ML072630427
| ML072630427 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 09/21/2007 |
| From: | Travis Tate NRC/NRR/ADRO/DORL/LPLIII-1 |
| To: | Balduzzi M Entergy Nuclear Operations |
| Poole Justin 301-415-2048 | |
| References | |
| TAC MD3165 | |
| Download: ML072630427 (11) | |
Text
September 21, 2007 Mr. Michael Balduzzi Sr. Vice President, Regional Operations NE Entergy Nuclear Operations, Inc.
440 Hamilton Avenue White Plains, NY 10601
SUBJECT:
PALISADES NUCLEAR PLANT - REQUEST RELIEF NO. 1 FROM REQUIREMENTS OF AMERICAN SOCIETY OF MECHANICAL ENGINEERS BOILER AND PRESSURE VESSEL CODE REQUIREMENTS FOR REPAIR OF PRESSURIZER NOZZLE PENETRATIONS (TAC NO. MD3165)
By letter to the Nuclear Regulatory Commission (NRC), dated September 15, 2006, as supplemented on July 31, 2007, Nuclear Management Company, LLC (NMC, the former licensee), submitted Relief Request (RR) Nos. 1 and 2 to support the repair of pressurizer heater sleeve nozzles at Palisades Nuclear Power Plant (PNP). In this regard, NMC requested relief from certain requirements in American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI. RR No. 1 requested authorization to use ASME Code Case N-638-1 when performing a temper bead weld process to install an outer diameter pad plug on pressurizer nozzle penetrations for repairs. RR No. 2 is related to the flaw evaluation of the weld and has been previously addressed in a separate correspondence, dated September 18, 2007.
The NRC staff has reviewed and evaluated the licensees submittal and concludes that the proposed alternative provides an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), the proposed alternative is authorized for the repair of the subject pressurizer nozzle penetrations for the remainder of the fourth 10-year inservice inspection interval at PNP.
Sincerely,
/Peter S. Tam for/
Travis Tate, Acting Chief Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No.: 50-255
Enclosure:
Safety Evaluation cc w/encl: See next page
Mr. Michael Balduzzi Sr. Vice President, Regional Operations NE Entergy Nuclear Operations, Inc.
440 Hamilton Avenue White Plains, NY 10601
SUBJECT:
PALISADES NUCLEAR PLANT - REQUEST RELIEF NO. 1 FROM REQUIREMENTS OF AMERICAN SOCIETY OF MECHANICAL ENGINEERS BOILER AND PRESSURE VESSEL CODE REQUIREMENTS FOR REPAIR OF PRESSURIZER NOZZLE PENETRATIONS (TAC NO. MD3165)
By letter to the Nuclear Regulatory Commission (NRC), dated September 15, 2006, as supplemented on July 31, 2007, Nuclear Management Company, LLC (NMC, the former licensee), submitted Relief Request (RR) Nos. 1 and 2 to support the repair of pressurizer heater sleeve nozzles at Palisades Nuclear Power Plant (PNP). In this regard, NMC requested relief from certain requirements in American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI. RR No. 1 requested authorization to use ASME Code Case N-638-1 when performing a temper bead weld process to install an outer diameter pad plug on pressurizer nozzle penetrations for repairs. RR No. 2 is related to the flaw evaluation of the weld and has been previously addressed in a separate correspondence, dated September 18, 2007.
The NRC staff has reviewed and evaluated the licensees submittal and concludes that the proposed alternative provides an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), the proposed alternative is authorized for the repair of the subject pressurizer nozzle penetrations for the remainder of the fourth 10-year inservice inspection interval at PNP.
