ML042740628
| ML042740628 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 10/14/2004 |
| From: | Richard Laufer NRC/NRR/DLPM/LPD1 |
| To: | Kansler M Entergy Nuclear Operations |
| Milano P, NRR/DLPM , 415-1457 | |
| References | |
| TAC MC1263, TAC MC1264, TAC MC1265, TAC MC1266 | |
| Download: ML042740628 (20) | |
Text
October 14, 2004 Mr. Michael R. Kansler, President Entergy Nuclear Operations, Inc.
440 Hamilton Avenue White Plains, NY 10601
SUBJECT:
RELIEF REQUEST NOS. 65, 66, 3-34 AND 3-35 REGARDING ALTERNATIVE NONDESTRUCTIVE EXAMINATION QUALIFICATION REQUIREMENTS, INDIAN POINT NUCLEAR GENERATING UNIT NOS. 2 AND 3 (TAC NOS.
MC1263, MC1264, MC1265 AND MC1266)
Dear Mr. Kansler:
By letter dated October 30, 2003, as supplemented on September 9, 2004, Entergy Nuclear Operations, Inc. (the licensee), submitted Relief Request (RR) Nos. 65 and 66 for Indian Point Nuclear Generating Unit No. 2 (IP2) and RRs 3-34 and 3-35 for Indian Point Nuclear Generating Unit No. 3 (IP3). Relief was requested from the non-destructive examination performance demonstration requirements of Appendix VIII, Supplements 2, 3, and 10, to Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code).
Specifically, the licensee proposed to use, as alternatives: (1) the Performance Demonstration Initiative (PDI) developed qualification requirements for inspection of certain Class 1, Category B-F, pressure retaining piping welds, subject to ultrasonic examination to the Supplement 10 criteria, and (2) the PDI developed qualification requirements to inside surface inspection of Class 1, Category B-J , pressure retaining piping welds subject to Supplements 2 and 3 criteria.
The RRs are for the third 10-year inservice inspection (ISI) intervals at each unit.
The Nuclear Regulatory Commission (NRC) staff reviewed the proposed alternatives in the subject RRs. The results are provided in the enclosed safety evaluation.
The NRC staff has concluded that the proposed alternatives to the ASME Code requirements in RRs 65, 66, 3-34, and 3-35 provide an acceptable level of quality and safety. Pursuant to 10 CFR 50.55a(a)(3)(i), the proposed alternatives are authorized for the remainder of the third ISI interval which is until April 3, 2006, for IP2 and until July 20, 2009, for IP3. Regarding the 0.125-inch root mean square error for depth sizing flaws in dissimilar metal weld test specimens during procedure, equipment, and personnel qualification discussed in the Addenda to RRs 65 and 3-34, the staff finds the requirement to be impractical at this time. The staff concludes that the proposed acceptance criteria will provide reasonable assurance of structural integrity.
Therefore, granting relief pursuant to 10 CFR 50.55a(g)(6)(i) 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
M. Kansler requirements were imposed on the facility. The licensees proposed alternative is authorized for IP2 and IP3 for the remainder of the third 10-year ISI intervals.
If you should have any questions, please contact Patrick Milano at 301-415-1457.
Sincerely,
/RA/
Richard J. Laufer, Chief, Section 1 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-247 and 50-286
Enclosure:
Safety Evaluation cc w/encl: See next page
M. Kansler requirements were imposed on the facility. The licensees proposed alternative is authorized for IP2 and IP3 for the remainder of the third 10-year ISI intervals.
If you should have any questions, please contact Patrick Milano at 301-415-1457.
Sincerely,
/RA/
Richard J. Laufer, Chief, Section 1 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-247 and 50-286
Enclosure:
Safety Evaluation cc w/encl: See next page DISTRIBUTION:
PUBLIC T. Chan G. Matakas, R-I C. Miller, EDO PDI-1 R/F P. Milano S. Little ACRS C. Holden A. Keim G. Hill (2) OGC R. Laufer B. McDermott, R-I Accession Number: ML042740628 OFFICE PDI-1:PM PDI-1:LA EMCB:SC OGC PDI-1:SC NAME PMilano SLittle TChan DFruchtes RLaufer DATE 09/28/04 9/30/04 09/28/04 10/12/04 10/13/04 OFFICIAL RECORD COPY
Indian Point Nuclear Generating Unit Nos. 2 & 3 cc:
Mr. Gary Taylor Ms. Charlene Faison Chief Executive Officer Manager, Licensing Entergy Operations, Inc. Entergy Nuclear Operations, Inc.
1340 Echelon Parkway 440 Hamilton Avenue Jackson, MS 39213 White Plains, NY 10601 Mr. John Herron Director of Oversight Senior Vice President and Entergy Nuclear Operations, Inc.
Chief Operating Officer 440 Hamilton Avenue Entergy Nuclear Operations, Inc. White Plains, NY 10601 440 Hamilton Avenue White Plains, NY 10601 Mr. James Comiotes Director, Nuclear Safety Assurance Mr. Fred Dacimo Entergy Nuclear Operations, Inc.
