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MONTHYEARET 10-0019, CFR 50.55a Request for Alternative to ASME Code Case N-579, Use of Nonstandard Nuts, Class 1, 2, and 3, Mc, CS Components and Supports Construction Section III, Division 1.2010-06-10010 June 2010 CFR 50.55a Request for Alternative to ASME Code Case N-579, Use of Nonstandard Nuts, Class 1, 2, and 3, Mc, CS Components and Supports Construction Section III, Division 1. Project stage: Request ML1020400142010-07-23023 July 2010 Acceptance Review, Request for Alternative to ASME Code Case N-579, Use of Nonstandard Nuts, Class 1, 2, and 3, Mc, CS Components and Supports Construction, Section III, Division 1. Project stage: Acceptance Review ML1029901322010-11-18018 November 2010 Request for Alternative to ASME Code Case N-579 on Use of Nonstandard Hydraulic Nuts on the Excess Letdown Heat Exchanger Project stage: Other 2010-06-10
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Category:Letter
MONTHYEARML24025A0992024-01-25025 January 2024 Withdrawal of Request for Exemption from Specific 10 CFR Part 73 Requirements ML24018A0792024-01-22022 January 2024 Individual Notice of Consideration of Issuance of Amendment to Renewed Facility Operating License, Proposed Nshcd and Opportunity for a Hearing (EPID L-2024-LLA-0007) (Letter) ML24018A1382024-01-18018 January 2024 Inservice Inspection Request for Information ML24018A2482024-01-18018 January 2024 License Amendment Request to Modify the Implementation Date of License Amendment No. 238 IR 05000482/20230042024-01-11011 January 2024 Integrated Inspection Report 05000482/2023004 ML23356A0722024-01-0404 January 2024 Supplemental Information Needed for Acceptance of Requested Licensing Actions Exemption from Specific 10 CFR Part 73N Requirements (EPID L-2023-LLE-0048) (Redacted Version) WO 23-0002, Operating Corp., Summary of Actions Implemented for EA-18-165, Confirmatory Order, NRC Inspection Report 05000482/2019010 and NRC Investigation Report 4-2018-0082023-12-26026 December 2023 Operating Corp., Summary of Actions Implemented for EA-18-165, Confirmatory Order, NRC Inspection Report 05000482/2019010 and NRC Investigation Report 4-2018-008 ML23348A3662023-12-18018 December 2023 Notification of an NRC Fire Protection Baseline Inspection (NRC Inspection Report 05000482 2024012) and Request for Information ML23334A2502023-11-30030 November 2023 Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation ML23299A2662023-11-29029 November 2023 Issuance of Amendment No. 238 Modified Implementation Date of License Amendment No. 237 ML23331A4972023-11-27027 November 2023 Supplement to License Amendment Request to Modify the 90-Day Implementation of License Amendment No. 237 ML23325A2112023-11-20020 November 2023 Submittal of Request for Exemption from Specific Provisions in 10 CFR 73.55 ML23320A2772023-11-16016 November 2023 License Amendment Request to Revise Ventilation Filter Testing Program Criteria in Technical Specification 5.5.11.b and Administrative Correction of Absorber in Technical Specification 5.5.11 ML23311A2082023-11-0909 November 2023 Reassignment of U.S. Nuclear Regulatory Commission Branch Chief in the Division of Operating Reactor Licensing for Plant Licensing Branch IV ML23305A3472023-11-0101 November 2023 Revision of One Form That Implements the Radiological Emergency Response Plan (RERP) ML23292A3592023-10-19019 October 2023 License Amendment Request to Modify the 90-Day Implementation of License Amendment No. 237 ML23292A3572023-10-19019 October 2023 Operating Corporation, Request for Correction in Response to Issuance of Amendment No. 237 and Corresponding Safety Evaluation ML23277A2772023-10-11011 October 2023 Regulatory