ML073330001
| ML073330001 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 12/18/2007 |
| From: | Hiltz T NRC/NRR/ADRO/DORL/LPLIV |
| To: | Parrish J Energy Northwest |
| Lyon C Fred, NRR/DORL/LPL4, 301-415-2296 | |
| References | |
| TAC MD3905 | |
| Download: ML073330001 (13) | |
Text
December 18, 2007 Mr. J. V. Parrish Chief Executive Officer Energy Northwest P.O. Box 968 (Mail Drop 1023)
Richland, WA 99352-0968
SUBJECT:
COLUMBIA GENERATING STATION - REQUEST FOR RELIEF NO. 2ISI-32 FOR THE SECOND 10-YEAR INSERVICE INSPECTION PROGRAM INTERVAL (TAC NO. MD3905)
Dear Mr. Parrish:
By letter dated December 14, 2006, as supplemented by letters dated July 30 and October 2, 2007, Energy Northwest (the licensee) submitted request for relief, 2ISI-32, from certain requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code), for the second 10-year inservice inspection (ISI) program interval at Columbia Generating Station (CGS). Specifically, the licensee requested relief from ASME Code volumetric examination requirements for selected welds with less than essentially 100 percent coverage. The ASME Code for the second 10-year ISI program interval at CGS is the 1989 Edition with no Addenda. The second 10-year ISI program interval at CGS began on February 10, 1995, and ended on December 12, 2005.
The licensees request was arranged by component and numbered from 2ISI-32-1 through 2ISI-32-21. Based on the information provided in the relief request, the NRC staff concluded that requests for relief 2ISI-32-1 through 2ISI-32-20 were acceptable. The licensee withdrew request 2ISI-32-21 by its letter dated July 30, 2007.
For relief requests 2ISI-32-1 through 2ISI-32-20, relief is granted based on the determination that it is impractical for the licensee to comply with the specified requirement. Granting relief pursuant to paragraph 50.55a(g)(6)(i) of Title 10 of the Code of Federal Regulations (10 CFR) is authorized by law and will not endanger life or property or the common defense and security, and is otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility. The licensees proposed alternative provides reasonable assurance of the structural integrity of the components.
The above relief requests are applicable to the second 10-year ISI program interval for CGS.
All other ASME Code,Section XI, requirements for which relief was not specifically requested and approved in this relief request remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
J. V. Parrish The detailed results of the NRC staffs review are provided in the enclosed safety evaluation. If you have any questions concerning this matter, please call Mr. F. Lyon of my staff at (301) 415-2296.
Sincerely,
/RA/
Thomas G. Hiltz, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-397
Enclosure:
Safety Evaluation cc w/encl: See next page
J. V. Parrish The detailed results of the NRC staffs review are provided in the enclosed safety evaluation. If you have any questions concerning this matter, please call Mr. F. Lyon of my staff at (301) 415-2296.
Sincerely,
/RA/
Thomas G. Hiltz, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-397
Enclosure:
Safety Evaluation cc w/encl: See next page DISTRIBUTION:
PUBLIC LPLIV Reading RidsAcrsAcnwMailCenter RidsNrrDciCpnb RidsNrrDorlLpl4 RidsNrrLAJBurkhardt RidsNrrPMFLyon RidsOgcRp RidsRgn4MailCenter DPelton, EDO RIV DNaujock, NRR/DCI/CPNB ADAMS Accession No.: ML073330001
- memo dated 11/26/07 OFFICE DORL/LPL4/PM DORL/LPL4/LA DCI/CPNB/BC OGC DORL/LPL4/BC NAME FLyon JBurkhardt TChan*
MLoftus THiltz DATE 12/4/07 12/3/07 11/26/07 12/17/07**
12/18/07 OFFICIAL AGENCY RECORD
November 2007 Columbia Generating Station cc:
Chairman Energy Facility Site Evaluation Council P.O. Box 43172 Olympia, WA 98504-3172 Mr. Gregory V. Cullen Manager, Regulatory Programs Energy Northwest Mail Drop PE20 P.O. Box 968 Richland, WA 99352-0968 Chairman Benton County Board of Commissioners P.O. Box 190 Prosser, WA 99350-0190 Mr. William A. Horin, Esq.
Winston & Strawn 1700 K Street, N.W.
