ML022030480
| ML022030480 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 08/20/2002 |
| From: | Jacob Zimmerman NRC/NRR/DLPM/LPD1 |
| To: | Price J, Danni Smith Dominion Nuclear Connecticut |
| Nerses V, NRR//DLPM, 415-1484 | |
| References | |
| TAC MB3093 | |
| Download: ML022030480 (21) | |
Text
August 20, 2002 Mr. J. A. Price Site Vice President - Millstone Dominion Nuclear Connecticut, Inc.
Mr. David A. Smith Rope Ferry Road Waterford, CT 06385
SUBJECT:
MILLSTONE POWER STATION, UNIT NO. 3-RELIEF FROM ASME CODE REQUIREMENTS RELATED TO THE INSERVICE INSPECTION PROGRAM, SECOND 10-YEAR INTERVAL, RELIEF REQUEST IR-2-21 THROUGH IR-2-26 (TAC NO. MB3093)
Dear Mr. Price:
By letter dated September 27, 2001, as supplemented on May 30, 2002, Dominion Nuclear Connecticut, Inc., submitted a request for six reliefs from the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code,Section XI, requirements for certain inservice inspections (ISI) of component welds. These reliefs were requested for Millstone Power Station, Unit No. 3 (MP3) for the second 10-year inspection interval of the ISI Program and scheduled for implementation during the fall 2002 refueling outage.
The U.S. Nuclear Regulatory Commission (NRC) staff has completed its review of the subject request for reliefs. As documented in the enclosed Safety Evaluation, for reliefs IR-2-21, IR-2-22, IR-2-23, IR-2-24 and IR-2-25, Rev.1, the staff concludes that ASME B&PV Code requirements are impractical for the subject welds/components. Therefore, pursuant to 10 CFR 50.55a(g)(6)(i), the NRC staff grants relief for the proposed alternative for MP3 for the second 10-year ISI interval, on the basis that the proposed inspection provides reasonable assurance of structural integrity. For relief request number IR-2-26, Rev. 1, the staff concludes the licensees alternative provides an acceptable level of quality and safety. Therefore, the staff authorizes the proposed alternative pursuant to 10 CFR 50.55a(a)(3)(i) for the second 10-year ISI interval at MP3.
Sincerely,
/RA/
Jacob I. Zimmerman, Acting Chief, Section 2 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-423
Enclosure:
Safety Evaluation cc w/encl: See next page
- See previous concurrence OFFICE PDI-2/PM PDI-2/LA EMCB/SC*
OGC*
PDI-2/SC(A)
NAME VNerses TClark TChan APHodgdon JZimmerman DATE 8/20/02 8/20/02 07/31/02 08/08/02 8/20/02
Millstone Power Station Unit 3 cc:
Ms. L. M. Cuoco Senior Nuclear Counsel Dominion Nuclear Connecticut, Inc.
Rope Ferry Road Waterford, CT 06385 Edward L. Wilds, Jr., Ph.D.
Director, Division of Radiation Department of Environmental Protection 79 Elm Street Hartford, CT 06106-5127 Regional Administrator, Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 First Selectmen Town of Waterford 15 Rope Ferry Road Waterford, CT 06385 Mr. P. J. Parulis Manager - Nuclear Oversight Dominion Nuclear Connecticut, Inc.
Rope Ferry Road Waterford, CT 06385 Mr. W. R. Matthews Vice President and Senior Nuclear Executive - Millstone Dominion Nuclear Connecticut, Inc.
Rope Ferry Road Waterford, CT 06385 Ernest C. Hadley, Esquire P.O. Box 1104 West Falmouth, MA 02574-1104 Mr. John Markowicz Co-Chair Nuclear Energy Advisory Council 9 Susan Terrace Waterford, CT 06385 Mr. Evan W. Woollacott Co-Chair Nuclear Energy Advisory Council 128 Terrys Plain Road Simsbury, CT 06070 Mr. D. A. Christian Senior Vice President - Nuclear Operations and Chief Nuclear Officer Innsbrook Technical Center - 2SW 5000 Dominion Boulevard Waterford, CT 06385 Mr. C. J. Schwarz Director -Nuclear Station Operations and Maintenance Dominion Nuclear Connecticut, Inc.