Vice President, Operations Indian Point Energy Center Entergy Nuclear Operations, Inc. 295 Broadway, Suite 2 Indian Point Energy Center P.O. Box 249 295 Broadway, Suite 2 Buchanan, NY 10511-0249 P.O. Box 249 Buchanan, NY 10511-0249 Mr. Patric Conroy Manager, Licensing Mr. Christopher Schwarz Entergy Nuclear Operations, Inc.
General Manager, Plant Operations Indian Point Energy Center Entergy Nuclear Operations, Inc. 295 Broadway, Suite 2 Indian Point Energy Center P. O. Box 249 295 Broadway, Suite 2 Buchanan, NY 10511-0249 P.O. Box 249 Buchanan, NY 10511-0249 Mr. John M. Fulton Assistant General Counsel Mr. Dan Pace Entergy Nuclear Operations, Inc.
Vice President Engineering 440 Hamilton Avenue Entergy Nuclear Operations, Inc. White Plains, NY 10601 440 Hamilton Avenue White Plains, NY 10601 Regional Administrator, Region I U.S. Nuclear Regulatory Commission Mr. Randall Edington 475 Allendale Road Vice President Operations Support King of Prussia, PA 19406 Entergy Nuclear Operations, Inc.
440 Hamilton Avenue Senior Resident Inspector, Indian Point 2 White Plains, NY 10601 U. S. Nuclear Regulatory Commission 295 Broadway, Suite 1 Mr. John McCann P.O. Box 38 Director, Nuclear Safety Assurance Buchanan, NY 10511-0038 Entergy Nuclear Operations, Inc.
440 Hamilton Avenue White Plains, NY 10601
Indian Point Nuclear Generating Unit Nos. 2 & 3 cc:
Senior Resident Inspector, Indian Point 3 Mr. William DiProfio U. S. Nuclear Regulatory Commission PWR SRC Consultant 295 Broadway, Suite 1 139 Depot Road P.O. Box 337 East Kingston, NH 03827 Buchanan, NY 10511-0337 Mr. Dan C. Poole Mr. Peter R. Smith, President PWR SRC Consultant New York State Energy, Research, and 20 Captains Cove Road Development Authority Inglis, FL 34449 Corporate Plaza West 286 Washington Avenue Extension Mr. William T. Russell Albany, NY 12203-6399 PWR SRC Consultant 400 Plantation Lane Mr. Paul Eddy Stevensville, MD 21666-3232 Electric Division New York State Department Mr. Alex Matthiessen of Public Service Executive Director 3 Empire State Plaza, 10th Floor Riverkeeper, Inc.
Albany, NY 12223 25 Wing & Wing Garrison, NY 10524 Mr. Charles Donaldson, Esquire Assistant Attorney General Mr. Paul Leventhal New York Department of Law The Nuclear Control Institute 120 Broadway 1000 Connecticut Avenue NW New York, NY 10271 Suite 410 Washington, DC, 20036 Mayor, Village of Buchanan 236 Tate Avenue Mr. Karl Coplan Buchanan, NY 10511 Pace Environmental Litigation Clinic 78 No. Broadway Mr. Ray Albanese White Plains, NY 10603 Executive Chair Four County Nuclear Safety Committee Mr. Jim Riccio Westchester County Fire Training Center Greenpeace 4 Dana Road 702 H Street, NW Valhalla, NY 10592 Suite 300 Washington, DC 20001 Ms. Stacey Lousteau Treasury Department Entergy Services, Inc.
639 Loyola Avenue Mail Stop: L-ENT-15E New Orleans, LA 70113
Indian Point Nuclear Generating Unit Nos. 2 & 3 cc:
Mr. Robert D. Snook Assistant Attorney General State of Connecticut 55 Elm Street P.O. Box 120 Hartford, CT 06141-0120 Mr. David Lochbaum Nuclear Safety Engineer Union of Concerned Scientists 1707 H Street NW, Suite 600 Washington, DC 20006
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REQUEST FOR RELIEF NOS. 65, 66, 3-34 AND 3-35 ENTERGY NUCLEAR OPERATIONS, INC.
INDIAN POINT NUCLEAR GENERATING UNIT NOS. 2 AND 3 DOCKET NOS. 50-247 AND 50-286
1.0 INTRODUCTION
The inservice inspection (ISI) of American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (ASME Code) Class 1, Class 2, and Class 3 components is performed in accordance with Section XI of the ASME Code and applicable edition and addenda as required by 10 CFR 50.55a(g), except where specific relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i). 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) will meet the requirements, except the design and access provisions and the preservice 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 Code incorporated by reference in 10 CFR 50.55a(b) twelve months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein. The ISI Code of record for Indian Point Nuclear Generating Unit No. 2 (IP2) and Indian Point Nuclear Generating Unit 3 No. (IP3) third 10-year ISI intervals is the 1989 Edition.
By letter dated October 30, 2003, as supplemented on September 9, 2004, Entergy Nuclear Operations, Inc. (the licensee), submitted Relief Request (RR) 65 (with Addenda) and RR 66 for IP2 and RR 3-34 (with Addenda) and RR 3-35 for IP3. The requests pertain to certain procedure and performance qualification requirements of the ASME Code for nondestructive examination of pressure retaining piping welds.