Sincerely,
/Peter S. Tam for/
Travis Tate, Acting Chief Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No.: 50-255
Enclosure:
Safety Evaluation Distribution:
PUBLIC LPL3-1 R/F RidsNrrLATHarris RidsNrrPMMChawla RidsNrrDorlLpl3-1 RidsOgcRp RidsRgn3MailCenter TBloomer, EDO Region III RidsAcrsAcnwMailCenter ADAMS ACCESSION NO.: ML072630427
- per Memo dated September 17, 2007 OFFICE LPL3-1 LPL3-1/PM LPL3-1/LA CPNB/BC RLRC/BC OGC LPL3-1/(A)BC NAME JPoole MChawla THarris EW for TChan*
KChang RKM for MSmith (NLO)
TTate TSP for DATE 09/21/07 09/21/07 09/21/07 09/17/07 09/21/07 09/19/07 09/21/07 OFFICIAL RECORD COPY
Palisades Plant cc:
Supervisor Covert Township P. O. Box 35 Covert, MI 49043 Office of the Governor P. O. Box 30013 Lansing, MI 48909 U.S. Nuclear Regulatory Commission Resident Inspector's Office Palisades Plant 27782 Blue Star Memorial Highway Covert, MI 49043 Michigan Department of Environmental Quality Waste and Hazardous Materials Division Hazardous Waste and Radiological Protection Section Nuclear Facilities Unit Constitution Hall, Lower-Level North 525 West Allegan Street P.O. Box 30241 Lansing, MI 48909-7741 Michigan Department of Attorney General Special Litigation Division 525 West Ottawa St.
Sixth Floor, G. Mennen Williams Building Lansing, MI 48913 Mr. Michael R. Kansler President & CEO/CNO Entergy Nuclear Operations 1340 Echelon Parkway Jackson, MS 39213 Mr. John T. Herron Sr. Vice President Entergy Nuclear Operations 1340 Echelon Parkway Jackson, MS 39213 Sr. Vice President, Engineering and Technical Services Entergy Nuclear Operations, Inc.
1340 Echelon Parkway Jackson, MS 39213 Mr. Christopher J. Schwarz Site Vice President Entergy Nuclear Operations Palisades Nuclear Plant 27780 Blue Star Memorial Highway Covert, MI 49043 General Manager, Plant Operations Entergy Nuclear Operations Palisades Nuclear Plant 27780 Blue Star Memorial Highway Covert, MI 49043 Mr. Oscar Limpias Vice President, Engineering Entergy Nuclear Operations 1340 Echelon Parkway Jackson, MS 39213 Mr. John F. McCann Director, Nuclear Safety & Licensing Entergy Nuclear Operations 440 Hamilton Avenue White Plains, NY 10601 Ms. Charlene D. Faison Manager, Licensing Entergy Nuclear Operations 440 Hamilton Avenue White Plains, NY 10601 Mr. Ernest J. Harkness Director, Oversight Entergy Nuclear Operations 1340 Echelon Parkway Jackson, MS 39213
Mr. William C. Dennis Assistant General Counsel Entergy Nuclear Operations 440 Hamilton Avenue White Plains, NY 10601 Mr. Joseph P. DeRoy VP, Operations Support Entergy Nuclear Operations, Inc.
1340 Echelon Parkway Jackson, MS 39213 Ms. Laurie A. Lahti Manager, Licensing Palisades Nuclear Plant 27780 Blue Star Memorial Highway Covert, MI 49043 Mr. John A. Ventosa GM, Engineering Entergy Nuclear Operations 440 Hamilton Aveune White Plains, NY 10601 Director, NSA Palisades Nuclear Plant 27780 Blue Star Memorial Highway Covert, MI 49043 Mr. William DiProfio 48 Bear Hill Road Newton, NH 03858 Mr. William T. Russell 400 Plantation Lane Stevensville, MD 21666 Mr. Gary Randolph 1750 Ben Franklin Drive, 7E Sarasota, FL 34246
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST NO. 1 FOR ALTERNATIVE REPAIR TECHNIQUE ON PRESSURIZER HEATER SLEEVE PENETRATIONS PALISADES NUCLEAR POWER PLANT ENTERGY NUCLEAR OPERATION, INC.