Rope Ferry Road Waterford, CT 06385 Senior Resident Inspector Millstone Nuclear Power Station c/o U.S. Nuclear Regulatory Commission P. O. Box 513 Niantic, CT 06357 Mr. G. D. Hicks Director - Nuclear Station Safety and Licensing Dominion Nuclear Connecticut, Inc.
Rope Ferry Road Waterford, CT 06385 Mr. D. A. Smith Manager - Licensing Dominion Nuclear Connecticut, Inc.
Rope Ferry Road Waterford, CT 06385 Ms. Nancy Burton 147 Cross Highway Redding Ridge, CT 00870
Millstone Power Station Unit 3 cc:
Mr. William D. Meinert Nuclear Engineer Massachusetts Municipal Wholesale Electric Company Moody Street P.O. Box 426 Ludlow, MA 01056 Mr. S. E. Scace Director - Nuclear Engineering Dominion Nuclear Connecticut, Inc.
Rope Ferry Road Waterford, CT 06385 Mr. M. J. Wilson Manager - Nuclear Training Dominion Nuclear Connecticut, Inc.
Rope Ferry Road Waterford, CT 06385
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SECOND 10-YEAR INTERVAL INSERVICE INSPECTION REQUEST FOR RELIEFS MILLSTONE POWER STATION, UNIT NO. 3 DOMINION NUCLEAR CONNECTICUT, INC.
DOCKET NUMBER 50-423
1.0 BACKGROUND
By letter dated September 27, 2001, as supplemented on May 30, 2002, Dominion Nuclear Connecticut, Inc.(licensee or DNC), submitted a request for six reliefs from the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code,Section XI, requirements for certain inservice inspections (ISI) of component welds. These reliefs were requested for Millstone Power Station, Unit No. 3 (MP3) for the second 10-year inspection interval of the ISI Program and scheduled for implementation during the fall 2002 refueling outage.
2.0 REGULATORY EVALUATION
Inservice inspection of the ASME Code Class 1, 2, and 3 components is performed in accordance with Section XI of the ASME B&PV Code and applicable addenda as required by Title 10 of the Code of Federal Regulations (10 CFR) Section 50.55a(g), except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i). Section 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used, when authorized by the U.S. Nuclear Regulatory Commission (NRC), if the applicant demonstrates that (i) the proposed alternatives would provide an acceptable level of quality and safety or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1, 2, and 3 components (including supports) shall meet the requirements, except the design and access provisions and the pre-service examination requirements, set forth in the ASME Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that inservice examination of components and system pressure tests conducted during the first 10-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME B&PV Code incorporated by reference in 10 CFR 50.55a(b) 12 months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein. In accordance with 10 CFR 50.55a(b), the applicable version of the ASME B&PV Code for MP3 is the 1989 Edition, with no Addenda for the second 10-year inservice inspection interval.
Enclosure
3.0 TECHNICAL EVALUATION
3.1 RELIEF REQUEST IR-2-21 Components for Which Relief is Requested Code Class 1, Examination Category B-A, Item Number B1.40, Head to Flange Weld identified as Weld Number 101-101 Code Requirement ASME Section XI Class 1, ASME B&PV Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, 1989 Edition with no Addenda; Table IWB-2500-1, Examination Category B-A, Item Number B1.40, requires a volumetric and surface examination of essentially 100% of the weld length.
Code Requirement from which Relief is Requested Pursuant to 10 CFR 50.55a(g)(5)(iii) relief is requested from performing the volumetric examination on the inaccessible portions of the subject vessel weld to the extent required by the ASME B&PV Code.
Licensees Proposed Alternative A.
The subject weld will receive 100% surface examination in accordance with ASME Section XI (IWB-2500-1)
B.