Audit Summary Concerning Review of Request Number CI3R-01 for Proposed Alternative Inspection Frequency for Containment Unbonded Post Tensioning System Components ML23284A2392023-10-11011 October 2023 NRC Initial Operator Licensing Examination Approval 05000482/2023301 ML23276B4552023-10-0303 October 2023 Technical Specification 5.6.8 Post Accident Monitoring (PAM) Report ML23264A8682023-09-21021 September 2023 Independent Spent Fuel Storage Installation Registration of Dry Storage Canister WC-EOS-37PTH-008-B4L, WC-EOS-37PTH-007-B4L, and WC-EOS-37PTH-002-B4L ML23256A2062023-09-14014 September 2023 Withdrawal of Requested Licensing Action Exemption from Specific 10 CFR Part 73 Requirements ML23165A2502023-08-31031 August 2023 Issuance of Amendment No. 237 Request for Deviation from Fire Protection Requirements ML23243A0002023-08-31031 August 2023 Wolf Generating Station - Withdrawal of Request for Exemption from Specific 10 CFR Part 73 Requirements IR 05000482/20230052023-08-23023 August 2023 Updated Inspection Plan for Wolf Creek Nuclear Operating Corporation, Unit 1 (Report 05000482/2023005) - Mid-Cycle Letter 2023 ML23232A0012023-08-19019 August 2023 Revision of One Procedure That Implements the Radiological Emergency Response Plan (Rerp). Includes EPP 06-009, Rev. 13 ML23221A3932023-08-0909 August 2023 Submittal of Request for Exemption from Specific 10 CFR Part 73 Requirements ML23220A4222023-08-0808 August 2023 Supplement to License Amendment Request (LAR) for Deviation from Fire Protection Program Requirements ML23201A1212023-08-0707 August 2023 Issuance of Amendment No. 236 Revision to Technical Specifications to Adopt TSTF-554, Revise Reactor Coolant Leakage Requirements ML23130A2902023-07-26026 July 2023 Issuance of Amendment No. 235 Revision to Technical Specifications to Adopt TSTF-577, Revised Frequencies for Steam Generator Tube Inspections IR 05000482/20230022023-07-11011 July 2023 Integrated Inspection Report 05000482/2023002 ML23167A0042023-06-26026 June 2023 Audit Plan to Support Review of Request for Alternative Containment Inservice Inspection Frequency IR 05000482/20234012023-06-21021 June 2023 Security Baseline Inspection Report 05000482/2023401 ML23171B1312023-06-20020 June 2023 Additional Supplement to License Amendment Request to Adopt TSTF-577-A, Revision 1, Revised Frequencies for Steam Generator Tube Inspections ML23151A4162023-05-31031 May 2023 Revision of One Form That Implements the Radiological Emergency Response Plan (RERP) for Wolf Creek Generating Station (WCGS) ET 23-0006, CFR 50.55a Request Number CI3R-01 for the Third Containment Inservice Inspection Program Interval for Proposed Alternative Frequency to Containment Unbonded Post-Tensioning System Components2023-05-17017 May 2023 CFR 50.55a Request Number CI3R-01 for the Third Containment Inservice Inspection Program Interval for Proposed Alternative Frequency to Containment Unbonded Post-Tensioning System Components WO 23-0014, Response to NRC Regulatory Issue Summary 2023-01, Preparation and Scheduling of Operator Licensing Examinations2023-05-17017 May 2023 Response to NRC Regulatory Issue Summary 2023-01, Preparation and Scheduling of Operator Licensing Examinations ML23132A1532023-05-12012 May 2023 Transmittal of 2022 Annual Financial Reports WM 23-0009, Financial Assurance Requirements for Decommissioning Nuclear Power Reactors 10 CFR 50.75(f)(1)2023-05-10010 May 2023 Financial Assurance Requirements for Decommissioning Nuclear Power Reactors 10 CFR 50.75(f)(1) ML23135A1172023-05-0808 May 2023 Redacted Version of Revision 36 to Updated Safety Analysis Report ML23117A2112023-04-27027 April 2023 Annual Exposure Report (2022) ML23117A1342023-04-27027 April 2023 2022 Annual Radioactive Effluent Release Report Report 46 2024-01-04