Enclosure
2.0 RELIEF REQUEST RR-65 FOR IP2 AND RR 3-34 FOR IP3 2.1 Components for Which Relief is Requested ASME Code,Section XI, 1989 Edition, Class 1, Category B-F, Pressure Retaining Piping Welds, subject to ultrasonic examination using procedures, personnel, and equipment qualified to ASME Code,Section XI, 1995 Edition, 1996 Addenda, Appendix VIII, Supplement 10 criteria for the remainder of the third 10-year ISI intervals at IP2 and IP3.
IP2 DISSIMILAR METAL WELDS Item Number Drawing Number Weld Number B5.10 206913 RPVS21-1A B5.10 206913 RPVS21-14A B5.10 206913 RPVS22-1A B5.10 206913 RPVS22-14A B5.10 206913 RPVS23-1A B5.10 206913 RPVS23-14A B5.10 206913 RPVS24-1A B5.10 206913 RPVS24-14A B5.40 206918 PZRS1 B5.40 206918 PZRS2 B5.40 206918 PZRS3 B5.40 206918 PZRS4 B5.40 206918 PZRS5 B5.40 206918 PZRS6 B5.70 206914 SGS 21R-4 B5.70 206914 SGS 21R-5 B5.70 206915 SGS 22R-4 B5.70 206915 SGS 22R-5 B5.70 206916 SGS 23R-4
Item Number Drawing Number Weld Number B5.70 206916 SGS 23R-5 B5.70 206917 SGS 24R-4 B5.70 206917 SGS 24R-5 IP3 DISSIMILAR METAL WELDS Item Number Drawing Weld Numbers B5.10 1-4100 1(DM), 16(DM)
B5.40 1-4500 1(DM)
B5.40 1-4501 1(DM)
B5.40 1-4502 1(DM)
B5.40 1-4503 1(DM)
B5.40 1-4504 16(DM)
B5.40 1-4505 1(DM)
B5.70 1-4400 5(DM), 6(DM) 2.2 Applicable Code Requirements The following items are from ASME Code,Section XI, Appendix VIII, Supplement 10 and identify the specific requirements that are addressed in this request for relief.
Item 1 - Paragraph 1.1(b) states in part - Pipe diameters within a range of 0.9 to 1.5 times a nominal diameter shall be considered equivalent.
Item 2 - Paragraph 1.1(d) states - All flaws in the specimen set shall be cracks.
Item 3 - Paragraph 1.1(d)(1) states - At least 50% of the cracks shall be in austenitic material.
At least 50% of the cracks in austenitic material shall be contained wholly in the weld or buttering material. At least 10% of the cracks shall be in ferritic material. The remainder of the cracks may be in either austenitic or ferritic material.
Item 4 - Paragraph 1.2(b) states in part - The number of unflawed grading units shall be at least twice the number of flawed grading units.
Item 5 - Paragraph 1.2(c)(1) and 1.3(c) state in part - At least 1/3 of the flaws, rounded to the next higher whole number, shall have depths between 10% and 30% of the nominal pipe wall thickness. Paragraph 1.4(b) distribution table requires 20% of the flaws to have depths between 10% and 30%.
Item 6 - Paragraph 2.0 the first sentence states - The specimen inside surface and identification shall be concealed from the candidate.
Item 7 - Paragraph 2.2(b) states in part - The regions containing a flaw to be sized shall be identified to the candidate.
Item 8 - Paragraph 2.2(c) states in part - For a separate length sizing test, the regions of each specimen containing a flaw to be sized shall be identified to the candidate.
Item 9 - Paragraph 2.3(a) states - For the depth sizing test, 80% of the flaws shall be sized at a specific location on the surface of the specimen identified to the candidate.
Item 10 - Paragraph 2.3(b) states - For the remaining flaws, the regions of each specimen containing a flaw to be sized shall be identified to the candidate. The candidate shall determine the maximum depth of the flaw in each region.
Item 11 - Table VIII-S2-1 provides the false-call criteria when the number of unflawed grading units is at least twice the number of flawed grading units.
2.3 Licensees Proposed Alternative and Basis The licensee proposed the following alternatives to the selected paragraphs in the 1995 Edition with 1996 Addenda of the ASME Code,Section XI, Appendix VIII, Supplement 10, requirements for IP2 and IP3. The proposed alternative, as stated by the licensee, will be implemented through the Performance Demonstration Initiative (PDI) Program. The alternatives are specified for each of the Appendix VIII items listed above.
Item 1 - The proposed alternative to Paragraph 1.1(b) states:
The specimen set shall include the minimum and maximum pipe diameters and thicknesses for which the examination procedure is applicable. Pipe diameters within a range of 1/2 in. (13 mm) of the nominal diameter shall be considered equivalent. Pipe diameters larger than 24 in. (610 mm) shall be considered to be flat. When a range of thicknesses is to be examined, a thickness tolerance of
+/-25% is acceptable.