The subject weld will receive a volumetric examination of the accessible areas (73%) in accordance with ASME Section XI (IWB-2500-1)
C.
MP3 will perform visual examination during system leakage tests as required by Section XI (IWB-2500-1) and Code Case N-498-1 (approved in Regulatory Guide 1.147, Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1, Revision 12, dated May 1999)
Based on the 73% ultrasonic (UT) examination and the 100% surface examination to be performed on the subject reactor vessel head-to-flange weld, and the monitoring and tests for leakage, DNC believes the proposed alternative provides an acceptable level of quality and safety by providing reasonable assurance of structural integrity of the subject weld.
Licensees Basis for Requesting Relief Geometric configuration and permanent obstructions limit the volumetric examination of the subject weld. The examination is limited to approximately 73% coverage of the volumetric exam using the most current examination technology. Access to this weld is limited to essentially one side due to the forged flange configuration. Additionally, obstructions exist on the top side of the weld due to permanently attached head lifting lugs. Based on the configuration and permanent obstructions, relief is requested from complying with the 100%
required volumetric examination coverage of this weld during the second 10-year ISI interval at MP3.
The limitations described above were included in a request for relief during the first 10-year ISI interval.
Evaluation The ASME B&PV Code requires 100% volumetric and surface examination of the reactor pressure vessel head-to-flange weld during each inspection interval. The configuration of the subject weld and permanent obstructions limit the obtained coverage to approximately 73% of the required volume. Therefore, the ASME B&PV Code-required 100% volumetric examination is impractical to achieve. To gain access for 100% coverage, the component would have to be redesigned and modified. This would place a significant burden on the licensee.
The licensee is able to obtain a significant portion (73%) of the required volumetric coverage.
In addition, the licensee will complete the ASME B&PV Code-required 100% surface examination. These examinations should detect any existing patterns of degradation, and provide reasonable assurance of continued structural integrity of the weld. Visual examinations are also performed as part of system leakage tests. Considering the impracticality of the ASME B&PV Code volumetric coverage requirement and the extent of examinations performed, reasonable assurance of structural integrity is provided. Therefore, relief is granted for the UT coverage obtained for the subject weld in accordance with 10 CFR 50.55a(g)(6)(i) for the second 10-year ISI interval at MP3.
If the licensee is unable to obtain 73% of the examination volume on each of the subject welds, it will need to submit an additional request for relief.
3.2 RELIEF REQUEST IR-2-22 Components for Which Relief is Requested Code Class 1, Examination Category B-D, Item Number B3.130, Steam Generator Nozzle to Vessel Welds having the following identification numbers:
03-003-SW-U 04-004-SW-U 03-003-SW-V 04-004-SW-V Code Requirement A volumetric examination of essentially 100% of the weld length shall be conducted in accordance with the 1989 Edition of the ASME B&PV Code, Table IWB-2500-1.
Code Requirement from Which Relief is Requested Pursuant to 10 CFR 50.55a(g)(5)(iii) relief is requested from performing the volumetric examination on the inaccessible portions of the subject vessel weld to the extent required by the ASME B&PV Code.
Licensees Basis for Relief Geometric configurations limit the volumetric examination of the subject welds. The examinations are limited to approximately 56% coverage for the volumetric exam using the most current examination technology for each weld. Access to these welds is limited to essentially one side due to the nozzle geometry with an outside taper which precludes meaningful examination results on the nozzle side. Based on the configuration, relief is requested from complying with the 100% required examination coverage of the subject steam generator nozzle-to-vessel welds during the second 10-year (ISI) interval at MP3.
Licensees Proposed Alternate Examinations A.
The subject welds will receive a volumetric examination of the accessible areas (56%) in accordance with ASME Section XI (IWB-2500-1)
B.
MP3 will perform visual examination during system leakage tests as required by Section XI (IWB-2500-1) and Code Case N-498-1 (approved in Regulatory Guide 1.147, Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1, Revision 12, dated May 1999)
Based on the 56% UT examination coverage and monitoring and tests for leakage, the licensee believes the proposed alternative provides an acceptable level of quality and safety by providing reasonable assurance of structural integrity of the subject welds.