DOCKET NUMBERS 50-255
1.0 INTRODUCTION
By letter to the Nuclear Regulatory Commission (NRC), dated September 15, 2006, Nuclear Management Company, LLC (NMC, the former licensee) submitted Relief Request (RR) No. 1 regarding relief from certain requirements of American Society of Mechanical Engineers Boiler and Pressure Vessel (ASME) Code,Section XI, for the repair of pressurizer nozzle penetrations at Palisades Nuclear Plant (PNP). Specifically, NMC proposed to use, as an alternative, ASME Code Case N-638-1, Similar and Dissimilar Metal Welding Using Ambient Temperature Machine Gas Tungsten Arc Welding (GTAW) Temper Bead Technique,Section XI, Division 1, with one exception, for the repair. This alternative would be used in lieu of the requirements contained in the 2001 Edition through 2003 Addenda of the ASME Code,Section XI, IWA-4220. The proposed alternative will be utilized to perform welding of an outer diameter pad plug design on pressurizer heater sleeve penetrations.
The NRC requested additional information by letter dated June 15, 2007. A teleconference between the NRC staff and Entergy Nuclear Operations, Inc. (ENO, the current licensee), was held on July 17, 2007, to discuss the RR. By letter dated July 31, 2007, ENO provided response to the NRC staffs request for additional information (RAI).
The September 15, 2006, NMC letter also requested approval of RR No. 2. The results of the NRC staff review of RR No. 2 will be provided in a separate safety evaluation (SE).
2.0 REGULATORY EVALUATION
Pursuant to Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Section 50.55a(g)(4),
ASME Code Class 1, 2, and 3 components (including supports) must 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.
ENCLOSURE 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 ASME Code of Record for the current, third 10-year ISI interval at PNP is the 2001 Edition through 2003 Addenda ASME Code,Section XI.
Pursuant to 10 CFR 50.55a(a)(3), alternatives to requirements may be authorized by the NRC if the licensee demonstrates that: (i) the proposed alternatives 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.
3.0 PROPOSED ALTERNATIVE RELIEF REQUEST NO. 1 3.1
Reason for Request
The licensee is developing a repair plan that does not involve post-weld heat treatment (PWHT).
Therefore, the licensee requested relief from ASME Code,Section XI, IWA-4220, because repairs made in accordance with the original construction Code (ASME Code, Section Ill), as allowed per IWA-4220, would require PWHT at elevated temperatures.
ASME Code, Section Ill, Article 5, would require an 1100 °F minimum PWHT. ASME Code,Section XI, IWA-4610, eliminates the high temperature PWHT, but still requires a 300 °F preheat. PWHT or preheat of the pressurizer is impractical due to its size and location.
3.2 ASME Code Component Affected The affected components are the PNP pressurizer vessel heater sleeves. The PNP pressurizer has 120 heater sleeves penetrating the bottom head. The pressurizer assembly was fabricated in accordance with the ASME Code, Section Ill, Class A components.
3.3
Applicable Code Edition and Addenda
The applicable code edition and addenda for the pressurizer vessel heater sleeve repair is the ASME Code,Section XI, 2001 Edition through 2003 Addenda.
The original construction Code of Record for the PNP pressurizer vessel is ASME Code, Section Ill, Class A, 1965 Edition, including addenda through winter 1965.
ASME Code,Section XI, IWA-4220, CODE APPLICABILITY, established the requirements for code usage for repair/replacements.
3.4 Proposed Alternative and Basis The licensee requested to use ASME Code,Section XI, Code Case N-638-1, Similar and Dissimilar Metal Welding Using Ambient Temperature Machine Gas Tungsten Arc Welding (GTAW) Temper Bead Technique, with one exception, as a proposed alternative to the requirements of ASME Code Section XI, IWA-4220.
