ML052560006
| ML052560006 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 09/19/2005 |
| From: | Darrell Roberts NRC/NRR/DLPM/LPD1 |
| To: | Kansler M Entergy Nuclear Operations |
| Ennis R, NRR/DLPM, 415-1420 | |
| References | |
| TAC MC0959 | |
| Download: ML052560006 (16) | |
Text
September 19, 2005 Mr. Michael Kansler President Entergy Nuclear Operations, Inc.
440 Hamilton Avenue White Plains, NY 10601
SUBJECT:
SAFETY EVALUATION OF RELIEF REQUEST B VERMONT YANKEE NUCLEAR POWER STATION (TAC NO. MC0959)
Dear Mr. Kansler:
By letter dated October 1, 2003, as supplemented on May 11, and August 24, 2005, Entergy Nuclear Vermont Yankee, LLC and Entergy Nuclear Operations, Inc. (Entergy or the licensee) submitted Relief Request B-5 for Vermont Yankee Nuclear Power Station (VYNPS). The relief request pertains to the third 10-year inservice inspection (ISI) interval at VYNPS, which concluded on August 31, 2003. During this interval, 49 welds were identified that received less than the essentially 100% coverage examination required by Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code). Therefore, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) Section 50.55a(g)(5)(iii),
Entergy requested relief on the basis that the required essentially 100% coverage examination was impractical due to physical obstructions and limitations imposed by design, geometry, and materials of construction of the subject components. Most of the welds are associated with reactor vessel nozzles.
The Nuclear Regulatory Commission (NRC) staff has completed its review of Relief Request B-5 as documented in the enclosed Safety Evaluation (SE). Our SE concludes that compliance with the ASME Code requirements for the volumetric or surface coverage of the subject welds is impractical due to component configurations. The staff finds that the examination coverage of the accessible weld volume or area, as completed by the licensee, provides reasonable assurance of structural integrity of the subject welds. Therefore, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i) for the third 10-year ISI interval of VYNPS. This granting of 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.
All other ASME Code,Section XI requirements for which relief was not specifically requested and authorized herein by the NRC staff remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
M. Kansler If you have any questions regarding this matter, please contact the VYNPS Project Manager, Mr. Richard B. Ennis, at (301) 415-1420.
Sincerely,
/RA/
Darrell J. Roberts, Chief, Section 2 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-271
Enclosure:
As stated cc w/encl: See next page
M. Kansler If you have any questions regarding this matter, please contact the VYNPS Project Manager, Mr. Richard B. Ennis, at (301) 415-1420.
Sincerely,
/RA/
Darrell J. Roberts, Chief, Section 2 Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-271
Enclosure:
As stated cc w/encl: See next page DISTRIBUTION PUBLIC CRaynor OGC CAnderson, RGN-I PDI-2 Reading REnnis ACRS STurk, OGC CHolden TChan DLPM DPR VBucci, OIG DRoberts AKeim SLee Accession No.: ML052560006 *SE dated 9/8/05 - no significant changes made OFFICE PDI-2/PM PDI-2/LA EMCB/SC* OGC PDI-2/SC NAME REnnis CRaynor TChan JBonanno DRoberts DATE 9/14/05 9/14/05 9/8/05 9/16/05 9/19/05 OFFICIAL RECORD COPY
Vermont Yankee Nuclear Power Station cc:
Regional Administrator, Region I Ms. Carla A. White, RRPT, CHP U. S. Nuclear Regulatory Commission Radiological Health 475 Allendale Road Vermont Department of Health King of Prussia, PA 19406-1415 P.O. Box 70, Drawer #43 108 Cherry Street Mr. David R. Lewis Burlington, VT 05402-0070 Pillsbury, Winthrop, Shaw, Pittman, LLP 2300 N Street, N.W. Mr. James M. DeVincentis Washington, DC 20037-1128 Manager, Licensing Vermont Yankee Nuclear Power Station Ms. Christine S. Salembier, Commissioner P.O. Box 0500 Vermont Department of Public Service 185 Old Ferry Road 112 State Street Brattleboro, VT 05302-0500 Montpelier, VT 05620-2601 Resident Inspector Mr. Michael H. Dworkin, Chairman Vermont Yankee Nuclear Power Station Public Service Board U. S. Nuclear Regulatory Commission State of Vermont P.O. Box 176 112 State Street Vernon, VT 05354 Montpelier, VT 05620-2701 Director, Massachusetts Emergency Chairman, Board of Selectmen Management Agency Town of Vernon ATTN: James Muckerheide P.O. Box 116 400 Worcester Rd.
