME TECHNOLOGIES, INC.
9-6
.- -- - .. . . _ . - - - . - - . _ - - _- .. - ._ - - .- . . . _ - .- - - ~_- _ - . _
i 1
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- Combining these uncertainties to obtain the measured voltage (V_) as a function of the true voltage yields the
equation:
i V_,= V e,,,+ ( Z,cqxa,cqx Ve ,,,) + ( Z,,,, x a,,,, x Ve ,,,)
Eq. 9-4 l Solving for V. yields the following relationship:
t V ,,
j y'"*, 1+Zacq%0A @*Zana1#0 anal Eq. 9-5 [26] '
To obtain an EOC voltage, a randomly selected value from the
- growth distribution is then added to the 'true' BOC voltage. '
i i
This growth value is obtained from the cumulative growth +
distribution shown in Table 9-2. To obtain the growth value, '
a random number from a uniform distribution is generated.
The cumulative growth distribution is then entered at this {
random value. The growth value used in the simulation is {
] obtained by interpolating between the discrete growth values l
- - in the distribution. I t
Accounting for the eddy current uncertainties and defect !
- growth, the EOC voltage becomes
- i
- Va* Verve *b Vgrowth 'b i
1 {
V V**** l, a=1+Zacqxa ncq+ Z,n,; x a,n,, + A V9 '***h l
l Eq. 9-6 i
The Monte Carlo simulation calculates an EOC voltage for {
l l
i each BOC indication. The simulation starts in the smallest I BOC voltage bin and calculates as many independent EOC I 3 voltages as there are indications in this bin. This process l l is repeated for each bin until EOC voltages have been !
] calculated for all of the BOC indications. Each sampling of i
all of the BOC indications is defined as a ' trial'. Many J FRAMATOME TECHNOLOGIES, IN'. . !
, 9-7 1 I
trials (at least 100,000) are performed and the results are averaged to obtain an EOC voltage distribution. The i predicted EOC 6 voltage distribution for the 'C' steam generator is shown in Figure 9-3.
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION f
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i IABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION l
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l TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR " sis AT H/L TSPs l
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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1 TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs-1995 INSPECTION
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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'STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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l TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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1 TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION '
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs !
1995 INSPECTION
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TABLE 9-1 STP-1 FIELD BOBBIN CALLS FOR DSIs AT H/L TSPs 1995 INSPECTION
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TABLE 9-2 BOUNDING VOLTAGE GROWTH DISTRIBUTION FOR SOUTH TEXAS PROJECT UNIT 1
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1 FIGURE 9-1 STP-1 C S/G BOC 6 VOLTAGE DISTRIBUTION l
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FIGURE 9-2 STP-1 BOUNDING VOLTAGE GROWTH DISTRIBUTION (FROM TABLE 9-2)
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FIGURE 9-3 STP-1 C S/G EOC 6 PREDICTED VOLTAGE DISTRIBUTION
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10.0 PROBABILITY OF BURST 10.1 Introduction Calculation of conditional burst probability should be performed per the guidance of Section 2.a of Enclosure 1 of the Generic Letter. This is a calculation to assess the voltage distribution of the indications left in service against a threshold value.
Per the Generic Letter, Licensees should perform an evaluation prior to plant restart to confirm that the steam generator tubes will retain adequate structural and leakage integrity until the next scheduled inspection. The first portion of this evaluation, referred to as the conditional burst probability calculation, assesses the voltage distribution of the axial ODSCC indications left in service against a threshold value of 1 x 104 probability of rupture under postulated main steam line break (MSLB) conditions.
The conditional burst probability calculation is intended to provide a conservative assessment of tube structural integrity during a postulated MSLB occurring at end-of-cycle (EOC). It is used to determine whether the NRC needs to focus additional attention on the particular voltage repair limit application. If.the calculated conditional burst probability exceeds 1 x 10 4 , the licensee should notify the NRC per the guidance provided in Section 6 of the Generic Letter.
STP Compliance with Requirement 10.1.1 STP Probability of Burst In compliance with Section 2.a of Enclosure 1 of the Generic Le,tter, a conditional probability of burst was calculated for South Texas Unit 1 at EOC
- 06. The most limiting probability of burst (POB) was[ ]d FP in the 'C' SG compared to the 1 x 104 threshold level identified by the staff as not requiring additional evaluation or justification.
FRAMATOME TECHNOLOGIES, INC.
10-1
The value was determined in accordance with the methodology described in Section 10.2. This method utilizes Monte Carlo simulations in accordance with 2.b.2 of Enclosure 1 of the Generic Letter and Reference. 26. The Monte Carlo program accounts for defect growth and ECT uncertainties as discussed in Section 9. The program also accounts for uncertainties in the burst pressure vs. voltage correlation and material properties.
10.2 Conditional Probability of Burst Durina MSLB For the Generic Letter,-the conditional probability of burst refers to the probability that the burst pressure associated with 1 or more indications in the faulted steam generator will be less than the maximum pressure differential associated with a postulated MSLB (2560 psid) assumed to occur at EOC. A methodology should be submitted for NRC review and approval for calculating this conditional burst probability. After the NRC approves a mcthod for ;
calculating conditional probability of burst, licensees may l reference the approved method. This methodology should :
involve (1) determining the distribution of indications as a .
function of their voltage response at beginning of cycle i (BOC), as discussed in Section 2.b.1 of Enclosure 1 of the
[
Generic Letter, '( 2 ) projecting this BOC distribution to an !
EOC voltage distribution based on consideration of voltage i growth due to defect progression between inspections, as !
discussed in Section 2.b.2 (2) and voltage measurement uncertainty, as discussed in Section 2.b.2(1), and (3) evaluating the conditional probability of burst for the projected EOC voltage distribution using the correlation between burst pressure and voltage discussed in Section 2.a.1. The solution methodology should account for !
uncertainties in voltage measurement (Section 2.b.2 (1) ) the !
distribution of potential voltage growth rates applicable to I each indication (Section 2.b.2 (2) ) , and the distribution of potential burst pressure as a function of voltage (Section [
2.a.1). Monte Carlo simulations constitute an acceptable FRAMATOME TECHNOLOGIES, INC.
10-2 l,
approach for accounting for these various sources of uncertainty.
STP Con;pliance with Requirement In compliance with 2a items (1) and (2) of Enclosure 1 of the Generic Letter, a BOC voltage distribution was determined and this distribution was projected to an EOC voltage distribution as discussed in Section 9 of this report. In compliance with 2a, item (3), of the Generic Letter for evaluating the conditional probability of burst, a Monte Carlo simulation was utilized. This method is discussed below.
In the Monte Carlo simulation, a burst pressure is calculated for each indication. This burst pressure is based on the end-of-cycle voltage as determined in Section
- 9. The calculated $drst pressure is then compared to the accident pressure differential to determine if that tube would burst under accident conditions.
The burst pressure calculation accounts for uncertainties in the burst pressure vs. bobbin voltage model as specified in the. Generic Letter, as well as material properties associated with the tubes. [
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The first step in the random estimation of the correlation is to calculate a random variance of the error of the burst i pressure about the regression line.
2 n-2 2 2 Grandan* Greg*Sv0 reg
%y(n-2) , randan Eq. 10-1
[26]
where n = number of data pairs 2
x = random deviate from the Chi-square distribution for n-2 degrees of freedom o, = variance from the regression data Therefore, the random standard deviation can be calculated as:
Orandan"0 2 " Orch Eq. 10-2 where f, = factor as defined in Eq. 10-1 The random intercept for the regression is calculated as:
ao=ao+2 nS5?
Eq. 10-3
[26) where ao = intercept from the regression equation Zi = a random normal deviate V =
value from the estimated variance-covariance matrix of the parameters F
FRAMATOME TECHNGLMIES, INC.
10-4
The random slope.is calculated as:
v21 1 2 v*' + 2 V-22 a =a +2, /VG 3h V11 Eq. 10-4
[26]
where ai = slope from the regression equation Z,Z3 2
= random normal deviates V9 = values from the estimated variance-covariance matrix of the parameters The values for the estimated variance-covariance matrix of the parameters are calculated as follows.
V=fV, j3 y j3 Eq. 10-5
[26] ;
where '
Vgyp = values for the variance-covariance e matrix from the regression data The estimated parameters of the correlation as calculated above are then used to estimate a burst pressure for each indication.
P,g=a +n a 11og ( Vj) +2 ja2 Eq. 10-6 (26]
where '
Pr u = burst pressure corresponding to material with the reference flow stress FRAMATOME TECHNOLOGIES, INC.
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)
l
j This value must now be. corrected for the varying material l properties. A random estimate of the flow stress is ;
obtained as: ,
J S, =S,,+ to, ;
Eq. 10-7 ,
-[26] !
i where S. = mean flow stress t = random t-distribution value ;
o, = standard deviation of the flow stress The mean and standard deviation of the flow stress for ,
Westinghouse 3/4 inch tube material is shown in Table 10-1. .
Table 10-1 :
Material Properties For !
Westinghouse Alloy 600 Mill Annealed 3/4" x 0.043" Tubing (26]
Yield Strength Mean 45.78 kai !
Tensile Strength Mean 97.35 kai ,
Flow Stress Mean 71.57 ksi !
, r 5- Flow Stress Standard 3.5668 ksi l Deviation Sample Size 627 The final estimate of the burst pressure is then' calculated i as: i l [
Si Pi = P,,f g
\ tef Eq. 10-8 l [26]
l l FRAMATOME TECHNOLOGIES, INC. I L 10-6 l
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This value for the burst pressure is compared to the MSLB differential pressure to determine if the tube would burst under accident conditions.
Burst pressures are calculated for each indication in the steam generator. The number of indications with burst pressures resulting in failures is counted for each trial.
If the number of indications resulting in a burst in a single trial is greater than or equal to one, then that trial is counted as one trial with a burst. Due to application of the 0.6 probability of detection, some of the voltage bins may contain fractional parts of indications (e.g., 0.3 or 0.7). If, due to these fractional indications, the number of indications resulting in a burst in a single trial is less than one, then that fractional value is added to the number of trials with a burst tube.
The best estimate for the probability of burst is the number of trials with a burst divided by the total number of trials. The 95% upper confidence limit for the probability of burst is calculated using a set of subroutines. The bases of these routines is contained in Reference 29. The source of the approximations used in these routines is Reference 30.
The results of the STP-1 probability of burst evaluation are summarized in Table 10-2 below. These results were obtained by running the Monte Carlo simulation for 1 x 106 trials. ;
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TABLE 10-2 STP-1 EOC-5 PROBABILITY OF BURST RESULTS
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]d' 10.3 Burst Pressure Versus Bobbin Voltace Per the Generic Letter, an empirical model, for 3/4-inch diameter tubing, should be used to relate burst pressure to bobbin voltage response for purposes of estimating the conditional probability of burst during a postulated MSLB.
f This model should explicitly account for burst pressure '
uncertainty as indicated by scatter of the supporting test l data and should also account for the parametric (i.e., slope ;
and intercept) uncertainty of the regression fit of the data. The supporting data sets for 3/4-inch diameter tubing include all applicable data consistent with the industry r recommendations as stated in the Generic Letter. {
STP Compliance with Requirements ,
i 10.3.1 Burst Pressure - Voltage Correlation Database l To comply with Section 2.a.1 of Enclosure 1 of the !
Generic Letter a correlation between burst !
pressure and bobbin voltage amplitude was !
developed by EPRI(3) . The relationship between ,
burst pressure and voltage is used to establish a i voltage threshold to ensure that the structural !
requirements of Regulatory Guide 1.121 are FRAMATOME TECHNOLOGIES, INC.
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satisfied during normal operating and postulated accident loading conditions. The correlation for the 3/4-inch diameter tubing is based on 45 model boiler specimens and 46 pulled-tube specimens from operating plants as summarized in Table 10-3. The data from tests of pulled tubes and model boiler specimens were combined to form an aggregate database which was then used to develop the burst pressure correlations described later.
The database used for the development of the burst correlation (Burst Strength vs. Bobbin Coil Voltage Amplitude) for 3/4 inch diameter tubing is derived from model boiler specimens and pulled tubes. All of the data were derived from Alloy 600 tubing with 3/4 inch OD and 0.043 inch nominal r wall thickness. The model boiler test results for 3/4 inch tubing are described in detail in Reference 3.
On the basis of References 27, exclusion of data criteria 1-3 , all data were reviewed by EPRI for identification of data which were excluded from the databases supporting the ARC correlations for ODSCC. Table 10-4 summarizes the data removed from the burst database by EPRI [27,28). Per the Generic Letter (1) , data excluded under criteria 1, 2a, and 2b are acceptable exclusion criteria.
The data excluded from the EPRI database was reviewed by FTI for this evaluation. FTI concurs that the excluded data meets the criteria contained Reference 27 and 28 and therefore was not included in this evaluation.
10.3.2 Burst Pressure Correlation for 3/4" Dia. Tubing The bobbin coil voltage amplitude and burst pressure data of Table 10-3 were used to determine a correlation between burst pressure and bobbin voltage amplitude. The data considered are shown FRAMATOME TECHNOLOGIES, INC.
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in Figure 10-1 along with the results of the correlation analyses.
From the methodology discussed in Section 6 of Reference 3, the correlation line for the burst- ,
voltage correlation is given by:
[
le FP Eq. 10-9
[3]
where the burst pressure is measured in ksi and the bobbin amplitude is measured in volts. The correlation line from the equation above is shown in Figure 10-1.
Per Enclosure 1 of the Generic Letter, Section 2.a.1, the burst pressure model should account for
. data scatter of the linear regression fit. l l
Therefore, the residual values were plotted against the predicted burst pressures. The results, shown in Figure 10-2, indicate a scatter about a mean of zero for the full range of predicted burst pressures. Per Reference 3, this scatter for the data indicates an acceptable set of data points and an acceptable correlation.
A cumulative probability plot of the ordered residuals was also prepared and is shown in Figure 10-3. Verification of the regression is obtained by plotting the ordered residuals on normal probability paper. Since the data form a straight line, it has been shown that the distribution of the residuals is normal, as proven in Reference 3.
In order to determine the voltage structural limit (Vst) for STP, the 95% prediction bound was reduced to a level corresponding to the 95%/95% lower FRAMATOME TECHNOLOGIES, INC.
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._ .- . .. _ __.____m ._.- _ _ _ _ _ _ .. _ _ _ _ _ - .
i i !
u tolerance limit (LTL) for the material properties of the tubes. The estimated standard deviation of the residuals, i.e., the error of the estimate, j S,, of the burst pressure was [ ]d FP ksi. The i lower 95% prediction curve adjusted for 95%/95% f lower tolerance limit on material properties, is defined by the equation: l
[
JEPEq. 10-10
[6] ,
where: a = (Su + Sy) at 650 0F ,
Su = tube material ultimate tensile !
strength Sy = tube material yield strength !
ao = constant from regression [Eq. 10-9]
ai = Slope from regression [Eq. 10-9] :
Vi = Voltage ,
Psi =
Mean Burst Pressure at (V i) t - Student's t-distribution value corresponding to the upper tail area of 5% !