ASME Code Case N-638-1 has been conditionally accepted and approved for use by the NRC per Regulatory Guide 1.147, Inservice Inspection Code Case Acceptability-ASME Code,Section XI, Division 1, Revision 14. ASME Code Case N-638-1 permits the use of the ambient temperature machine GTAW temper bead technique for pressurizer heater sleeve nozzle repairs. This technique does not require PWHT. The proposed repair method is described in of RR No. 1 and is generally described in paragraph 3.4.1 below. The licensee proposed one exception to the ASME Code Case N-638-1. The exception is described as follows:
ASME Code Case N-638-1 Examination Volume ASME Code Case N-638-1, section 4.0(b), requires that the final weld, and the band around the area defined in paragraph 1.0(d), shall be examined using surface and ultrasonic inspection methods when the completed weld has been at ambient temperature for at least 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. ASME Code Case N-638-1, section 1.0(d), defines this inspection requirement as the area to be welded, and a band around the area, of at least 1-1/2 times the component thickness, or five inches, whichever is less. The vessel thickness at the lower head is nominally 4-1/8-inch. Application of this ASME Code Case N-638-1 requirement would require an examination area including the weld pad area and an area extending five inches around the weld pad area. The weld pad has square dimensions of approximately 3-1/4-inches on a side. Adding the examination area of five additional inches around provides a total area defined by a square of dimensions of approximately 13-1/4-inches x 13-1/4-inches. Other pressurizer penetrations would interfere with ASME Code Case N-638-1 defined area.
As a modification to the ASME Code Case N-638-1 requirement, the licensee proposes to use the examination area defined by ASME Code,Section III, 2001 Edition through 2003 Addenda, NB-5244, "Weld Buildup Deposits at Openings for Nozzles, Branch, and Piping Connections." This area consists of the weld metal buildup, the fusion zone and the parent metal beneath the weld metal buildup. The licensee planned to examine the entire weld buildup pad area using liquid penetrant (PT) and ultrasonic (UT) examinations. A complete description of the inspection plan, including the acceptance criteria, is provided in Attachment 1 of RR No. 1.
Based on the above, the licensee concluded that the proposed alternative would provide an acceptable level of quality and safety, pursuant to 10 CFR 50.55a(a)(3)(i).
3.4.1 Pressurizer Heater Sleeve Nozzle Proposed Repair and Inspection Plan:
The licensee is developing a repair plan based on the use of an outer diameter pad plug. The licensee is planning to design the repair in accordance with the requirements of ASME Code, Section Ill. The need for this ASME Code, Section Ill, design analysis is contingent on the results of the pressurizer inspection. If a repair is necessary, the licensee planned to perform the ASME Code, Section Ill, design analysis. The licensee is not requesting relief from any ASME Code, Section Ill requirement. Therefore, the structural and leakage integrity of the primary system pressure boundary would be maintained by the repaired heater sleeve design. The general repair approach consists of the following steps:
Step 1 - Cutting the existing Alloy 600 nozzle outboard of the J-groove weld:
See Figure 1 of Attachment 1 to RR No. 1 for the pressurizer heater sleeve penetration configuration.
Step 2 - Perform Examination of Pressurizer Base Material:
Perform surface examination of the base material prior to weld buildup. The surface examination would be evaluated to the 2001 Edition through 2003 Addenda of ASME Code,Section III, NB-5350.
Perform UT examination of the base material prior to weld buildup. The UT examination would be evaluated in accordance with the 2001 Edition through 2003 Addenda of ASME Code,Section III, NB-3532.1(b)(1).
Step 3 - Replace the Removed Nozzle Portion with an Alloy 690 Backing Plug:
Tack weld shall be applied to hold the plug in place prior to installing the weld pad over the plug. The acceptance of the plug material is to be demonstrated in an ASME Code, Section Ill compliance analysis should a repair be necessary.
Step 4 - Install a Welded Pad of Weld Metal Over the Nozzle Opening and Backing Plug:
A welded pad of Alloy 52/152 would be deposited over the nozzle opening and backing plug using the ambient temper bead method of ASME Code Case N-638-1. The weld buildup pad has a minimum thickness of 0.25 inches, and is a square pad with a half width of 1.584 inches minimum, excluding the taper transition area to the pressurizer surface. See Figure 2 of Attachment 1 to RR No. 1 for proposed weld pad configuration.
