ML103060070
| ML103060070 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 09/30/2010 |
| From: | Kleinsmith S GE-Hitachi Nuclear Energy Americas |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| DRF #0000-0007-9747, Rev 1, 0000-0124-0988, Rev 0 | |
| Download: ML103060070 (14) | |
Text
Attachment 1 "Evaluation of Indication in Peach Bottom Unit 2 Vessel Closure Head Weld (CH-C-2),"
Report Number 0000-0124-0988, September 2010
HITACHI GE Hitachi Nuclear Energy 3901 Castle Hayne Rd Wilmington, NC 28401 0000-0124-0988 Revision 0 Class II DRF #0000-0007-974 7 Revision I September 2010 EVALUATION OF INDICATION IN PEACH BOTTOM UNIT 2 VESSEL CLOSURE HEAD WELD (CH-C-2)
(UT Examination P2R18)
Prepared for Exelon Corp.
Peach Bottom Atomic Power Station, Unit 2 Responsible Engineer:
S. Kleinsmith, Lead Engineer Mechanical Analysis - Structural & Fracture Mechanics Group Responsible Verifier:
Technical Reviewer:
R. Wu, Technical Leader Mechanical Analysis - Structural & Fracture Mechanics Group H. Mehta, Chief Consulting Engineer
0000-0124-0988-RO DISCLAIMER OF RESPONSIBILITY Important Notice Regarding the Contents of this Report Please Read Carefully The only undertakings of GE Hitachi Nuclear Energy (GEH) respecting information in this document are contained in the contract between Exelon Corporation and GEH, Contract # 00000833 Release 00673 (Provided by Exelon), effective 03/17/2010, as amended to the date of transmittal of this document, and nothing contained in this document shall be construed as changing the contract. The use of this information by anyone other than Exelon Corporation - Peach Bottom Unit 2, or for any purpose other than that for which it is furnished by GEH, is not authorized; and with respect to any unauthorized use, GEH makes no representation or warranty, express or implied, and assumes no liability as to the completeness, accuracy, or usefulness of the information contained in this document, or that its use may not infringe privately owned rights.
Copyright, GE Hitachi Nuclear Energy, 2010 ii
0000-0124-0988-RO REVISION
SUMMARY
No.
Change 0
1st Issuing of Document (Disposition of Indication/Flaws found in welds CH-C-2) iii
0000-0124-0988-RO Table of Contents Subject Page No.
- 1.
EX EC U T IV E S U M M A RY......................................................................................................................
1
- 2.
INTRODUCTION AND REPORT OUTLINE..............................................................................
2 2.1.
In tro d u c tio n......................................................................................................................................
2 2.2.
R e p o rt O u tlin e.................................................................................................................................
2
- 3.
INSPECTION REPORTS
SUMMARY
AND FLAW GEOMETRY..........................................
3 3.1.
Inspection Reports Sum m ary..............................................................................................
3 3.1.1.
Peach Bottom, Unit 2 - Refueling Outage Thirteen (P2R-13).......................
3 3.1.2.
Peach Bottom, Unit 2 - Refueling Outage Eighteen (P2R-18)......................
3 3.1.3.
P2R-13 / P2R-18 Indication/Flow Location Comparison...............................
4 3.2.
F la w G e o m e try...............................................................................................................................
4 3.2.1.
FLAW GEOMETRIES CONSIDERED IN EVALUATION...........................................
4
- 4.
Meridional Weld Flaw vs. Indication # 9 Flaw Orientation........................................
6 4.1.
Meridional Weld Indication vs. Circumferential Weld Indication.......................
6 4.2.
ASME Section XI Code Comparison (1989 Edition without addenda vs. 2001 Edition with 2003 addenda)............
6 4.2.1. T ab le IW B -3 5 10 -1.................................................................................................................
6 4.2.2.
IW B -3 6 0 0.................................................................................................................................
6
- 5.
FRACTURE MECHANICS EVALUATION/REVIEW................................................................
7 5.1.
Evaluation / Review Sum m ary...........................................................................................
7 5.2.
Indication/Flow Com parison.............................................................................................
7
- 6.
SU M M ARY AN D CO NCLUSIO NS.................................................................................................
8 7.
R E F E R E N C E S.............................................................................................................................................