Sp = Standard Deviation of Residuals (error of estimate) !
n - Total number of-data points used ,
j = index i
average of the voltages BarVo =
A Monte Carlo simulator is used to predict EOC I
voltages as an input to the probability of burst model. Each resulting EOC voltage is processed i via a " randomized regression" version of the burst !
pressure-voltage correlation, where the intercept and slope are randomly taken from their bivariate ;
normal distribution. The t-distribution with n-2 :
degrees of freedom is also randomly chosen for the l r
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. simulation. The simulator also randomly samples from a uniform distribution of the material properties of the tubes. A mean value of flow stress of 71.57 and a flow stress standard deviation of 3.5668 from a sample size f 627 j samples was used per Reference 26 for the material !
properties of 3/4" Alloy 600 mill annealed SG tubing. The predicted probability of burst ~is I then calculated from the simulation. j P
In order to determine the repair limit (Section 6) for STP, the voltage structural limit at MSLB conditions is calculated utilizing Equation 10-10.
Using this' Equation, the Va corresponding to 1.43 i times faulted differential pressure, or [ Jd FP is[ ]d FP volts. The [ ] dFP pressure differential is 1.43 x APmw, where APma is equal to [ ] dFP . The lower 95% prediction bound for i LTL material property is shown in Figure 10-1. l 10.4 South Texas Project Unit 1 Data from Pulled Tubes
]
During the 1REO4 and 1REOS refueling outages, STP-1 pulled ,
tubes containing an axial ODSCC-type indications in the TSP regions. The testing procedure and pulled tube burst test ,
data from South Texas is described in detail in Reference 4 j and Reference 32. The burst test result from the STP-1 l pulled tubes are shown in Table 10-3 and Figure 10-1. I l' F t
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TABLE 10-3 f27.281 VOLTAGE-BURST-LEAK RATE-PROBABILITY OF LEAK DATA TABLE l
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TABLE 10-3 f27.281 VOLTAGE-BURST-LEAK RATE-PROBABILITY OF LEAK DATA TABLE
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TABLE 10-3 f27.281 VOLTAGE-BURST-LEAK RATE PROBABILITY OF LEAK DATA TABLE
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FRAMATOME TECHNOLOGIES, INC.
10-17
TABLE 10-3 f27.281 VOLTAGE-BURST-LEAK RATE-PROBABILITY OF LEAK DATA TABLE
[
] EP
NOTES:
- 1. All voltages normalized to the recommended values of Reference 27,28.
- 3. Normalized to 150 ksi flow stress (sum of yield and ultimate stress).
- 4. Column indicates application of specimen in leak rate and/or burst correlation. 0= No, ! =Yes i
- 5. Leak rate inferred from destructive examination crack morphology.
- 6. N.R. Not Reliable, not used in leak rate correlation. ]
- 8. . Included per NRC directive. i
- 9. Data excluded per outlier criteria 2a. ;
- 10. Burst test showed insignificant extension at the corrosion crack tips. Derefore, the burst pressure is a nunimum value since [
burst is defined to include crack extension.
f II. Data meeting exclusion criteria 3.
t t
l f
I 1
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i i
1' i
L l
FRAMATOME TECHNOLOGIES, INC.
10-18 l
TABLE 10-4 [27,28]
BASIS FOR EXCLUDING DATA FROM TILE 3/4 INCII BURST CORRELATION
[
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) EP FRAMATOME TECHNOLOGIES, INC.
10-19
- i l
t FIGURE 10-1 [27,28] j BURST PRESSURE vs. BOBBIN AMPLITUDE '
FOR 3/4 INCH ALLOY 600 S/G TUBE MODEL BOILER AND FIELD DATA
[ i i
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1 f
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FRAMATOME TECHNOLOGIES, INC.
10-20 4
- . - - . . . . . - . _ . - . _ _ . . . - . . . - _ _ . . - . . . . _ . ~ . . . . ~ . . - . - - . . . . . . -.-. .. - . - .
1 i
- j. i i
. 1
- FIGURE 10-2 [27,28] .!
BURST PRESSURE.vs. BOBBIN AMPLITUDE l l RESIDUALS vs. PREDICTED VALUES b
4
- 1
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. s FRAMATOME TECHNOLOGIES, INC.
4' !
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~. - - - _ . . . . - . . . - -. . . . _. .. .-._ _. -.,-........- .. . ...- - . . - ... .__. -. .
1 f
1
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4 4
i FIGURE 10-2 [27,28] ,
BURST PRESSURE vs. BOBBIN AMPLITUDE l ACTUAL vs. EXPECTED CUMULATIVE PROBABILITY i a
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i FRAMATOME TECHNOLOGIES, INC. 7
, 10-22 )
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11.0 EVALUATION OF LEAKAGE ;
i 11.1. Introduction -
i i Calculation of leakage should be performed per the guidance ,
I of Section 2.b of Enclosure 1 of the Generic Letter. This
} calculation, in conjunction with the use.of licensing basis assumptions for calculating offsite releases, enables !
licensees to demonstrate that the applicable limits of 10
{ CFR 100 continue to be met.
Per-the Generic Letter, a methodology should be submitted for calculating the total primary-to-secondary leak rate in '
I the faulted steam generator during a postulated MSLB assumed i to occur at EOC. This methodology involves (1) determining the distribution of indications as a function of their j voltage response at beginning of cycle (BOC) as discussed in i
. Section 2.b.1, (2) projecting this BOC distribution to an j EOC voltage distribution based on consideration of voltage j growth due to defect progression between inspections as discussed in Section 2.b.2 (2) and voltage measurement uncertainty as discussed in Section 2.b.2 (1) , and (3) evaluating the total leak rate model as discussed in Section ;
!; 2.b. 3 (2) . The solution methodology should account for uncertainties in voltage measurement (Section 2.b.2 (1) ) , the ;
i distribution of potential voltage growth rates applicable to each indications (Section 2.b. 2 (2) ) , the uncertainties in
, the probability of leakage as a function of voltage (Section 2.b.3 (1) ) , and the distribution of potential conditional ;
leak rates as a function of voltage (Section 2.b.3 (2)) . !
4 Monte Carlo simulations are an acceptable method for
- accounting for these sources of uncertainty provided that the calculated total leak rate reflects an upper 95% '
quantile value.
1 This portion of the tube integrity evaluation is intended to !
assure that the total leak rate from the affected steam generator (SG) during a postulated MSLB occurring at EOC i
p would be less than that which could lead to radiological ;
releases in excess of the licensing basis for the plant. If ;
4 I
~FRAMATOME TECHNOLOGIES, INC.
11-1 i
. I t
calculated leakage exceeds the allowable limit determined by the licensing basis dose calculation, licensees can either repair tubes, beginning with the largest voltage indications until the leak limit is met, or reduce reactor coolant system specific iodine activity.
11.2 Calculation of Proiected MSLB Leakace Using the projected EOC voltages as calculated from the method presented in Section 9, the leakage for the postulated MSLB is calculated utilizing two models: (1) the probability of leakage model and (2) the conditional leak rate model. As previously discussed in Section 2.b of the Generic Letter, Monte Carlo techniques are an acceptable approach for accounting for uncertainties implicit in these models.
STP Compliance with Requirements 11.2.1 Calculation of Projected MSLB Leakage for STP In compliance with Section 2.b.3 of the Generic Letter, the probability of leakage correlation and the conditional leak rate correlation provide the ,
basis for a best-estimate ODSCC leak rate model.
The methodology described in Section 11.3 and 11.4 of this report is consistent with that prescribed by Reference 6 and 26.
The probability of leakage (POL) model for STP was )
developed using field and laboratory data provided by EPRI [3,6,27,28) . Due to a number of ;
uncertainties in the input variables to the ODSCC leak rate model, the leak rate for an individual tube may deviate from the value predicted by this j correlation. ;
l I
l FRAMATOME TECHNOLOGIES, INC. '
11-2 l
l l
i A Monte Carlo simulator is used to predict the leak rate under MSLB conditions at EOC. The !
simulator program accounts for the uncertainties !
by randomly varying the parameters of both the POL i and leak rate correlations. The random values for .
j the slope, intercept, and standard deviation are i determined in accordance with Reference 26. This l procedure is similar to the method described.in- !
Section 10 for the burst pressure correlation. !
The random correlation parameters are used for all of the EOC voltages for a single trial. At the !
beginning of the next trial, a new set of i parameters are estimated. !
i For the POL correlation, the values of the ;
parameters are randomly estimated as follows.
90"D +2 5 o 1 Eq. 11-1 l
[26]
)
2 v21 !
91=n1 +22 v* * + 2 V- !
y a%
22 v11 Eq. 11-2 (26) i !
where x
2
= random deviate from the Chi-square distribution for n-2 degrees of freedom i I
Zi = a random normal deviate :
n o, ni = parameters from the regression data I
, Vg = values from the estimated variance-
, covariance matrix ;
I I
i i 4
i FRAMATOME TECHNOLOGIES, INC. I 11-3 I
f Since the data for the POL correlation are binary, there is no standard deviation term to estimate.
For the leak rate correlation, the standard deviation can be estimated as:
Otandcen"O re "O reg \
2
% (n-2) , tandern Eq. 11-3
[26]
where n = number of data pairs o,m
- standard deviation from regression data x2 = random deviate from the Chi-square distribution for n-2 degrees of freedom l
The random intercept for leak rate correlation is estimated as:
Po=bo +24 %
Eq. 11-4 (26) where bo = intercept from the regression equation Z = a random normal deviate ,
Vy = value from the estimated variance-covariance matrix of the parameters 4
FRAMATOME TECHNOLOGIES, INC.
~
11-4
The random slope.for the leak rate correlation is estimated as:
p1=bi +22 **+2 V-22 y 3$ V12
, Eq. 11-5
[26) where
- bl - slope from the regression equation i Zi = random normal deviates Vij = values from the estimated variance-covariance. matrix of the parameters
- - The values for the estimated variance-covariance of the parameters are calculated as
h Vij= f,Vjp,,g; Eq. 11-6 l- [26]
j where i
fv = factor as defined in Eq. 11-3 j Vg,g = values for the variance-covariance matrix from the regression data
! After all of the parameters are estimated, the end-of-cycle voltages are calculated as discussed i in Section 9. For each EOC voltage, a probability l f of leakage is calculated using the estimated i i
parameters. A random number between 0 and 1 is l then selected from a uniform distribution and is
.e- compared to the estimated POL value. If the i random number is greater than the POL, then that indication is considered to have no leakage under j MSLB conditions. In this case, a leak rate l calculation is not necessary and the program ;
l returns to calculate the POL for the next EOC If the random number is less than the voltage.
- POL, then the indication is considered to leak.
. FRAMATOME TECHNOLOGIES, INC.-
11-5 i-.
1
. ~ -- --m.. - . - - - - . ..v.-- . , . , _ _ _ -
For those EOC voltages that result in leakage, the amount of leakage munt be cniculated from the j estimated leak rate parametero. This random cotimated leak rate is calculated as:
0; = 10E *
- 8d S W '#"a'"
Eq. 11-7
[2G)
This leak rate is added to a summing variable which totala the leak rates for all of the indications in the steam generator which result in leakage. After all of the BOC indications have l been processed, the total leak rate for that trial is saved to a file and another trial is started.
l At the end of the last Monte Carlo trial, the data l in the file containing the individual trial leak rates for the steam generator is sorted, and a 95%/95% one-sided upper tolerance limit is determined on a distribution-free basis. This is done to ensure a conservative measure of the leak l rate for the faulted steam generator under MSLB conditions. Reference 31 explains the method used to determine the 954/95% one-sided upper tolerance limit.
The 95%/95% one-sided upper tolerance limit for leakage calculated during MSLB at EOC 06 at STP-1 in approximately[ } d"'f or steam generator C. For an accident, this leakage must be evaluated in the form of offsite dose release per 2.b.4 of the Generic Letter and is addressed in Section 11.5 of this report. The resulto for all of the STP-1 steam generators are shown in Table 11-1.
FRM4ATOME TECHNOLOGIES, INC.
11-6
._ __ . _ . . - . _ . . _ _ _ _ . . _ _ _ , _ ~ . _ _ . - . . _ . - _ . _ . . _ _ _ .__.- . _ _ _ - . . . ,
l l
l TABLE 11-1 :
1 PROJECTED EOC-6 LEAK RATE !
[ !
1 i
i
]dH' ;
l 11.3 Probability of Leakace as a Function of Voltace The probability of leakage (POL) model should utilize the :
log-logistic functional form (1) . This model should explicitly account for parameter uncertainty of the POL functional fit of the data. The supporting data sets for 3/4-inch diameter tubing include all applicable data l consistent with industry recommendations as stated in the !
I Generic Letter.
STP Compliance with Requirements ;
i 11.3.1 Probability of Leakage Model ]
Per the Generic Letter, once the EOC distribution I
has been determined, the probability of leakage i (POL) needs to be evaluated. Probability of l leakage is determined from the magnitude of the !
bobbin coil voltage measurement for a specific TSP l intersection. For a number of TSP intersections l containing equal amounts of degradation, based on i voltage, a proportion is statistically predicted t to be leakers, while the remaining proportion is !
predicted to be non-leaking, i
FRAMATOME TECHNOLOGIES, INC. ,
11-7 5 i
Based on industry test data, the logistic function best represents.the probability of-leakage (POL) and therefore was used-for the leak rate model (6) . This probability distribution function is appropriate for binary-type variables, such as'the leak /no-leak designation. The POL-for an ODSCC
. produced voltage measurement at a specific TSP location is therefore determined by:
I
} EPgg, yy g
[6]
where: P= probability of leakage V= voltage measurement at TSP location no= coefficient determined from analysis ni = coefficient determined from analysis The parameters of the logistic function are determined from an iterative maximum likelihood procedure which is applied to the leak /no-leak data.
A probability of leak model was developed using the method described in Appendix D of Reference 6.
A logistic regression fitting procedure from Reference 24 was applied to the data set shown in Table 1 of Reference 27 and amended by Reference 28.
On the basis of the Reference 27 and 28 exclusion criteria 1-3, all data documented in Reference 27 amd 28 were reviewed by EPRI for identification of data which were excluded from the databases supporting the ARC correlations for ODSCC. FTI FRAMATOME. TECHNOLOGIES, INC.
11-8
excluded data on the basis of Criteria 1 and 2 in I this analysis based on review of the data and the
, requirements of the Generic Letter. The data I excluded from the probability of leakage correlation are summarized in Table 11-3 of this ;
report. i The resulting parameter estimates for the POL !
model are depicted in Table 11-2, below. The ;
factors needed to estimate the uncertainty for the POL model were computed using the method shown in l
Reference 6., Appendix D. The values for the !
variance-covariance estimates are also listed below.