Technical Basis - The change in the minimum pipe diameter tolerance from 0.9 times the diameter to the nominal diameter minus 0.5 inch provides tolerances more in line with industry practice. Though the alternative is less stringent for small pipe diameters they typically have a thinner wall thickness than larger diameter piping. A thinner wall thickness results in shorter sound path distances that reduce the detrimental effects of the curvature. This change maintains consistency between Supplement 10 and the recent revision to Supplement 2.
Item 2 - The proposed alternative to Paragraph 1.1(d) states:
At least 60% of the flaws shall be cracks, the remainder shall be alternative flaws. Specimens with IGSCC [intergranular stress corrosion cracking] shall be used when available. Alternative flaws, if used, shall provide crack-like reflective characteristics and shall be limited to the case where implantation of cracks produces spurious reflectors that are uncharacteristic of actual flaws. Alternative flaw mechanisms shall have a tip width of less than 0.002 in (.05 mm). Note, to avoid confusion the proposed alternative modifies instances of the term "cracks" or "cracking" to the term "flaws" because of the use of alternative flaw mechanisms.
Technical Basis - [...] Implanting a crack requires excavation of the base material on at least one side of the flaw. While this may be satisfactory for ferritic materials, it does not produce a useable axial flaw in austenitic materials because the sound beam, which normally passes only through base material, must now travel through weld material on at least one side, producing an unrealistic flaw response. In addition, it is important to preserve the dendritic structure present in field welds that would otherwise be destroyed by the implantation process. To resolve these issues, the proposed alternative allows the use of up to 40% fabricated flaws as an alternative flaw mechanism under controlled conditions. The fabricated flaws are isostatically compressed which produces ultrasonic reflective characteristics similar to tight cracks.
Item 3 - The proposed alternative to Paragraph 1.1(d)(1) states:
At least 80% of the flaws shall be contained wholly in weld or buttering material.
At least one and a maximum of 10% of the flaws shall be in ferritic base material.
At least one and a maximum of 10% of the flaws shall be in austenitic base material.
Technical Basis - Under the current [ASME] Code, as few as 25% of the flaws are contained in austenitic weld or buttering material. Recent experience has indicated that flaws contained within the weld are the likely scenarios. The metallurgical structure of austenitic weld material is ultrasonically more challenging than either ferritic or austenitic base material. The proposed alternative is therefore more challenging than the current ASME Code.
Item 4 - The proposed alternative to Paragraph 1.2(b) states:
Detection sets shall be selected from Table VIII-S10-1. The number of unflawed grading units shall be at least one and a half times the number of flawed grading units.
Technical Basis - [Table VIII-S10-1] provides a statistically based ratio between the number of unflawed grading units and the number of flawed grading units.
The proposed alternative reduces the ratio to 1.5 times to reduce the number of test samples to a more reasonable number from the human factors perspective.
However, 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 acceptance criteria for the statistical basis are in [new] Table Vlll-S10-1.
Item 5 - The proposed alternative to the flaw distribution requirements of Paragraph 1.2(c)(1) (detection) and 1.3(c) (length) is to use the Paragraph 1.4(b)
(depth) distribution table (see below) for all qualifications.
Flaw Depth Minimum
(% Wall Thickness) Number of Flaws 10-30% 20%
31-60% 20%
61-100% 20%
In addition, the proposed alternative includes the following: "At least 75% of the flaws shall be in the range of 10 to 60% of the wall thickness."
Technical Basis - The proposed alternative uses the depth sizing distribution for both detection and depth sizing because it provides for a better distribution of flaw sizes within the test set. This distribution allows candidates to perform detection, length, and depth sizing demonstrations simultaneously utilizing the same test set. The requirement that at least 75% of the flaws shall be in the range of 10 to 60% of wall thickness provides an overall distribution tolerance yet the distribution uncertainty decreases the possibilities for testmanship that would be inherent to a uniform distribution. It must be noted that it is possible to achieve the same distribution utilizing the present requirements, but it is preferable to make the criteria consistent.
Item 6 - The proposed alternative to Paragraph 2.0 first sentence states:
For qualifications from the outside surface, the specimen inside surface and identification shall be concealed from the candidate. When qualifications are performed from the inside surface, the flaw location and specimen identification shall be obscured to maintain a "blind test.
Technical Basis - The current [ASME] Code requires that the inside surface be concealed from the candidate. This makes qualifications conducted from the inside of the pipe (e.g., PWR [pressurized-water reactor] nozzle-to-safe-end
welds) impractical. The proposed alternative differentiates between ID [inner diameter] and OD [outer diameter] scanning surfaces, requires that they be conducted separately, and requires that flaws be concealed from the candidate.
This is consistent with the recent revision to Supplement 2.
Items 7 and 8 - The proposed alternatives to Paragraphs 2.2(b) and 2.2(c) state:
... containing a flaw to be sized may be identified to the candidate.
Technical Basis - The current [ASME] Code requires that the regions of each specimen containing a flaw to be length sized shall be identified to the candidate.
The candidate shall determine the length of the flaw in each region (Note, that length and depth sizing use the term "regions" while detection uses the term "grading units" - the two terms define different concepts and are not intended to be equal or interchangeable). To ensure security of the samples, the proposed alternative modifies the first "shall" to a "may" to allow the test administrator the option of not identifying specifically where a flaw is located. This is consistent with the recent revision to Supplement 2.