Evaluation The ASME B&PV Code requires 100% volumetric examination of nozzle-to-vessel welds for steam generators.
The licensee was unable to obtain the volumetric code coverage of 100% of the subject welds.
The examination for the subject weld is limited due to nozzle geometry/configuration. To gain access for 100% coverage, the component would have to be redesigned and modified. This would place a significant burden on the licensee. Therefore, the code-required 100%
volumetric examination is impractical to achieve.
The licensee is able to obtain 56% UT coverage of the subject welds. In addition, the licensee monitors and tests for leakage. Based on the volumetric examination coverage achieved, combined with the leakage monitoring and tests, the staff finds that significant degradation, if present, would be detected. As a result, reasonable assurance of structural integrity has been provided. Therefore, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i) for the second ISI interval at MP3.
If the licensee is unable to obtain 56% of the examination volume on each of the subject welds, it will need to submit an additional request for relief.
3.3 RELIEF REQUEST IR-2-23 Components for Which Relief is Requested Four Code Class 1, Examination Category B-F, Item Number B5.70, Steam Generator Nozzle-to-Pipe welds, identified as:
RCS-LP3-FW-4 RCS-LP4-FW-4 RCS-LP3-FW-5 RCS-LP4-FW-5 Code Requirement A volumetric and surface examination of essentially 100% of the weld length shall be conducted in accordance with the 1989 Edition of the ASME B&PV Code, Table IWB-2500-1.
Code Requirement from Which Relief is Requested Pursuant to 10 CFR 50.55a(g)(5)(iii), relief is requested from performing the volumetric examination on the inaccessible portions of the subject vessel welds to the extent required by the ASME B&PV Code.
Licensees Basis for Relief Geometric configuration limits the volumetric examination of the subject welds. The examinations are limited to approximately 56% coverage for the volumetric examinations using the most current examination technology. Access to these welds is limited to essentially one side due to the nozzle geometry with an outside surface taper which precludes meaningful examination results on the nozzle side. Based on the configuration, relief is requested from complying with the 100% required examination coverage of the subject welds during the second 10-year ISI interval for MP3.
Licensees Proposed Alternative Examination A.
The subject welds will receive 100% surface examination in accordance with ASME Section XI (IWB-2500-1).
B.
The subject welds will receive a volumetric examination from the accessible elbow side in accordance with ASME Section XI (IWB-2500-1)
C.
MP3 will perform visual examination during system leakage tests as required by Section XI (IWB-2500-1) and Code Case N-498-1 (approved in Regulatory Guide 1.147, Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1, Revision 12, dated May 1999)
Based on the 56% UT volumetric examinations and the 100% surface examinations to be performed on the subject dissimilar metal welds, and monitoring and tests for leakage, the licensee believes the proposed alternative provides an acceptable level of quality and safety by providing reasonable assurance of structural integrity of the subject welds.
Evaluation The ASME B&PV Code requires 100% volumetric examination of the subject dissimilar metal nozzle-to-pipe welds for the steam generators.
The staff reviewed the information submitted by the licensee. The nozzle geometry and the cast connection make volumetric examinations impractical to perform to the extent required by the ASME B&PV Code for the subject welds. To perform the required UT examination on the entire volume of the welds, the nozzles and safe ends would require design modification to sufficiently improve the geometry to allow complete UT examination. Imposition of this requirement would cause a considerable burden on the licensee. Therefore, the ASME B&PV Code-required 100% volumetric examination is impractical to achieve.
Based on the 56% UT examinations and the 100% surface examinations that are performed on the subject welds, and monitoring and tests for leakage, the staff concludes that significant degradation, if present, would be detected. Therefore reasonable assurance of structural integrity is provided. Therefore, relief is granted for the subject welds pursuant to 10 CFR 50.55a(g)(6)(i) for the second 10-year ISI interval for MP3.
