ML12340A764
| ML12340A764 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 03/19/2009 |
| From: | Bass A Structural Integrity Associates |
| To: | Entergy Nuclear Operations, Atomic Safety and Licensing Board Panel |
| SECY RAS | |
| References | |
| RAS 23566, 50-247-LR, 50-286-LR, ASLBP 07-858-03-LR-BD01 0900235.401.R0 | |
| Download: ML12340A764 (21) | |
Text
United States Nuclear Regulatory Commission Official Hearing Exhibit Entergy Nuclear Operations, Inc.
In the Matter of:
(Indian Point Nuclear Generating Units 2 and 3)
ASLBP #: 07-858-03-LR-BD01 Docket #: 05000247 l 05000286 Exhibit #: ENT000579-00-BD01 Identified: 10/15/2012 Admitted: 10/15/2012 Withdrawn:
Rejected: Stricken: ENT000579 Other: Submitted: October 2, 2012 lJ Structural Integrity Associates, Inc.
Report No.: 0900235.401.RO Project No.: 0900235.00 March 19,2009 G-Scan' Assessment of 8" Condensate Water Storage Tank Return Line CD-183 Inspection Date: February lih, 2009 Prepared for:
Entergy Indian Point Generating Station Unit 2 Prepared by:
Structural Integrity Associates, Inc.
Cerritos, California
- t, n Prepared by
- _ _----
- "?::::;:""=2===_ _ _ _ __ Date: 03113/09 Alex Bass Reviewed by: Date: 03/l3/09 Larry Weigel Approved by: Date: 03/19/09 Ken Rach tJ StmctIJrallntfJgrity AssOCiates, Inc.
REVISION CONTROL SHEET Document Number: 0900235.401.RO
Title:
G-Scan' Assessment of8" Condensate Storage Tank Return Line CD-183 Client: Entergy, Indian Point Generating Station, Unit 2 SI Project Number: 0900235.00 Section Pages Revision Date Comments All All o 03/19/09 Initial Issue tJ StrtlctllftlllntBgrity Associates, Inc.
Table of Contents Section Page
1.0 INTRODUCTION
.............................................................................................................. 1 2.0 INSPECTION AND TESTING TECHNIQUE ............................................................... 1 2.1 G-Scan' Technique ........................................................................................................ 1 2.2 B-Scan Technique ............................................................................................................ 4 3.0 INSPECTION RESULTS ................................................................................................. 6 4.0
SUMMARY
AND CO*NCLUSIONS ................................................................................ 7 APPENDIX A G_SCAN' SHOTS ..............................................................................................8 APPENDIX B CAD ISOMETRIC DRAWINGS ...................................................................... 11 APPENDIX C EQUIPMENT AND TECHNICIAN CERTIFICATES .................................. 13 0900235040 l.RO e Structumllnte,rity Associates, Inc.
List of Tables Table I: Description ofG-Scan' Indication Coding ................................................................... .4 Table 2: Summary of the G-Scan' Results ................................................................................... 6 Table 3: Summary of the B-Scan Results ....................................................................................... 7 List of Figures Figure 1: Typical G-Scan' data and corresponding pipe features ................................................ 2 Figure 2: Detectable combinations of flaw depth and width for G-Scan' inspection of 8.625-inch x 0.322-inch wall pipe ...................................................................................................... 3 Figure 3: B-Scan Image of Corrosion .............................................................................................. 5 0900235.401.RO ii tJ Structumllntegrity Associates, Inc.
1.0 INTRODUCTION
Structural Integrity Associates, Inc. (SI) performed a long range guided wave (G-ScanTM) inspection at Entergy Indian Point Generating Station, Unit 2 (Entergy) on February 17ili , 2009.
Allen Schuele was the lead inspector on site during the Entergy inspection. The G-ScanTM inspection was performed on 8" Condensate Storage Tank Return Line CD-I83 to screen several pre-selected sections of pipe for wall loss. The inspection was performed while the plant was in operation and water was flowing through the pipes.
