NL-07-2116, Pressurizer Nozzle Full Structural Weld Overlays Nondestructive Examination Results - Fall 2007 Outage (1R21)
| ML073180046 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 11/12/2007 |
| From: | George B Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| ALA-07-149, NL-07-2116 | |
| Download: ML073180046 (24) | |
Text
Southern Nuclear Operating Company, Inc.
Post Office Box 1295 Birmingham, Alabama 35201-1295 Tel 205.992.5000 SOUTHERN...\\..
COMPANY November 12, 2007 Energy to Serve Your World sM Docket Nos.: 50-348 NL-07-2116 U. S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, D. C. 20555-0001 Joseph M. Farley Nuclear Plant - Unit 1 Pressurizer Nozzle Full Structural Weld Overlays Nondestructive Examination Results - Fall 2007 Outage (1 R21)
Ladies and Gentlemen:
Southern Nuclear Operating Company (SNC) completed the Performance Demonstration Initiative (PDI) qualified ultrasonic examination (UT) of the Farley Nuclear Plant (FNP) Unit 1 pressurizer nQzzle full structural weld overlays (FSWOL) on October 31, 2007. This activity was accomplished in accordance with SNC's alternative ISI-GEN-ALT-06-03, Rev. 2, which was approved per NRC safety evaluation report (SER) dated April 3, 2007 (TAC Nos. MD2794, MD2795, MD2796 and MD2797). Prior to the Farley 1R21 outage, SNC requested, by letter NL-07-1179, dated June 27,2007, a modification to the alternative to revise the 48-hour hold-time requirements defined in section 3(a)2, section 3(a)3, and Appendix 4 section 3.0(a). The NRC gave verbal approval for this change in a conference call on October 5,2007.
Page 18 of the SER dated April 3, 2007 includes the following statement:
"the licensee will provide the NRC, within 14 days after the completion of the ultrasonic examination of the weld overlay installations, (1) the examination results of the weld overlays, (2) a discussion of any repairs to the overlay material and/or base metal and the reason for repair, and (3) will perform the subsequent lSI in accordance with 0-4300 of Appendix 0 to the ASME Code,Section XI.
II contains the requested examination and repair information. As noted in the enclosure, the UT acceptance examination of nozzle 4501 resulted in a repair of two areas. In addition, the final ultrasonic examination of nozzles 4501, 4502, and 4504 detected laminar flaws which were found to be acceptable in accordance with the flaw acceptance standards of ASME Section XI, IWB 3514-3.
The approved SNC Alternative requires that planar flaws be assumed under each laminar indication which might limit future ultrasonic examinations. The assumed planar flaws for nozzles 4501 and 4504 required analytical evaluation to ASME
U. S. Nuclear Regulatory Commission NL-07-2116 Page 2 Section XI, IWB-3640 per the alternative; these evaluations, included in, showed the assumed planar flaws to be of an acceptable size. contains the SNC commitment to perform subsequent lSI on the Unit 1 pressurizer nozzle FSWOLs in accordance with 0-4300 of Appendix O.
All six Unit 1 pressurizer nozzles to safe-end welds were mitigated during the 1R21 outage. Bare metal visual examinations were not performed because of the application of the weld overlays. For Farley Unit 1, this letter satisfies the 14 day reporting requirement of the SER dated April 3, 2007 and the 60-day reporting requirements committed to by SNC letter dated March 6, 2007. Since all six pressurizer nozzle to safe-end welds have been mitigated, no future 60-day reports will be submitted.
This letter contains one NRC commitment. If you have any questions, please advise.