Items 9 and 10 - The proposed alternative to Paragraph 2.3(a) and 2.3(b) state:
. . . regions of each specimen containing a flaw to be sized may be identified to the candidate.
Technical Basis - The current [ASME] Code requires that a large number of flaws be sized at a specific location. The proposed alternative changes the "shall" to a "may" which modifies this from a specific area to a more generalized region to ensure security of samples. This is consistent with the recent revision to Supplement 2. It also incorporates terminology from length sizing for additional clarity.
Item 11 - The proposed alternative modifies the acceptance criteria of Table VIII-S2-1 [with a new Table VIII-S10-1] as follows:
Technical Basis - The proposed alternative is identified as new Table [VIII-]S10-1 above. It was modified to reflect the reduced number of unflawed grading units and allowable false calls. As a part of ongoing [ASME] Code activities, Pacific Northwest National Laboratory (PNNL) has reviewed the statistical significance of these revisions and offered the revised Table [VIII-]S10-1.
2.4 Staff Evaluation The licensee proposed to use the program developed by PDI that is similar to the ASME Code requirements. The differences between the ASME Code and the PDI program are discussed below.
2.4.1 Item 1 - Paragraph 1.1(b)
The ASME Code requirement of 0.9 to 1.5 times the nominal diameter are equivalent was established for a single nominal diameter. When applying the ASME Code-required tolerance to a range of diameters, the tolerance rapidly expands on the high side. Under the current ASME Code requirements, a 5-inch OD pipe would be equivalent to a range of 4.5-inch to 7.5-inch diameter pipe. Under the proposed PDI guidelines, the equivalent range would be reduced to 4.5-inch to 5.5-inch diameter. With current ASME Code requirements, a 16-inch nominal diameter pipe would be equivalent to a range of 14.4 to 24-inch diameter pipe. The proposed alternative would significantly reduce the equivalent range of 15.5-inch to 16.5-inch
diameter pipe. The difference between ASME Code and the proposed alternative for diameters less than 5 inches is not significant because of shorter metal path and the lesser beam spread associated with smaller diameter piping. The proposed alternative is considered more conservative overall than current ASME Code requirements. The NRC staff finds that the proposed alternative will provide an acceptable level of quality and safety and, therefore, is acceptable.
2.4.2 Item 2 - Paragraph 1.1(d)
The ASME Code requires all test flaws to be cracks. Manufacturing test specimens containing cracks free of spurious reflections and telltale indicators is extremely difficult in austenitic material. To overcome these difficulties, PDI developed a process for fabricating flaws that produce ultrasonic testing (UT) acoustic responses similar to the responses associated with real cracks. PDI presented its process for discussion at public meetings held June 12 through 14, 2001, and January 31 through February 2, 2002, at the Electric Power Research Institute (EPRI) Nondestructive Examination (NDE) Center, Charlotte, NC. The NRC staff attended these meetings and determined that the process parameters used for manufacturing fabricated flaws resulted in acceptable acoustic responses. The NRC staff finds that the proposed alternative will provide an acceptable level of quality and safety and, therefore, is acceptable.
2.4.3 Item 3 - Paragraph 1.1(d)(1)
The ASME Code requires that at least 50 percent of the test flaws be contained in austenitic material, and 50 percent of the flaws in the austenitic material shall be contained fully in weld or buttering material. This means that at least 25 percent of the total flaws must be located in the weld or buttering material. Field experience shows that flaws identified during ISI of dissimilar metal welds are more likely to be located in the weld or buttering material. The grain structure of austenitic weld and buttering material represents a much more stringent ultrasonic scenario than that of a ferritic material or austenitic base material. Flaws made in austenitic base material are difficult to create free of spurious reflectors and telltale indicators. The proposed alternative of 80 percent of the flaws in the weld metal or buttering material provides a challenging testing scenario reflective of field experience and minimizes testmanship associated with telltale reflectors common to placing flaws in austenitic base material. The NRC staff considers the proposed alternative to be more conservative than current ASME Code requirements. The NRC staff finds that the proposed alternative will provide an acceptable level of quality and safety and, therefore, is acceptable.
2.4.4 Item 4 - Paragraph 1.2(b) and Item 11 - Paragraph 3.1 The ASME Code requires that detection sets meet the requirements of Table VIII-S2-1, which specifies the minimum number of flaws in a test set to be 5 with 100-percent detection. The current ASME Code also requires the number of unflawed grading units to be two times the number of flawed grading units. The proposed alternative would follow the detection criteria of the table beginning with a minimum number of flaws in a test set being 10, and reducing the number of false calls to 11/2 times the number of flawed grading units. The changes to Table VIII-S2-1 are shown in Table VIII-S10-1. The NRC staff finds that the proposed alternative satisfies the pass/fail objective established for Appendix VIII performance demonstration acceptance criteria. The NRC staff finds that the proposed alternative will provide an acceptable level of quality and safety and, therefore, is acceptable.