In addition to the G-Scan' piping interrogation, B-Scan ultrasonic inspection was used to measure the nominal wall thickness of each pipe segment and to "prove-up" specific G-Scan' results by quantifying the depth of corrosion at specific locations of interest. B-Scan readings were taken within the G-Scan' collar "dead zone" (Le., typically a 2-3 foot length of pipe under and immediately adjacent to the G-Scan' collar-shown as a solid green vertical stripe in the G-Scan traces) to insure the integrity ofthe pipe.
2.0 INSPECTION AND TESTING TECHNIQUE 2.1 G-Scan' Technique The torsional guided wave system used in this examination is the third generation GUL System developed by the Imperial College ofthe UK and manufactured by Guided Ultrasonics LTD.
The torsional waves are computer generated at a continuous range of frequencies from 18 to 40 KHz.
The G-Scan' system is a low frequency ultrasonic guided wave technique developed for the rapid survey of pipes to detect both internai and external corrosion. Guided wave ultrasonic inspection uses multiple transducer arrays to direct sound energy in a circumferential mode, which creates torsional guided waves. These torsional waves propagate down the pipe and reflect off features such as welds, supports, or areas of wall loss. Reflections are presented in a 0900235.401.RO 1 e Strucllll1lllntflgrity Associates, Inc.
pseudo A-scan format on the computer screen in either black (axi-symmetric reflection) or red (non-axi-symmetric reflection) as illustrated in Figure 1 below. The black lines' amplitude is proportional to the total cross sectional area change. The red lines' amplitude is inversely proportional to the extent that the cross sectional area change covers the circumference of the pipe. Interpretation of the inspection results is based on integration of these two signals' amplitude, symmetry, and wave shape, and incorporates detailed pipe design, installation, and operational information.
2.0
-F 1.5
~.o Q.
E
<C O.5 0.0 Welds Figure 1: Typical G-Scan' data and corresponding pipe features Under optimum conditions, the G-Scan' system is sensitive to metal loss as low as 3% of the pipe wall cross sectional area, but under actual field conditions reliable detection of metal loss flaws should be generally assumed at between 6% and 9%.
Figure 2 illustrates the typical flaw size detection limits for G-Scan' when used on 8" pipe, like those inspected at Entergy. For this survey 5% sensitivity was empirically estimated.
0900235.401.RO 2 e Stmt:turallnttlflrlty Associates, Inc.
8.625-inch x O.322-inch Pipe GScan Flaw Detection Limits at Indicated % Sensitivity 0.320 0.300 0.280 0.260 0.240
_ 0.220
.t::.
g 0.200
~ ~:~:
Gl Q 0.140
~ 0.120 i! 0.100 0.080 0.060 0.040 0.020 0.000 o 1 2 3 4 5 6 7 8 9 1011 1213 14151617 18192021 22232425 2627 Flaw Circumferential Figure 2: Detectable combinations of flaw depth and width for G-Scan' inspection of 8.625-inch x 0.322-inch wall pipe Depending upon the sound attenuation characteristics of the pipe, coating, and contents, this inspection technique can interrogate up to 200 feet in each direction for tests conducted on above-ground pipe in good condition and 75 feet for underground pipe. However, guided waves are significantly attenuated when passing through mechanical couplings and some types of fittings. Generally, the guided wave signals cannot be accurately interpreted after passing through flanges, some reducers, victaulic couplings, or multiple elbows. As a result, the inspectable distance will often be less than 100 feet in each direction.
The G-Scan' survey technique is very accurate at locating the axial position of piping anomalies. G-Scan' can identifY whether the anomaly is at the top, bottom, or sides of the pipe, but cannot distinguish between internal and external anomalies. This technique is best used as a pipe survey tool. Estimates of the wall thickness change can be derived from the data, but 0900235.401.RO 3 {J Blfflelurallntllgrlty Associates, Inc.
accurate measurement of flaw dimensions require that the anomaly be inspected using a technique capable of more quantitative measurements of wall thickness. SI uses B-Scan ultrasonic inspection to perform detailed examination of anomalies detected by G-Scan' on accessible pipe segments. ID versus OD corrosion cannot be distinguished with the G-Scan' system.