Sincerely, B. J. George Manager, Nuclear Licensing
Enclosures:
- 1. Weld Overlay Examination Results and Repairs
- 2. ASME Section XI, IWB-3640 Evaluations
- 3. Regulatory Commitment List
U. S. Nuclear Regulatory Commission NL-07-2116 Page 3 cc:
Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Mr. J. R. Johnson, Vice President - Farley Mr. D. H. Jones, Vice President - Engineering RTYPE: CFA04.054; LC# 14673 U. S. Nuclear Regulatory Commission Dr. W. D. Travers, Regional Administrator Ms. K. R. Cotton, NRR Project Manager - Farley Mr. E. L. Crowe, Senior Resident Inspector - Farley Joseph M. Farley Nuclear Plant - Unit 1 Pressurizer Nozzle Full Structural Weld Overlays Weld Overlay Examination Results and Repairs Farley Unit 1 Weld Overlay Examination Results and Repairs Results PT of Mitigation Layer PT of Overlay PDI UT Exam PDIUT Nozzle I PTofBase Post PDI UT Repairs ResultslRepairs ResultslRepairs Results I
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NONE Spray the area was re-examined indications; I after light 4503
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NONE Safety the area was re-examined with NRI NRI - No Recordable Indications E1-1 Farley Unit 1 Weld Overlay Examination Results and Repairs Results PT of Mitigation Layer PT of Overlay PDIUT PDIUTExam Nozzle Post PDI UT Repairs PT of Base ResultslRepairs ResultslRepairs Re-exams Results Metal The UT POI examination after examination on the FSWOL detected The pre-POI O-degree UT the repair detected two laminar laminar indications which did not indications: # 3 is about 0.43 meet the acceptance criteria. Farley inches in depth on the pipe side made the decision to remove of the safe-end to pipe weld.
indications # I and # 2 prior to The surface area of the performing the POI UT examination.
lamination is 0.3 square inches Repair areas consisted of an oval with a maximum corrected shaped area approximately 6-inches dimension of 1.0-inch measured by lO-inches (indication # I) and a at the surface of the weld smaller area on the opposite side of overlay while #4 is about 0.38 the FSWOL (indication # 2).
inches in depth at the nozzle buttering (nozzle side of the NRI Alloy-600 weld) for the nozzle NONE FSWOL and grinding was performed NRI A repair was implemented on the NRI to safe-end weld. The surface to remove the unacceptable O-degree area of the lamination is 0.3 UT indications. The initial PT square inches with a maximum examination after grinding showed corrected dimension of I.O-inch two PT indications. Additional measured at the surface of the grinding was performed and the final weld overlay. (See the figures PTwas NRI.
on pages EI-5 and EI-6 for The ground-out area was re-welded locations; all dimensions are in with PT examination performed after inches.)
These laminar the first layer after repair and after indications are acceptable per welding was completed. Both IWB-35 14-3.
examinations resulted in NRI.
4501 Safety NRI - No Recordable Indications E1-2 Farley Unit 1 Weld Overlay Examination Results and Repairs PT of Mitigation Layer ResultslRepairs PT of Overlay ResultslRepairs POIUT POI UT Exam Nozzle Post POI UT Repairs Re-exams Results Reduction in coverage does occur because of the two laminations: # 3 results in an axial beam reduction total of 0.01% and no circumferential beam reduction exists while #
4 results in an axial beam reduction total of 0.47% and the circumferential beam reduction total of 0.45%.
Assumed axial and 4501 circumferential planar flaws Safety under indications # 3 and # 4 were compared to ASME Table IWB-35 14-2: for (Cont'd.)
indication # 3, the assumed largest planar flaw has an alt of 10.3% versus an allowable of 9.2%. This resulted in a requirement to perform an IWB-3640 evaluation.
See for the detailed analytical evaluation.
Indication # 4 would have an assumed largest planar flaw with an alt of 8.6% a$
compared to the allowable of 9.5%.
E1-3 Farley Unit 1 Weld Overlay Examination Results and Repairs Nozzle 4501 Safety (Cont'd.)
PT of Mitigation Layer ResultslRepairs PT of Overlay ResultslRepairs PDIUT Exam Results Post POI UT Repairs The reduction in coverage is small for indication # 3 plus the laminar indication is away from the nozzle to safe-end weld and therefore, it will not impact the area of interest for future examinations.
The reduction in coverage is small for indication # 4 such that there is a reasonable assurance that a PWCSS indication growing into the upper 25% (of the original dissimilar metal weld) would be detected.
PDIUT Re-exams E1-4
Farley Unit 1 Figure Showing Nozzle 4501 Indication #3 Plot Farley Unit 1 Pressuriur Safety Nozzle 4501 2700 Profile
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I 04.30 E1-6 Farley Unit 1 Weld Overlay Examination Results and Repairs Nozzle PT of Mitigation Layer ResultslReDairs PT of Overlay ResultslRepairs PDI UT Exam Results Post PDI UT Repairs PDIUT Re-exams One Indication; after 4502 grinding, the area was NRI NRI re-examined with no Safety indications noted.