9 Iv
0000-0124-0988-RO I
EXECUTIVE
SUMMARY
The reactor pressure vessel closure head at Peach Bottom Atomic Power Station, Unit 2 (PBAPS-2) was ultrasonically (UT) examined [Reference 11 during refueling outage eighteen (P2R-18). There were multiple indications/flaws noted in the Closure Head to Flange Weld (CH-C-2) region. All but one of the indications/flaws were classified as being indications/flaws without through wall dimension or were deemed acceptable based on the Section XI, Table IWB-3510-1 [Reference 4].
Therefore the GEH Customer Notification Form [Reference 2] states that this one (1) indication/flaw (Indication #9) will require evaluation with IWB-3600 to allow continued operation.
The Indication/flaw (Indication #9) is in the circumferential weld approximately seventeen (17) inches away from the closest meridional weld and is orientated transverse to the weld in the plate region of the weld. Therefore the flaw/indication is in the same plane (i.e. same orientation) to the meridional weld indications/flaws that were evaluated in 2002 [Reference 3]. Based on the geometry it was determined that the 2002 meridional weld flaw evaluation & method [Reference 3] remains valid/applicable for this Closure Head to Flange weld (CH-C-2) indication/flaw.
This report summarizes the evaluation/comparison that compared the one (1) indication/flaw with through wall dimension and length reported in the PBAPS-2 UT examination [Reference 1] to the allowable indication/flaw depth and length evaluated in the P2-R14 "The Evaluation Of Indications In Peach Bottom Unit 2 Vessel Closure Head For Continued Operation" [Reference 3].
Based on this evaluation/comparison it is concluded that the indication/flaw (Indication #9) found in the PBAPS-2 Closure Head to Flange (Weld CH-C-2) region during the Refueling Outage (P2R-18) UT examination [Reference 1] is acceptable by the flaw acceptance criteria of the ASME Section X1 Code [Reference 4]. Therefore, it is concluded that the subject indication/flaw (Indication # 9) in the Closure Head to Flange Weld (CH-C-2) region is acceptable for continued operation in "as-is" condition.
I
0000-0124-0988-RO 2
INTRODUCTION AND REPORT OUTLINE 2.1.
Introduction In September 2010, GEH Engineering was contacted/contracted to determine if an indication/flaw (Indication #9) reported in the P2R-18 Customer Notification Form [Reference 21 for the Closure Head to Flange Weld (CH-C-2) region could be dispositioned based on the 2002 GE Nuclear Energy (GENE) fracture mechanics evaluation [Reference 31 that meets the IWB-3600 acceptance criteria of the 1989 with no addenda ASME Section XI Code [Reference 51. It was also requested that GEH determine if the 2002 evaluation [Reference 31 remains applicable if the 2001 with 2003 addenda ASME Section XI Code [Reference 41 was considered.
This report summarizes the fracture mechanics and ASME Code evaluation/comparison that was performed to disposition the one (1) indication/flaw (Indication #9) in the Closure Head to Flange Weld (CH-C-2) region.
2.2.
Report Outline Section 3 of this report provides a brief flaw description of the indication/flaw and previous disposition history.
It will summarize the UT inspection results and describes the flaw geometry considered in the evaluation. Section 4 summarizes why the 2002 meridional indication/flaw evaluation/methodology
[Reference 31 is applicable for the Closure Head to Flange (CH-C-2) indication/flow (Indication #9).
Section 5 provides the results of the fracture mechanics evaluation/comparison of the P2R-18 indication/flaw to the 2002 GE Nuclear Energy (GENE) fracture mechanics evaluation [Reference 31 bounding evaluated indication/flaw size geometry. Finally, summary and conclusions are presented in Section 6.
0000-0124-0988-RO 3
INSPECTION REPORTS
SUMMARY
AND FLAW GEOMETRY 3.1.
Inspection Reports Summary 3.1.1. Peach Bottom, Unit 2 - Refueling Outage Thirteen (P2R-13)
The reactor pressure vessel closure head at Peach Bottom Atomic Power Station, Unit 2 (PBAPS-2) was ultrasonically (UT) examined [Reference 6] during refueling outage thirteen (P2R-13).
There were multiple indications/flaws noted in the Closure Head to Flange Weld (CH-C-2) region. All of the indications/flows were classified as being indications/flaws without through wall dimension or were deemed acceptable based on the Section XI, Table IWB-3510-1 [Reference 51.