Vernon, VT 05354-0116 Framingham, MA 01702-5399 Operating Experience Coordinator Jonathan M. Block, Esq.
Vermont Yankee Nuclear Power Station Main Street 320 Governor Hunt Road P.O. Box 566 Vernon, VT 05354 Putney, VT 05346-0566 G. Dana Bisbee, Esq. Mr. John F. McCann Deputy Attorney General Director, Nuclear Safety Assurance 33 Capitol Street Entergy Nuclear Operations, Inc.
Concord, NH 03301-6937 440 Hamilton Avenue White Plains, NY 10601 Chief, Safety Unit Office of the Attorney General Mr. Gary J. Taylor One Ashburton Place, 19th Floor Chief Executive Officer Boston, MA 02108 Entergy Operations 1340 Echelon Parkway Ms. Deborah B. Katz Jackson, MS 39213 Box 83 Shelburne Falls, MA 01370
Vermont Yankee Nuclear Power Station cc:
Mr. John T. Herron Mr. Ronald Toole Sr. VP and Chief Operating Officer 1282 Valley of Lakes Entergy Nuclear Operations, Inc. Box R-10 440 Hamilton Avenue Hazelton, PA 18202 White Plains, NY 10601 Ms. Stacey M. Lousteau Mr. Danny L. Pace Treasury Department Vice President, Engineering Entergy Services, Inc.
Entergy Nuclear Operations, Inc. 639 Loyola Avenue 440 Hamilton Avenue New Orleans, LA 70113 White Plains, NY 10601 Mr. Raymond Shadis Mr. Brian OGrady New England Coalition Vice President, Operations Support Post Office Box 98 Entergy Nuclear Operations, Inc. Edgecomb, ME 04556 440 Hamilton Avenue White Plains, NY 10601 Mr. James P. Matteau Executive Director Mr. Michael J. Colomb Windham Regional Commission Director of Oversight 139 Main Street, Suite 505 Entergy Nuclear Operations, Inc. Brattleboro, VT 05301 440 Hamilton Avenue White Plains, NY 10601 Mr. William K. Sherman Vermont Department of Public Service Mr. John M. Fulton 112 State Street Assistant General Counsel Drawer 20 Entergy Nuclear Operations, Inc. Montpelier, VT 05620-2601 440 Hamilton Avenue White Plains, NY 10601 Mr. Jay K. Thayer Site Vice President Entergy Nuclear Operations, Inc.
Vermont Yankee Nuclear Power Station P.O. Box 0500 185 Old Ferry Road Brattleboro, VT 05302-0500 Mr. Kenneth L. Graesser 38832 N. Ashley Drive Lake Villa, IL 60046 Mr. James Sniezek 5486 Nithsdale Drive Salisbury, MD 21801
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO RELIEF REQUEST B-5 FOR THE THIRD 10-YEAR INTERVAL OF THE INSERVICE INSPECTION PROGRAM ENTERGY NUCLEAR VERMONT YANKEE, LLC AND ENTERGY NUCLEAR OPERATIONS, INC.
VERMONT YANKEE NUCLEAR POWER STATION DOCKET NO. 50-271
1.0 INTRODUCTION
By letter dated October 1, 2003, as supplemented on May 11, and August 24, 2005, Entergy Nuclear Vermont Yankee, LLC and Entergy Nuclear Operations, Inc. (Entergy or the licensee) submitted Relief Request B-5 for Vermont Yankee Nuclear Power Station (VYNPS). The relief request pertains to the third 10-year inservice inspection (ISI) interval at VYNPS, which concluded on August 31, 2003. During this interval, 49 welds were identified that received less than the essentially 100% coverage examination required by Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code). Therefore, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) Section 50.55a(g)(5)(iii),
Entergy requested relief on the basis that the required essentially 100% coverage examination was impractical due to physical obstructions and limitations imposed by design, geometry, and materials of construction of the subject components. Most of the welds are associated with reactor vessel nozzles.
