ML043620233
| ML043620233 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 03/29/2005 |
| From: | Gramm R NRC/NRR/DLPM/LPD4 |
| To: | Overbeck G Arizona Public Service Co |
| Fields M B, NRR/DLPM, 415-3062 | |
| References | |
| TAC MC4486, TAC MC4487, TAC MC4488 | |
| Download: ML043620233 (9) | |
Text
March 29, 2005 Mr. Gregg R. Overbeck Senior Vice President, Nuclear Arizona Public Service Company P. O. Box 52034 Phoenix, AZ 85072-2034
SUBJECT:
PALO VERDE NUCLEAR GENERATING STATION, UNITS 1, 2, AND 3 -
RELIEF REQUEST NO. 27 RE: QUALIFICATION REQUIREMENTS FOR INSIDE SURFACE EXAMINATION OF PRESSURE RETAINING PIPING WELDS (TAC NOS. MC4486, MC4487, AND MC4488)
Dear Mr. Overbeck:
By letter dated September 14, 2004, Arizona Public Service Company submitted Relief Request No. 27, for the Palo Verde Nuclear Generating Station (Palo Verde), Units 1, 2, and 3, requesting Nuclear Regulatory Commission (NRC) approval of an alternative to American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) requirements for inspection of pressure retaining welds.
The ASME Code,Section XI, 1995 Edition, 1996 Addenda, Appendix VIII, Supplement 3, requires qualification of procedures, personnel, and equipment for examination of inside surface examination of Class 1 of Category B-J, pressure retaining piping welds. In lieu of these requirements, Relief Request No. 27 requests the use of a technical alternative developed by the Performance Demonstration Initiative (PDI) for qualification requirements for pressure retaining piping welds, as coordinated with the proposed alternative for Supplement 10 implementation program to ASME Code, Appendix VIII.
Based on the enclosed Safety Evaluation, the NRC staff concludes that the proposed alternative to use PDI developed alternative qualifications for pressure retaining piping welds, in lieu of existing Code requirements under ASME Code,Section XI, Appendix VIII, Supplements 10 and 3, provides an acceptable level of quality and safety. Therefore,
pursuant to 50.55a(a)(3)(i) of Title 10 of the Code of Federal Regulations, the NRC staff authorizes the proposed alternative at Palo Verde, Units 1, 2, and 3 for the second 10-year inservice inspection interval. All other requirements of the ASME Code, Sections III and XI for which relief has not been specifically requested and approved remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.
Sincerely,
/RA/
Robert A. Gramm, Chief, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. STN 50-528, STN 50-529 and STN 50-530
Enclosure:
Safety Evaluation cc w/encl: See next page
pursuant to 50.55a(a)(3)(i) of Title 10 of the Code of Federal Regulations, the NRC staff authorizes the proposed alternative at Palo Verde, Units 1, 2, and 3 for the second 10-year inservice inspection interval. All other requirements of the ASME Code, Sections III and XI for which relief has not been specifically requested and approved remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.
Sincerely,
/RA/
Robert A. Gramm, Chief, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. STN 50-528, STN 50-529 and STN 50-530
Enclosure:
Safety Evaluation cc w/encl: See next page DISTRIBUTION:
PUBLIC RidsNrrPMMFields GHill (6)
PDIV-2 r/f RidsNrrLADBaxley TChan RidsNrrDlpmLpdiv (HBerkow) RidsOgcRp RidsNrrDlpmDpr RidsNrrDlpm Lpdiv2 (RGramm) RidsAcrsAcnwMailCenter JDixon-Herrity, EDO RidsRgn4MailCenter (TPruett)
ACCESSION NO: ML043620233 NRR-028 OFFICE PDIV-1/PE PDIV-2/PM PDIV-1/LA EMCB OGC Nlo PDIV-2/SC NAME MThorpe- MFields DBaxley TChan NWildermann RGramm Kavanaugh w/comments DATE 01/12/05 03/29/05 01/12/05 03/17/05 03/28/05 03/29/05 OFFICIAL RECORD COPY
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION INSERVICE INSPECTION PROGRAM RELIEF REQUEST NO. 27 ARIZONA PUBLIC SERVICE COMPANY, ET AL.
PALO VERDE NUCLEAR GENERATING STATION, UNITS 1, 2, AND 3 DOCKET NOS. STN 50-528, STN 50-529, AND STN 50-530
1.0 INTRODUCTION
By letter dated September 14, 2004, Arizona Public Service Company (APS or the licensee) submitted Relief Request No. 27 for the Palo Verde Nuclear Generating Station (Palo Verde),
Units 1, 2, and 3 requesting NRC approval of an alternative to an American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) requirements for inspection of Class 1 pressure retaining piping welds. The ASME Code,Section XI, 1995 Edition, 1996 Addenda, Appendix VIII, Supplement 3, requires qualification of procedures, personnel, and equipment for examination of inside surface examination of Class 1 of Category B-J, pressure retaining piping welds. In lieu of these requirements, Relief Request No. 27 requests the use of a technical alternative developed by the Performance Demonstration Initiative (PDI) for qualification requirements for pressure retaining piping welds, as coordinated with the proposed alternative for supplement 10 implementation program to ASME Code, Appendix VIII.