Indication #5 was determined to be located at an azimuth location of 660.5 inches.
The flaw was detected only while scanning in the CCW direction.
The indication's "W" distance (distance from the weld centerline) was 3.1 inches.
According to the data sheet, this was a spot indication (meaning that no movement of the search unit was possible without losing the reflector) oriented transverse to the weld.
The flaw was evaluated and found to be acceptable, using the limited positional data available.
This examination was preformed using Pre-PDI examination techniques.
The Indication/flaw geometry was reported as: "2a" = 0.60" (therefore "a"
=0.30"), "I" = 0.60", and "t" = 4.5". This resulted in "a/t" = 6.67% < 7.6% (allowable for "a/I" of 0.50 [Reference 5]). Therefore deemed acceptable based on the Section Xl,.
Table IWB-3510-1 [Reference 51.
3.1.2. Peach Bottom, Unit 2 - Refueling Outage Eighteen (P2R-18)
The reactor pressure vessel closure head at Peach Bottom Atomic Power Station, Unit 2 (PBAPS-2) was ultrasonically (UT) examined [Reference 1] during refueling outage eighteen (P2R-18).
There were multiple indications/flaws noted in the Closure Head to Flange Weld (CH-C-2) region. All but one of the indications/flaws were classified as being indications/flaws without through wall dimension or were deemed acceptable based on the Section XI, Table IWB-3510-1 [Reference 4].
Indication #9 was the one (1) indication/flaw that requires additional evaluation with IWB-3600 to allow continued operation.
Indication (#9) was determined to be located at an azimuth of 660 inches. The flaw was detected while scanning in both the CW and CCW directions.
The indication's "W" distance (distance from the weld centerline) was -4.5".
The P2R18 data was gathered using a PDI demonstrated examination.
The Indication/flaw was reported as being transverse to the weld and having a geometry of: "2a" = 0.42" (therefore "a" =0.21"), "I" = 1.00", "t" = 4.5" and "S" = 1.56".
This resulted in "a/t" = 4.6% > 3.3% (allowable for "a/I" of 0.20 [Reference 41).
Therefore deemed not acceptable based on the Section XI, Table IWB-3510-1
[Reference 4).
3
0000-0124-0988-RO 3.1.3. P2R-13 / P2R-18 Indication/Flaw Location Comparison The location of the indications in P2R13 (Indication #5) versus P2R18 (Indication 49) is well within the measurement accuracy possible for manual examination techniques on RPV Closure Head welds. GE Hitachi has determined that the indications are from the some reflector. The flaw/indication geometries differ due to the newer/more accurate inspection techniques.
3.2.
Flaw Geometry This section discusses the one (1) indication/flaw (Indication #9) that displayed tip signals and possessed a through wall dimension and was classified as exceeding the requirements of Table IWB-3510-1 [Reference 41.
Dimensions of this one (1) indication/flaw are characterized in Table 3-1.
The Reactor Pressure Vessel Examination / Reactor Pressure Vessel Sizing Data Sheet can be found in reference 2.
3.2.1.
FLAW GEOMETRIES CONSIDERED IN EVALUATION Figure 3-1 shows the criteria used to determine if the indications/flaws that are to be evaluated need to be characterized as surface or sub-surface type flaws for the purpose of fracture mechanics analysis.
Figure 3-1(A) shows the parameters used for surface proximity evaluation. Figure 3-1(B) shows the parameters used for sub-surface proximity evaluation.
The guidance for this characterization is provided in Article IWA-3000
[Reference 4]. For this evaluation (Closure Head to Flange Weld Flaw Evaluation) the nominal flaw sizes (truncated to the hundredths term) are evaluated/compared to the allowable flaw sizes. This is consistent with the GE method previously accepted by the BWR Vessel & Internals Project (BWRVIP).
It is seen in Table 3-1 that indication #9 is to be characterized as sub-surface indication because (S > 0.4a).
Table 3-1 Listing of Ultrasonic Indication in the Closure Head to Flange Weld (Circumferential Weld CH-C-21 at Peach Bottom Unit 2 Weld ID IND #
I 2a a
0.4*a S
a/I (in.)
(in.)
(in.)
(in.)
(in.)