2.0 REGULATORY REQUIREMENTS The 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 10 CFR 50.55a(g), except where specific written relief has been granted by the Nuclear Regulatory Commission (NRC or Commission) pursuant to 10 CFR 50.55a(g)(6)(i). Pursuant to 10 CFR 50.55a(a)(3), 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 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 applicable ASME Section XI Code for the VYNPS third 10-year ISI interval is the 1986 Edition with no Addenda. 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.
Pursuant to 10 CFR 50.55a(g)(5), if the licensee determines that conformance with an examination requirement of Section XI of the ASME Code is not practical for its facility, information shall be submitted to the Commission in support of that determination and a request made for relief from the ASME Code requirement. After evaluation of the determination, pursuant to 10 CFR 50.55a(g)(6)(i), the Commission may grant relief and may impose alternative requirements that are determined to be authorized by law, will not endanger life, property, or the common defense and security, and are otherwise in the public interest, giving due consideration to the burden upon the licensee that could result if the requirements were imposed.
3.0 RELIEF REQUEST B-5 3.1 Components for Which Relief is Requested Table 1 lists the components pertaining to VYNPS Relief Request B-5.
Table 1 Section XI Component Description Condition Limiting Coverage Examination Category System and Coverage %
Item No. Number B-D RPV Vessel-to- Weld proximity to nozzle blend Ultrasonic B3.90 N1A Nozzle radius limits scanning to one testing (recirculation) side (UT) 50.4%
B-D RPV Vessel-to- Weld proximity to nozzle blend UT B3.90 N1B Nozzle radius limits scanning to one 50.4%
(recirculation) side B-D RPV Nozzle-to- Weld proximity to nozzle blend UT B3.90 N2A Vessel radius limits scanning to one 51.6%
(recirculation) side
Section XI Component Description Condition Limiting Coverage Examination Category System and Coverage %
Item No. Number B-D RPV Nozzle-to- Weld proximity to nozzle blend UT B3.90 N2B Vessel radius limits scanning to one 51.6%
(recirculation) side B-D RPV Nozzle-to- Weld proximity to nozzle blend UT B3.90 N2C Vessel radius limits scanning to one 51.6%
(recirculation) side B-D RPV Nozzle-to- Weld proximity to nozzle blend UT B3.90 N2D Vessel radius limits scanning to one 51.6%
(recirculation) side.
B-D RPV Nozzle-to- Weld proximity to nozzle blend UT B3.90 N2E Vessel radius limits scanning to one 51.6%
(recirculation) side.
B-D RPV Nozzle-to- Weld proximity to nozzle blend UT B3.90 N2F Vessel radius limits scanning to one 51.6%
(recirculation) side.
B-D RPV Nozzle-to- Weld proximity to nozzle blend UT B3.90 N2G Vessel radius limits scanning to one 51.6%
(recirculation) side.
B-D RPV Nozzle-to- Weld proximity to nozzle blend UT B3.90 N2H Vessel radius limits scanning to one 51.6%
(recirculation) side.
B-D RPV Nozzle-to- Weld proximity to nozzle blend UT B3.90 N2J Vessel radius limits scanning to one 51.6%
(recirculation) side.
B-D RPV Nozzle-to- Weld proximity to nozzle blend UT B3.90 N2K Vessel radius limits scanning to one 51.6%
(recirculation) side.
B-D RPV Vessel-to- Weld proximity to nozzle blend UT B3.90 N3A Nozzle radius limits scanning to one 51.6%
(main steam) side.
B-D RPV Vessel-to- Weld proximity to nozzle blend UT B3.90 N3B Nozzle radius limits scanning to one 51.6%
(main steam) side.
B-D RPV Vessel-to- Weld proximity to nozzle blend UT B3.90 N3C Nozzle radius limits scanning to one 51.6%
(main steam) side.
Section XI Component Description Condition Limiting Coverage Examination Category System and Coverage %
Item No. Number B-D RPV Vessel-to- Weld proximity to nozzle blend UT B3.90 N3D Nozzle radius limits scanning to one 51.6%
(main steam) side.
B-D RPV Nozzle-to-vessel Weld proximity to nozzle blend UT B3.90 N4A (feed water) radius limits scanning to one 63.3%
side.