The UT PDI examination detected one laminar indication approximately 0.25 inches in depth on the safe-end side of the safe-end to pipe weld. The surface area of indication # I is 0.78 square inches with a maximum corrected dimension of 2.6 inches measured at the surface of the weld overlay.
(See the figure on page EI-8 for location; all dimensions are in inches.)
This laminar indication is acceptable per IWB-35 14-3.
Reduction in coverage does occur because of the indication; it results in an axial beam reduction total of 1.38% and a circumferential beam reduction total of 1.42%.
Assumed axial and circumferential planar flaws under indication # I were compared to ASME Table IWB-35 14-2 and the assumed largest planar flaw has an alt of 6.7% versus an allowable of 9.4%.
The reduction in coverage is small plus indication # I is away from the nozzle to safe-end weld and therefore, it will not impact the area of interest for future examinations.
NONE NONE NRI - No Recordable Indications E1-7 Farley Unit 1 Figure Showing Nozzle 4502 Indication #1 Plot l.8mIIw' F1lIW lndIcallonIf
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E1-8 Farley Unit 1 Weld Overlay Examination Results and Repairs Nozzle Results PT of Base Metal PT of Mitigation Layer ResultslRepairs PT of Overlay ResultslRepairs PDIUTExam Results Post PDI UT Repairs PDIUT Re-exams 4504 NRI NRI NRI Relief The UT PDI examination detected three indications: # I is a laminar indication about 0.27-inches in depth on the pipe side of the safe-end to pipe weld. The surface area of the lamination is 1.5 square inches with a maximum corrected dimension of 3.0 inches calculated at the indication depth. Indication # 2 is a spot indication about 0.25-inches in depth on top of the safe-end to pipe weld.
This indication has no width and a length of 0.7-inches. Indication # 3 is a laminar indication about 0.25-inches in depth on top of the safe-end to pipe weld. The surface area of the lamination is 0.2 square inches with a maximum corrected dimension of 0.7 inches measured at the surface of the weld overlay.
(See the figures on pages EI-II and EI-12 for locations; all dimensions are in inches.)
These laminar indications are acceptable per IWB-35 14-3.
Laminar indications # I and # 3 were compared to ASME Section IWA 3360-1 where it was determined that thev were evaluated seDaratelv.
NONE NONE NRI - No Recordable Indications E1-9 Farley Unit 1 Weld Overlay Examination Results and Repairs Nozzle Results PTofBase Metal PT of Mitigation Layer ResultslRepairs PT of Overlay ResultslRepairs PDI UT Exam Results Post PDI UT Repairs PDIUT Re-exams 4504 Relief (Cont'd.)
There is no reduction in coverage on the nozzle to safe-end weld.
Coverage loss occurs on the safe-end to pipe weld because of the two laminations: the combined laminar indications result in an axial beam reduction total of 2.42% and a circumferential beam reduction total of 2.23%.
Assumed axial and circumferential planar flaws under laminar indications # I and # 3 were compared to ASME Table IWB 3514-2: for indication # I, the assumed largest planar flaw has an alt of 21.1 % versus an allowable of 9.6%. This resulted in a requirement to perform an IWB-3640 evaluation.
See Enclosure 2 for the detailed analytical evaluation.
Indication # 3 would have an assumed largest planar flaw with an alt of 8.3% as compared to the allowable of 9.3%.
The reduction in coverage is small plus the laminar indications are away from the nozzle to safe-end weld.
Therefore, they will not impact the area of interest for future examinations.