CH-C-2 9 (@308')
1.00 0.42 0.21 0.084 1.56 0.21 Surface/Subsurface Check: A Flaw characterized as surface flaw if S < 0.40. This is not the case, so flaw is deemed to be sub-surface.
4
0000-0124-0988-RO I - No.
A.
OBVIOUS SURFACE FLAW Notes:
[1]
[2]
B.
SURFACE or SUB-SURFACE[ 1] FLAW Flaw characterized as surface flaw if S < 0.4a.
If Classified as Surface Flaw '2a' dimension becomes 'a' for flaw evaluation.
Figure 3-1 Parameters for Surface Proximity Evaluation 5
0000-0124-0988-RO 4
Meridional Weld Flaw vs. Indication # 9 Flaw Orientation.
4.1.
Meridional Weld Indication vs. Circumferential Weld Indication Indication #9 in the P2R-18 examination [Reference 1] is described as being transverse to the circumferential weld (i.e. going from the flange to the dollar plate) and in the shell section of the weld.
The indications in the 2002 GENE fracture mechanics evaluation [Reference 3) are parallel with the meridional weld (i.e. going from the flange to the dollar plate).
Therefore indication #9 in the P2R-18 examination [Reference 11 is in the same plane as the meridional welds evaluated in reference 3. This means that the same evaluation methodology and loading would be applicable to both. Therefore the 2002 GENE fracture mechanics evaluation
[Reference 31 can be used for evaluation of Indication #9 in the P2R-18 examination
[Reference 11 as long as the 2002 bounding evaluation indication's geometry bounds Indication #9's geometry.
4.2.
ASME Section XI Code Comparison (1989 Edition without addenda vs. 2001 Edition with 2003 addenda) 4.2.1. Table IWB-3510-1 The two different years of the ASME Section Xl, Table IWB-3510-1 [Reference 5 and 41 were compared and determined to be the same. Therefore either code year can be referenced and there is no evaluation modification needed to go from the 1989 Edition without Addenda [Reference 51 to the 2001 Edition with 2003 Addenda
[Reference 41.
4.2.2. IWB-3600 The two different years of the ASME Section X1, IWB-3600 through and including IWB-3613 [Reference 5 and 41 were compared and determined to be the same. Therefore either code year can be referenced and there is no evaluation modification needed to go from the 1989 Edition without Addenda [Reference 51 to the 2001 Edition with 2003 Addenda [Reference 4].
6
0000-0124-0988-RO 5
FRACTURE MECHANICS EVALUATION/REVIEW 5.1.
Evaluation / Review Summary The 2002 GE Nuclear Energy (GENE) fracture mechanics evaluation
[Reference 3] was reviewed to determine if the method and evaluation results are applicable/valid to disposition the indication/flaw (Indication #9) in the Closure Head to Flange Weld ICH-C-2).
- The "Assumptions" section (4.1 of the 2002 report) remains applicable/valid.
- The "Applied and Weld Residual Stresses" section (4.2 of the 2002 report) remains applicable/valid.
- The "K Calculation Methodology" section (4.3 of the 2002 report) discusses the "K" calculation being performed for surface flaws. The surface flaw evaluation method considers the flaw through wall depth to be "a".
Indication #9 in the CH-C-2 weld is considered to be sub-surface. The sub-surface flaw evaluation method considers the flaw through wall depth to be "2a".
This is the only difference in the calculation methodology. Both evaluations use the same equations and input variables. Therefore as long as "a" is what is compared, not the flaw thru wall depth, the evaluations/results are applicable/valid.
- The "Fatigue Crack Growth" section (4.4 of the 2002 report) is conservative as it assumes the indication/flaw is exposed to the reactor water environment.
- The "Allowable K Values" section (4.5 of the 2002 report) remains applicable/valid.
Therefore as long as "a" is what is compared, not the flaw thru wall depth, when comparing the indication #9 geometry to the bounding indication/flaw geometry used in the 2002 GENE fracture mechanics evaluation
[Reference 31 evaluation/results is applicable/valid dispositioning the indication/flaw (Indication #9) in the Closure Head to Flange Weld (CH-C-2).
5.2.