{
TABLE 11-2 t PROBABILITY OF LEAKAGE PARAMETERS
[
i l
l I
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where: no= coefficient determined from analysis ;
ni = coefficient determined from analysis i rn - variance-covariance value determined ]
from the analysis j rn - variance-covariance value determined i from the analysis ,
o Pn - variance-covariance value determined I from the analysis
- i I
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FRAMATOME TECHNOLOGIES, INC.
11-9 1
a 11.4 Conditional Leakace Rate under MSLB Conditions ;
F The conditional leak rate model should incorporate a linear _ !
regression fit to the log of the leak rate data for 3/4-inch diameter tubing, as a function of_the log of the bobbin 'I i
voltage and should account for both data scatter and parameter uncertainty of the linear regression fit. Use of this approach is subject to demonstrating that the linear :
regressior. fit' is valid at the 5% level with a "p-value" test. If this condition is not satisfied, the linear regression fit should be assumed to have' zero slope (i.e., !
the linear regression fit should be assumed to be constant '
with voltage).
The supporting data set for 3/4-inch diameter tubing includes all applicable data consistent with the industry i recommendations as stated in the Generic Letter. l l
STP Compliance with Requirements l 11.4.1 Conditional Leak Rate versus Voltage Model Database i In compliance with 2.b.3 (2) of Enclosure 1 of the Generic Letter, the database used for the ,
development of the leak rate correlation (MSLB [
Leak Rate versus Bobbin Coil Voltage Amplitude) for 3/4 inch diameter tubing is derived from model t
boiler specimens and pulled tubes. All of the data were derived from Alloy 600 tubing with 3/4 ;
inch OD and 0,043 inch nominal wall thickness.
The model boiler test results for 3/4 inch tubing are described in detail in Reference 3. The j database used for the Leak Rate - Voltage correlation is shown in Table 10-3 of this report.
)
On the basis of the Reference 3 exclusion criteria i 1-3, all data documented in References 3, 27 and ,
28 were reviewed by EPRI for identification of
{
i FRAMATOME TECHNOLOGIES, INC. !
11-10
- f
.. _ -- - - _ _ _ _ . __ - 3
_ _ - = _
i l
l l
l data which were excluded from the databases supporting the ARC correlations for ODSCC. FTI excluded data on the basis of Criteria 1 and 2 in ,
this analysis based on review of the data and the requirements of the Generic Letter. Table 11-4 !
summarizes the data removed from the leak rate correlation database by EPRI [3, 27, 28] .
11.4.2 Leak Rate Versus Voltage Correlation The bobbin coil voltage amplitude and leak rate data of Table 10-3 were used to determine a correlation between leak rate and bobbin voltage.
The data considered are shown in Figure 11-1 along with the results of the correlation analyses. ,
From the methodology discussed in Section 7 of Reference 3, the correlation between leak rate and bobbin voltage is achieved by considering the log of the voltage as the independent variable and the log of the leak rate as the dependent variable.
The correlation line for the leak rate-voltage correlation for 46 data points is given byr log (O) = bo + b ilog (V) where: bo = [ ]d FP bi = [ ]d FP Q =
Leak Rate (1/hr)
V - Voltage Therefore: log (Q) = [ ]d FP Eq. 11-9 Solving for Q gives the following equation.
O=104*hl SM Eq. 11-10 FRAMATOME TECHNOLOGIES, INC.
11-11
The error of the estimate from the evaluation, S,,
was[ ]dFP. A 95% prediction band for individual values of leak rate, 0 3 , as a function ,
of voltage was also calculated per for following equation:
I
] EPEq. 11-11
[3]
where: bo = constant from regression [Eq.11-9]
b i
= constant from regression [Eq.11-9]
Vi = Voltage Qi = Leak Rate at (Vi) t = Student's t-distribution corresponding to the upper tail area of 5%
Sp = Standard Deviation of Residuals ]
(error of estimate) n = number of data points used j = index Bar Vo = average of the voltages A plot of the expected leak rate is provided in Figure 11-1.
- 11.4.3 Analysis of Residuals Per the Generic Letter Section 2.b.3 (2) , the leak rate model should account for data scatter of the linear regression fit. Figure 11-2 shows the scatter plot of the log (Q) residuals as a function of the prediction log (Q) for the MSLB pressure of
[ 3dFP. The arrangement of the points is non-descript, indicating no apparent correlation between the residuals and the predicted values.
FRAMATOME TECHNOLOGIES, INC.
11-12
- .-- - .. . - .- _ - . . ~ .- .-
i i
I The cumulative probability plot prepared for MSLB l differential pressure of ( ]d FP is shown in Figure 11-3. A straight line'is approximated, typical of the behavior of normally distributed f residuals. !
c d
Given the results of the residuals scatter plot f i and the normal probability plot, it is appropriate
{
- to use the regression curve and statistics can be '
l used for the prediction of leak rate as a function l
. of boboin amplitude, and for the establishment of l statistical inference bounds. ,
- 11.5 Calculations of Offsite and control Room Doses !
4 i For the MSLB leak rate calculated above, offsite and control I i
room doses should be calculated utilizing currently accepted licensing basis assumptions. Licensees should note that' !
q Enclosure 2 of the Generic Letter provides example Technical ,
Specification (TS) pages for reducing reactor coolant system !
) specific iodine activity limits. Reactor Coolant system !
iodine activities may be reduced to .35 microcurie per gram j l dose equivalent I-131. Licensees wishing to reduce iodine j 4
activities below this level should provide a justification supporting the request that addresses the release rate data. t Reduction of reactor coolant iodine activity is an acceptable means for accepting higher projected leakage rates and still meeting the applicable limits of 10 CFR 100 utilizing licensing basis assumptions.
STP Compliance with Requirements 11.5.1 Leakage Evaluation Per 10 CFR 100 The maximum allowable end of cycle primary-to-secondary steam generator leak rate will be ,
evaluated to determine whether the radiological consequences will remain within the limits of 10 l CFR 100 and GDC 19 design criteria for STP during I a postulated main steam line break. I l
l FRAMATOME TECHNOLOGIES, INC.
11-13
-1
)
I The evaluation will be based on an acceptance i criteria of 30 rem thyroid dose at the Exclusion -
Area Boundary per the Standard Review Plan (NUREG 0800) Section 15'.1.5, Appendix A. For the pre- l accident spike,,the initial primary coolant l activity was 60 pCi/gm dose equivalent Iodine 131 {
(I 131), and for the concurrent spike the activity was 1 pCi/gm. The secondary coolant activity was O.1 pCi/gm I 131. The leak rate in the three j intact steam generators was assumed to be the !
proposed Technical Specification limit of 150 !
gallons per day (about 0.1 gpm) in each generator. ;
The leak rate from the reactor coolant system was !
assumed to be 1 gpm also per the technical l specification.
The activity released to the environment due to a main steam line break was analyzed in two distinct releases: 1. the release of the iodine activity ,
that has been established in the secondary coolant t prior to the accident, and 2, the release of the primary coolant iodine activity due to tube ,
leakage. The bounding leak rate will be ;
determined and maintained as part of the design i basis.
The STP-1 EOC 6 predicted leakage is [
] d" which is much less than the current design basis leakage of 1 !
gpm. Therefore, it is reasonable that the 150 gpd
{ proposed technical specification limit per steam '
generator is sufficient to preclude unexpected
[
crack propagation leakages which would result in a MSLB dose release in excess of 10 CFR 100 or GDC 19.
l 1
I .
i j FRAMATOME TECHNOLOGIES, INC. '
11-14
- - - . . . . ~ - , _ _ _ _ . - - - - . - . ~ - - . . . . . . . . - - _ , . ,
5 i
TABLE 11-3 [3,27,28] -
BASIS FOR EXCLUDING DATA FROM THE 3/4" PROBABILITY 0F LEAK CORRELATION '
[ !
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6 i
3 i
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'FRAMATOME TECHNOLOGIES , Ir ,,
11-15
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TABLE 11-4 [3,271 BASIS FOR EXCLUDING DATA FROM 3/4" LEAK RATE CORRELATION
[
EP J
FRAMATOME TECHNOLOGIES, INC.
11-16 f
f i
l FIGURE 11-1 [3,27]
2560 PSI MSLB LEAK RATE VS. BOBBIN AMPLITUDE i 3/4" TUBES, MODEL BOILER AND FIELD DATA
! I i
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]c FP FRAMATOME TECHNOLOGIES, INC.
11-17
FIGURE 11-2 f3,271 RESIDUALS VS, PREDICTED LOG OF LEAK RATES 3/4" TUBES, MODEL BOILER AND FIELD DATA I l t
i i
I i
+
i i
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=
t
]C FP I
I t
i l
1 l
l FRAMATOME TECHNOLOGIES, INC.
11-18
FIGURE 11-3 [3,271 CUMULATIVE PROBABILITY OF RESIDUAL LEAK RATES
[
]c FP FRAMATOME TECHNOLOGIES, INC.
11-19
4 l
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This Page Left Blank ls 1
J 1
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_ . _ _ . . .. . _ _ _ . _ _ _ _ _ _ _ . . . . _ ._._ __...- _ . _ - ~ __ _
l l l
l 12.0 OPERATIONAL LEAKAGE LIMITS '
)I - .12.1 Introduct.19B-
.i The operational. leak limit is a defense-in-depth measure j i
that provides a means for identifying leaks during operation !
to enable. repair before such leaks result.in tube failure. l Review of leakage monitoring measures includes'the f procedures for timely' detection, trending, and response to l rapidly increasing leaks. .The objective'is to ensure that j should a significant leak _be experienced in service', it will-be detected and the plant shutdown in a timely manner to l reduce the likelihood of potential tube rupture. l l
t 12.2 Ooerational Leakace Limits Per.the Generic Letter, the operational leakage limit shoul'd !
be reduced to 150 gallons per day (gpd) through each steam l generator.
Licensees should review their plant specific leakage l monitoring measures to ensure that if a significant in- I service leak occurs, it will be detected and~the plant ;
shutdown in a timely manner to reduce the likelihood of tube i rupture. Specifically, the effectiveness of the plants' ,
procedures to ensure timely detection, trending, and .
response to rapidly increasing leaks should be assessed. l Alarm setpoints on primary-to-secondary leakage detection instrumentation and the various criteria for specific !
operator actions in response to detected leakage must also ,
be evaluated. I i
Steam generator tubes with known leaks should be repaired j prior to returning the steam generators to service following l a steam generator inspection outage. l l
i t
FRAMATOME TECHNOLOGIES, INC.
12-1
_ _ . ._- . - _ . _ . ~ . . . . . _ , _ - - - - . - - .
I STP Complieuc with Requirement HL&P will, in its Revised Technical Specification submittal, commit to an operational leakage limit of 150 gpd per steam generator, for STP-1.
HL&P has reviewed STP-1 plant specific leakage monitoring procedures and actions to ensure that any leaks that develop during an operational cycle will be detected, trended, and the plant shutdown in a timely manner.
HL&P has committed to repair all tubes with known leaks prior to returning steam generators to service following an inspection outage.
I FRAMATOME TECHNOLOGIES, INC.
12-2
13.0 REPORTING REQUIREMENTS 13.1 Introduction Per Section 6 of Enclosure 1 of the Generic Letter, documentation reporting the EOC voltage distribution, cycle growth rate distribution, voltage distribution for EOC repaired indications (indications confirmed and unconfirmed by MRPC) and NDE uncertainty distribution in predicting the next EOC distribution shall be submitted to the NRC.
13.2 Threshold Criteria for Recuirina Prior Staff Acoroval to Continue with Voltaae-Based criteria This guidance allows licensees to implement the voltage-based repair criteria on a continuing basis after the NRC staff has approved the initial TS amendment. However, there are several situations for which the NRC staff must receive prior notification before a licensee can continue with the implementation of the voltage-based repair criteria:
13.2.a If the projected EOC voltage distribution results in an estimated leakage greater than the leakage limit (determined from the licensing basis calculation), then the licensee should notiry the NRC of this occurrence and provide an assessment of its significance prior to returning the SGs to service. If it'is not practical to complete this calculation prior to returning the SGs to service, the measured EOC voltage distribution can be used (from the previous cycle of operation) as an alternative (refer to Section 2.c of Enclosure 1 of the Generic Letter). If it is determined that the projected calculated leakage will exceed the leakage limit (during the operating cycle) after the SGs are returned to service, then licensees should provide an assessment of the safety significance of the occurrence, describe the compensatory measures being taken to resolve the issue, and follow any other applicable FRAMATOME TECHNOLOGIES, INC.
13-1 1
1 reportablity-regulations.
13.2.b If (1) indications are identified that extend beyond the confines of the TSP or (2) indications
', are identified that appear to be circumferential
, in nature, or (3) are attributable tx) primary k water stress corrosion cracking, the NRC staff should be notified prior to returning the steam generators to service.
j 13.2.c If the calculated conditional probability of burst j based on the projected EOC voltage distribution i exceeds 1 x 10-2, licensees should notify NRC and
- provide an assessment of the significance of this occurrence prior to returning the steam generators j' to service. This assessment should address the j safety significance of the calculated conditional j probability. If it is not practical to complete
! this calculation prior to returning the SGs to service, the measured EOC voltage distribution can i be used (from the previous cycle of operation) as an alternative (refer to Section 2.c of Enclosure 1 of the Generic Letter) .
STP Compliance with Requirements i
13.2.1 STP Threshold Criteria for Requiring Prior Staff Approval to Continue with. Voltage-Based Criteria Per Section 6.a of Enclosure 1 of the Generic Letter STP will notify the NRC if th'e actual measured voltage distribution results in an j estimated leakage during the previous operating 4
cycle greater than the leakage limit determined
) from Section 11 and 12 of this report. STP will notify the NRC if indications are identified that extend beyond the TSP or indications that appear to be circumferential in nature prior to returning l the SGs to service. STP will notify the NRC if
} the calculated conditional probability of burst FRAMATOME TECHNOLOGIES, INC.
13-2
4 based on the EOC voltage distribution is greater than 1 x 10 2 prior to returning the SGs to
, service, 13.3 Information To Be Provided Followina Each Restart The following information should be submitted to the NRC staff within 90 days of each restart following a steam generator inspection:
(a) The results of metallurgical examinations performed for tube intersections removed from the steam generator.
If it is not practical to provide all the results within 90 days, as a minimum, the burst test, leakage test and morphology conclusions should be provided within 90 days. The remaining information should be submitted when it becomes available.