2.0 REGULATORY REQUIREMENTS The inservice inspection (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 edition and addenda as required by 50.55a(g) of Title 10 of the Code of Federal Regulations (10 CFR),
except where specific written relief has been granted by the NRC pursuant to 10 CFR 50.55a(g)(6)(i). The regulation at 10 CFR 50.55a(a)(3) states in part 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.
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 (ISI) 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 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. The ISI Code of record for the second 10-year interval for Palo Verde, Units 1, 2, and 3 is the 1992 Edition, 1992 Addenda of Section XI of the ASME Code. The components (including supports) may meet the requirements set forth in subsequent editions and addenda of the ASME Code incorporated by reference in 10 CFR 50.55a(b) subject to the limitations and modifications listed therein and subject to Commission approval.
3.0 LICENSEE&S BASIS FOR PROPOSED ALTERNATIVE 3.1 Component for Which Relief is Requested:
ASME Code,Section XI,1992 Edition, Addenda 1992, Class 1, Category B-J, Item Numbers B9.11 and B9.12, Pressure Retaining Piping Welds ultrasonically examined from the inside surface of Pressurized Water Reactors using procedures, personnel, and equipment qualified to ASME Section XI, 1995 Edition, 1996 Addenda, Appendix VIII, Supplement 3 criteria.
3.2 Code Requirement:
Table VIII-3110-1 of Appendix VIII to ASME Section XI, 1995 Edition, 1996 Addenda, Supplement 3 criteria apply.
3.3 Licensees Proposed Alternative:
The licensee proposes to use the alternative program discussed below for implementation of Appendix VIII, Supplement 3, as coordinated with the proposed alternative for the Supplement 10 implementation program. The PDI Program alternative is described in the submittal. The licensee stated the PDI will administer the alternative program.
3.4 Licensees Basis for Relief (As Stated):
Depending upon the particular design, the nozzle to main coolant piping may be fabricated using ferritic, austenitic, or cast stainless components and assembled using ferritic, austenitic, or dissimilar metal welds. Additionally, differing combinations of these assemblies may be in close proximity, which typically means the same ultrasonic essential variables are used for each weld and the most challenging ultrasonic examination process is employed (e.g., the ultrasonic examination process associated with a dissimilar metal weld would be applied to a ferritic or austenitic weld). Palo Verde Units 1, 2, & 3 are Combustion Engineering (CE) designed plants, and the piping and welds connected to the reactor vessel are ferritic material with stainless steel clad. A list and sketch for which relief is requested has been provided in Attachment 1 to this request [dated September 14, 2004].
Separate qualifications to Supplements 2, 3, and 10 are redundant when done in accordance with the PDI Program. For example, during a personnel qualification to the PDI Program, the candidate would be exposed to a minimum of 10 flawed grading units for each individual supplement. Personnel qualification to Supplements 2, 3, and 10 would therefore require a total of 30 flawed grading
units. Test sets this large and tests of this duration are impractical. Additionally, a full procedure qualification (i.e. 3 personnel qualifications) to the PDI Program requirements would require 90 flawed grading units. This is particularly burdensome for a procedure that will use the same essential variables or the same criteria for selecting essential variables for all 3 supplements.
To resolve these issues, the PDI Program recognizes the Supplement 10 qualification as the most stringent and technically challenging ultrasonic application. The essential variables used for the examination of Supplements 2, 3, and 10 are equivalent and a coordinated implementation would be sufficiently stringent to qualify all 3 Supplements if the requirements used to qualify Supplement 10 are satisfied as a prerequisite. The basis for this conclusion is the fact that the majority of the flaws in Supplement 10 are located wholly in austenitic weld material, which is known to be challenging for ultrasonic techniques due to the variable dendritic structure of the weld material. Flaws in Supplements 2 and 3 are located in fine-grained base materials, which are known to be less challenging.
Additionally, the proposed alternative is more stringent than current Code requirements for a detection and length sizing qualification. For example, the current Code would allow a detection procedure, personnel, and equipment to be qualified to Supplement 10 with 5 flaws, Supplement 2 with 5 flaws, and Supplement 3 with 5 flaws, a total of only 15 flaws. The proposed alternative of qualifying Supplement 10 using 10 flaws and adding on Supplement 2 with 5 flaws and Supplement 3 with 3 flaws results in a total of 18 flaws which will be multiplied by a factor of 3 for the procedure qualification.
Based on the above, the use of a limited number of Supplement 2 or 3 flaws is sufficient to access the capabilities of procedures and personnel who have already satisfied Supplement 10 requirements. The statistical basis used for screening personnel and procedures is still maintained at the same level with competent personnel being successful and less skilled personnel being unsuccessful. The proposed alternative is consistent with other coordinated qualifications currently contained in ASME Section XI, Appendix VIII.