Wall loss is reported using two measures of defect dimensions - Estimated Cross sectional Loss (ECL) and the extent of circumference affected. The black (axi-symmetric) signal reflections indicate the estimated change in pipe cross sectional area, expressed as the percentage ECL. The circumferential extent of a feature is indicated by the ratio of red (non-axi-symmetric) signal amplitude to black (axi-symmetric) signal amplitude.
The terms and colors shown in Table 1 are used to interpret and report corrosion indications:
Table 1: Description of G-Scan' Indication Coding Estimated Wall Indication Type Color Loss Minor Black Oto20%
Medium Blue 21%to 49%
Severe Red 50% and greater 2.2 B-Scan Technique The Phoenix Ultrasonic B-Scan imaging system utilized during this inspection can profile the pipe wall in two dimensions, verify original wall thickness, and profile corrosion pitting. The Ultrasonic B-Scan scanning system provides a cross sectional video view of pipe thickness by scanning in teal time. As the scan head passes over each section Of pipe, the video screen displays general wall thickness and remaining wall thickness at corroded areas and isolated corrosion pits. When corrosion pits are located, the diameter and depth of these pits are profiled.
Examples of the display are included in Figure 3 below.
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Log File Name:
Instrument Serial Number:D03 Transducer: 5 Mhz Part Number: 84" Straight segement Location 1 Inspector: Allen Schuele Level III Company: ABC Pipeline 1
TYPE:T*SCAN IF BLOCK: O.l)464(
POS:ENCODED L-A . . . .It--+--':'1 ECHO-BLK: 0.023 MEAS TIME: 62.91 MULT:IP*1ST ZEAO:3047 POL:POS p-_ _ _ _ _ __ VElOCITY:O.2320 CONTrOl Y:CONTACT LOW:O.200 AGC:OFF DElAY:O.OOO Ip*SUP:OFF RANGE:1.253 SING/DUAl:DUAl RECT:RF GAIN: 54.30 dB INDEX:1 THRESH:40.0'% 1--_ _ _ _ _ _ _ _ _ _ _ _ _ _....., HIGH:1.400 IP BLOCK: 0.0802 B-scan 17 SCALE:7 Note 1: Pitting area lowest minimum was 0.247" Note 2: Pitting diameter 0.240* and 0.264" Note 3:
Figure 3: B-Scan Image of Corrosion Area 1: Digital display of thickness at location indicated by cursor at location "A" Area 2: RF display ofUT A-Scan signal associated with position indicated by cursor at "A" Area 3: B-Scan display Location A: Cursor used to select position Location B: Top (outside) surface of pipe Location C: Inside surface of pipe Location D: Typical indications of corrosion pits. Depth is measured by moving the cursor over the pit location (see note I for example). The width of the pit can also be measured (see note 2 for examples).
The display illustrates an axial scan length of about 5.8 inches at the selected scale.
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3.0 INSPECTION RESULTS The results of the G-Scan' inspection are summarized in Table 2 below. The detailed results of G-Scan' shot including the G-Scan TM waveforms are included in Appendix A. Appendix B includes CAD isometric drawing which illustrates the approximate piping configurations, locate where G-Scan TM shots were taken, list the UT thickness (B-Scan) results at each inspection location, and list the most relevant G-Scan' results of the 2009 inspection.
At a majority of the G-Scan' inspection locations, a B-Scan UT inspection was performed to quantify the nominal wall thickness and to "prove-up" specific G-Scan' results by quantifying the depth of corrosion at specific locations of interest. The results are included in both Table 3 and in the CAD drawing in Appendix B.
The G-Scan' inspection indicates that after more than 30 years in service, there is some level of degradation in the Unit 2 Condensate Storage Tank Return Line interrogated. Table 2 shows that the G-Scan' inspection found sporadic regions of pipe wall loss where there seems to be greater than "normal" general wall loss and localized pitting. The level of corrosion in the inspected areas of piping is estimated to be 20% to 85% wall loss +/- 10%. Possible through wall hole noted at feature +F9 located 16'7" from the collar in the positive direction.