(b) The following distributions should be provided in both tabular and graphical form. This information is to enable the staff to assess the effectiveness of the methodology, determine whether the degradation is changing significantly, determine whether the data supports higher voltage repair limits, and to perform confirmatory calculations:
(i) As found EOC voltage distribution - all
, indications found during the inspection regardless of MRPC confirmation (ii) cycle voltage growth rate distribution (i.e.,
from BOC to EOC- the data should indicate whether the distribution has been adjusted for the length of the operating interval, and the length of the operating interval should be provided (i.e.,in EFPY). The planned length of the next operating interval should also be provided (in EFPYs).
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4 (iii) voltage distribution for EOC repaired indications - distribution of indications presented in (i) above that were repaired (i.e., plugged or sleeved)
(iv) voltage distribution for indications left in service at the beginning of the next operating cycle regardless of MRPC confirmation - obtained from (i) and (iii) above (v) voltage distribution for indications left in service at the beginning of the next operating cycle that were confirmed by MRPC to be crack-like or not MRPC inspected (vi) non-destructive examination uncertainty distribution used in predicting the EOC (for the next cycle of operation) voltage distribution.
1 1
(c) The results of the tube integrity evaluations described in Section 2 of Enclosure 1 of the Generic Lettel and discussed in Sections 10.0 and 11.0 of this report.
Note that these calculations must be completed prior to restart to ensure that an adequate number of tubes have been repaired to meet the leakage limit and ensure continued tube integrity.
STP Compliance with Requiremento 13.3.1 Information To Be Provided by STP Following Restart Consistent with the Generic Letter requirements discussed in Section 13.3 of this report, the following actions shall be taken to ensure that the NRC is aware of the on-going status of STP ARC implementation. Beginning with the upcoming Refueling Outage 6 data for Unit 1 and subsequent FRAMATOME TECHNOLOGIES, INC.
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i I
outages; l (1) All indications found during the inspection regardless of MRPC confirmation will be :
reported to the NRC. l (2)- The cycle growth rate distribution will be-evaluated to determine whether the growth l rate assumed remains bounding. The results j of the growth rate distribution will be !
reported to'the NRC.
l (3) Voltage distribution for EOC repaired indications that were repaired will be :
reported to the NRC. ,
l i
(4) Voltage distribution for indications left in ;
service at the beginning of the next operating cycle regardless of MRPC !
confirmation will be reported to the NRC. l (5) Voltage. distribution for indications left in j service at the beginning of the next j operating cycle that were confirmed by MRPC l or not MRPC inspected will be reported to the {
NRC. '
(6) The results of the pulled tube data per ;
Section 8.0 shall be reviewed against the burst correlation data for continued I applicability or adjustment. The metallurgical examination and testing results shall be reported. The inspection data shall I be reviewed-along with destructive examination results to verify that the j morphology remains consistent with this submittal. Any indication of changing !
morphology or observation of cracks extending beyond the confines of the TSP shall be reported. !
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(7) Results of the tube integrity and leak rate evaluations described in Section 2 of Enclosure 1 of the Generic Letter to ensure that an adequate number of tubes have been repaired to meet the leakage limit and ensure -
continued tube integrity.
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______._ __. . _ . ~ _ _ . _ _ _ _ _ . _ _ _ . - . _ . _ . . _ _ _ . _ _ . _ . . _ . - . _ . _ . _ . _ _ . . , _ . . _ _ _ . _ _ _ _ _ _ _
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14.0 EXCLUSION OF INTERSECTIONS ,
4 i Per the NRC Generic Letter, the alternate repair criteria ;
l (ARC) cannot be applied to; ;
i !
j 1) Tube support plate intersections where the tubes may :
! potentially collapse or deform following a postulated
$ loss-of-coolant accident (LOCA) plus a safe shutdown l l' earthquake (SSE) event. l l 2) Tube support plate intersections having dent signals l
{ greater than 5 volts as measured with the bobbin probe.
l 3) TSP locations where there are mixed residuals of [
a '
j sufficient magnitude to cause a 1-volt ODSCC indication l (as measured with a bobbin probe) to be missed or l misread, ,
i I
l 4) Intersections with interfering signals from copper l deposits, and
- 5) Tube-to-flow distribution baffle plate intersections j l except as discussed in Section 2.a.3 of Enclosure 1 of [
t the Generic Letter.
5 l i !
l Items 2-3 are implementation issues which are addressed j through eddy current inspection requirements as delineated
- in Appendix A. Item 1 is addressed through analysis.
l Specifically, the tube locations adjacent to wedge supports at the upper tube support plates (TSPs) are of primary concern due to the potential yielding of the plate and subsequent deformation of the tubes during a MSLB.
j consequently, an evaluation of the support plates in these l regions is warranted. Since there is no known history for copper deposits at STP, the Item 4 requirement may not apply.
]
! l 14.1 Backaround -
e The concern in applying ARC to tube support plate FRAMATOME TECHNOLOGIES, INC.
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intersections near the wedge locations has the following
, basis. If a LOCA event were to occur coupled with a SSE event, the pressure (rarefaction) wave created primarily in the U-bend region will generate loads in the upper TSPs which are then reacted at the TSP-to-wrapper wedge locations. The loads generated may be exacerbated as a result of stimulation from SSE through acceleration or shaking of the steam generator. If the loads are of sufficient magnitude, deformation of the TSP in the vicinity of the wedge locations will occur, thereby deforming tubes in these areas as well. The significance of this deformation is related to the following scenario.
It may be possible that a significant amount of in-leakage occurs from secondary makeup water back to the core through opened ARC cracks in the tubes. Since the secondary side may still be near operating pressure, the large secondary-to-pr'imary AP may force in-leakage back through primary piping to the core. This in-leakage has the potential of diluting the boron injection from the emergency core cooling system thus, decreasing the overall neutron poisoning effect of the boron. An analysis was performed, as discussed in the following section, to identify tube locations which may potentially exhibit this failure mode so that they are excluded from application of ARC.
14.2 Tube Deformation Analysis at Wedae Locations Due to LOCA &
S B_SR l
14.2.1 Description of Loads l
LOCA loads are a resultant of pressure waves acting over various surf aces as a result of a postulated pipe-break. The first and largest contributing load acting on the upper tube support plate is caused by the rarefaction wave. This is a pressure wave initiated at the break location and travels through the tubes which causes a horizontal in-plane loading predominantly on the upper tube support plate. The second type of load is the LOCA shaking load. This load is due to the 1 1
l l
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l' response of;the RCS loop from the various hydraulic loadings..The third type'of load is the seismic load.
- The LOCA~ loads are-conserv&tively added together and a dynamic load factor is applied. The' seismic load is probabilistically combined via the'SRSS method with the LOCA load, LOCA As specified in GDC-4 (52 EE 41288), dynamic effects of pipe ruptures in nuclear power plant units may be excluded from the' design basis provided it is demonstrated that.the probability of pipe rupture'is extremely low under conditions consistent with the design of piping. Dynamic effects covered by this rule are missile generation, pipe whipping, pipe break' reaction forces, jet impingement forces, decompression waves within the ruptured pipe and dynamic or non-static pressurization in cavities, subcompartments, and compartments. The NRC has concluded in References 18 and 19 that STP is in compliance ~with GDC-4. As such, it has been demonstrated that the probability of a rupture of the primary reactor coolant piping and the surge line is extremely low. Hence, the dynamic effects of postulated pipe ruptures of the large primary piping and the surge line are eliminated from the design basis at STP. (Note: The pressurizer surge line was requalified for LBB due to stratified loads per References 20 and 8). Thus, the design loadings are the smaller attachment line breaks. For the analysis of the upper tube support plate at STP, a 12" diameter schedule 140 attachment line was considered as the design break.
LOCA loads for STP were developed based on loads from a similar replacement recirculating steam generator (RSG) model. The design load for the upper support plate utilized a postulated break in a 14" diameter Schedule 140 attachment line versus that from a 12" diameter Schedule 140 line design break as described in Section
~FRAMATOME TECHNOLOGIES, INC.
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(
t 5.3. The RSG model~ loads were evaluated specifically .
for applicability to the South Texas Plant and were
-determined to be conservative [11) . Some of the conservatisms used in the analysis include the following; o The loads were based on a larger attachment line break (14" diameter schedule 140 versus the actual STP 12" diameter schedule 140 line size). ,
t o A stress-strain curve based on the ASME Code minimum yield and tensile strength properties for the support plate was used. It is highly likely that the actual material has greater than Code minimum properties. ,
o The increase in yield strength due to the rapidly applied load-(high strain rate) was neglected. !
o It was assumed that the tube deformation is equal to the hole ID deformation in the finite element analysis even though a gap may exist. Also, the TSP stiffness neglected any contribution provided by the tubing. ,
o It was assumed that the interface between the support plate and wedges is frictionless even though the wedges were snugly installed and are securely welded to wrapper support blocks.
o It was assumed that the entire LOCA rarefaction load is reacted out at the top support plate only.
The resulting load on the TSP due to the rarefaction wave was[ ]d FP kips for STP. The associated shaking load was[ ]d FP kips. These loads were conservatively added and a dynamic load factor of 2 was applied, yielding a total LOCA load of[ ]dFP gipg (15]. ,
-FRAMATOME TECHNOLOGIES, INC 14-4
Seismic I The seismic loads considered result from ground motion
- during an earthquake. This motion causes an excitation of the steam generators in the form of acceleration response at the steam generator supports. The acceleration response is converted to a time history.
I response to determine the load contribution within the tubes and support plates. The loading evaluation was previously performed and the results are contained in the stress report [15] as in-plane loading of the tube support plates. The SSE load was determined to ,
l be[ ]dFP gipg, The total TSP load was determined to be [ ]d FP gipg by combining the LOCA loads probabilistically with the SSE load using SRSS [15] . ;
i j 14.2.2 Analysis Methodology f The steam generator upper tube support plate was input ,
- into an inelastic ANSYS finite element model to q evaluate the two wedge groups for one quadrant
- . (symmetry) as the bounding case for all wedge groups at the top support plate. An overall illustration of the
- model is provided in. Figure 14-1. A detailed view of
- the elements modeled is provided in Figures 14-2 and
- 14-3. The total load of[ ]d FPkips was applied to the finite element model. The loading and deformation results are provided in Reference 11. Each of the d
lower support plates were conservatively assumed to j 4 exhibit this worst case loading as well. However since l
] the wedge groups are vertically aligned, the number of I tubes affected is minimized. A summary of the excluded tubes is provided in Section 14.3.
i 14.3 Summarv of Excluded Tube Locations Figure 14-4 provides a sketch of the tube bundle showing the i TSP locations and designations for identifying the elevation l FRAMATOME TECHNOLOGIES, INC.
14-5
of the wedge group locations. . Figures 14-5 and 14-6 show the circumferential locations'of the wedge groups for the tube support plates. .The corresponding nomenclature from i South Texas Project is'also provided for additional i
information. The tube locations which deformed greater than the[ ]d FPinch criterion as described in Section 5.3 were characterized through the analysis (11) as unacceptable. 1
[
]dFP. Figures 14-7 through 14-10 summarize the exclusion tubes. Table 14-1 provides a summary of all excluded SG tubes due to deformation in the vicinity of the wedge locations.
l The total number of tubes excluded per steam generator is l
[ ]dFP. The most limiting wedge group location (32 degree l reference) [ ]dFP excluded due to tube deformation.
This large number of tubes excluded is mainly the result of l the previously described conservatisms used in developing and' evaluating the analysis results. A submittal for another plant shows the limiting wedge group exclusion region to be approximately 30 tubes for a similar steam generator with slightly higher loading conditions from a large primary pipe break (16]. The exclusion region for STP is nearly[ ]dFPtimes as large, for the limiting wedge group. Thus, the number of tubes excluded at STP is representative.
FRAMATOME TECHNOLOGIES, INC.
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I FIGURE 14-1
, TSP MODEL
[
L i
4 I
]d FP t
d e
I FRAMATOME TECHNOLOGIES, INC, 11-7
I FIGURE 14-2 MODEL ELEMENTS 32 DEGREE WEDGE LOCATION
[
l l
jd FP FRAMATOME TECHNOLOGIES, INC.
14-8
FIGURE 14-3
, MODEL ELEMENTS 16 DEGREE WEDGE LOCATION l
4 1
]d FP a
1 l
l
)
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14-9
FIGURE 14-4 TUBE BUNDLE SHOWING TSP ELEVATIONS FOR IDENTIFYING WEDGE GROUPS I
1
]d FP FRAMATOME TECHNOLOGIES, INC.
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FIGURE 14-5 WEDGE GROUP LOCATIONS: TSPs 1-11
[
]d FP 4
r FRAMATOME TECHNOLOGIES, INC.
14-11
FIGURE 14-6 WEDGE GROUP LOCATIONS: TSP 12
[
1 l
)d FP FRAMATOME TECHNOLOGIES, INC.
14-12
FIGURE 14-7 EXCLUDED TUBE REGION: TSPs 1-11 (NOZZLE SIDE)
[
]d FP Note: This drawing is a depiction of the tubes contained in this exclusion area. Only an actual tubesheet map should be used to show the exact tube exclusion locations.
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FIGURE 14-8
, EXCLUDED TUBE REGION: TSPs 1-11 (MANWAY SIDE)
{
]d FP Note: This drawing is a depiction of the tubes contained in this exclusion area. Only an actual tubesheet map should be used to show the exact tube exclusion locations.
. FRAMATOME TECHNOLOGIES, INC.
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l i
i l
i l
FIGURE 14-9 EXCLUDED TUBE REGION: TSP 12 (NOZZLE SIDE)
I I
)d FP Note: This drawing is a depiction of the tubes contained in this exclusion area. Only an actual tubesheet map should be used to show the exact tube exclusion locations.
i FRAMATOME TECHNOLOGIES, INC.
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I )
1 1
l FIGURE 14-10 EXCLUDED TUBE REGION: TSP 12 l (MANWAY SIDE) l
]
]d FP 1 Note: This drawing is a depiction of the tubes contained in this exclusion area. Only an actual tubesheet map -
should be used to show the exact tube exclusion locations.
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TABLE 14-1
SUMMARY
OF TUBES TO BE EXCLUDED FROM ARC ROW COLUMN (S) WEDGE GROUP QUADRAITIS
[
l l
I Jd FP i
)
1
. FRAMATOME TECHNOLOGIES, INC. I 14-17 4
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15.0 CONCLUSION
S This assessment demonstrates that a correlation relating tube
, burst pressure to bobbin voltage and main steam line break (MSLL) leakage to bobbin voltage can be used to conservatively satisfy the Reg Guide 1.121 guidelines for tube integrity at South Texas Project Unit 1.
Application of the generic ODSCC ARC methodology developed through EPRI is appropriate for South Texas Unit 1 ODSCC flaws, satisfies the NRC Generic Letter requirements on ODSCC ARC, and is consistent with other approved ODSCC ARC methodologies.
Enclosure 1 of the Generic Letter consists of six sections of requirements for a licensee to include in a proposed program to implement ARC. STP complies with these as follows:
(1) Confirmation that the degradation mechanism is predominantly axial ODSCC confined to the TSP.