Step 5 - Perform Nondestructive Examination (NDE) of Welded Pad:
Preservice inspection would be performed using PT and UT examination after the completed weld has been at ambient temperature for at least 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. The examination area is defined in ASME Code,Section III, 2001 Edition through 2003 Addenda, NB-5244, which consists of the weld buildup surface for PT examination and the weld buildup fusion zone-to-parent metal ensuring freedom from lack of fusion and laminar defects for UT examination.
The acceptance standards for the welded pad are ASME Code,Section III, 2001 Edition through 2003 Addenda, NB-5350, for the PT examination and ASME Code, Section Ill, 2001 Edition through 2003 Addenda, NB-5330, for the UT examination. Future inservice inspection of the welded pad would be performed each refueling outage using the VT-2 examination technique. Acceptance criteria will be ASME Code,Section XI, 2001 Edition through 2003 Addenda, IWB-3522.
3.4.2 Duration of the Proposed Request The licensee requested approval of the proposed alternative for the remainder of the fourth 10-year interval of the ISI program for PNP, which will conclude on or before December 13, 2015.
4.0 STAFF EVALUATION The licensee planned to implement a Welding Services Incorporated/Structural Integrity Associates outer diameter pad plug design should a repair be necessary during pressurizer inspection at PNP. In support of the proposed repair, the licensee requested relief from the applicable ASME Code,Section XI requirements. ASME Code,Section XI requires repairs that are performed in accordance with the original construction code (ASME Code,Section III) utilize a PWHT at elevated temperature. ASME Code,Section XI, requirements eliminate the need for PWHT; however, it still requires an elevated temperature preheat. The licensee requested relief from the requirements of PWHT and elevated preheat by proposing the use of ASME Code Case N-638-1. Typically, elevated preheat and PWHT are used to mitigate the effects of hydrogen embrittlement cracking due to the presence of excessive atomic hydrogen in ferritic materials. The machine GTAW temper bead process uses a welding process that is inherently free of hydrogen. The GTAW process relies on bare welding electrodes and bare wire filler metal with no flux to trap moisture. An inert gas blanket provides shielding for the weld and surrounding metal, which protects the region during welding from the atmosphere and the moisture it may contain and typically produces porosity free welds.
To further reduce the likelihood of any hydrogen evolution or absorption, specific controls will be used to ensure the welding electrodes, filler metal, and weld region are free of all sources of hydrogen. The licensee stated that base material cleanliness will be ensured by removing the mill scale (i.e., a loose layer of ferritic oxide) within several inches in and around the sleeve penetrations. Magnetic particle testing will be performed followed by PT on the pressurizer surface and the inside of the sleeve bore. All surfaces would be cleaned with an acceptable residue-free solvent to remove all surface grit and contaminants. Qualified NDE and welding personnel would clean, inspect and monitor the work to ensure that the annulus and weld region over and around the plug are free from potential sources of hydrogen or contaminants before and during the welding process. In addition, a surface and UT examination will be performed of the base metal prior to weld buildup. Any indications identified during examination of the base metal would be evaluated and/or repaired in accordance with ASME Code,Section XI, 2001 Edition through 2003 Addenda requirements.
The licensee stated that contact pyrometers would be used to verify preheat and interpass temperatures in accordance with ASME Code Case N-638-1, Sections 1.0(d) and 3.0(d). The interpass temperature will be measured every three to five passes on the first three weld layers and every six to ten passes on subsequent layers. Heat input beyond the third layer will not have a metallurgical affect on the low alloy steel heat-affected zone (HAZ). Thermocouples are not planned for use in repairs at PNP.
Research shows that carefully controlled heat input and bead placement allow subsequent welding passes to relieve stress and temper the HAZ of the base material. The use of the machine GTAW temper bead process will allow precise control of heat input, bead placement, bead size, and contour as compared to the SMAW process. Very precise control over these factors afforded by the machine GTAW process provides effective tempering of the HAZ.
Research and numerous procedure qualification tests performed on ASME base material category P-No. 3, Group No. 3, by the industry have shown that acceptable weld quality and HAZ impact toughness can be obtained using machine GTAW, ambient preheat, three controlled temper bead layers, and no PWHT.