Table 2: Summary of the G-Scan' Results Approx.
G* Circ.
location ECl Wall length of Reference Scan' Feature Affected Class Notes ft % loss Corrosion DWGNo.
Shot # %
This section of pipe appears to be 4796 +F2 4'2" 8 40 20 Minor a major concern. A*200607
+F3 5'3" 4 20 20 Minor
+FS 10'2" 4 20 20 Minor
+FB 15' 1" 17 20 85 Severe 3 in Possible through wall
+F9 16'1" 10 10 iOO Severe 2 in hole
+F10 18' 1 17 20 85 Sellere 4in 0900235.401.RO 6 {t Structura/lntegrlty Associates, Inc.
Table 3: Summary of the B-Scan Results Tnom Maximum Nominal Tmin Approx.
G-Scan' Measured Difference Pipe Size Measured wall loss Shot # in in in in %
(Note 1) (Note 2) 4796 8 0.314 0.328 0.014 4 Notes for Table 3:
[1] "Nominal Wall" (Tnom Measured) data represents the typical wall thickness of the pipe away from evidence of pitting or localized corrosion. The nominal wall thickness may be different from the original wall thickness if the pipe has experienced general corrosion around the majority of the circumference.
[2] The maximum wall thickness reduction is calculated from the difference between the specified nominal wall and the minimum thickness measured by B-Scan. In some cases, as a result of general corrosion, the measured nominal wall thickness could be different from the nominal wall thickness when the pipe was installed. As a result, the total wall thickness change could be greater than the amount reported here. On the other hand, some of the difference may not be caused by corrosion, but could be the result of normal variations in wall thickness that occur during the pipe manufacturing process.
4.0
SUMMARY
AND CONCLUSIONS The G"ScanTM / B"Scan inspections indicate that after more than 30 years in service, that there was some level of degradation in the Unit 2 Condensate Storage Tank Return Line interrogated.
The level of corrosion in the inspected areas of piping is estimated to be 20% to 85% wall loss
+/- 10%. Overall, the G-Scan' inspection found sporadic regions of pipe wall loss where there seems to be greater than "normal" general wall loss and localized pitting.
The greatest threat to the service Water piping seems to be pitting which could generate through wall holes sporadically throughout the system. Known leak verified at feature +F9 located 16'7" trom the collar in the positive direction.
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APPENDIX A G-SCAN' SHOTS 0900235.401.RO 8 tr Structural/ntllgrity Associates, Inc,
Associates, Inc.
Test 10' G3-14#4796 Pipe: 8" CD-l83 Ring: R2B08(930)
SHe: Indian Polni Unit 2 Coniig: 4.0FR. T(O,l)
Location: Sleeve +1'5" Caubration: Automatic (149.89 mV)
Size: 8 inch (8.175mm) Version: 3.94, Wavemaker G3-14 Tested: 17 Feb 200914:40 CHent: Entergy Tested by: Allen Schuele!SIAj Procedure: GU 1.1 DAGs: CaII=7%, Weld=23%
General Notes; Un~ 2 Drawing number A-200607. Condensate Storage Tank Retum Line CD-183.
Ukrasonic B-Scan thickness measurements were taken at the conar location "Y' nominal 0.328" minimum 0.314".
5% shot sens~ivity Distance (ft)
- 4796.wg3 0900235.401.RO 9 t; Structural/ntegrlty Associates, Inc.
Associates, Inc.
Test ID' G3-14#4796 Pipe 8" CD-183 Rins: R2B08(930)
Site: Indian Point Unit 2 ConfJg: 4,OFR T(O,l)
Location: Sleeve +1'5' Caubration: Automatic (149,89 mY)
Size: 8 inch (8,175mm) Version: 3,94, Wavemaker G3-14 ECl'--Extent-'-' Notes
° 50
- 4796,wg3 0900235040 LRO 10 t) Structural Integrity Associates, Inc.