Washington, DC 20006-3817 Mr. Matt Steuerwalt Executive Policy Division Office of the Governor P.O. Box 43113 Olympia, WA 98504-3113 Ms. Lynn Albin Washington State Department of Health P.O. Box 7827 Olympia, WA 98504-7827 Technical Services Branch Chief FEMA Region X 130 - 228th Street, SW Bothell, WA 98021-9796 Mr. Mike Hammond Department of Homeland Security FEMA/REP 130 - 228th Street SW Bothell, WA 98021-9796 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-4005 Senior Resident Inspector U.S. Nuclear Regulatory Commission P.O. Box 69 Richland, WA 99352-0069 Mr. Ken Niles Assistant Director Oregon Department of Energy 625 Marion Street NE Salem, OR 97301-3727 Special Hazards Program Manager Washington Emergency Management Div.
127 W. Clark Street Pasco, WA 99301
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SECOND 10-YEAR INSERVICE INSPECTION PROGRAM INTERVAL REQUEST FOR RELIEF NO. 2ISI-32 ENERGY NORTHWEST COLUMBIA GENERATING STATION DOCKET NO. 50-397
1.0 INTRODUCTION
By letter dated December 14, 2006 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML063620147), as supplemented by letters dated July 30, and October 2, 2007 (ADAMS Accession Nos. ML072190587 and ML072840053, respectively),
Energy Northwest (the licensee) submitted request for relief 2ISI-32, from certain examination requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code), for the second 10-year inservice inspection (ISI) program interval at Columbia Generating Station (CGS). The licensees request was arranged by component and numbered from 2ISI-32-1 through 2ISI-32-21. Specifically, the licensee requested relief from ASME Code volumetric examination requirements for selected welds with less than essentially 100 percent coverage at CGS. The ASME Code for the second 10-year ISI program interval at CGS is the 1989 Edition with no Addenda. The second 10-year ISI program interval at CGS began on February 10, 1995, and ended on December 12, 2005.
By its letter dated July 30, 2007, the licensee withdrew relief request 2ISI-32-21.
The U.S. Nuclear Regulatory Commission (NRC) staffs evaluation for each relief request and status of approval is discussed below.
2.0 REGULATORY REQUIREMENTS Title 10 of the Code of Federal Regulations (10 CFR), Section 50.55a(g) sets forth the inservice inspection (ISI) requirements for boiling and pressurized water-cooled nuclear power facilities.
In particular, 10 CFR 50.55a(g)(4), mandates that ASME Code Class 1, 2, and 3 components (including supports) meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in the ASME Code,Section XI, to the extent practical within the limitations of design, geometry, and materials of construction of the components. Thereafter, 10 CFR 50.55a(g)(4)(i) requires that ISI 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 Code, which was 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. The ASME Code of record for CGSs second 10-year interval ISI program, which began on February 10, 1995, is the 1989 Edition of Section XI of the ASME Code, with no addenda.
ISI of the ASME Code Class 1, 2, and 3 components is to be performed in accordance with Section XI of the ASME Code, and applicable addenda, as required by 10 CFR 50.55a(g). The regulation at 10 CFR 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if the licensee 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.
10 CFR 50.55a(g)(5)(i) requires that the ISI program for a boiling or pressurized water-cooled nuclear power facility be revised by the licensee, as necessary to comply with 10 CFR 50.55a(g)(4). However, if the licensee determines that conformance with certain code requirements is impractical for its facility, 10 CFR 50.55a(5)(iii) requires the licensee shall notify the Commission and submit information to support the determinations. Determinations provided pursuant to 10 CFR 50.55a(g)(5) are evaluated by the Commission under 10 CFR 50.55a(g)(6) and may be granted if the Commission finds that the relief request is authorized by law and will not endanger life or property or the common defense and security and is otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the requirements were imposed upon the facility.
3.0 EVALUATION The information provided by the licensee in support of the request for relief from ASME Code requirements has been evaluated and the basis for disposition is documented below. For clarity, the request has been evaluated in several parts according to ASME Code,Section XI, Table IWB-2500-1 or Table IWC-2500-1.
3.1 Request for Relief 2ISI-32-1 and -2, Examination Category B-D, Item B3.90, Full Penetration Welded Nozzles in Vessels 3.1.1 ASME Code Requirement Examination Category B-D, Item B3.90, requires 100 percent volumetric examination, as defined by Figures IWB-2500-7(a) through (d), as applicable, of Class 1 nozzle-to-vessel welds on the reactor pressure vessel (RPV). The required examination volume includes the full weld and adjacent base material for a distance equal to one-half of the vessel wall thickness. ASME Code Case N-460, "Alternative Examination Coverage for Class 1 and Class 2 Welds," an alternative approved for use by the NRC in Regulatory Guide (RG) 1.147, Revision 14, "Inservice Inspection Code Case Acceptability," states that a reduction in examination coverage due to part geometry or interference for any Class 1 and Class 2 weld is acceptable provided that the reduction is less than 10 percent, i.e., greater than 90 percent examination coverage.