If the licensee is unable to obtain 56% of the examination volume on each of the subject welds, it will need to submit an additional request for relief.
3.4 RELIEF REQUEST IR-2-24 The Components for Which Relief is Requested ASME Code Class 2, Examination Category C-B, Item Number C2.21, Steam Generator Nozzle-to-Head Weld, identified as Weld Number 03-053-SW-T Code Requirement A volumetric and surface examination of essentially 100% of the weld length shall be conducted in accordance with the 1989 Edition of the ASME B&PV Code, Table IWB-2500-1.
Code Requirement from Which Relief is Requested Pursuant to 10 CFR 50.55a(g)(5)(iii) relief is requested from performing the volumetric examination on the inaccessible portions of the subject nozzle-to-head weld to the extent required by the code.
Licensees Basis for Relief Geometric configuration and permanent obstructions limit the volumetric examination of the subject weld. The examination is limited to approximately 62% coverage for the volumetric exam using the most current examination technology. Access to this weld is limited to essentially one side due to the nozzle geometry with an outside surface taper precluding meaningful examination results. Additionally, permanent obstructions consisting of permanently mounted insulation supports for the steam generator restrict the scanning area. Based on the configuration and permanent obstructions, relief is requested from complying with the 100%
required volumetric examination coverage of this weld during the second 10-year ISI interval at MP3.
Licensees Proposed Alternative A.
The subject weld will receive 100% surface examination in accordance with ASME Section XI (IWB-2500-1).
B.
The subject weld will receive a volumetric examination of the accessible areas (approximately 62%) in accordance with ASME Section XI (IWB-2500-1).
C.
MP3 will perform visual examination during system leakage tests as required by Section XI (IWB-2500-1) and Code Case N-498-1 (approved in RG 1.147, Revision 12, dated May 1999)
Based on the 62% ultrasonic volumetric examination and the 100% surface examination performed on the subject steam generator nozzle-to-head weld, and monitoring and tests for leakage, the licensee believes that the proposed alternative provides an acceptable level of quality and safety by providing reasonable assurance of structural integrity of the subject weld.
Evaluation The ASME B&PV Code requires 100% volumetric examination of the subject steam generator nozzle-to-head weld (weld number 03-053-SW-T).
The staff reviewed the information submitted by the licensee. Geometric configuration and permanent obstructions limit the volumetric examination of the subject weld. Access to this weld is limited to essentially one side due to the nozzle geometry having an outside surface taper which precludes meaningful examination results. Additionally, permanent obstructions consisting of mounted insulation supports for the steam generator restrict the scanning area.
The licensee is able to examine approximately 62% of the required examination volume. To perform the required UT examination on the entire volume of the weld, the nozzle and the mounted insulation supports would require design modification to sufficiently improve the geometry and remove the obstructions. Imposition of this requirement would cause a considerable burden on the licensee. Therefore, the Code-required 100% volumetric examination is impractical to achieve.
Considering the 62% UT examination and the 100% surface examination that are performed on the subject welds as well as the monitoring and tests for leakage, the staff concludes that significant degradation, if present, would be detected. Therefore, reasonable assurance of structural integrity is provided. Relief is granted for the subject weld pursuant to 10 CFR 50.55a(g)(6)(i) for the second 10-year ISI interval for MP3.
If the licensee is unable to obtain 62% of the examination volume on the subject weld, it will need to submit an additional request for relief.
3.5 RELIEF REQUEST IR-2-25, Rev. 1 Components for Which Relief is Requested ASME Code Class 2, Examination Category C-F-1, Item Number C5.10, Circumferential Pipe Welds identified in Table 1.