2.4.5 Item 5 - Paragraph 1.2(c)(1) and 1.3(c)
For detection and length sizing, the ASME Code requires at least one third of the flaws be located between 10 and 30 percent through-wall thickness and one third located greater than 30 percent through-wall thickness. The remaining flaws would be located randomly throughout the wall thickness. The proposed alternative sets the distribution criteria for detection and length sizing to be the same as the depth sizing distribution, which stipulates that at least 20 percent of the flaws be located in each of the increments of 10-30 percent, 31-60 percent and 61-100 percent. The remaining 40 percent would be located randomly throughout the wall thickness. With the exception of the 10-30 percent increment, the proposed alternative is a subset of the current ASME Code requirements. The 10-30 percent increment would be in the subset if it contained at least 30 percent of the flaws. The change simplifies assembling test sets for detection and sizing qualifications and is more indicative of conditions in the field. The NRC staff finds that the proposed alternative will provide an acceptable level of quality and safety and, therefore, is acceptable.
2.4.6 Item 6 - Paragraph 2.0 The ASME Code requires the specimen inside surface be concealed from the candidate. This requirement is applicable for test specimens used for qualification performed from the outside surface. With the expansion of Supplement 10 to include qualifications performed from the inside surface, the inside surface must be accessible while maintaining the specimen integrity.
The proposed alternative requires that flaws and specimen identifications be obscured from candidates, thus maintaining blind test conditions. The NRC staff considers this to be consistent with the intent of ASME Code requirements. The NRC staff finds that the proposed alternative will provide an acceptable level of quality and safety and, therefore, is acceptable.
2.4.7 Items 7 and 8 - Paragraph 2.2(b) and 2.2(c)
The ASME Code requires that the location of flaws added to the test set for length sizing shall be identified to the candidate. The proposed alternative is to make identifying the location of additional flaws an option. This option provides an additional element of difficulty to the testing process because the candidate would be expected to demonstrate the skill of detecting and sizing flaws over an area larger than a specific location. The NRC staff considers the proposed alternative to be more conservative than current ASME Code requirements. The NRC staff finds that the proposed alternative will provide an acceptable level of quality and safety and, therefore, is acceptable.
2.4.8 Items 9 and 10 - Paragraph 2.3(a) and 2.3(b)
In paragraph 2.3(a), the ASME Code requires that 80 percent of the flaws be sized in a specific location that is identified to the candidate. The proposed alternative permits detection and depth sizing to be conducted separately or concurrently. In order to maintain a blind test, the location of flaws cannot be shared with the candidate. For depth sizing that is conducted separately, allowing the test administrator the option of not identifying flaw locations makes the testing process more challenging. The NRC staff considers the proposed alternative to be more conservative than current ASME Code requirements. The NRC staff finds that the proposed alternative will provide an acceptable level of quality and safety and, therefore, is acceptable.
In paragraph 2.3(b), the ASME Code also requires that the location of flaws added to the test set for depth sizing shall be identified to the candidate. The proposed alternative is to make identifying the location of additional flaws an option. This option provides an additional element of difficulty to the testing process because the candidate would be expected to demonstrate the skill of finding and sizing flaws in an area larger than a specific location. The NRC staff considers the proposed alternative to be more conservative than current ASME Code requirements. The NRC staff finds that the proposed alternative will provide an acceptable level of quality and safety and, therefore, is acceptable.
2.5 Conclusion The NRC staff has determined that the proposed alternative to Supplement 10, as administered by the EPRI-PDI Program, will provide an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), the NRC staff authorizes the proposed alternative described in the licensees letter dated October 30, 2003, for RR-65 and RR 3-34 for the remainder of the third 10-year ISI intervals at IP2 and IP3. All other ASME Code,Section XI requirements for which relief was not specifically requested and approved in the subject relief requests remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.
3.0 RELIEF REQUEST RR-65 ADDENDA FOR IP2 AND RR 3-34 ADDENDA FOR IP3 3.1 Components for Which Relief is Requested ASME Code Class 1 - Reactor Vessel to Primary Piping Dissimilar metal field welds See 2.1 above.
3.2 Applicable Code Requirement Procedures must be qualified to the ASME Code,Section XI, Appendix VIII, Supplement 10, Paragraph 3.2 sizing error value of less than or equal to 0.125-inch root mean square (RMS).
3.3 Licensee's Proposed Alternative and Basis The licensee's vendor is presently developing improvements in its depth sizing performance.
The vendor's current performance does not meet the ASME Code 0.125-inch RMS acceptance criteria. The licensee proposes to evaluate the depth sizing performance of the selected vendor and determine the appropriate sizing error to consider during flaw evaluations. The difference between the achieved sizing error and the Code-required value of 0.125-inch RMS would be added to the size of flaws measured during the examination for the purpose of flaw evaluation.
It is the licensee's position that compensating for the flaw through-wall sizing error band in fracture mechanics evaluation will provide an acceptable margin of safety in the inservice examination of IP2 and IP3 nozzle to primary loop dissimilar metal welds.
The licensee's submittal dated September 9, 2004, provided additional information to address the vendor's actual depth sizing RMS error value. The vendor achieved 0.189-inch RMS instead of the ASME Code, Appendix VIII, Supplement 10, Paragraph 3.2 requirement for depth sizing weld defects with a 0.125-inch RMS error value.