B-D RPV Nozzle-to-vessel Weld proximity to nozzle blend UT B3.90 N4B (feed water) radius limits scanning to one 63.3%
side.
B-D RPV Nozzle-to-vessel Weld proximity to nozzle blend UT B3.90 N4C (feed water) radius limits scanning to one 63.3%
side.
B-D RPV Nozzle-to-vessel Weld proximity to nozzle blend UT B3.90 N4D (feed water) radius limits scanning to one 63.3%
side.
B-D RPV Nozzle-to-vessel Weld proximity to nozzle blend UT B3.90 N5A (core spray) radius limits scanning to one 67.1%
side.
B-D RPV Nozzle-to-vessel Weld proximity to nozzle blend UT B3.90 N5B (core spray) radius limits scanning to one 67.1%
side.
B-D RPV Nozzle-to-vessel Weld proximity to nozzle blend UT B3.90 N6A (head spray) radius limits scanning to one 52.5%
side.
B-D RPV Nozzle-to-vessel Weld proximity to nozzle blend UT B3.90 N6B (head spray) radius limits scanning to one 52.5%
side.
B-D RPV Vessel-to-nozzle Weld proximity to nozzle blend UT B3.90 N7 (head vent) radius limits scanning to one 49.1%
side.
B-D RPV Vessel-to-nozzle Weld proximity to nozzle blend UT B3.90 N8A (jet pump inst) radius limits scanning to one 65.9%
side.
B-D RPV Vessel-to-nozzle Weld proximity to nozzle blend UT B3.90 N8B (jet pump inst) radius limits scanning to one 65.9%
side.
Section XI Component Description Condition Limiting Coverage Examination Category System and Coverage %
Item No. Number B-D RPV Vessel-to nozzle Weld proximity to nozzle blend UT B3.90 N9 (CRD-capped) radius limits scanning to one 61.6%
side.
B-D RPV Nozzle-to-vessel Weld proximity to nozzle blend UT B3.90 N10 (SLC) radius limits scanning to one 42.8%
side. Additional limitation due to RPV support skirt B-D RPV Nozzle inner Support skirt UT B3.100 N10-IR radius (SLC) 88.3%
B-F RPV Nozzle-to-safe Flange bolting and surface UT B5.10 N6A-SE end depression 58%
(head spray)
B-F RPV Nozzle-to-safe Flange bolting UT B5.10 N6B-SE end 89.9%
(head spray)
B-H RPV Bottom head to Outside diameter (OD) of weld Penetrant B8.10 support support skirt inaccessible due to biological testing (PT) skirt shield wall and insulation 50%
B-J Core Spray Valve-to-pipe Pipe-to-valve configuration UT B9.11 CS4B-MF5 (one-sided exam) 38.6%
B-J RHR Pipe-to-valve Pipe-to-valve configuration UT B9.11 RH28-12 (one-sided exam) 82.5%
B-J RHR Valve-to-elbow Elbow-to-valve configuration UT B9.11 RH29-10 (one-sided exam) and branch 82.1%
connection obstruction B-J RHR Valve-to-pipe Pipe-to-valve configuration UT B9.11 RH32-8 (one-sided exam) and OD 73.8%
surface configuration B-K Recirc 8 Lug welds Pipe clamp on bottom of shear PT B10.10 RR-89,90 lugs 77.8%
B-O CRD CRD Housing- Two 1"-diameter support rods UT B14.10 02-27HF to-flange 85.2%
B-O CRD CRD Housing- Two 1"-diameter support rods UT B14.10 02-27SH to-flange 85.2%
Section XI Component Description Condition Limiting Coverage Examination Category System and Coverage %
Item No. Number B-O CRD CRD Housing- Two 1"-diameter support rods UT B14.10 26-03HF to-flange 85.2%
B-O CRD CRD Housing- Two 1"-diameter support rods UT B14.10 34-39HF to-flange 85.2%
C-A RHR RHR Heat Flange geometry and 12 UT C1.10 A-HTEX exchanger welded attachments 80.2%
10-4 shell-to-flange C-C RHR RHR Heat Limited access between shell Magnetic C3.10 A-RHR-CC- exchanger and floor particle 4 welded support testing 80.1%
C-F-2 Condensate Pipe-to-valve Valve configuration UT C5.51 CT27-S30 84.5%
C-F-2 Feedwater Valve-to-pipe Valve configuration UT C5.51 FW-17-S5 (one-sided exam) 79.8%
C-F-2 RHR Valve-to-pipe Weld OD profile configuration UT C5.51 RH3D-S206 (limited circumferential scan) 79.0%
C-F-2 RCIC Pipe-to-valve Valve configuration UT Augment RC3-S15 (0.280" thick) 80.5%
NUREG RWCU Pipe-to-flange Flange configuration UT 0313 CU54-16 (class 3) 57.3%
3.2 Applicable ASME Code Edition and Addenda The Section XI ASME Code of record for the third 10-year ISI interval at VYNPS is the 1986 Edition with no Addenda.