Indication/Flaw Comparison The 2002 GENE fracture mechanics evaluation [Reference 3] was performed for a bounding indication/flaw size. The bounding indication/flaw size has a through wall depth ("a") of 0.25", a length ("1" of 3.75" and an "a/I" of 0.067. From looking at Table 3-1, one can see that indication #9 has an "a" depth of 0.21", a length (1T1) of 1.0" and an "a/I" of 0.21. Both the ("a" & "I") parameters are bounded by the bounding indication/flaw size and as seen in table 4-1 of Reference 3 the smaller "a/I" ratio, the larger the "K applied", so "a/i" is also bounded. Therefore Indication #9 is bounded by the 2002 GENE fracture mechanics evaluation [Reference 3] that meets the IWB-3600 acceptance criteria of the ASME Section Xl Code [Reference 5 & 41 and it is concluded that the subject flaw is acceptable for continued operation in as-is condition.
7
0000-0124-0988-RO 6
SUMMARY
AND CONCLUSIONS The reactor pressure vessel closure head at Peach Bottom Atomic Power Station, Unit 2 (PBAPS-2) was ultrasonically examined during refueling outage eighteen (P2R-18). There were several indications noted in the Closure Head to Flange Weld (CH-C-2). One (1) indication/flaw displayed tip signals and possessed a through-wall dimension and did not meet the acceptance standards IWB-3510 of ASME Section XI (2001 Edition with 2003 Addenda). The Section Xl Code allows for the acceptance of such flaws for continued service if they meet the requirements of Paragraph IWB-3600, Analytical Evaluation of Flaws.
A fracture mechanics evaluation, meeting these requirements (for the 1989 Edition without addenda) was performed in 2002 for the Meridional Head Welds for the refueling outage fourteen (P2R-14) UT examination indications/flaws based on a bounding flaw size.
The indication/flaw "a" and "1" dimension calculated in the UT examination for P2R-18 were compared to the "a" and "1" dimension used in the 2002 bounding indication/flaw fracture mechanics evaluation.
Based on this evaluation/comparison it is concluded that the indication/flaw (Indication #9) found in PBAPS-2 Closure Head to Flange Weld (CH-C-2) region during the refueling outage (P2R-18) are acceptable by the flaw acceptance criteria of the ASME Section Xl Code (for either the 1989 Edition without addenda or the 2001 Edition with 2003 Addenda). The flaw acceptance criteria/methodology of the ASME Section XI Code for the 1989 Edition without addenda and the flaw acceptance criteria of the ASME Section Xl Code for the 2001 Edition with 2003 addenda were reviewed and deemed to be the same for this evaluation.
Therefore, it is concluded that the subject indication/flaw (Indication # 9) in the P2R-18 CH-C-2 weld, even after accounting for projected crack growth for the life of the plant including license renewal (60 total years), is acceptable for continued operation in as-is condition using the flaw evaluation acceptance criteria methodology of IWB-3600 in the ASME Section XI Code, 2001 Edition with 2003 addenda.
8
0000-0124-0988-RO 7
REFERENCES
[1]
GE Nuclear Energy, Peach Bottom Unit 2 - P2R18 UT Examination Report
- 008700 for Weld ID - CH-C-2 Closure Head to Flange Weld. Preliminary report Contained in GEH DRFneFile 0000-0124-0995.
Official report to be contained in GEH DRF 0000-0122-9171.
[21 GEH Nuclear Energy (RE: Wade Miller), Peach Bottom Unit 2 - P2R18 UT Customer Notification Form # CNF-016 R1, Project # 168975, WO No:
C0231094-06 for Weld ID - CH-C-2 (Closure Head to Flange Weld), September, 27, 2010. Contained in GEH DRFneFile 0000-0124-0995.
[31 GE Nuclear Energy (RE: S. Kleinsmith), "The Evaluation Of Indications In Peach Bottom Unit 2 Vessel Closure Head For Continued Operation", GENE, San Jose, CA, Report No. 0000-0007-9747, Revision 1, Dated September 2002.
[4]
ASME Boiler and Pressure Vessel Code, Section X1, Rules for In-Service Inspection of Nuclear Power Plant Components, ASME, 2001 Edition with 2003 Addenda.
[5]
ASME Boiler and Pressure Vessel Code,Section XI, Rules for In-Service Inspection of Nuclear Power Plant Components, ASME, 1989 Edition without Addenda.
[6]
GE Nuclear Energy, Peach Bottom Unit 2 - P2R13 UT Examination Report
9