For flaw assessment purposes, the licensee will add the difference between the Code-required value of 0.125-inch and the vendor achieved value of 0.189-inch (i.e., 0.064 inch) to the measured depth of indications recorded. This will add a value of 0.064 inch to the measured flaw depth prior to assessment of the indication in accordance with the requirements of ASME Code,Section XI.
3.4 Staff Evaluation Supplement 10 of Appendix VIII to the ASME Code,Section XI requires that examination procedures, equipment, and personnel meet specific criteria for flaw depth sizing accuracy.
The Code specifies that the maximum error of flaw depth measurements, as compared to the true flaw depths, must be less than or equal to 0.125-inch RMS error value. The industry is in the process of qualifying personnel to Supplement 10 as implemented by the PDI program.
However, for demonstrations performed from the inside surface of a pipe weldment, personnel have been unsuccessful at achieving the 0.125-inch RMS error depth sizing criterion. At this time, achieving the 0.125-inch RMS error is impractical for some vendors. The vendor contracted by the licensee has only been capable of achieving an accuracy of 0.189-inch RMS error. The licensee has proposed to use 0.189-inch RMS error to size any detected flaws during the remainder of the third 10-year ISI interval. The licensee would add the difference (0.064 inch) between the Code required RMS error (0.125-inch) and the demonstrated accuracy (0.189-inch) to the measurements acquired from flaw sizing.
From performance demonstrations of typical hot leg and cold leg weld examinations with a wall thickness of 2.5 inches, the NRC staff gathered information which suggests that the RMS error values were independent of flaw depth. In the thickness range of test specimens, 0.125-inch RMS error of the flaw depth measurement would be approximately 5 percent tolerance on RMS percent of the typical wall thickness and, likewise, 0.189-inch RMS error would translate to approximately 7.5 percent of the RMS percent of the typical wall thickness. The increase in error of 2.5 percent of the measured flaw depth is less than the planar flaw acceptance criteria in Table IWB-3514-2. The NRC staff considers that the flaw depth adjustment proposed by the licensee will ensure a conservative bounding flaw depth value.
3.5 Conclusion Based on the above evaluation, the NRC staff has determined that achieving the 0.125-inch RMS error for depth sizing flaws in dissimilar metal weld test specimens during qualification of ultrasonic examination procedure, equipment and personnel for the subject welds is impractical at this time. The staff concludes that the proposed acceptance criteria will provide reasonable assurance of structural integrity. Therefore, relief is granted for IP2 and IP3 for the remainder of the third 10-year ISI intervals, pursuant to 10 CFR 50.55a(g)(6)(i). The granting of this relief 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. In addition, the licensees proposed alternative is authorized. 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.
4.0 RELIEF REQUEST RR-66 FOR IP2 AND RR 3-35 FOR IP3 4.1 Components for Which Relief is Requested ASME Code,Section XI, 1989 Edition, Class 1, Category B-J, Item Numbers B9.11 and B9.12, Pressure Retaining Piping Welds ultrasonically examined from the inside surface using procedures, personnel, and equipment qualified to ASME Code,Section XI, 1995 Edition, 1996 Addenda, Appendix VIII, Supplements 2 and 3 criteria.
4.2 Applicable Code Requirements Relief is requested from the qualification requirements contained in ASME Code,Section XI, 1995 Edition with 1996 Addenda, Appendix VIII, Supplement 2, Supplement 3 and Supplement 10 as specified in Table VIII-3110-1, for the applicable piping welds.
4.3 Licensees Proposed Alternative In lieu of the requirements of ASME Code,Section XI, 1995 Edition, 1996 Addenda, Appendix VIII, Table VIII-3110-1, the PDI Program for implementation of Appendix VIII, Supplements 2 and 3, in coordination with alternative PDI Supplement 10 is requested to be used (see RR-65 and RR 3-34 in Section 2.0 of this report regarding Supplement 10 implementation) for the remainder of the third 10-year ISI intervals at IP2 and IP3.
The proposed program is the program which has been submitted to the ASME Code for consideration as a new Supplement 14 to Appendix VIII, Qualification Requirements for Coordinated Implementation of Supplement 10, 2, and 3 for Piping Examinations Performed from the Inside Surface.
4.4 Licensees Basis for Relief The RPV nozzles to main coolant piping contain ferritic, austenitic, and cast stainless steel components and were assembled using austenitic and dissimilar metal welds. These austenitic and dissimilar metal welds are in close proximity to each other, which means the same ultrasonic essential variables would be employed (e.g., the ultrasonic examination process associated with a dissimilar metal weld would be applied to a ferritic or austenitic weld).
With regard to qualification requirements for the inspection of such welds, separate qualifications to Supplements 2, 3, and 10 are redundant when done in accordance with the industrys PDI Program. For example, during personnel qualification to the PDI Program, a candidate would be exposed to a minimum of ten flawed grading units for each supplement.
Personnel qualification for Supplements 2, 3, and 10 would require a minimum of 30 flawed grading units. Additionally, a full procedure qualification (three personnel qualifications per supplement) to the PDI Program requirements for three supplements would require a minimum of 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 the three supplements.