3.3 ASME Code Requirements ASME Code,Section XI, 1986 Edition, in examination categories B-D (Full Penetration Welds of Nozzles in Vessels), B-F (Pressure-Retaining Dissimilar Metal Welds), B-H (Integral Attachments for Vessels), B-J (Pressure-Retaining Welds in Piping), B-K (Integral Attachments for Piping, Pumps, and Valves), B-O (Pressure-Retaining Welds in Control Rod Housings),
C-A (Pressure-Retaining Welds in Pressure Vessels), C-C (Integral Attachments for Vessels, Piping, Pumps, and Valves), and C-F-2 (Pressure-Retaining Welds in Carbon or Low Alloy Steel Piping) requires essentially 100% volumetric and/or surface examinations of the above welds.
ASME Section XI Code Case N-460, which has been approved for use by the NRC in Regulatory Guide (RG) 1.147, Revision 13, allows credit for full volume coverage of welds if it can be shown that greater than 90% of the required volume has been examined.
3.4 ASME Code Requirement from Which Relief is Requested Relief is requested from the requirement to examine essentially 100% of the required volume specified in the ASME Code,Section XI, 1986 Edition. Due to physical obstructions, and limitations imposed by design, geometry and materials of construction of the subject components the ultrasonic examination coverage did not meet the 90% examination requirements of ASME Code Case N-460.
3.5 Licensees Basis for Relief Pursuant to 10 CFR 50.55a(g)(5)(iii), relief is requested on the basis that the required essentially 100% coverage examination is impractical due to physical obstructions and limitations imposed by design, geometry, and materials of construction of the component.
Relief is requested from performing a complete essentially 100% coverage examination of the required volume and/or area as applicable for the identified components in Table 1.
VYNPS obtained a construction permit on July 7, 1967. The piping systems and associated components were designed and fabricated before the examination requirements of ASME Code Section XI were formalized and published. Since this plant was not specifically designed to meet the requirements of ASME Code Section XI, literal compliance is not feasible or practical within the limits of the current plant design.
Physical obstructions imposed by design, geometry and materials of construction are typical of vessel appurtenances, biological shield wall, insulation support rings, structural and component support members, adjacent component weldments in close proximity, unique component configurations (valves and pumps), and dissimilar metal weldments.
As a minimum, all components received the required coverage examination(s) to the extent practical with regard to the limited or lack of available access. The examinations conducted confirmed satisfactory results evidencing no unacceptable flaws present. The licensee has concluded that if any active degradation mechanisms were to exist in the subject welds, those degradations would have been identified in the examinations performed. The basis for this conclusion derives from the statistical approach put forth in Appendix A (of the licensees submittal dated October 1, 2003). The licensee states that the statistical approach concludes that even for large reductions in coverage, the reduction in degradation detection confidence is insignificant.
Examination Category B-D, Full Penetration Welds of Nozzles in Vessels Item B3.90, Nozzle to Reactor Vessel Welds For the subject Examination Category B-D, Item B3.90 welds as listed in Table 1, the nozzle material is carbon steel (CS) and the vessel material is CS. The licensee stated that during the ultrasonic examination of the welds, approximately 42.8% to 67.1% coverages of the required examination volumes were obtained. The coverage reported represents the aggregate
coverage of all scans performed using 0E, 40E and 60E scan angles. Scanning was unable to be performed from the nozzle side of the welds. The licensee stated the scanning limitations were caused by the close proximity of the weld to the nozzle blend radius which prevented scanning from both sides of the weld. In order to scan all of the required surfaces for the inspection of these welds, the nozzles would have to be redesigned to allow scanning from both sides of the welds, which is impractical. There were no recordable indications found during the inspections of these welds.