STP Compliance with Requirement During 1RE04 and 1RE05, STP pulled 6 tubes to verify ODSCC is the dominant degradation mechanism at the TSP. The indications at the TSP were burst tested to demonstrate that the dominant mechanism affecting the burst and leakage properties of the tube is axially oriented ODSCC.
(2) Confirmation that the steam generator tubes will retain adequate structural and leakage integrity until the next scheduled inspection.
STP Compliance with Requirement Section 10 of this report discusses the methodology used to calculate the probability of burst for STP EOC-6. The probability of burst for SG 'C' is[ ]dP for EOC-6, which is well within the threshold value of 1 x 10-2 provided by the NRC in the Generic Letter. Section 11 of this report FRAMATOME TECHNOLOGIES, INC.
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1 i
' discusses the mc r,hodology used to calculate the predicted
- conditional MSLB leak rate of the steam generators at STP.
For STP-1, EOC-6 leak rates were calculated for each steam generator. Steam generator 'C' had the largest leak rate of
( !]dFPgpd which is well within the current design basis of 4 ( .]dFP (3) Inspection scope, data acquisition, and data analysis j should be performed .in a manner consistent with the 7 methodology utilized to develop the voltage limits. -
- STP Compliance with Requirement Section 7 and Appendix A of this report address the NDE I j inspection criteria and ECT analysis requirements to be followed during 1REO6 and future outages at STP in accordance
- with the requirements provided by the Generic Letter.
l 4
(4) Implementation of voltage-based plugging criteria should i include a program of tube removals for testing and L examination as described in Section 4 of Enclosure 1 of !
the Generic Letter.
F 4
STP Compliance with Requirement
- Section 8 discusses the requirements for tube removal and i examination at STP during 1RE05 and future outages.
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l (5) The operational leakage limit should be reduced to 150 gpd through each steam generator STP Compliance with Requirement Section 12 of this report addresses operational leakage limits at STP-1. In compliance with the Generic Letter, STP will review leakage monitoring measures to ensure that a significant leak will be detected.
(6) Reporting Requirements -
amendment to the Technical Specifications STP Compliance with Requirement STP will submit the amendment to the TS with the submittal of this report to the NRC.
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16.0 REFERENCES
- 1. NRC Generic Letter 95-05: " Voltage-Based Repair Criteria for the Repair of Westinghouse Steam Generator Tubes Affected by Outside Diameter Stress Corrosion Cracking", August 3, 1995.
- 2. [
4 JEP
- 3. [
J EP
- 4. [
]C FP
- 5. NRC Regulatory Guide 1.121 " Bases for Plugging Degraded PWR Steam Generator Tubes", August 1976.
- 6. [
.J
] EP
- 7. [
]C FP
- 8. USNRC to HL&P Letter, "NRC Bulletin 88-11, " Pressurizer Surge Line Thermal Stratification - South Texas Project, Units 1 and 2 (TAC No. 72168)", September 17, 1990.
- 9. "ASME Boiler and Pressure Vessel Code",Section III, Subsection NB and Division I Appendices, 1989 Edition.
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- 10. [
]c
- 11. [
]c
- 12. NRC letter from Allen R. Johnson to Robert C. Mecredy
- " Application of Leak-Before-Break Technology, R.E.
Ginna Nuclear Power Plant (TAC No. M86376)", Docket th).
50-244, 1993.
I
- 13. [
]c FP ,
- 14. [
]C FP J
- 15. HL&P Document No. 120 (1) 00019-CWN, "Model E2 Steam Generator Stress Report" and addendum.
Reference [15] is not available for entry into the BWNT Records Center, but may be referenced for use on Task 1101 of BWNT Contract 1010277. Use of this reference is permitted by BWNT Procedure, BWNT-0402-01, Appendix 2.
- 16. NRC Letter from George F. Dick, Jr. to D.L. Farrar
" Issuance of Amendments (TAC Nos. M90052 and M90053),
dated October 24, 1994; Amendment No. 66, Docket STN 50-454 p.15.
- 17. Meeting Minutes with Industry 1/18/95, Resolution of Public Comments NRC Draft GL 94-XX.
- 18. NUREG-0781, " Safety Evaluation Report related to the operation of South Texas Project, Units 1 & 2",
Supplement No. 2, January 1987.
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19 NUREG-0781, " Safety Evaluation Report related to the operation of South Texas Project, Units 1 & 2",
Supplement No. 4, July 1987.
- 20. HL&P to USNRC Letter ST-HL-AE-3016, " Pressurizer Surge Line Thermal Stratification", March 14, 1989.
- 21. NUREG-1477, " Voltage-Based Interim Plugging Criteria for Steam Generator Tubes", June, 1993.
- 22. NUREG-0800, " Radiological Consequences of Main Steam Line Failures Outside Containment of a PWR, Rev. 2, July, 1981.
- 23. WCAP-13523, "V.C. Summer Steam Generator Tube Plugging Criteria for Indications at Tube Support Plate, Westinghouse Non-Proprietary, January, 1993.
- 24. BMDP Solo, Version 4, BMDP Statistical Software, Inc.,
12121 Wilshire Blvd, Los Angeles, CA 90025.
- 25. HL&P Letter, PFN M18.05.02, ST-HS-2U-0009, Mechanical Properties of Unit 1 and Unit 2 Steam Generator Tubing, dated. February 18, 1994.
- 26. WCAP-14277 NON-PROPRIETARY CLASS 3 (SG-95-01-007), SLB Leak Rate and Tube Burst Probability Analysis Methods for ODSCC at TSP Intersections, January, 1995.
- 27. Westinghouse Letter to David A. Steininger (EPRI), NSD-JNE-3143, Revised ARC Database for 3/4" Tubes, dated I
December 1, 1995.
- 28. Westinghouse Letter from V(Seena) Srinivas (Westinghouse) to John Fox (STP), Response to STP's Request for Clarifications on Revised ARC Database for 3/4" Tubes, dated December 14, 1995.
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i
- 29. Huebel J.G. and G.K. Myers, " Tables of Confidence Bounds for Failure Probabilities", UCRL-51990, Lawrence Livermore Laboratory, UCAL at Livermore, January 8, 1976.
- 30. Abramowitz, M. and I.A. Stegun, Editors, " Handbook of Mathematical Functions", National Bureau of Standards Applied Mathematics Series 55, loth Printing, December,
, 1972.
- 31. Carver, H.C. and S.S. Wilks, Editors, "The Annals of Mathematical Statistics", The Official Journal of the Institute of Mathematical Statistics, Volume 29, No.2, June, 1958.
- 32. LTC: 96:0016-02:01 " Failure Analysis of Steam Generator
- Tubing from South Texas Project Unit 1", September, 1995. ;
r d
c
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_ _ . - _ _ . . _ _ _ . _ . . _ . . . . _ _ . _ _ _ . _ . _ . _ _ . _ _ _ _ . _ m._..._.___._._
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! APPENDIX A :
1 1
i
- NDE DATA ACQUISITION AND ANALYSIS REQUIREMENTS ,
! i i A.1 INTRODUCTION ;
i i j This appendix documents required techniques for the l l inspection of South Texas Project Units 1&2 steam generator i l- tubes related to the identification of ODSCC at the tube l support plate regions.
l t
j This appendix contains requirements which provide direction '
- in applying the ODSCC alternate repair criteria (ARC) described in this report. The procedures for eddy current !
testing using bobbin coil (:BC) and rotating pancake coil -
l (RPC) techniques are summarized. The procedures given apply l
- to the bobbin coil inspection, except as explicitly noted j for MRPC inspection. !
l
)
The following sections define specific acquisition and -
i analysis parameters and methods to be used for the i inspection of steam generator tubing.
?
A.2 DATA ACQUISITION I
i l The following guidelines are specified for non-destructive
] examination of the tubes within TSP at South Texas Project Unit 1 and Unit 2. .
i A.2.1 Instrumentation >
Eddy current equipment shall be the Zetec MIZ-18 ,
, or engineering approved equivalent. (
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! A.2.2 Probes !
A.2.2.1 Bobbin Coil Probes To maximize consistency with laboratory ;
ARC data, differential probes with the l l following parameters shall'be used for ;
3 examination of tube support plate
{ intersections:
l 0.610 outer diameter 1
i
- two bobbin coils, each 60 mils long
! x 60 mils deep, with 60 mils l between coils (coil centers i
a separated by 120 mils) :
In addition, the probe design must l
incorporate centering features that l provide for minimum probe wobble and i
offset; the centering features must I maintain constant probe center to tube
! ID offset for nominal diameter tubing.
! For locations which must be inspected I
with smaller than nominal diameter
! probes, it is essential that the reduced a
4 diameter probe be calibrated to the j , reference normalization (Section A.2.6.1
{ and A.2.6.2) and that the centering feature permit constant probe center to tube ID offset. ;
1 r
l A.2.2.2 Rotating Pancake Coil Probes j Pancake coils designs (vertical dipole moment) with a coil diameter d, where d j is 0.060" s d s 0.125", shall be used.
While other multi-coil (i.e., 1, 2, or
- 3-coil) probes can be utilized, it is
- recommended that if a 3-coil single 4
FRAMATOME TECHNOLOGIES, INC.
- A-2
pancake probe is used, any voltage __
measurements should be made with the probe's pancake coil rather than its circumferential or axial coil.
A.2.3 Calibration Standards A.2.3.1 Bobbin Coil Standards The bobbin coil calibration standards contain the following items:
Voltace Normalization Standard:
One 0.052" diameter 100% through wall hole Four 0.028" diameter through wall holes, 90 degrees apart in a single plane around the tube circumference; the hole diameter tolerance shall be +/- 0.001" One 0.109" diameter flat bottom hole, 60% through from the OD Four 0.187" diameter flat bottom holes, 20% through from the OD, l spaced 90 degrees apart in a single plane around the tube circumference. The tolerance on hole diameter and depth shall be
+/- 0.001".
A simulated support ring, 0.75" long, comprised of SA-285 Grade C --
carbon steel or equivalent for Unit 1 and comprised of SA-240 type 405 stainless steel or equivalent for Unit 2. If' mix residuals are shown FRAMATOME TECHNOLOGIES, INC.
A-3
to be equivalent, then carbon steel can be used for both units.
All holes shall be machined using a mechanical drilling technique. This calibration standard will need to be calibrated against the reference standard used for the ARC laboratory work by direct testing or through the use of a transfer standard.
Probe Wear Standard A probe wear standard is used for monitoring the degradation of probe centering devices leading to off-center coil positioning and potential variations in flaw amplitude responses. This standard shall include four 0.052" +/-
0.001" diameter through-wall holes, spaced 90 degrees apart around the tube circumference with an axial spacing such that signals can be clearly distinguished from one another. See Figure A-1.
A.2.3.2 Rotating Probe Standard A satisfactory MRPC standard may l
contain:
Two axial EDM notches, located at the same axial position but 180 degrees apart circumferential, each 0.006" wide and 0.5" long, one 80%
and one 100% through wall from the OD.
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Two axial EDM notches, located at the same axial position but 180 .
degrees apart circumferentially, each 0.006" wide and 0.5" long, one 60% and one 40% through-wall from the OD.
Two circumferential EDM notches, one 50% through wall from the OD with a 75 degree (0.49") arc l length, and one 100% through wall with a 26 degree (0.17") arc length, with both notches 0.006" wide.
A simulated support segment 270 degrees in circumferential extent, 0.75" thick, comprised of SA-285 Grade C carbon steel or equivalent for Unit.1 and comprised of SA-240 type 405 stainless steel or equivalent for Unit 2.
l Similar configurations which satisfy the intent of calibrating MRPC probes for OD axial and circumferential cracking are l
satisfactory. The center to center distance between the support plate simulation and the nearest slot shall be at least 1.25". The center to center distance between the EDM notches shall be at least 1.0". The tolerance for widths and depths of the notches shall be 0.001". The tolerance for the slot lengths shall be 0.010".
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i A.2.4 Application of Bobbin Coil Wear Standard A calibration standard has been designed to monitor bobbin coil probe wear. During steam generator examination, the bobbin probe is inserted into the wear monitoring standard; the initial (new probe) amplitude response from each of the four holes is determined and compared on an individual basis with subsequent measurements.
Signal amplitudes from the individual holes -
compared with their initial amplitudes - must remain within 15% of their initial amplitude (i.e., { (worn-new) /new} ) for an acceptable probe wear condition. If this condition is not satisfied, then the probe must be replaced. Two options exist for addressing the tubes inspected by the worn probe since the last calibration.
- 1) If any of the last probe wear standard signal amplitudes prior to probe replacement exceeds the 15% limit, say by a variable value, x%, then indications measured since the last acceptable probe wear measurement that are within x% of the repair limit must be re-inspected with the new probe.
- 2) obtain all preliminary voltages with no probe wear standard. Then reinspect the preliminary indications that are above 75% of the repair limit voltage with a new probe that is subject to probe wear guidelines. Wear measurements should be taken before and after each inspection.
A.2.4.1 Bobbin Coil Wear Standard Placement Under ideal circumstances, the incorporation of a wear standard in line with the conduit and guide tube configuration would provide continuous monitoring of the behavior of bobbin FRAMATOME TECHNOLOGIES, INC.
A-6
probe wear. However, the curvature of the channelhead places restrictions on the length of in line tubing inserts which can be accommodated. The spacing i of the ASME Section XI holes and the l wear standard results in a length of l tubing which cannot be freely positioned within the restricted space available.
The flexible conduit sections inside the channelhead, together with the guide tube, limit the space available for additional in line components. Voltage l responses for the wear standards are sensitive to bending of the leads, and l mock up tests have shown sensitivity to the robot end effector position in the tubesheet, even when the wear standard is placed on the bottom of the l
channelhead. Wear standard measurements l
must permit some optimization of positions for the measurement and this should be a periodic measurement for inspection efficiency. The pre-existing requirement to check calibration using the ASME tubing standard is satisfied by
- periodic probing at the beginning and end of each probe's use as well as at four hour intervals. This frequency is adequate for wear standard purposes as well. Evaluating the probe wear under _
uncontrollable circumstances would present variability in response due to channelhead orientations rather than j changes in the probe itself.
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l A.2.5 Acquisition Parameters The following parameters apply to bobbin coil data acquisition and should be incorporated in the applicable inspection procedures to supplement (not necessarily replace) the parameters normally used.
A.2.5.1 Test Frequencies This technique requires the use of bobbin coil 550 kHz and 130 kHz test i frequencies in the differential mode.
It is recommended that the absolute mode I
also be used, at test frequencies of 130 kHz and 10 kHz. The low frequency (10 kHz) channel should be recorded to provide a means of verifying tube j support plate edge detection for flaw )
location purposes. The 560/130 kHz mix or the 550 kHz differential channel is used to access changes in signal amplitude for the probe wear standard as well at or flaw detection.