E1-10 Farley Unit 1 Figure Showing Nozzle 4504 Indication #1 Plot FARLEY 1 RELIEF NOZZLE 4504 INDICA TIDN L EVALUATED AT 180 0
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YlITH 8.4 8.4 8.2 Farley Unit 1 Figure Showing Nozzle 4504 Indications #2 &3 Plot
8.1 FARLEY 1 RELIEF NOZZLE 4504 INDICA TIONS 2 AND 3, EVALUATED AT goo PROFILE
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Joseph M. Farley Nuclear Plant - Unit 1 Pressurizer Nozzle Full Structural Weld Overlays ASME Section XI, IWB*3640 Evaluations
Westinghouse Electric Company Westinghouse Nuclear Services P.O. Box 355 Pittsburgh, Pennsylvania 15230-0355 USA November 9,2007 ALA-07-149 Mr. J. R. Johnson Vice President Farley Project Southern Nuclear Operating Company Farley Nuclear Plant US Highway 95,5 Miles South OfColumbia Columbia, AL 36319 ATTN: Keith Wooten SOUTHERN NUCLEAR OPERATING COMPANY JOSEPH M. FARLEY NUCLEAR PLANT UNIT 1 IWB 3600 Evaluations for SWOL
Dear Mr. Johnson:
Attached are Westinghouse internal letters LTR-PAFM-07-154 and LTR-PAFM-07-153. These are identical to those supplied via the reference letter, except the Proprietary Class has been removed. These letters may be included in your report to the NRC with no proprietary restriction.
Should you have any questions, please feel free to contact Chris Ng at 724-722-6030 or me at 412-374-3365.
Very truly yours, E. C. Arnold, Manager Southern Nuclear Projects jag Electronically Approved Records are Authenticated in The Electronic Document Management System
Westinghouse Non-Proprietary Class 3 Westinghouse To: Rick Rishel cc: Lee Stern From: Chris Ng Ext: 724-722-6030 Fax: 724-722-5597 Your ref:
Our ref: LTR-PAFM-07-154 Date: November 9, 2007
Subject:
Evaluation of Masked Flaw due to Laminar Flaw in the Weld Overlay of Farley Unit 1 Safety Nozzle "4501" References
- 1. WesDyne Letter WDI-PJF-1303511-TCR-002, Rev. 0,
Subject:
"Tabulation of an Assumed Planar Flaw Due to a Laminar Flaw Indication Unacceptable to Table IWB 3514-2 Pre-Service Examination Standards - Farley Unit 1 SWOL Safety Nozzle 4501".
- 2. WesDyne International, Evaluation #: Farley Unit 1, Safety Nozzle 4501, Flaw Indication Evaluation to Southern Nuclear Operating Company Relief Request, October 30,2007.
- 3. Southern Nuclear Operating Company, ISI-GEN-ALT-06-03: Proposed Alternative in Accordance with 10CFR50.55a(a)(3)(i), Application of Pressurizer Nozzle Full-Structural Weld Overlays, Revision 2.0.
- 4. ASME Boiler and Pressure Vessel Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components." Appendix C, 2001 Edition with 2003 Addenda.
As a result of the structural weld overlay being implemented at the Farley Unit 1, laminar indication was discovered in the Safety Nozzle "4501" weld overlay material [1]. The laminar indication on the Safety Nozzle "4501" was found to be acceptable to the flaw acceptance standards of IWB 3514-3 for laminar indications [2]. However, SNC Proposed Alternative [3]
requires that flaws be postulated under the laminar indication, which might be masked from UT examination. Per Reference 1, one of the postulated masked flaws does not meet the Table IWB-3514-2, Pre-Service Examination Standards and is shown in Table 1 below:
Page 2 of2 Our ref: LTR-PAFM-07-154 Table 1 Postulated Safety Nozzle "4501" Masked Flaw Configuration (inches) [1]
Postulated Flaw Orientation Circumferential Proximity to Outside Surface (S) 0.43 in Postulated Total Flaw Depth (2a) 0.13 in Postulated Half Flaw Depth (a) 0.065 in Postulated Total Flaw Length (I) 0.90 in Weld Overlay Thickness (tswol )
0.63 in Total Flaw Depth / Weld Overlav Thickness 0.21 Flaw evaluation was performed in accordance with the SNC Proposed Alternative requirements
[3] and the rules of IWB-3640 in Section XI code [4]. For the geometry of interest, the calculated stress ratios for normal/upset and emergency/faulted conditions are 0.28 and 0.31 respectively.
With flaw length to circumference ratio of 0.036, the allowable circumferential flaw depth to thickness ratio is 75% for the geometry of interest in accordance with Tables C-5310-1 to C 5310-4.