TABLE 1 Weld Number (Configuration)
Examination Coverage Attained
(%)
CHS-31-FW-1 (pipe-to-valve)
UT 50 CHS-31-FW-3 (reducer-to-valve)
UT 37.5 CHS-31-FW-4 (pipe-to-valve)
UT 50 CHS-32-1-SW-D (pipe-to-elbow)
UT 75 CHS-32-FW-1 (pipe-to-valve)
UT 50 CHS-33-1-SW-B (pipe-to-flange)
UT 50 CHS-33-FW-1 (pipe-to-valve)
UT 50 CHS-33-FW-17 (pipe-to-flange)
UT 75 CHS-33-FW-4 (pipe-to-valve)
UT 50 SIL-157-FW-3 (pipe-to-valve)
UT 50 Notes: Weld CHS-32-1-SW-D (pipe-to-elbow) configuration would normally allow for a two-sided exam. However, the axial scan direction was limited to one side due to interference from an adjacent weld within close proximity to the subject weld.
Weld CHS-33-FW-17 (pipe-to-flange) configuration allowed for circumferential scan on both the pipe and flange side to increase the examination coverage to 75%.
Code Requirement A volumetric and surface examination of essentially 100% of the weld length shall be conducted in accordance with the 1989 Edition of the ASME B&PC, Table IWC-2500-1.
Code Requirement from Which Relief is Requested Pursuant to 10 CFR 50.55a(g)(5)(iii), relief is requested from the 100% volumetric examination coverage requirement for austenitic piping welds having single-sided access.
Basis for Relief The Final Rule to 10 CFR 50.55a published September 22, 1999, requires that if access is available, the weld shall be scanned in each of the four directions (parallel and perpendicular to the weld) where required. Coverage credit may be taken for single-sided exams on ferritic piping. However, for austenitic piping, a procedure must be qualified with flaws on the inaccessible side of the weld. There are currently no Performance Demonstration Initiative (PDI) qualified single-sided examination procedures that demonstrate equivalency to two-sided examination procedures on austenitic piping welds. Current technology is not capable of reliably detecting or sizing flaws on the far side of an austenitic weld for configurations common to United States nuclear applications.
The PDI program conforms with the Final Rule regarding single-sided access for piping. PDI Qualification Summary (PDQS) certificates for austenitic piping list the limitation that single-sided examination is performed on a best-effort basis. The best-effort qualification is provided in place of a complete single-sided qualification to demonstrate that the examiners qualification and the subsequent weld examination is based on the best available technology.
Based on the configuration of the subject circumferential pipe welds, relief is requested from complying with the 100% required examination coverage for the subject listed welds. The examination coverage listed in Table 1 is the actual coverage obtained and does not take credit for the far side of the weld.
Licensees Proposed Alternate Examinations A.
The subject weld will receive 100% surface examination in accordance with ASME Section XI (IWB-2500-1).
B.
The subject weld will receive a volumetric examination utilizing the best available techniques, as qualified through the PDI for Supplement 2 with demonstrated best effort for single-sided examination, from the accessible side of the weld.
C.
Visual examination will be performed during system leakage tests as required by Section XI (IWB-2500-1) and Code Case N-498-1 (approved in the Regulatory Guide 1.147, Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1, Revision 12, dated May 1999).
The licensee believes the proposed alternative will provide an acceptable level of quality and safety by providing reasonable assurance of structural integrity of the subject welds.
Evaluation The ASME B&PV Code requires a volumetric examination of essentially 100% of the weld length for each of the subject welds listed in Table 1.
The staff reviewed the information submitted by the licensee. Geometric configuration and permanent obstructions limit the volumetric examination of the subject welds. Access to the welds is limited to essentially one side due to component configuration and geometry which precludes meaningful examination results. The licensee is able to examine between 37.5% and 75% of the required examination volume for each of the subject welds. To perform the required UT examination on the entire volume of these welds would require design modifications to sufficiently improve the geometry and configurations. Imposition of this requirement would cause a considerable burden on the licensee. Therefore, the code-required 100% volumetric examination is impractical to achieve.
Considering the 37.5% to 75% UT examination and the 100% surface examination that are performed on the subject welds as well as monitoring and tests for leakage, the staff concludes that significant degradation, if present, would be detected. Reasonable assurance of structural integrity is provided. Therefore, relief is granted for the subject welds pursuant to 10 CFR 50.55a(g)(6)(i) for the second 10-year ISI interval for MP3.