MAPC frequencies should include channels adequate for detection of OD degradation in the range of 100 kHz to 550 kHz, as well as a low frequency channel to provide support location of the TSP edges.
A.2.5.2 Digitizing Rate A minimum digitizing rate of 30 samples per inch should be used for both bobbin and MRPC. Combinations of probe speeds and instrument sample rates shoula be chosen such that:
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Samole Rate (samoles/sec.) 2 30 (samples /in.)
Probe Speed (in./sec. )
A.2.6 Analysis Parameters This section discusses the methodology for establishing bobbin coil data analysis variables such as spans, rotations, mixes, voltage scales, and calibration curves. Although indicated depth measurement may not be required to support an alternative repair limit, the methodology for establishing the calibration curves is presented. The use of these curves is recommended for consistency in reporting and to provide compatibility of results with subsequent inspections of the same steam generator and for comparison with other steam generators and/or plants.
A.2.6.1 Bobbin Coil 550 kHz Differential Channel Rotations: The signal from the 100% through-wall hole should be set to 40* (+/- 1 degree) with the initial signal excursion down and to the right during probe withdrawal.
Voltace Sca3g: The peak-to-peak signal
- j. amplitude of the signal from the four 20%
j through-wall holes should be set to produce a j voltage equivalent to that obtained from the i ARC lab standard. The laboratory standard l normalization voltage is 4.0 volts at 550 i kHz.
i j_ The transfer / field standard will be
} calibrated against the laboratory standard !
j using a reference laboratory probe to j
- establish voltages for the field standard i that are equivalent to the above laboratory
! standard. These equivalent voltages are then i j set on the field standard to establish (
l- calibration voltages for any other standard. ;
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Voltage normalization to the standard t calibration voltages at 550 kHz is the preferred normalization to minimize analyst sensitivity in establishing the mix.
However, if the bobbin probes used result in ,
a 550/130 kHz mix to 550 kHz voltage ratios differing from the laboratory standard ratio of 0.6.9 by more than 5% (0.66 to 0.72), the 550/130 kHz mix calibration voltage should be used for voltage normalization.
Once the probe has been calibrated on the 20%
through-wall holes, the voltage response of new bobbin coil probes for the 20-80% ASME through-wall holes should not differ from the nominal voltage by more than i 10%.
As an alternative, probes can be supplied with certificatica of meeting the variability requirements upon shipment from the vendor.
Calibration Curve: Establish a phase versus depth calibration curve using measured signal phase angles in combination with the "as-built" flaw depths for the 100%, 60%, and 20%
holes.
A.2.6.2 Bobbin Coil 550/130 kHz Differential Mix Channel Rotations: Probe motion is set horizontal with the initial excursion of the signal from the single 100% through-wall hole going down i
and to the right during probe withdrawal.
voltace Scale: The peak-to-peak signal amplitude of the signal from the four 20%
i through-wall holes should be set to produce a voltage equivalent to that obtained from the l
ARC lab standard. The laboratory standard
, normalization voltage is 2.75 volts for the i
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550/130 kHz mix.
Calibration Curve: Mix 1 is a 550/130 kHz
. differential support mix; mix on ASME standard support ring. Set 3-point phase angle-depth calibration curve using ASME.
100%, 60%, and 20% drill hole signals. Mix 1 is the primary channel for reporting indications at support structures.
A.2.6.3 Rotating Pancake Coil Inspection Rotations: Probe motion is set horizontal
(+/- 5 degrees) with the initial excursion of the signal from the 100% through-wall notch directed upwards during probe withdrawal.
Voltace Scale: The MRPC amplitude will be referenced to 20 volts for a 0.5" long 100%
through wall notch at 300 kHz. Each channel shall be set individually to the desired amplitude for the EDM notches on the plant standards.
A.2.7 Analysis Methodology Bobbin coil indications at support plates attributable to ODSCC are quantified using the Mix 1 (550 kHz/130 i kHz) data channel. This is illustrated with the example shown in Figure A-2. The 550/130 kHz mix i channel or other channels appropriate for flaw 4 detection (550 kHz, 300 kHz, or 130 kHz) may be used to
- locate the indications of interest within the support i plate signal. The largest amplitude portion of the
- Lissajous signal representing the flaw should then be measured using the 550/130 kHz Mix 1 channel to establish the peak-to-peak voltage as shown in Figure A-2. Initial placement of the dots for identification l of the flaw location may be performed as shown in l Figures A-3 and A-4, but the final peak-to-peak measurements must be performed on the Mix 1 Lissajous i
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signal to include the full flaw segment of the signal.
It may be necessary to iterate the positions of the dots between the identifying frequency and the 550/130 kHz mix to obtain proper placement. As can be seen in Figure A-4, failure to do so can reduce the voltage reasurements of Mix 1 by as much as 65% to 70% due to the interference of the-support plate signal in the raw frequencies. The voltage as measured from Mix 1 is then entered as the analysis of record for comparison with the repair limit voltage.
To support the uncertainty allowances maintained in the ARC, the difference in amplitude measurements for each indication will be limited to 20%. If the voltage values called by the independent analysts deviate by more than 20% and one or both of the calls exceeds 1.0 volts, analysis by the resolution analyst will be performed. These triplicate analyses result in assurance that the voltage reported departs from the correct call by no more than 20%.
1 There is no industry recognized method for measuring i the eddy current test signal-to-noise ratio to determine which_ data is too noisy and should be re- !
acquired. However, the EPRI Steam Generator Management I
^
Program has been tasked with identifying or developing such methods. Until such methods are identified, electrical noise in excess of 0.3 volts peak-to-peak on channel 1 will be rejected and the data will be re- -
acquired. ;
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A.2.8 Reporting Guidelines The reporting requirements identified below are in ,
addition to any other reporting requirements specified f by the user.
A.2.8.1 Minimum Requirements All bobbin coil flaw indications in the 550/130 kHz mix channel at the tube support plate intersections regardless of the peak-to-peak signal amplitude must be reported.
All TSP locations with indications exceeding 1.0 volt must be examined with MRPC probes.
A.2.8.2 Additional Requirements For each reported indication, the following information should also be recorded:
Tube identification (row, column)
Signal amplitude (volts)
Signal phase angle (degrees)
Test channel (ch#)
Axial position of tube (location)
Extent of test (extent)
MRPC reporting requirements should include as a minimum: type of degradation (axial, circumferential, or other), maximum voltage and location of the center of the crack within the TSP. The crack axial center to edge need not coincide with the position of the maximum amplitude. Locations which do not exhibit flaw-like indications in the MRPC isometric plots may continue in service, except that all intersections exhibiting flaw-like bobbin behavior and bobbin amplitudes in excess of the repair limit voltage must be repaired, notwithstanding the MRPC analyses. MRPC isometrics should be interpreted by the analyst to characterize FRAMATOME TECHNOLOGIES, INC.
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i the signals observed; only featureless ,
isometrics are to'be reported as NDD.
Signals not interpreted as flaws include ,
dents, liftoff, deposits, copper, magnetite, etc. MRPC indications with circumferential ,
cracks or cracks extending outside the TSP must be repaired. ;
A.3 DATA EVALUATION A.3.1 Use of 550/130 Differential Mix for Extracting the ,
Bobbin Flaw Signal l In-order to identify a discontinuity in the composite :
signal as an indication of a flaw in the tube wall, a simple signal processing procedure of mixing the data I from the two test frequencies is used which reduces the ;
interference from the support plate signal by ;
approximately'one order of magnitude. The test frequencies most often used for this signal processing I are 550 kHz and 130 kHz for 43 mil wall Alloy 600 i tubing. Any of the differential data channels ,
including the mix chanael may be used for flaw !
detection (though the 130 kHz for 43 mil wall Alloy 600 {
tubing is often subject to the influence from many s different effects), but the final evaluation of signal ,
detection, amplitude and phase angle will be made from the 550/130 kHz differential mix channel. Upon detection of a flaw signal in the differential mix i channel, confirmation from other raw channels is not I required; all such signals must be reported as indications of possible ODSCC. The voltage scale for the 550/130 kHz differential channel should be '
normalized as described in Section A.2.6.1 and A.2.6.2.
The present evaluation procedure requires that there is >
no minimum voltage for flaw detection purposes and that l all flaw signals, however small, be identified. The intersections with flaw signals 2 1.0 volt will be inspected with MRPC, unless the tube is to be plugged
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3 A-14
_ . _ _ _ _ . _-- ~ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ . _ _ _ _ _ . _ _ . - -
l or sleeved. Although the signal. voltage is not a measure of flaw depth, it is an indicator of the tube burst pressure when the flaw is identified as axial ODSCC with or without minor IGA. If an indication is not confirmed by MRPC, no action is required and the tube may remain in service.
A.3.2 Amplitude Variability It has been observed that voltage measurements taken from the same data by different analysts may vary, even when using identical analysis guidelines. This is largely due to differences in the analyst interpretation of where to place the dots on the Lissajous figure for the peak-to-peak amplitude measurement. Figures A-5 and A-6 show the correct placement of the dots on the Mix 1 Lissajous figures for the peak-to-peak voltage amplitude measurements for two tubes from Plant S. In Figure A-5, the placement is quite obvious. In Figure A-6, the placement requires slightly more of a judgement call. Figure A-7 and A-8 show these same two tubes with peak-to-peak measurements being made, but in both cases the dots have been placed at locations where the normal max-rate dots would be located. The reduction in the voltage amplitude measurement is 19.3% in Figure A-7 and 16.3%
in Figure A-8. While this is an accepted method of analysis for phase-angle measurements, it is not appropriate for the voltage amplitude measurements required.
. In Figures A-5 and A-6, the locations of the dots for the peak-to-peak measurements being performed from Mix 1 show the corresponding dots on the 550 kHz raw frequencies as also being located at the peak or maximum point of the flaw portion of the Lissajous figure. In no case should the dots to measure the voltage amplitude be at locations less than the maximum points of the flaw portion of the 550 kHz raw frequency.
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A-15
I Figure A-9 is an example of where the dots have been ,
placed on the transition region of the 550 kHz raw frequency data Lissajous figure that this does not correspond to the maximum voltage measurement. The ,
correct placement on the Mix 1 Lissajous figure is
]
shown in Figure A-10. Thi s placement also corresponds to the maximum voltage me qurement on the 550 kHz raw frequency data channel.
In some cases, it will be found that little if eny definitive help is available from the use of the raw frequencies. Such an example is shown in Figure A-11, l where there are no significantly sharp transitions in any of the raw frequencies. Consequently, the placement of the measurement dots must be made completely on the basis of the Mix 1 channel Lissajous figure as shown in the upper left of the graphic. An i even more difficult example is shown in Figure A-12. ;
The logic behind the placement of the dots in the Mix 1 is that sharp transitions in the residual support plate i signals can be observed at the locations of both dots.
In the following~ graphic, Figure A-13, somewhat the #
same logic could be applied in determining the flaw-like portion of the signal from the Mix 1 Lissajous pattern. However, inasmuch as there is no sharp, clearly defined transition, coupled with the fact that the entry lobe into the support plate is distorted on !
l all of the raw frequencies, the dots should be placed ;
are shown in Figttre A-14. This is a conservative i i
approcch and should be taken whenever a degree of doubt as to the dot placement exists.
l It is noted that by utilizing these techniques,
{ identification of flaws is improved and that l conservative amplitude measurements are promoted. The I Mix 1 traces which result from this approach confirms l the model of TSP ODSCC which represents the degradation as a series of microcrack segments axially integrated
, by the bobbin coil; i.e., short segments of changing
, phase angle direction represent changes in average FRAMATOME TECHNOLOGIES, INC.
A-16 1
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depth with changing axial position. This procedure may not yield the maximum bobbin dept.h call. If maximum depth is desired for information purposes, shorted segments of the overall crack may have to be evaluated to obtain the maximum depth estimate. However, the peak-to-peak voltages as described herein must be reported, even if a different segment is used for the depth call. j A.3.3 Alloy Property Changes This signal manifests itself as part of the support plate " mix residual" in both the differential and absolute mix channels. It has often been confused with r copper deposit as the cause. Such signals are often found at support plate intersections of operating plants, as well as in some model boiler test samples, and are not necessarily indicative of tube wall degradation. Six support plate intersections from "
Plant A, judged as free of tube wall degradation en the basis of the mixed differential channel using the guidelines given in Section A.2.7 of this documen:, i were pulled in 1989. Examples of the bobbin coil field .
data are shown in Figure A-15 (inspection' data frcm a plant with 7/8" diameter tubing). The mix residual for this example is approximately 3 volts in the differential mix channel and no discontinuity suggestive of a flaw can be found in this channel. An offset in the absolute mix channel which could be confused as a possible indication is also present.
These signals persisted without any significant change i even after chemically cleaning the OD and ID of the ;
tubes. The destructive examination of these intersections showed very minor or no tube wall degradation. Thus, the overall " residuals" of both the differential and the absolute mix channels were nc:
indications of tube wall degradation. One needs to examine the detailed structure of the " mix residual" l (as outlined in Section A.2.7) in order to assess the possibility that a flaw signal is present in the FRAMATOME TECHNOLOGIES, INC.
s A-17
1 residual composite. Verification of the integrity of TSP intersections exhibiting alloy property or artifact signals is accomplished by MRPC testing of a representative sample of such signals.
A.3.4 Denting and Copper Influences The South Texas Project Units 1 & 2 have not experienced significant corrosion-assisted denting nor do they have reported indications indicative of copper deposits.
A.3.4.1 Dent Interference
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]d FP A.3.5 MRPC Flaw Characterization The MRPC inspection of some support plate intersections with bobbin coil indications > 1.0 volts is required in order to verify the applicability of the alternate repair limit. This is based on establishing the presence of ODSCC with minor IGA as the cause of the bcbbin indications.
The signal voltage for MRPC data evaluation will be based on 20 volts for the 100% throughwall 0.5" long EDM notch at all frequencies.
The nature of the degradation and its orientation (axial or circumferential) will be determined from careful examination of the isometric plots of the MRPC data. The presence of axial ODSCC at the support plates has been well documented, but the presence of circumferential indications related to ODSCC at support l
FRAMATOME TECHNOLOGIES, INC.
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plate intersections has also been established by tube {
pulls at two plants. Figure A-16 to A-18 show' examples of single and multiple axial ODSCC from Plant S.
i Figure A-19 is an example of a circumferential indication related to ODSCC at a tube support plate location from another plant. If circumferential involvement results from circumferential cracks as opposed to multiple axial crack, discrimination between axial and circumferentially oriented cracking can be generally established for affected are lengths of about I
45 degrees to 60 degrees or larger. Axial cracking has been found by pulled tube exams for MRPC arcs of 150 degrees when the axial extent is significant, such as > '
O.2 inch. i Pancake coil resolution is considered adequate for separation between circumferential and axial cracks. <
This can be supplemented by careful interpretation of 3-coil results. Since denting has not occurred at the 1 South Texas Project Units 1&2 units, circumferential j cracking is not expected to happen.