The licensee stated it would meet the specified ASME Code Case N-638-1 conditional requirement as follows: UT examinations shall be demonstrated for the repaired volume using representative samples which contain construction type flaws. The acceptance criteria of NB-5330 of Section III edition and addenda approved in 10 CFR 50.55a apply to all flaws identified within the repaired volume. However, they could not meet the requirement for final weld examination area as specified in section 4.0(b) of ASME Code Case N-638-1 due to component interferences. Section 4.0(b) requires that the final weld, and the band around the area defined in section 1.0(d) shall be examined using surface and UT methods when the completed weld has been at ambient temperature for a minimum of 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. The area to be examined is defined in section 1.0(d) as the area to be welded and a band around the area of at least 1.5 times the component thickness or five inches, whichever is less. Application of this ASME Code Case N-638-1 requirement would require an examination area of approximately 175 square inches. The location of adjacent pressurizer penetrations would interfere with ASME Code Case N-638-1 defined area. Due to the configuration of the weld pad repair, NMC proposed to use the examination area defined by ASME Code,Section III, 2001 Edition through 2003 Addenda, subsection NB-5244, Weld Buildup Deposits at Openings for Nozzles, Branch, and Piping Connections. This area consists of the weld metal buildup, the fusion zone and the parent metal beneath the weld metal buildup. The licensee proposed to examine the entire weld buildup pad area using PT and UT examinations.
ASME Code Case N-638-1 was originally written to be applied to the repair of partial and full penetration groove welds. However, nothing in ASME Code Case N-638-1 precludes its use in other applications, such as the current NMC proposed application of an alloy 52/152 weld pad deposited over an outer diameter plug of alloy 690 and the pressurizer alloy steel base metal.
The welding principles involved and application of the weld filler metal are the same as for a groove weld design. When performing a full penetration groove weld between two pieces of thick low alloy steel (over 1-inch thick) using a low alloy steel filler metal, there can be significant residual stresses built up in the base metal from contraction of the weldment. These stresses can cause distortion and cracking of the base metal a significant distance from the weld groove.
To make certain that these types of defects do not remain in the weld area away from the weld groove, the code has extended the area of the NDE well into the base metal.
The weld pad filler metal specified for the subject repair is nickel based Alloy 52/152 and will be applied as a weld buildup using a GTAW temper bead process centered on the existing nozzle opening overlapping the installed backing plug. The Alloy 52 filler metal is more ductile than the pressurizer low alloy steel base metal. The thickness of weld pad is 0.25-inches, much less than the 4.125-inch pressurizer lower head nominal thickness. The weld pad is a relatively small square design approximately 3-inches per side not counting the tapered transition. Therefore, the residual stress built up in the base metal as a result of weldment contraction will be much less than that from a full penetration groove weld. Because this is a surface application utilizing the temper bead process, there will be minimal impact to the volume of metal in the area surrounding the weld. Since this weld is applied to the exterior surface of the pressurizer vessel, there is no additional useful information that can be gained by extending a volumetric examination beyond the adjacent area surrounding the weld.
Moreover, a preservice PT and UT examination will be performed. The PT examination will inspect the weld pad surface whereas the UT examination will inspect the full weld pad thickness including the weld pad fusion zone-to-parent metal. This UT examination will ensure freedom from lack of fusion and laminar defects so the structural integrity of the pressurizer is not adversely affected. Based on the above evaluation, the staff has determined that the proposed alternative for the repair of pressurizer heater sleeve penetrations is acceptable because it provides an acceptable level of quality and safety.
5.0 CONCLUSION
Based on the information provided in the licensees submittal and RAI response, the NRC staff has determined that the licensees proposed alternative is acceptable because it provides an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), the proposed alternative is authorized for the repair of pressurizer vessel nozzle penetrations for the remainder of the fourth 10-year interval of the ISI program at PNP.
All other ASME Code,Section XI requirements for which relief was not specifically requested and approved in this relief request remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
Principal contributor: D. Tarantino, NRR Date: September 21, 2007