3.1.2 Licensees ASME Code Relief Request In accordance with 10 CFR 50.55a(g)(5)(iii), the licensee requested relief from the ASME Code-required 100 percent volumetric examination of the Class 1 nozzle-to-shell weld on RPV head Nozzles N7 and N18.
3.1.3 Licensees Basis for Relief Request The basis for the impracticality for compliance is that only 88 percent examination coverage of Weld N7 was obtainable due to the configuration of the nozzle-to-vessel weld design. Full code examination volume was obtained in both axial directions and one circumferential direction.
The other circumferential direction scan was limited by the nozzle radius configuration.
The basis for the impracticality for compliance of Weld N18 was due to the configuration of the nozzle-to-vessel weld design. The licensee recalculated the examination composite coverage of nozzle-to-vessel weld N18 using the examination volume of Figure IWB-2500-7(b) of the 1989 Edition of ASME Code,Section XI. The total composite coverage was determined to be 63 percent. Full examination volume was obtained in both axial directions and one circumferential direction. The other circumferential direction scan was limited by the nozzle radius configuration.
A significant volume of the N7 and N18 nozzle welds and base material were examined to provide reasonable assurance that any service-induced flaws would be detected. The weld volumes were interrogated using 0, 45, 60, and 70 refracted longitudinal (RL) transducers. The ultrasonic technique was performed in accordance with ASME Section Xl, Appendix VIII, as modified by 10 CFR 50.55a and Relief Request 2ISI-24, which was approved by letter from S. Dembeck (NRC) to J. Parrish (licensee) dated April 25, 2001 (ADAMS Accession No. ML011150323). No indications were detected in the base material or welds. The results of all 33 Category B-D weld examinations performed during the second ISI interval have been reviewed. There were no unacceptable flaws identified by these examinations.
3.1.4 Licensees Proposed Alternative Examination (as stated)
The proposed alternative is to examine the weld to achieve at least 88 percent and 63 percent examination coverage, respectively for N7 and N18. A significant volume of the weld and base material was examined to provide reasonable assurance that any service induced flaws would be detected. The weld volume was interrogated using 0, 45 and 60 shear wave transducers and 70 degree RL transducers. The examinations applied the current knowledge and techniques available to obtain the maximum amount of coverage to the extent practical within the limitations of design, geometry, and materials of construction of the component. No indications were detected in the base material nor weld.
3.1.5 Staff Evaluation The ASME Code requires 100 percent volumetric examination of the subject Class 1 RPV nozzle-to-vessel welds. However, complete examination is restricted by the geometric configuration of the nozzle. This condition makes 100 percent volumetric examination 1 Sketches and technical descriptions provided by the licensee are not included in this report.
impractical to perform for nozzle-to-vessel welds at Nozzles N7 and N18. To obtain full ASME Code examination coverage, the RPV head-to-nozzle configurations would require design modifications. Imposing this requirement would create a burden on the licensee; therefore, the ASME Code-required 100 percent volumetric examination is impractical.
As shown on the sketches and technical descriptions1 included in the licensees submittal, examination of the subject nozzle-to-vessel welds was performed to the extent practical, with the licensee obtaining volumetric coverage of approximately 88 percent and 63 percent, respectively, for the subject welds at Nozzles N7 and N18. The transition area of the nozzle forgings on the uphill side of the RPV head does not allow for adequate placement of transducers on the nozzle side of the weld to examine the full volume including adjacent base material equal to one-half of the thickness of the head, as required by the ASME Code. No ultrasonic indications were detected during the performance of ultrasonic testing (UT) on these welds. In addition, the licensee examined all 33 Examination Category B-D welds during the second ISI interval, and no unacceptable flaws were noted during these examinations.
The licensee has shown that it is impractical to meet the ASME Code-required 100 percent volumetric examination coverage for the subject welds due to the design configuration which limits scanning from the nozzle side in the uphill transition area. Based on the volumetric coverages obtained during the examinations, in conjunction with the examinations performed on the remainder of the RPV nozzle welds, the staff concludes that if significant service-induced degradation occurred in the subject welds, there is reasonable assurance that evidence of it would be detected by the examinations that were performed.