The proposed PDI alternate program is provided in Attachment 2 [to the licensees September 14, 2004, submittal]. It has been submitted to the ASME Code Committee for consideration as new Supplement 14 to ASME Section XI, Appendix VIII.
4.0 NRC STAFF EVALUATION The licensee proposes an alternative to the qualification requirements of ASME Section XI, Appendix VIII, Supplement 3 criteria. The Code currently requires separate qualifications for Supplement 2 for austenitic piping, Supplement 3 for ferritic piping, and Supplement 10 for austenitic-to-ferritic piping. Qualifications for each supplement would require a minimum of 10 flaws each for a total of 30 flaws minimum. The minimum number of required flaws establishes a statistical-based pass/fail objective for each supplement. However, using
separate qualification processes for each supplement, when performed together, would unnecessarily expand the number of ferritic and austenitic flaws required to be identified.
The ASME Code recognizes that flaws in austenitic material are more difficult to detect and size than flaws in ferritic material. In addition, Supplement 12 of the ASME Code established a precedent for implementing Supplement 3 as an add-on to a Supplement 2 qualification in lieu of separate Supplements 2 and 3 qualifications. This add-on consists of a minimum of 3 flaws in ferritic material. A statistical evaluation of this approach and Supplement 12's acceptance criteria satisfies the pass/fail objective established for Appendix VIII performance demonstration acceptance criteria.
The licensees proposed alternative builds upon the precedent and experiences of Supplement 12 by starting with the most challenging Supplement 10 qualifications, as implemented by the PDI Program (PDI Supplement 10), and adding a sufficient number of flaws to demonstrate the personnel skills and procedure effectiveness of the less challenging Supplement 3 qualifications. A PDI Supplement 10 performance demonstration has at least 1 flaw with a maximum of 10 percent of the total number of flaws being in the ferritic material. The rest of the flaws are in the more challenging austenitic material due to the variable dendritic structure of the weld material. When expanding the PDI Supplement 10 qualification to include Supplement 3, the proposed alternative would add a minimum of 3 flaws in ferritic material to the performance demonstration. The performance demonstration results added to the appropriate PDI Supplement 10 results must satisfy the acceptance criteria of the PDI Supplement 10. A statistical evaluation performed by the Pacific Northwest National Laboratories, an NRC contractor, showed that the proposed alternative acceptance criteria satisfied the pass/fail objective established for Appendix VIII for an acceptable performance demonstration.
5.0 CONCLUSION
Based on the above evaluation, the NRC staff concludes that use of a limited number of flaws to qualify Supplement 3 as coordinated with the PDI developed alternative to Supplement 10, will provide equivalent flaw detection to that of the ASME Code-required technique for the piping welds. The staff finds that the licensee<s proposed alternative provides an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), the NRC staff authorizes the proposed alternative to the Code requirement in Relief Request No. 27 for Palo Verde, Units 1, 2, and 3 for the second 10-year ISI interval.
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: M. Thorpe-Kavanaugh Date: March 29, 2005
Palo Verde Generating Station, Units 1, 2, and 3 cc:
Mr. Steve Olea Mr. John Taylor Arizona Corporation Commission Public Service Company of New Mexico 1200 W. Washington Street 2401 Aztec NE, MS Z110 Phoenix, AZ 85007 Albuquerque, NM 87107-4224 Douglas Kent Porter Ms. Cheryl Adams Senior Counsel Southern California Edison Company Southern California Edison Company 5000 Pacific Coast Hwy Bldg DIN Law Department, Generation Resources San Clemente, CA 92672 P.O. Box 800 Rosemead, CA 91770 Mr. Robert Henry Salt River Project Senior Resident Inspector 6504 East Thomas Road U.S. Nuclear Regulatory Commission Scottsdale, AZ 85251 P. O. Box 40 Buckeye, AZ 85326 Mr. Jeffrey T. Weikert Assistant General Counsel Regional Administrator, Region IV El Paso Electric Company U.S. Nuclear Regulatory Commission Mail Location 167 Harris Tower & Pavillion 123 W. Mills 611 Ryan Plaza Drive, Suite 400 El Paso, TX 79901 Arlington, TX 76011-8064 Mr. John Schumann Chairman Los Angeles Department of Water & Power Maricopa County Board of Supervisors Southern California Public Power Authority 301 W. Jefferson, 10th Floor P.O. Box 51111, Room 1255-C Phoenix, AZ 85003 Los Angeles, CA 90051-0100 Mr. Aubrey V. Godwin, Director Brian Almon Arizona Radiation Regulatory Agency Public Utility Commission 4814 South 40 Street William B. Travis Building Phoenix, AZ 85040 P. O. Box 13326 1701 North Congress Avenue Mr. M. Dwayne Carnes, Director Austin, TX 78701-3326 Regulatory Affairs/Nuclear Assurance Palo Verde Nuclear Generating Station P.O. Box 52034 Phoenix, AZ 85072-2034 Mr. Hector R. Puente Vice President, Power Generation El Paso Electric Company 310 E. Palm Lane, Suite 310 Phoenix, AZ 85004 November 2003