If the licensee is unable to obtain the volumes stated in Table 1 on the subject welds, it will need to submit an additional request for relief.
3.6 RELIEF REQUEST IR-2-26, Rev. 1 The Components for Which Relief is Requested ASME Code Class 1, Examination Category B-H, B8.20, Pressurizer Support Skirt to Shell Weld, Identified as Weld Number 03-007-SW-X.
Code Requirement A surface examination of essentially 100% of the pressurizer integrally welded attachments shall be conducted in accordance with the 1989 Edition of the ASME B&PV Code, Table IWB-2500-1 as defined by Figure IWB-2500-13.
Code Requirement from Which Relief is Requested Pursuant to 10 CFR 50.55a(g)(5)(iii), relief is requested from performing the surface examination on the inaccessible portions of the pressurizer support skirt to vessel shell weld.
The inaccessible portion corresponds to the interior surface C-D as shown in Figure IWB-2500-13.
Licensees Basis for Relief Geometric configuration of the support skirt-to-shell weld limits the surface to be examined to the one accessible side, corresponding to examination surface A-B, as shown in Figure IWB-2500-13. The licensees provided sketch shows the interior portion of the subject weld to be inaccessible to a meaningful surface examination. Also, high radiation levels within the support skirt would result in an estimated personnel exposure of an additional 7.2 Rem to complete scaffolding, insulation removal/replacement, weld preparation and best-effort examination.
Based on the geometric configuration with limited access and the radiation hazards, relief is requested from complying with the 100% required surface examination coverage of this weld during the second 10-year ISI interval for MP3.
Licensees Proposed Alternative Examination A.
The subject welds will receive a surface examination of the accessible exterior weld surface A-B as shown in Figure IWB-2500-13, in accordance with ASME Section XI (IWB-2500-1).
B.
The subject weld will receive a best-effort UT examination to achieve the maximum practicable coverage of the required examination volume as depicted in figure IWB-2500-13. This examination will be performed from the outside surface of the skirt attachment.
Based on the surface examination being performed on 100% of the exterior weld surface A-B as shown in Figure IWB-2500-13, and a best-effort UT examination from the outside surface of the skirt attachment, the licensee believes the proposed alternative provides an acceptable level of quality and safety by providing reasonable assurance of structural integrity of the subject weld.
Evaluation The ASME B&PV Code requires a surface examination of both the outside and inside welded surfaces as depicted in Figure IWB-2500-13 of the ASME B&PV Code. The inside examination requires personnel entry to the area inside the skirt. To gain access to the interior skirt weld would require scaffolding, insulation removal/replacement, weld preparation, and best-effort examination in a high radiation area. The licensee estimated personnel exposure to be 7.2 Rem.
The licensee proposes an alternative to perform the Code required surface examination of the external surface in conjunction with a best-effort volumetric examination from the outside surface. The weld volume capable of being examined is through wall. Therefore, crack(s) propagating from the inside weld surface would be detectable. The staff believes that a best-effort volumetric examination, in combination with the outside surface examination of the skirt weld, will provide reasonable assurance of structural integrity and an acceptable level of quality and safety.
Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), the staff hereby authorizes the proposed alternative for the second ISI interval at MP3.
4.0 CONCLUSION
Based on the above evaluations for relief requests IR-2-21, IR-2-22, IR-2-23, IR-2-24, and IR-2-25, Rev.1, the staff concludes that the ASME B&PV Code requirements are impractical for the subject welds/components. The licensees proposed examinations provide reasonable assurance of structural integrity of the weld/component; therefore, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i) for the second 10-year inspection interval at MP3. For relief request number IR-2-26, Rev. 1, the staff concludes the licensees alternative provides an acceptable level of quality and safety. Therefore, the staff authorizes the proposed alternative pursuant to 10 CFR 50.55a(a)(3)(i) for the second 10-year inspection interval at MP3.
Principal Contributor: A. Keim Date: August 20, 2002