3.2 Request for Relief 2ISI-32-3, -4, and -5, Examination Category B-F, Item B5.130, Pressure Retaining Dissimilar Metal Welds 3.2.1 ASME Code Requirement Examination Category B-F, Item B5.130, requires 100 percent surface and volumetric examination, as defined by Figure IWB-2500-8, of Class 1 circumferential dissimilar metal butt welds in piping equal to or greater than 4-inch nominal pipe size (NPS) in diameter. ASME Code Case N-460, "Alternative Examination Coverage for Class 1 and Class 2 Welds," as an alternative approved for use by the NRC in RG 1.147, Revision 14, "Inservice Inspection Code Case Acceptability," states that a reduction in examination coverage due to part geometry or interference for any Class 1 and 2 weld is acceptable provided that the reduction is less than 10 percent, i.e., greater than 90 percent examination coverage.
3.2.2 Licensees ASME Code Relief Request In accordance with 10 CFR 50.55a(g)(5)(iii), the licensee requested relief from the ASME Code-required 100 percent volumetric examination for Class 1 dissimilar metal piping butt welds 10HPCS(1)-3, 12RHR(1)A-14, and 12RHR(1)B-10.
2 The licensees table is not included in this report.
3 The licensees drawing is not included in this report.
3.2.3 Licensees Basis for Relief Request (as stated)
The reason the examination was limited for 10HPCS(1)-3 was the configuration of the safe end which does not allow full code coverage from the safe end side. The reason the examination was limited for welds 12RHR(1)A-14 and 12RHR(1)B-10 is the configuration of the safe end and valve body did not allow full coverage scanning from both the safe end and valve side.
3.2.4 Licensees Proposed Alternative Examination (as stated)
The proposed alternative is to examine the welds to achieve at least the examination coverage identified in Table 22, Column 3 for each weld. The examinations applied all the current knowledge and techniques to obtain the maximum amount of coverage to the extent practical within the limitations of design, geometry and materials of construction of the component. The entire weld population Code Category B-F was examined. Of the forty three (43) ASME Code Category B-F welds, the three welds listed in Table 2 were the only ones where essentially 100 percent code coverage was not obtained. This represents a significant total volume of welds examined in this category. No indications were detected in the base material nor welds for all the volume examined in this category.
3.2.5 Response to Request for Additional Information (as stated)
All subject weld configurations at CGS are included in the mock-up sets and procedure scope, and are part of the Performance Demonstration Initiative (PDI) for Appendix VIII, Supplement 10 qualifications.
3.2.6 Staff Evaluation The ASME Code requires 100 percent volumetric and surface examination of all Class 1 dissimilar metal piping welds. In addition, the ASME Code requires that the volumetric examination be conducted from both sides of these pressure retaining circumferential welds.
However, the geometric configurations of the subject welds limit ultrasonic scanning from both sides of the weld. For the licensee to achieve 100 percent volumetric coverage, the subject welds would have to be redesigned and modified. This would place a significant burden on the licensee, thus the ASME Code-required 100 percent volumetric examinations are impractical.
Weld 10HPCS(1)-3 is a circumferential butt weld joining an Alloy 600 safe-end to an SA-508 wrought carbon steel safe-end extension. As shown by the drawing3 in the licensees submittal, the Alloy 600 safe-end has a slight transition adjacent to the weld which limits scanning from the safe-end side. The weld was examined with 45-degree shear waves and 45-and 60-degree refracted longitudinal waves, which resulted in approximately 85 percent of the ASME Code-required volume.
Welds 12RHR(1)A-14 and 12RHR(1)B-10 are circumferential welds joining stainless steel safe-end or transition pieces to SA-350 carbon steel valves. The valve bodies restrict scanning due to the steep transition adjacent to the subject welds. Because of the extreme valve body transition, ultrasonic scans are limited to the safe-end or transition piece only, which resulted in the licensee obtaining approximately 26 and 29 percent, respectively, for the subject welds.
However, the licensee examined all 43 Examination Category B-F dissimilar metal welds during the second ISI interval, with greater than 90 percent ASME Code coverage being achieved on 38 of these welds. Considering the impracticality due to the outside surface geometry of the subject welds and the ASME Code coverage obtained on other Class 1 dissimilar metal welds, the staff concludes that if significant service-induced degradation occurred in the subject welds, there is reasonable assurance that evidence of it would be detected by the examinations that were performed.