[Table view] Category:Safety Evaluation
MONTHYEARML23299A2662023-11-29029 November 2023 Issuance of Amendment No. 238 Modified Implementation Date of License Amendment No. 237 ML23256A2882023-09-20020 September 2023 Authorization and Safety Evaluation for Alternative Request No. I4R-08 ML23165A2502023-08-31031 August 2023 Issuance of Amendment No. 237 Request for Deviation from Fire Protection Requirements ML23201A1212023-08-0707 August 2023 Issuance of Amendment No. 236 Revision to Technical Specifications to Adopt TSTF-554, Revise Reactor Coolant Leakage Requirements ML23130A2902023-07-26026 July 2023 Issuance of Amendment No. 235 Revision to Technical Specifications to Adopt TSTF-577, Revised Frequencies for Steam Generator Tube Inspections ML22252A1512022-11-0404 November 2022 Issuance of Amendment No. 234 Diesel Generator Completion Time Extension for Technical Specification 3.8.1, AC Sources - Operating ML22199A2942022-08-16016 August 2022 Issuance of Amendment No. 233 Removal of Table of Contents from the Technical Specifications ML22069A0562022-05-18018 May 2022 Issuance of Amendment No. 232 Regarding Revision to the Emergency Plan Related to On-Shift Staffing ML22021B5982022-02-23023 February 2022 Issuance of Amendment No. 231 Revision of Technical Specification 3.3.2, Engineered Safety Feature Actuation System (ESFAS) Instrumentation ML21210A2472021-09-0303 September 2021 Issuance of Amendment No. 230 Revision of Technical Specification 3.6.3 and Surveillance Requirement 3.6.3.1 to Allow Use of a Blind Flange ML21095A1922021-07-20020 July 2021 Issuance of Amendment No. 229 Change to Owner Licensee Names ML21061A0782021-04-23023 April 2021 Issuance of Amendment No. 228 Regarding Replacement of Engineered Safety Features Transformers with New Transformers That Have Active Automatic Load Tap Changers ML21053A1172021-04-0808 April 2021 1 - Issuance of Amendment No. 227 TS Change Risk-Informed Justification for the Relocation of Specific Surveillance Frequency Requirements to a Licensee Controlled Program Based on TSTF-425 ML20276A1492020-12-0707 December 2020 Issuance of Amendment No. 226 Extension of Type a and Type C Leak Rate Test Frequencies ML20302A0802020-10-30030 October 2020 Request to Use a Provision of a Later Edition of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Section XI ML20111A3372020-04-27027 April 2020 Request from Relief from Requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code Case N-666-1 ML19353C5002020-02-27027 February 2020 Issuance of Amendment No. 224 Revision to Technical Specification 3.3.5, - Loss of Power (LOP) Diesel Generator (DG) Start Instrumentation, - ML19291A0182019-11-12012 November 2019 Request for Relief I4R-07, Utilize Code Case N-513-4 - Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping of American Society of Mechanical Engineers Boiler and Pressure Code Section XI ML19182A3452019-08-19019 August 2019 Issuance of Amendment No 222 Revise Technical Specifications to Adopt TSTF Traveler TSTF-529, Clarify Use and Application Rules ML19100A1222019-05-31031 May 2019 Issuance of Amendment No. 221 License Amendment Request for Transition to Westinghouse Core Design and Safety Analyses Including Adoption of Alternative Source Term ML19052A5462019-04-0101 April 2019 Issuance of Amendment No. 220 Revision to the Emergency Plan ML18334A0132018-12-12012 December 2018 Request for Relief from the Requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Code Case N-666-1 ML18283A0492018-10-18018 October 2018 Request for Relief I4R-6 from ASME Code Visual Examination Requirements for Reactor Vessel Head Penetration