To resolve these issues, the PDI Program recognizes the Supplement 10 qualification as the most stringent and technically challenging ultrasonic application. The same Supplement 10
essential variables are used for the examinations subject to the requirements of Supplements 2 and 3. A coordinated add-on implementation would be sufficiently stringent for qualification to the requirements of Supplements 2 and 3 if the requirements used for qualification to Supplement 10 are satisfied as a prerequisite. The basis for this conclusion is the fact that the majority of the flaws addressed in Supplement 10 are located in the austenitic weld material.
This configuration is known to be challenging for ultrasonic techniques due to the variable dendritic structure of the weld material. Conversely, the flaws addressed in Supplements 2 and 3 are located in fine-grained base materials, which are known to be less challenging for ultrasonic techniques.
Additionally, use of the PDI Program for implementation of Supplement 2 requirements in coordination with Supplement 10 implementation would be more stringent than current Code requirements for detection and length sizing qualifications. For example, the current Code would allow a detection procedure, personnel, and equipment to be qualified to Supplement 10 requirements with 5 flaws, Supplement 2 requirements with 5 flaws, and Supplement 3 requirements with 5 flaws, for a total of only 15 flaws. The proposed alternative of qualifying to Supplement 10 requirements using a minimum of 10 flaws and adding on Supplement 2 requirements with 5 flaws and Supplement 3 requirements with 3 flaws results in a total of 18 flaws which will be multiplied by a factor of 3 (PDI multiplier) for the minimum number of flaws in Supplements 10, 2, and 3 procedure qualification.
Based on the above, the use of a limited number of Supplement 2 or 3 flaws is sufficient to assess the capabilities of procedure and personnel who have already satisfied Supplement 10 requirements. The statistical basis used for screening personnel and procedures is still maintained to 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 Appendix VIII.
4.5 Staff Evaluation The licensee requested relief from selected qualification requirements of ASME Code,Section XI, Appendix VIII, Supplements 2 and 3 for examinations performed from the inside surface of piping. The ASME Code currently requires separate qualifications for austenitic piping (Supplement 2), for ferritic piping (Supplement 3), and for dissimilar metal piping (Supplement 10). Qualifications for each supplement would entail a minimum of 10 flaws for each supplement, requiring at least 30 flaws for the 3 supplements. The minimum number of flaws per supplement established a statistical-based pass/fail objective which is identified in the submittal as Table VIII-S10-1. The process of a single qualification for each supplement would greatly expand the minimum number of ferritic and austenitic flaws required to be identified which would also raise the pass/fail acceptance criteria specified in Table VIII-S10-1.
The ASME Code recognized that flaws in austenitic material are more difficult to detect and size than flaws in ferritic material. The prevailing reasoning concluded that a Supplement 3 qualification following a Supplement 2 qualification had diminished returns on measuring personnel skills and procedure effectiveness. Therefore, in lieu of separate Supplement 2 and Supplement 3 qualifications, the ASME Code applied the diminishing return logic in Supplement 12, which provides for a Supplement 3 add-on to a Supplement 2 qualification.
The add-on consists of a minimum of three flaws in ferritic material. All of the flaws in the ferritic material must be detected with no false detections. A statistical evaluation of
Supplement 12 acceptance criteria satisfied the pass/fail objective established for Appendix VIII performance demonstration acceptance criteria.
The proposed alternative builds upon the experiences associated with Supplement 12 by starting with the most challenging Supplement 10 qualifications, as implemented by the PDI program (see Section 2.0 of this safety evaluation), and adding a sufficient number of flaws to demonstrate the personnel skills and procedure effectiveness of the less challenging Supplement 2 and Supplement 3 qualifications. A PDI Supplement 10 performance demonstration requires at least one 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. When expanding the Supplement 10 qualification with an add-on Supplement 2 and Supplement 3 qualification, the proposed alternative would add a minimum of five flaws in austenitic material and three flaws in ferritic material to the performance demonstration. All of the add-on flaws must be detected with no false detections. Therefore, a combined Supplement 2 and Supplement 3, add-on to a Supplement 10 qualification requires a minimum of 8 flaws in the detection performance demonstration test in addition to the minimum of 10 flaws for a Supplement 10 qualification. For the sizing performance demonstration, the Supplement 2 and Supplement 3 results are added to the appropriate Supplement 10 results which must satisfy the acceptance criteria of 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 criteria specified in Table VIII-S10-1 of the licensees submittal.
The NRC staff has determined that the use of a limited number of flaws to qualify personnel, procedures and equipment to Supplement 2 or Supplement 3 in coordination with the PDI developed implementation of Supplement 10 (see Section 2.0 of this report), will provide equivalent flaw detection performance to that required by the ASME Code. As such, the licensees proposed alternative provides an acceptable level of quality and safety.
4.6 Conclusion The NRC staff has determined that the proposed alternative to use the industrys PDI program for implementation of Appendix VIII, Supplements 2 and 3 as coordinated with the PDI program for implementation of Appendix VIII, Supplement 10, will provide an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), the NRC authorizes the proposed alternative for the remainder of the third 10-year ISI intervals at IP2 and IP3. 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: A. Keim Date: October 14, 2004