3.3 Requests for Relief 2ISI-32-6 through -20, Examination Category B-J, Item B9.11, Pressure Retaining Welds in Piping 3.3.1 ASME Code Requirement Examination Category B-J, Item B9.11, requires essentially 100 percent surface and volumetric examination, as defined by Figure IWB-2500-8, of the length of Class 1 circumferential butt welds for piping equal to or greater than 4-inch NPS in diameter. Essentially 100 percent, as clarified by ASME Code Case N-460, "Alternative Examination Coverage for Class 1 and Class 2 Welds," is greater than 90 percent coverage of the examination volume, or surface area, as applicable. ASME Code Case N-460 has been approved for use by the NRC in RG 1.147, Revision 14, "Inservice Inspection Code Case Acceptability."
3.3.2 Licensees ASME Code Relief Request In accordance with 10 CFR 50.55a(g)(5)(iii), the licensee requested relief from the ASME Code-required volumetric examination coverage requirements for circumferential piping welds shown in Table 3.3.1.
Table 3.3.1 Examination Category B-J Requests for Relief Weld ID Coverage Weld Type Cause of Limitation 6RCIC(1)-40 86%
Pipe-to-valve Support attachment weld 24RRC(1)A-14 50%
Pipe-to-valve Valve body configuration 24RRC(1)A-15 50%
Valve-to-pipe Valve body configuration 24RRC(1)A-18 50%
Pipe-to-valve Valve body configuration 24RRC(1)A-19 50%
Valve-to-elbow Valve body configuration 24RRC(1)B-12 50%
Pipe-to-valve Valve body configuration 24RRC(1)B-16 50%
Pipe-to-valve Valve body configuration 24RRC(1)B-17 50%
Valve-to-elbow Valve body configuration Table 3.3.1 Examination Category B-J Requests for Relief Weld ID Coverage Weld Type Cause of Limitation 24RRC(2)A-10 50%
Valve-to-pipe Valve body configuration 24RRC(2)B-8 50%
Valve-to-pipe Valve body configuration 24RRC(2)B-10 50%
Elbow-to-pump Pump body configuration 24RRC(2)B-11/8CAP-1 50%
Cap-to-sweep-o-let Sweep-o-let configuration 24RRC(2)B-11/4RRC(4)-4S 50%
Pipe-to-sweep-o-let Sweep-o-let configuration 24RRC(2)B-8/4RRC(8)-4S 50%
Pipe-to-sweep-o-let Sweep-o-let configuration 24RRC(2)B-8/4RRC(4)-4S 50%
Pipe-to-sweep-o-let Sweep-o-let configuration 3.3.3 Licensees Basis for Relief Request For [Weld] 6RCIC(1)-40, the reason the examination was limited for the weld listed above is that the support attachment welded to the pipe did not allow full coverage scanning from the attachment side.
For 24RRC(1)A-14, 24RRC(1)A-15, 24RRC(1)A-18, 24RRC(1)B-12, 24RRC(1)B-16, 24RRC(2)A-10, 24RRC(2)B-8, 24RRC(1)B-17, and 24RRC(1)A-19, the reason the examination was limited for the welds listed above is that the configuration of the valve body did not allow full coverage scanning from the valve side.
For 24RRC(2)B-10, the reason the examination was limited for the above weld is that the configuration of the pump body did not allow full coverage scanning from the pump side.
For 24RRC(2)B-8/4RRC(8)-4S, 24RRC(2)B-8/4RRC(4)-4S, 24RRC(2)B-11/8CAP-1, and 24RRC(2)B-11/4RRC(4)-4S, the reason the examination was limited for the above welds is that the configuration of the sweep-o-let did not allow full coverage scanning from the sweep-o-let side.
3.3.4 Licensees Proposed Alternative Examination (as stated)
The proposed alternative is to examine the welds to achieve at least the examination coverage identified in Table 3.3.1 above for each weld. The examinations performed applied all the current knowledge and techniques to obtain the maximum amount of coverage to the extent practical within the limitations of design, geometry and materials of construction of the component. No indications were detected in the base material nor welds.
3.3.5 Staff Evaluation The ASME Code requires 100 percent volumetric and surface examination of selected Class 1 circumferential piping welds. In addition, the ASME Code requires that the volumetric examination be conducted from both sides of these pressure retaining welds. However, the geometric configurations of the subject welds limit ultrasonic scanning from both sides of the weld. For the licensee to achieve 100 percent volumetric coverage, the subject welds would have to be redesigned and modified. This would place a significant burden on the licensee, thus the ASME Code-required 100 percent volumetric examinations are impractical.