Examination Category B-D, Full Penetration Welds of Nozzles in Vessels Item B3.100, Reactor Vessel Nozzle Inside Radius Section For the subject Examination Category B-D, Item B3.100 inside radius section as listed in Table 1, the licensee stated that during the ultrasonic examination of the inside radius approximately 88.3% coverage of the required examination volume was obtained. Scanning was limited due to the reactor pressure vessel support skirt. There were no recordable indications found during the inspections of the subject component.
Examination Category B-F, Pressure-Retaining Dissimilar Metal Welds Item B5.10, Reactor Vessel Nozzle to Safe End Welds For the two subject Examination Category B-F, Item B5.10 head spray nozzles, the licensee was able to obtain approximately 58% of the required volume for N6A-SE and 89.9% of the required volume of N6B-SE. The examinations were limited by the flange bolting and for N6A-SE had an additional limitation due to a surface depression. There were no recordable indications found during the inspections of these welds.
Examination Category B-H, Integral Attachments for Vessels Item B8.10, Reactor Vessel Bottom Head to Support Skirt For the subject bottom head to support skirt weld, the licensee performed a surface examination from the inner surface. The outside surface of the support skirt weld received a surface examination on a very limited area. The licensee stated that the examination coverage obtained is approximately 50% for the inner and outer surfaces of the weld. The licensee performed a complete surface examination on the inner surface of the weld. Access to the outside surface is limited by non-removable insulation. Only two access regions are available for examination on the outside of the skirt.
Examination Category B-J, Pressure-Retaining Welds in Piping Item B9.11, Circumferential Welds 4-inch Nominal Pipe Size or Larger For the core spray component CS4B-MF5 valve-to-pipe weld, the licensee stated that only 38.6% of the required examination volume was obtained in accordance with Appendix VIII requirements. The coverage reported represents the aggregate coverage of all scans performed. The licensee stated that scanning was limited due to the configuration of the pipe to valve which prevented scanning from both sides of the weld. In order to scan all of the required surfaces for the inspection of this weld, the pipe-to-valve would have to be redesigned to allow scanning from both sides of the weld, which is impractical. There were no recordable indications found during the inspection of this weld.
For the residual heat removal (RHR) components RH28-12 pipe-to-valve, RH29-10 valve-to-elbow and RH32-8 valve-to-pipe welds, the licensee stated that 82.5%, 82.1%, and 73.8% of the required examination volumes were obtained. These examinations were performed prior to the implementation of Appendix VIII requirements. The licensee stated that scanning was limited due to the configuration of the pipe-to-valve which prevented scanning from both sides of the welds. In order to scan all of the required surfaces for the inspection of these welds, the pipe-to-valve interfaces would have to be redesigned to allow scanning from both sides of the weld, which is impractical. There were no recordable indications found during the inspection of these welds.
Examination Category B-K, Integral Attachments for Piping, Pumps, and Valves Item B10.10, Integrally Welded Attachments - Piping The licensee was able to inspect 77.8% of the required surface area using PT of the subject eight lug welds. The examination was limited due to a pipe clamp on the bottom of the shear lugs. There were no recordable indications found during the examination of the lugs.
Examination Category B-O, Pressure-Retaining Welds in Control Rod Housings Item B14.10, Welds in CRD Housing - Reactor Vessel The licensee was able to inspect 85.2% of the required volume for the four subject control rod drive (CRD) welds using UT in accordance with ASME Code Section V. The examination was limited due to two 1-inch rods located 180E from each other around the CRD. The licensee provided drawings that show the obstruction which limits the inspection in both the perpendicular and parallel scans adjacent to the rods. In order to scan all of the required surfaces for the inspection of this weld, redesign would be required to allow scanning in the region of the rods, which is impractical. There were no recordable indications found during the inspection of these welds.
Examination Category C-A, Pressure-Retaining Welds in Pressure Vessels Item C1.10, Shell Circumferential Welds The licensee obtained a coverage of 80.2% during the ultrasonic examination of the RHR heat exchanger shell-to-flange weld A-HTEX 10-4. The examination was limited due to the flange geometry and 12 welded attachments. Substantial burden would be incurred to achieve additional coverage of the subject weld. Based on the coverage achieved, it is judged that patterns of degradation would have been detected. There were no recordable indications found during the inspection of the weld.