APPENDIXB CAD ISOMETRIC DRAWINGS 0900235.40 LRO 11 tt StructurallntBllnty Associates, Inc.
8" CONDENSATE STORAGE TANK RETURN LINE CD-183 s*
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APPENDIXC EQUIPMENT AND TECHNICIAN CERTIFICATES 0900235.401.RO 13 l) Stl1lcturallntegrity Associates, Inc.
Certificate This is to certify that acbieved level 2 proficiency in the use of the Wavemaker' G3 Pipe Screening System achieved by successfully completing the Guided Ultrasonics Ltd. training course use of the Wavemaiker' 03 Pipe Screening System. and. demonstrating sufficient IDaerstanding of the use of guided ultrasonics by both written and practical examination.
Date: JI October 2008 Course Tutor; David Alleyne
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For validity of this qualification refer to the operator qualification card 0900235.401.RO 14 ~ Structurallntsgrlty Associates, Inc.
CERTIFICATE OF CONFORMANCE
~t...""nt .... 1 Integrity Associates Date: Decem her 17, 2008 Gridley Place Date Due: Marcb 17, 2009 CA90703 P.O.#: V-LW T07 11 05KK Item Quantity Model No. Description Serial No.
G3 Wavernaker Long Range Guided 0314 Wave System
~ln,~tr1l1ment Condition:
Received: In Tolerance Returned: In Tolerance Integrity Associates, Inc. hereby certifies that the above Instrument(s) meet/or manufacturer's applicable performance specifications and is/are in good working The equipment used to calibrate these instruments is traceable to the National Institute Standard and Technology within limitation of the N.I.S.T.'s calibration service.
N.I.S.T Trace No.
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lJ Structurallntegrfty Associates, Inc.
Test ID: G3-14#4780 Pipe: 3* cat. g3-14 Ring: R2F03(1375)
Site: office Conlig: 1_SFR, T(O,l)
Location: flange -Z S* Calibration: Automatic (1440_07 mV)
Size: 3 inch Version: 3_96, Wavemaker G3-14 Tested: Dec 17 2008 18:40 Client: office Tested by: Allen Schuele[SlA) Procedure: GU 1.1 DAGs: CalI=7%, Weld"'23%
General Nates: Fiberglass Tape Measure Serial No, 1581206820, 3" Test Loop Serial No. SI-0501.
Notes Il1{jicatlOn 2. detected 3132" Hole gro<Y>e_ 25% Ole. Arrected.
+1"1 4'2'" 1.08
-F1 .2'6" 18.9 0900235 AO l.RO 16 tJ Structurallntellrlty Associates, Inc.
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1781! Gegrgetown la **
- Huntington !!eaeh
- CA 97647
- Phqpe 714-893-2438
- Fax 714.897.3849
\lleb Site btttrllwww ndts~
CERTIFICATE OF CONFOR.l\1ANCE Strueturallntegrity & Associates Date: April 01, 2008 16912 Gridley Place Date Due: April Gt, 2009 Cerritos, CA 90703 P.O.#: 9920 USA NOTS#: P040108G Attn: Larry Weigel 562-944-8210 Quantity Model No. Description Serial No.
PHOENIX ULTRASONIC 04061005M B*SCAN IMAGING SYSTEM Instrument Condition:
Received: In Tolerance.
Returned: In Tolerance NDT Systems hereby certifies that the above Instrument(s) meetJor exceed manufacturer's applicable performance specifications and Ware in good working order. The equipment(s) used to calibrate these instruments is traceable to the National Institute of Standard and Technology within limitation of the NJ.S.T.*s calibration service. The policies and procedures at this facility comply with ML-STD-45562A. The above stated results are applicable only to the items listed on this Certificate. This Certificate may not be reproduced, except in full, with out the written approval of NDT Systems, Inc.
N.I.S.T. Trace No.
Temperature: 72 Deg F.
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