The licensee has determined that certain CGS welds had ultrasonic examination coverage limitations of less than 100 percent of the ASME Code-required weld and adjacent material volumes. The limitations encountered during the performance of the ultrasonic examinations on the subject welds were caused by various component configurations (see Table 3.3.1 above).
In addition, a rule change in 10 CFR 50.55a(b)(2)(xv)(A)(2) restricts taking credit for "single-sided" examinations without qualifying a "single-sided" ASME Code,Section XI, Appendix VIII, performance demonstration procedure, using flaws located on the opposite side of the weld. Because of the examination limitations, and rule change in the regulations, the licensee was only allowed to credit the examination coverages for the subject welds to 50 percent of the ASME Code-required volume(s). The examination coverages attained for the subject welds found no degradation in the examined area.
Previous ultrasonic examinations on the subject welds were conducted using the prescriptive requirements of the ASME Code,Section XI, Appendix III. Under these requirements, the examination coverage attained for each weld was approximately 100 percent from one side, with no degradation found in the examined areas.
Though previous and current UT examination scan paths and angles are similar, the current coverage requirements are based on using a procedure qualified to ASME Code,Section XI, Appendix VIII, Supplements 2 and 3. At the time of the examinations, no qualified procedure existed for single-side austenitic welds. Paragraph 50.55a(b)(2)(xv) of 10 CFR requires that if access is available, the weld shall be scanned in each of the four directions (parallel and perpendicular to the weld on each side of the weld centerline). Coverage credit may be taken for single side examinations on austenitic piping if a procedure is qualified with flaws on the inaccessible side of the weld. This procedure must demonstrate single-side access examination equivalency to "two-sided" examinations. Qualifications conducted by the industrys Performance Demonstration Initiative (PDI) at the Electric Power Research Institute (EPRI) NDE [Nondestructive Examination] Center do not currently meet the requirements of 10 CFR 50.55a(b)(2)(xv). Instead of a full single-side qualification, the EPRI PDI offers a best-effort approach, intended to demonstrate that the best available technology and ultrasonic methods are applied. Hence, the examinations conducted by the licensee represent this best-effort approach.
Although only 50 percent of the ASME Code-required coverage could be credited for the majority of these welds, the licensee applied both 45 and 60 degree shear and refracted longitudinal wave ultrasonic methods from the accessible pipe side of these welds. These methods would have provided limited volumetric coverage for the weld fusion zone and base materials on the opposite side of the welds. Given the weld configurations encountered, it is concluded that the ASME Code-required weld and base material volumes were examined to the maximum extent practical.
Current and previous examinations on the subject welds found no recordable indications or degradation in the examined areas. Further, it is reasonable to conclude that if significant degradation were present, it would be detected by the examinations that were performed.
3.4 Request for Relief 2ISI-32-21, Examination Category C-F-2, Item C5.51, Pressure Retaining Welds in Carbon or Low Alloy Steel Piping The licensee determined that a sufficient number of welds have been examined to meet ASME Code requirements for the second ISI interval; therefore, Request for Relief 2ISI-32-21 was withdrawn by its letter dated July 30, 2007.
4.0 CONCLUSION
S Based on the above review, the NRC staff concludes that compliance with ASME Code examination coverage requirements are impractical for the subject components listed in Requests for Relief 2ISI-32-1 through -20. Further, if significant service-induced degradation were to occur, there is reasonable assurance that evidence of it would have been detected by the alternative examinations performed by the licensee. Therefore, requests for relief 2ISI-32-1 through -20 are granted pursuant to 10 CFR 50.55a(g)(6)(i) for the second 10-year ISI interval at CGS. The granting of relief is authorized by law and will not endanger life, property, or the common defense and security and is otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.
Although this request for relief is granted, the relief granted is retroactive for CGSs second 10-year interval ISI program, which ended on December 12, 2005. Moreover, the licensee should note that 10 CFR 50.55a(g)(5)(iv) requires the basis for the relief determination to be, "demonstrated to the satisfaction of the Commission not later than 12 months after the expiration of...each subsequent 120-month period of operation during which the examination is determined to be impractical." Thus, any future requests for relief pursuant to 10 CFR 50.55a(g)(5)(iv) must, at a minimum, be filed before the expiration of 12 months following the 120-month period of operation.
All other ASME Code,Section XI, requirements for which relief was not specifically requested and approved in this relief request remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
Principal Contributor: D. Naujock Date: December 18, 2007