Examination Category C-C, Integral Attachments for Vessels, Piping, Pumps, and Valves Item C3.10, Pressure Vessel Integrally Welded Attachments The licensee obtained 80.1% of the required surface area using magnetic particle testing. The examination coverage was limited due to access between the vessel shell and the floor.
Substantial burden would be incurred to achieve additional coverage of the subject weld.
Examination Category C-F-2, Pressure-Retaining Welds in Carbon or Low Alloy Steel Piping Item C5.51, Circumferential Piping Welds The licensee obtained 84.5%, 79.8%, 79.0%, and 80.5% of the required examination volumes for welds CT27-S30, FW-17-S5, RH3D-S206, and RC3-S15, respectively, performed in accordance with Appendix VIII requirements. There were no indications of reportable size recorded for these welds. Based on the examination volumes obtained, it is judged that patterns of degradation would have been detected.
Class 3, Pipe-to-Flange Weld Augmented Examination for Intergranular Stress-Corrosion Cracking (NUREG-0313)
The licensee obtained 57.3% of the required examination volume for the pipe-to-flange weld CU54-16. The examination was performed in accordance with Appendix VIII requirements.
The examination was limited due to the flange configuration. The licensee believes that the examination performed would have detected any patterns of service-induced flaws.
In addition, the licensee performed Class 1, Examination Category B-P, pressure testing and VT-2 visual examinations to complement the limited scan examinations. The ASME Code requires that a pressure test be performed after each refueling outage for Class 1 components.
The pressure tests require a VT-2 visual examination for evidence of leakage. This testing provides adequate assurance of pressure boundary integrity.
In addition, the licensee performed Class 2, Examination Category C-H, pressure testing and VT-2 visual examination to complement the limited examination coverage. The ASME Code requires that a pressure test be performed once each period for Class 2 items. These tests require a VT-2 visual examination for evidence of leakage. This testing provides adequate assurance of pressure boundary integrity.
4.0 NRC STAFF EVALUATION The ASME Code,Section XI, 1986 Edition, requires volumetric and/or surface examination coverage of 100% of specific examination categories and item numbers. However, a reduction in examination coverage of less than 10% is acceptable due to interferences as provided in ASME Code Case N-460, Alternative Examination Coverage for Class 1 and Class 2 Welds which has been approved for use by the NRC in RG 1.147. The NRC staff has evaluated the information provided by the licensee in support of the limited volumetric or surface examinations of the subject welds identified in Table 1 as performed during the third 10-year ISI interval. The staff notes that the licensee provided, as part of its basis for relief, an argument based on a statistical study. This argument was included as Appendix A of the licensees letter dated October 1, 2003. At this time, the staff makes no judgement as to the acceptability of the statistical argument since the staffs review was not based, in any part, on the statistical study.
The NRC staff has determined that the examination coverage of the subject welds was reduced due to component configuration and geometries which restricted scanning. In order to meet the ASME Code requirements, the components would have to be redesigned, fabricated, and installed in the systems, which would impose a burden on the licensee. The licensee examined a significant portion of the subject welds. The extent of examination should have been able to identify any patterns of significant degradation. Therefore, the staff has determined that the
licensees limited examination coverage of the welds provide reasonable assurance of structural integrity. Based on the access limitations, it is impractical for the licensee to meet the ASME Code coverage requirements.
5.0 CONCLUSION
The NRC staff has reviewed the licensees submittal and has concluded that compliance with the ASME Code requirements for the volumetric or surface coverage of the subject welds is impractical due to component configurations. The staff has also determined that if the ASME Code requirements were to be imposed on the licensee, the components must be redesigned, which would impose significant burden on the licensee. The staff finds that the examination coverage of the accessible weld volume or area, as completed by the licensee, provides reasonable assurance of structural integrity of the subject welds. Therefore, relief is granted pursuant to 10 CFR 50.55a(g)(6)(i) for the third 10-year ISI interval of VYNPS. This granting of 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. All other ASME Code,Section XI requirements for which relief was not specifically requested and authorized herein by the NRC staff remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
Principal Contributor: A. Keim Date: September 19, 2005