The presence of IGA as a local effect directly adjacent to crack faces is expected to be indistinguishable from the crack responses and as such of no structural consequence. When IGA exists as a general phenomenon, the eddy current response is proportional to the volume of affected tube material, with phase angle corresponding to depth of penetration and amplitude relatively larger than that expected for small cracks.
The presence of distributed cracking, e.g., cellular SCC, may produce responses from microcracks of sufficient individual dimensions to be detected but not resolved by the MRPC, resulting in volumetric responses similar to three-dimensional degradation.
For hot leg TSP locations, there is little industry experience on the basis of tube pulls for volumetric degradation, i.e., actual wall loss or general IGA.
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1 A-22 i
I For cold leg TSP locations, considerable experience is available for volumetric degradation in the form of thinning of peripheral tubes, favoring the lower TSP elevations. Therefore, in the absence of confirmed pulled tube experience to the contrary, volumetric OD indications at hot-leg tube support plates should be considered to represent ODSCC.
A.3.6 Confinement of ODSCC/ IGA within the Support Plate Region
- The measurements of axial crack lengths from MRPC isometrics can be determined using the following analysis practices. For the location of interest, the low frequency channel (e.g., 10 kHz) is used to set a local scale for measurement. By establishing the' midpoint of the support plate response, a reference point for indication location is established.
Calibration of the distance scale is accomplished by setting the displacement between the 10 kHz absolute, upper and lower support plate transitions equal to 0.75 inch.
A.3.7 Length Determination with MRPC Probes At the analysis frequency, 300 kHz, the ends of the crack are located using the slope-intercept method; i.e., the leading and trailing edges of the signal pattern are extrapolated to cross the null baseline (See Figure A-26). The difference between these two j positions is the crack length estimate. Alternately, l the number of scan lines indicating the presence of the l flaw times the pitch of the rotating probe provides a conservative estimate of crack length which may then be corrected for beam spread.
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A-23
.. . . _ . . - . . ~ . _ - - _ . - . . _ . . _ . _ _ . _ . . _ _ _ _ . - - . .-. _.
A.3.8 MRPC Inspection Plan The MRPC inspection plan will include the following upon implementation of the ARC repair limits:
Bobbin voltage indications > 1 volt, Large residuals, '
and Dents > 5 volts A representative sample of 100 TSP intersections based on the following:
- 1) Artifact signals (alloy property changes) spanning the range of amplitudes observed during bobbin coil examination.
- 2) Dented tubes at TSP intersections with bobbin dent -
voltages exceeding 5 volts.
- 3) Bobbin indications less than 1 volt for justification of these indications as typical of ODSCC.
The 100 TSP intersections for MRPC inspection would be targeted toward a distribution on the order of 40 dents, 40 artifacts, artifacts, and 20 indications with bobbin voltages < 1.0 volts; this distribution will be adjusted to reflect field observations as appropriate.
Consideration for expansion of the MRPC inspection program would be based on identifying unusual or unexpected indications such as clear circumferential cracks. In this case, structural assessments of the significance of the indications would be used to guide the need for further MRPC inspection.
A.3.8.1 3-Coil MRPC Usage It is Houston Lighting & Power's standard practice to use 3-coil MRPC probes, incorporating a pancake coil, an axial FRAMATOME TECHNOLOGIES, INC.
A-24
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f preference coil, and a circumferential l' preference coil. Comparisons for ODSCC with bobbin amplitudes exceeding'1.0 volts have l shown that the pancake coil fulfills the need for discrimination between axial and .;
circumferential indications, when compared against the outputs of the preferred direction coils. Pancake coils have-been the basis for reporting MRPC voltages for model boiler and pulled tube indications in the ARC f database; these data permit semi-quantitative judgements on the potential significance of MRPC indications. The requirement for a pancake coil is satisfied by the single coil, 2-coil, and 3-coil probes in common use for MRPC inspections.
A.3.9 Noise Criteria Quantitative noise criteria (resulting from electrical noise, tube noise, or calibration standard noise) should be included in the data analysis procedures. >
Actions should be taken to correct the data by re-performing the calibration or re-inspecting the affected tube (s).
1 Eddy current data acquired from active tubes and
! calibrations standards shall be reviewed for the f
presence of electrical and tube noise. General eddy
< current data quality shall be monitored to ensure that a minimum 3:1 signal-to-noise ratio (S/N) is l
i maintained. This value of S/N is a commonly accepted industry value for data quality ensuring reliable
! signal detection.
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A.3.9.1 ID Chatter or Pilgering Noise -
Tubes identified with noire associated-with l ID' chatter or pilgering in excess of 5. volts I
peak-to-peak ~on Channel 1 shall also be 1
screened using Channel 5.
- A.3.9.2 Probe' Noise i
i Electrical noise due to a failing or I intermittent probe is readily recognizable as the noise signal often assumes the shape of.a.
l_ random square wave modulating the eddy
, current signal.
1
< Electrical noise in excess of 0.3 volts peak-l to-peak on Channel 1 will be rejected by the analyst and the tube re-examined, l
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A-26
FIGURE A-1 PROBE WEAR STANDARD SCHEMATIC I
] EP Figure derived from EPRI TR-100407, Rev. 2A, Appendix B.
FRAMATOME TECHNOLOGIES, INC.
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) {
(f 4(r n .s. ia m O S .i 2.n ,ml
{
len 4 r
_J _
Ian h _f._
,a _
. ,N
~
11H
)
BM -
seesie 1 ver 5d E 42 un vp, a.se g ., ,,, L"J,' , ,,,,","; ,0 su ) ) } g .
cu 4 j '"j j
",('
m 4 ~3 ,' ' ' ' a i to 9
/
, > I (
g ;
j j ':
t =
i 7
r Figure derived from WCAP-13523 [23]
FRAMATOME TECHNOLOGIES, INC.
A-31
. . - . . _ . . . . . . _ . . . . . - - _ _ _ =- __
FIGURE A-6 CORRECT PLACEMENT OF VECTOR DOTS ON MIX 1 LISSAJOUS TRACES FOR R22C40 36 CM y nix y 4.4a tis nar i 13 7.51 558 th os 1 182 scE.E tw era w TCC TEEL armotstmestDE = =
2F -F l
- 5/G E E UNii m m OUTLET
~--
$C 3 12M l +e.es l l (( th C -:
" -- EXTENT TEN l TEC l yg , $ PEED 22.81} in/see TRAIM 11C --
StC -- l 2x --
vpp 1.23 8 118 54 vpp 2.02 E 153 273 14C ~ t Is J l l J 2x A3"
% f l
I
%f I
Tf
~I 23.35 3ss th cn 3 333 23.es 13e Kn cn s 13a 12M 11M -- - -
gg -- , -
SH L- L M
I 151-424880 f vpp B.25 9 112 stauri e estra ses 64 Ypp 7.3s 9 81 83 W 8" I 2 88 : S8
\
rins s a s .i s i e l
l T s l
e P i-
'W \
W t
';; ; : H I
Figure derived from WCAP-13523 [23)
I l
FRAV.ATOME TECHNOLOGIES, INC.
A-32
FIGURE A-7 INCORRECT PLACEMENT OF VECTOR DOTS ON MIX 1 LISSAJOUS TRACE.S FOR R18C103 i
1 1
36 l CM i V ! IV 4.14 558 KA: CM 1 13 28.16 3ae the CH 3 66
$ Cue tw a Cu n TEC REf1 Maoist e ellDE = =
IC -6 '
1 5/G me'Jillem DUTLIT l h _
2M l *8.85 lll lilN re ._
~
EXTENT TEN l IEC l in h _~
$ PEED 19.12iin/sec l TRAIN 16C --
l 11C - -
l 12C --
) Vap 1. M G 62 Vp, 4.94 13C --
i i
i g 8 73 8 54 8 73
, i g leC - - 1 g-J-
q p y 7 14M I ' ( ' I 20.45 13e thz CM 5 67 3.98 I:5 n!I i 12 13N -
l
- 1> --
l SSH 3
l 3 --
m __ l y a .
/ ..
sg 4 / / staas2 e arrts see Vpe 3.81 8 25 3 73 Vpo 2.20 8 47 90s 6 F
- t s**: ** 1998
(: . . .
',uj ,. .
l Figure derived from WCAP-13523 (23]
FRAMATOME TECHNOLOGIES, INC.
A-33
FIGURE A-8 INCORRECT PLACEMENT OF VECTOR DOTS ON MIX 1 LISSAJOUS TRACES FOR R22C40 36 Ot ! Y nlX 1 V 4. 8 125 Mix 1 183 3.51 558 th: CM 1 182 C -
gg , ,, g ,,, g , ,
TI,e _
ic + , REEL es uCISE m mu S IDE = =
s sc
.-=
==
m . 11.- ouun C ,- 12n f .e.as ial llin
~2 ,
EXTENT TEN l TEC l 11C --
SPEED 22.81lin/see itAIN 120 --
l:
ue --
Vpe 1.83 8 124 et vpe 1.62 3g _ , 8 153 22
!6 / l /
2- -
2a -
9 f
% [
5 y l 13M -
l g
( 23.15 384 KA: CM 3 333 27.43 its gaz CH 5 13e 12M '
11H -- . -
en -- , -
su 6 L.
~
ism
" T l ] [ v, s.23 8 ill es t *resse l ,a ,,, ,,3 g ,,
/ \ ,
[=j,' , ,, =", js ,,q, a.,
% M .Q, W Sw' e
,' 'l'
- Y s W/
W ,
W Figure derived from WCAP-13523 (23]
FRAMATOME TECHNOLOGIES, INC, A-34
FIGURE A-9 INCORRECT MAXIMUM VOLTAGE DERIVED FROM PLACEMENT OF VECTOR DOTS ON TRANSITION REGION OF 550 kHz RAW FREQUENCY DATA LISSAJOUS TRACE FOR R42C44 36 CH 1 V MlI 1 V 3.38 1:$ n!I 1 13 6.77 554 thz CM ! 29 g,g E REEL DISE 310E
- . i SC ==
- I g
/ 12M l-8.99 l tl lllM g -- EXTENT l TEM l Tic l }
18C -- -> / SPEED l22.tElin/sec lf talN sic --
j-12c -- ?
sic -- o 14e I -'" ' ' , ' E 8" ~ ' ?' 8 '22
! b N- L V <~ K 7 sen 0
13.s3 b ~
f, ~ "F~
3ee ran cM 3 .. 33.s3 33, i,o cx s ..
12M --
q
/
12n l
sin -- -
f an -L p- ( k sw -__
4_ i a -- - - 6 etana 3 . rgs one rta v,, ..i. m ii. ,,,3... __ m s. m m , s,. s.. ,m
" - < Ls ts h ). 3 une a a > < s s i s
- - m- ,_
I %
3 Figure derived from WCAP-13523 (23) .
FRAMATOME TECHNOLOGIES, INC.
A-35 l . . - - - - - _ . - - - - - - _ _ _ _ _ _ _ _ _ _ _ _ _
i l
l I
l t
FIGURE A-10 CORRECT PLACEMENT OF VECTOR DOTS ON MIX 1 LISSAJOUS FIGURE FOR R42C44 36 0,1 V f,lE I V 3.30 1:5 MlI 1 10 6.71 554 Dr. CH 1 29 g g g 47 g, TEC g g g gg g s/G UMlf
- g, aftLET
=
Z r_-
~~
t j 12M l =4.99 l tl lI!M
$ EE -: __
cntxt rta l tre i is
= :; SPEED 22.86lIn/sec lTRAIM
[tC 11C -
j-a _-- +
l 1 ,C _- ,
- vpp 2.41 8 105 43a vpp 2.18 E 11e 56a "c
t p
~. -
t
- r
?
w, s
Y r
g F
p %
1 i < <
n,, __ n.n 3.. m. o, 2 .. n.u n. o. 5 ..
7> /
12M - - i-zu --
[
i i,, ___ -_
l *
- .-H (
2
= -r d ,,,-....
s g_ J' vp, i.e6 w *** * 'r: 3.m im itx ,
v,, S.,4 e is 62: 8 6: 42:
1 ) T T T eu. . ."I.,.
~"
t v-
-==f < _
J Figure derived from WCAP-13523 (23).
FRAMATOME TECHNOLOGIES, INC.
A-36
FIGURE A-11 PLACEMENT OF VECTOR DOTS BASED SOLELY ON MIX 1 LISSAJOUS FIGURE (NO SIGNIFICANT SHARP TRANSITIONS IN ANY OF THE RAW FREQUENCIES) -
R10C44 as en a y nix y 3.24 tis nix t is 2.35 SM Du CH & 19 gg g gg og 44 itC 1C*
gg== die EWi$ HE3 l/G UNIT
!E a (RITLIT
= - - ..-
se L 2n l w.se lil illk y ,
EXTENT tot l TEC l Ifi
$PCD 21.81lin/sec lTRA!M ltC - - -
12C r vp, 1.25 E 124 21: vp, t.es E 111 57 1.C
-_)- ) ( 6 ) (
ica I ,' % P W #
- N N % %
, 6 \ f \ f 22n ___ - --
n..i 3.. m , en 2 .. i4... in D m s <i un .
1 -
$ \ f( s it. - J w .
- f. .o m -. . .
. .m. -
e ., m v,, 2.u e 23. u -
v,, i .o "l,=l<> mi
) ( ) ( ,.. . , > . i . , .
4 - % ~
e '[. ,
y ,. p +, ,,
/
i / \
Figure derived from WCAP-13523 (23).
FRAMATOME TECHNOLOGIES, INC.
A-37
FIGURE A-12 PLACEMENT OF DOTS MARKING MIX 1 LISSAJOUS FIGURE FOR R16C26 l
EC E 16 @ 26 l rge E I. E I iQ A
, $/G UNIT OUTLIT J L IM l+19.95l:l lilN U EITENT-TEM l TEC l ]
== sectn 2e.54live.e fruin i
=_=_.
n-l n -
,,, ..s2 e .. su v, ..o e i.4 su i
_ _ l ( 6 L i (
a ~a r i s p t t <- I P 1 -
- ; 7 l \ ? .
,,, n . i. 2.. = ca 2 <s u .i. n. = a s u i l,_
I on -_ )
an --
f r s 11M --
BH --
, __. . . . .m W 8* e I er:13 as erge 2H Ypp 2. 9 Q 69 653 Ypp 1.74 8 25 .