Since the total depth of the postulated circumferential flaw masked by the laminar indication is 21 % of the weld overlay thickness, it can be concluded that the postulated circumferential flaw is acceptable in accordance with the IWB-3640 evaluation procedures/acceptance criteria and no repair to remove the laminar indication of concern is necessary.
Author: C. K. Ng*, Piping Analysis & Fracture Mechanics Verifier: A. Udyawar*, Piping Analysis & Fracture Mechanics
- Electronically approved records are authenticated in the Electronic Document Management System.
Westinghouse Non-Proprietary Class 3 Westinghouse To: Rick Rishel cc: Lee Stem From: Chris Ng Ext:
724-722-6030 Fax: 724-722-5597 Your ref:
Our ref: LTR-PAFM-07-l53 Date: November 9, 2007
Subject:
Evaluation ofMasked Flaw due to Laminar Flaws in the Weld Overlay ofFarley Unit 1 PORV Nozzle "4504" References
- 1. WesDyne Letter WDI-PJF-1303511-TCR-001, Rev. 0,
Subject:
"Tabulation of Assumed Planar Flaws Due to A Laminar Flaw Indication Unacceptable to Table IWB-3514-2 Pre Service Examination Standards - Farley Unit 1 SWOL".
- 2. WesDyne International, Evaluation #: Farley Unit 1, Relief Nozzle 4504, Flaw Indication Evaluation to Southern Nuclear Operating Company Relief Request, October 20,2007.
- 3. Southern Nuclear Operating Company, ISI-GEN-ALT-06-03: Proposed Alternative in Accordance with 10CFR50.55a(a)(3)(i), Application of Pressurizer Nozzle Full-Structural Weld Overlays, Revision 2.0.
- 4. ASME Boiler and Pressure Vessel Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components." Appendix C, 2001 Edition with 2003 Addenda.
As a result of the structural weld overlay being implemented at the Farley Unit 1, laminar indications were discovered in the PORV Nozzle "4504" weld overlay material [1]. The laminar indications on the PORV Nozzle "4504" were found to be acceptable to the flaw acceptance standards of IWB 3514-3 for laminar indications [2]. However, SNC Proposed Alternative [3]
requires that flaws be postulated under the laminar indication, which might be masked from UT examination. Per Reference 1, one of the postulated masked flaws does not meet the Table IWB-3514-2, Pre-Service Examination Standards and is shown in Table 1 below:
Page 2 of2 Our ref: LTR-PAFM-07-153 Table 1 Postulated PORV Nozzle "4504" Masked Flaw Configuration (inches) [1]
Postulated Flaw Orientation Axial Proximity to Outside Surface (S) 0.27 in Postulated Total Flaw Depth (2a) 0.27 in Postulated Half Flaw Depth (a) 0.135 in Postulated Total Flaw LenQth (I) 0.50 in Weld Overlay Thickness (tswol) 0.64 in Total Flaw Depth I Weld Overlay Thickness 0.42 Flaw evaluation was performed in accordance with the SNC Proposed Alternative requirements
[3] and the rules of IWB-3640 and Table IWB-3641-3 in Section XI code [4]. The result shows that the allowable axial flaw depth to thickness ratio is 75% for the geometry of interest. Since the total depth of the postulated axial flaw masked by the laminar indication is 42% of the weld overlay thickness, it can be concluded that the postulated axial flaw is acceptable in accordance with the IWB-3640 evaluation procedures/acceptance criteria and no repair to remove the laminar indication of concern is necessary.
Author: C. K. Ng*, Piping Analysis & Fracture Mechanics Verifier: A. Udyawar*, Piping Analysis & Fracture Mechanics
- Electronically approved records are authenticated in the Electronic Document Management System.
Joseph M. Farley Nuclear Plant - Unit 1 Pressurizer Nozzle Full Structural Weld Overlays Regulatory Commitment List Regulatory Commitment List The following table identifies those actions committed by Southern Nuclear Operating Company in this document for Farley Nuclear Plant. Any other statements in this submittal are provided for information purposes and are not considered regulatory commitments.
Commitment Type Scheduled Completion Date (If Required)
One-Time Action Continuing Compliance Perform subsequent lSI on the FNP Unit 1 pressurizer nozzle FSWOLs in accordance with 0-4300 of Appendix O.
X E3-1