E23
, un l
.. __ l l I I J ... . , ..... . , . i
- ' m = < m m %
c 1; ;>
W ^~W 4
? '> n= n s es l
l / \ .l l
l I
i l
Figure derived from WCAP-13523 [23]
FRAF.ATOME TECHNOLOGIES, INC. l A-38
FIGURE A-13 INCORRECT PLACEMENT OF VECTOR DOTS MARKING MIX 1 LISSAJOUS FIGURE FOR R30C74 35 CM 1 W CH 5 V 2.11 1:5 Mix 1 le 4.82 554 ch: CN 1 13 gg,, ,gk,f , C0L nc RIIL si u 015e u m slDE-i 5/G E60Hlimm DUTLIT m r SM l -4.83 l:l lllN 1C
-j cxitut Trn i C l p
$C 3
SPEED 21.14lIn/sec lf1AIN i
I'C %
11C vpp s.12 8 73 65: vpp 1.24 8 55 ses 12C l Q j l Q 13C --
,,c 9 % % P 1'-
/ ( l (
. . 2.2 see en: Cn 3 5 21. 12e en Cx s 2 leN 13H f"
12M 11H --
,8 l um,e.us, ,n, y, \ v,, 2.<a a 25 ssa ve. 2.74 e 222 : k'
- a 5 a::ri im
~
f an I \ l \ . " ' '.,o..l 2"
3p 4 y
W M v rue s
a >
ll to p 's- p ..
, ( ,
Figure derived from WCAP-13523 [23].
FRAMATOME TECHNOLOGIES, INC.
A-39
l l
FIGURE A-14 CORRECT PLACEMENT OF DOTS TO EFFECT MAXIMUM VOLTAGE - R30C74 l
l 1
l l
35 CM 1 W I CH 5 V 2.99 1:5 MIX 1 15 8.72 558 th: CM i 29 3; , g I REEL EiE 0!sK u m 81CE = =
5/G KBUNIT mum OWLET l
~ -
qg 2M l+23.90l d lllN, I ic --
Ik
_ C_C .
l N
~
O g itC --
vpp 1.It E 72 71 vpp 1.96 8 46 Ma igg - i ( f A 13C --
14C --
l j f N \
j .. 13.24 388 th: CH 3 45 21.18 130 Kha CM $ 71 l
14N --
l
- 1. --
_ y 12H --
11M --
~
scase e u rts ese g I vpp 5.36 8 2 52 vpp 5.t1 8 213 : s. so sse:si:rtim i \ t t '8" 3
$ E d N M -
f I P
\
F f
Pi Figure derived from WCAP-13523 [23].
FRAMATOME TECHNOLOGIES, INC.
A-40
' ' ~~
FIGURE A-15 EXAMPLE OF BOBBIN COIL FIELD DATA -
MIX RESIDUAL DUE TO ALLOY CHANGE l
33 1 Os ! V RII 2 V 6.98 400 Enz CH 1 248 8.22 2:6 n!I 2 42
- gg ,,, ggy ,, , g;L g 3 - X 400/100 Absolute "" "" o 8 " 5 8 =
l1/G mamuN! Tem it.noet j
{ _
3 lCITENT 1H l.a.001:156.431]
KG j t>0 ;
% $P[to *****lln/sec f -.- & Q L-
~
.. l W -
vpp 3.31 CCG 138 et vpp 2.16 CIC 231 la l l -
- ; .. .- x s x> % ' n 7 e I C45I. A 6 -4
~~
l 4.16 til n!X 1 252 19.45 2 H thz CM 3 351 1 L- --
. 400/100 Differential l :
- __ 1
/
l I
__ u M
l (i
- 4, c .4 . .. . ,
.c. . m1:
- vpp 2.8) C(G 144 08 vpp 7.4e CEC 59 sa ".4 a.. s as..s:ir ines
~~
[
~ 1 ( 316 f \ l ( l [ m.,,,s,s . s.s i e, r __ p w ' w , - x : ::: ' '
- w -
x v ,
s
~ . . . . . .
.- , l l } ) l ) ,
Figure derived from WCAP-13523 [23).
t FRAMATOME TECHNOLOGIES, INC.
A-41
FIGURE A-16 EXAMPLE OF MRPC DATA FOR SINGLE AXIAL INDICATION (SAI)
ATTRIBUTED TO ODSCC - PLANT S 08 4 V 34 CM S V 4.29 304 the Ot 4 88 @ M E > um. ap.. a-
@@ esas ss 1 :=::
s.. w um uns rs Hwssem arsona rtsm=> nuise ssiusies an I .e.x l 1 ljam feltu23 I O cens I lTR ICUJl lCitCl AXI AL $ PEED g.31lIn/sec lTtA!N vpp 1.21 DEC 22 et
\ % W t *'
V ~N AXIAL YlDi
8 CIRCUPW DENTIAL EXT 42 DEG b 0.53 y /~
1 j
I ;A /
- 2H+4.35 K -0.51 364 AXIAL ftA2 I AXIAL EXTs 0.53 IM j i
Figure derived from WCAP-13523 [23] .
FRAMATOME TECHNOLOGIES, INC.
A-42
FIGURE A-17 i MRPC DATA FOR SINGLE AXIAL ODSCC INDICATION (SAI) - PLANT S l
u cn 4 v cu s v 4.4, ne ar a t s a w s e,.
l l
[
m :::':'::
as, or was Lists; nisms tts/xasi s wiss ciiusess t2 M gn g ,g,37 l,l gj gy j
,,, 7 EXTENT tdt l TEM l )
casts I lTRIC22l l CIRC l Ax! AL $PCED 0.34 lIn/sec lTRA!K 9
Ypp 8.71 CEC 37 et
- / 1
/
L s .
% 3 -
/ J q ,
g Axx via e g CIRCUNFEREXilAL [XT: 174 DCC t i 3.43 ' ,:
P r .' 1M+4.42
-4.51 364 j
/ Ax!AL TRACI i L AXIAL EXia 8.24 IN l
i
^
V'i Figure derived from WCAP-13523 [23]
FRAMATOME TECHNOLOGIES, INC.
A-43
FIGURE A-18 MRPC DATA FOR MULTIPLE AXIAL ODSCC INDICATIONS (MAI) - PLANT S 38 Of 4 V CM 9 V 2.86 300 Dcr CH 4 183 (Q f( E > SCEE ha a Marm
@@ saan 64 A ::=
es. er scas (Ists: ss Ewaram slanets truscana 3 vitetits/sts) 2H l .g ,4 g l 3l
_( )
, , , , 7 cssts I ltticCERl cum ros i rtn l T lCittlugg SPED ll3n 8.38 lIn/sec l TRAIN v,, e.ss occ n .,
)
D J /
C "R i oie ,io, M asa Clacury DtOfTIE [rt s 31 DCE i
-4.43
- ..s, .
MIA itACE usu. txts e.<4 in i
Figure derived from WCAP-13523 [23]
FRAMATOME TECHNOLOGIES, INC.
A-44
______ _ . _ _ _ _ - _ _ - - _ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - - - - - - ~ - ~ ~ - - - -
FIGURE A-19 MRPC DATA FOR CIRCUMFERENTIAL ODSCC INDICATIONS AT DENTED UPPER AND LOWER TSP EDGES N*-' = a, d ,, 2 21
- RIE --- tyg
- i 75 $ cas
_ -4. 34
~
\
.3 4 ' 215 4'
- ~
gg -_ /
e -e.=
A TTtlN 19lllrin'2" .*!
- ".c"el: P, Mtwita:su se EA LM
.... ---; ,u....
acmrT:34 = 25E M
_ .a <. ,
, 4-
=-
~
[ '
f . '~ u E ttDI lillJn.",
" in
- Te,
.ormms se W Wf 64 W INfE MLM
=ta , e our emana, Figure derived from WCAP-13523 [23]
FRAMATOME TECliNOLOGIES, INC.
A-45
FIGURE A-20 EXAMPLE OF BOBBIN COIL FIELD DATA - FLAW SIGNALS FOR ODSCC AT DENTED TSP INTERSECTION FROM PLANT A l
l l ee l als 1 v i ot iy 7.2s see gh8 O I e4 5.H 3:5 att I 12
> e i
l l i 2N l *4.es lll tlk i , CITD!l TEC l ttn I l I
j $PCID teem,in/sec .rtain l _ j l
j Vee e 64 3 IE4 DNt vee e.83 M 121 Ost?
. 5.88 .ee ots 0: 1 23 7 4.11 1:5 mis t it!
I
_L_
i l l l e l
l 1
I . /
)
-k __
8 l
i b art 44-es s l ' .- scassa e sen ese t- see a retti:6e este
- ..u em .n . i .n m .e. ,.....,n.e,....,,.3
% i b hI b l' l Il .
4 iT M i T ' !' ; ;': '
Figure derived from WCAP-13523 [23].
FRAMATOME TECHNOLOGIES, INC.
A-46
- ~~
FIGURE A-21 EXAMPLE OF BOBBIN COIL FIELD DATA - FLAW SIGNALS FOR ODSCC AT DENTED TSP INTERSECTION FROM PLANT A l
led RLE & V Os 7 v 11.54 .ee th: Cu 3 .g 1.33 1:5 nts t :s _
J'. -
9 F 2n l ee . se l i{ .in
[ITDefl 7M l TDe n "1 L lMMM uW _c.
$PTD .eeeees [n/m .f tain t
~
i I
lI 4
l l . s.72 Egg in oni l . ..., ai oc 8.6 .ee ths CM i 21 . 76 125 nts 1 lel l
l M
l l
S l
Q-=-t .<
l n .<*-i
.c=>e art , s=
ie. n .., a.a. in.
I 2006 v.s e..a en esa vs. e.s. mu m rue . i ii si. i .ie-e we s
w
.e
. . . . , . . .., H
- - - t I Figure derived from WCAP-13523 [23).
f FRAMATOME TECHNOLOGIES, INC.
A-47
l l
FIGURE A-22 EXAMPLE OF BOBBIN COIL FIELD DATA - FLAW SIGNALS FOR ODSCC AT DENTED TSP INTERSECTION FROM PLANT A i
I l
l 40 0 miE 4 y CA 7 V 9.1$ ott Dtt Cn 1 (3 1.1e 1;$ als g 44
"" I
~ U l *0.98 l tl (b
~~
tzsturl tic l stn W E ll.H llR/ set IRAlb j
6 t
- ~~
Vpo 1.55 M let >t vae 3.65 G 131 wt
_" ~~
9.85 888 KAs Cu 4 63 5.74 til att t .e
. 6 ===
. 1
.= --.
. ___ s ,
y
-- - s m ,. . ,
.o . . -, .
Iked See 39 49:79:9 #Fil (
_ ..e i.,. e in
\ s j is .. i .n l
su n
)
m e,s, m.. ............,..
a + ;a
'% l % % l % s lll.l 7 ig 4' , .. , , , ...
I i
l Figure derived from WCAP-13523 (23]. ]
l FRI41ATOME TECHNOLOGIES, INC.
A-48 .
FIGURE A-23 EXAMPLE OF BOBBIN COIL FIELD DATA - FLAW SIGNALS FOR ODSCC AT DENTED TSP INTERSECTION FROM PLANT A fat als 8 V CM ) v 11.45 88 ths CM i 2 75 5.M 8:5 att i 2 72 f #CIL 3/G meus,1f __ igaogg]
, m g in g et.M l l .gn I CITENil TEC l T D, . a SPCID i s .M iint.ec ttaim
~
l #
l l
i . ...,3 m ,,i c, . . ,2 e i.. =1
-~
- _t1.65 *M th
- 01 8 2 75 5M til att 1 2 72 i
i .
.=.
~^
l \1.-
l l
6 - -...
.c.,. .n , -
__ -,.,,,....v.,
i ca
_. ww s.n Ein tM su va t i, M n m '
' .....i * ". 3 88+'s* ".
d ! b i 1 y jg 4-g "l'.'l'f'l .
Figure derived from WCAP-13523 [23].
FRA>'.ATOME TECliNOLOGIES, INC.
A-49
FIGURE A-24 EXAMPLE OF BOBBIN COIL FIELD DATA - FLAW SIGNALS FOR ODSCC AT DENTED TSP INTERSECTION FROM PLANT A es t als 3 y CM iV 9.15 ew th CM i 43 5.7e 1:5 att i se 8 81 j*e. M ltl .gn LITDftl TEC l ftM j l
, S M !8.M iin/ set itain
~
/
. k 6
vpy 3.21 3 333 ont v,, 3 , ,, g g.g y
_ 9.15 em ths CM 1 63 5.1e 1:5 als t se
- l
. - V
. \
I l
- I t
. iPC 42-W L
. SCEEBs 8 NTT 3E0
, had See N ($IMalfIMS l :
- _ vn. ut s m asa via v. ...a um .5 r., . n is,.",'...., ,,
, 1 , . . . ; ,,,
I
'd- I b b I h I.lll l*l y
l.
y- l 9 . . , , .. . i Figure derived from WCAP-13523 [23],
FRAMATOME TECHNOLOGIES, INC.
A-50
FIGURE A-25 EXAMPLE OF BOBBIN COIL FIELD DATA - FLAW SIGNALS FOR ODSCC AT DENTED TSP INTERSECTION FROM PLANT A 3e ' nts I T Os 1 v i 8.64 see ths CM L 3e e.16 til alt t gg SC J. S/C ggang 3M l *e.se lil :: .
' E UTEM7l 7t l ros , E s SPGD t * * * * ** in/ .ec Tiatn
+ __.
e i vpp 5.le M iLe " Eest vp. 3.77 e 136 Dief 5.48 *e8 thf CM 1 4.15 Z3 1:1 Alt 1 29
-m i
i I
l g - ...
- stunt e erffs sus i.. m ,, . . . . + . m
, a ,.
. ..n a li in . .. m ................,...
s , , , , ... . . ..
i Y Y '
> ,a a < a
.s. . .
s : e < . r Figure derived from WCAP-13523 [23).
FRAMATOME TECHNOLOGIES, INC.
A-51
FIGURE A-26 LOCATION OF ONE END OF AN INDICATION USING AN RPC PROBE l !.04 2 VERT .' _ CH 2 Hoc ;l De*EL NO - 2 lfD 9 ROW 33 Cut. 3 l W DIFsurt l l oan - 2 FT'EQ 400 kHz SPCM 156
. P ROTAT!0H - 354 DEO
= . .. . p> . . . . . . . . . N wt stara o<=T one - 2v I j FTIQ 440 kHz
' :: 1 SPm 156 3E ROTATIDH - 254 DEG C
jE RIOWT STRIP OsJr7 3 one - 2H
- R FREQ 480 kHe l 3I SMH 156 M ROTATION - 354 DEG sto +W.9
\
I l SYSTEM CDFERQT1CM
! M - CETALt.T j l e or cww- 4 l g . 12:23:29 m
- -......... . ..... . ... ..... ........ J8HRRY 1 1984 Colle FK:EG 112 's l a l 5 6 7 8 1
6N. '
l a aw. ps 6
. I 4 30 gtxe 3473 Figure derived from WCAP-13523 [23].
FRAMATOME TECHNOLOGIES, INC.
A-52
. . _ . . _ _