Nozzle Weld Specified by Code Case N-729-4 ML18040A6662018-03-12012 March 2018 Letter, Order, and Safety Evaluation Order Approving Indirect Transfer of Control of Renewed Facility Operating License No. NPF-42 ML17166A4092017-08-28028 August 2017 Issuance of Amendment No. 218, Request to Adopt Emergency Action Level (EAL) Scheme Pursuant to Nuclear Energy Institute (NEI) 99-01, Revision 6 ML17144A0092017-08-0202 August 2017 Safety Evaluation Regarding Implementation of Mitigating Strategies and Reliable Spent Fuel Pool Instrumentation Related to Orders EA-12-049 and EA-12-051 ML17202E9192017-08-0202 August 2017 Relief Request 14R-05 from Certain Pressure Test Requirements of the ASME Code for Reactor Pressure Vessel Leak-Off Lines for the Fourth 10 Year Inservice Inspection Interval ML17024A2412017-03-24024 March 2017 Issuance of Amendment No. 217 Revision to the Cyber Security Plan Implementation Schedule ML16320A0322016-11-30030 November 2016 Request for Relief I4R-, Alternative Risk-Informed Methodology in Selecting Class 1 and 2 Piping Welds, for the Fourth 10-Year Inservice Inspection Interval ML16179A2932016-08-0303 August 2016 Issuance of Amendment No. 216, Revise Technical Specification (TS) 4.2.1 and TS 5.6.5 to Allow Use of Optimized Zirlo as Approved Fuel Rod Cladding ML16179A4432016-08-0202 August 2016 Safety Evaluation, Request for Exemption from 10 CFR 50.46 and Appendix K to Allow Use of Optimized Zirlo as Approved Fuel Rod Cladding ML16081A1942016-04-15015 April 2016 Issuance of Amendment No. 215, Revise Technical Specification 3.8.1, AC Sources - Operating, Surveillance Requirements 3.8.1.10 and 3.8.1.14 Consistent with TSTF-276-A, Revise DG Full Load Rejection Test ML15183A0522015-09-11011 September 2015 Issuance of Amendment No. 214, Request to Revise Fire Protection Program Related to Alternative Shutdown Capability as Described in Updated Safety Analysis Report ML15203A0052015-08-28028 August 2015 Redacted, Issuance of Amendment No. 213, Revise Technical Specification 5.6.5, Core Operating Limits Report (Colr), for Large-Break Loss-of-Coolant Accident Analysis Methodology (Astrum) ML15169A2132015-07-28028 July 2015 Issuance of Amendment No. 212, Revise Technical Specifications to Adopt TSTF-523, Revision 2, Generic Letter 2008-01, Managing Gas Accumulation ML15190A2022015-07-13013 July 2015 Relief Request 13R-12, Extension of the Third Inservice Inspection Program Interval to Perform Reactor Vessel Stud Hole Ligament Examinations ML15134A0022015-05-15015 May 2015 Relief Request Nos. 4PR-01 and 4PR-02 and Withdrawal of 4VR-02, Alternative to Requirements of ASME Code Case OMN-21 and OM Code ISTB-3510(b)(1) for Pumps, Fourth 10-Year Inservice Testing Program ML15040A0202015-02-12012 February 2015 Relief Request I3R-10, Alternative from Pressure Test Requirements of ASME Code, Section XI, IWC-5220, Third 10-Year Inservice Inspection Interval ML15023A2202015-01-28028 January 2015 Relief Request 13R-11, Alternative from Pressure Test Requirements of ASME Code Section XI IWC-5220 for the Third 10-Year Inservice Inspection Interval ML14321A8642014-12-10010 December 2014 Relief Requests 13R-08, Reactor Pressure Vessel (RPV) Interior Attachments and 13R-09, RPV Pressure-Retaining Welds, Exam Interval Extensions, Third 10-year Inservice Inspection Interval ML14209A0232014-08-14014 August 2014 Issuance of Amendment No. 210, Modify License Condition Related to Approval of Revised Cyber Security Plan Implementation Milestone 8 Completion Date ML14156A2462014-08-0707 August 2014 Issuance of Amendment No. 209, Revise Technical Specification 5.6.5, Core Operating Limits Report (Colr), to Replace Westinghouse Methodologies ML14157A0822014-07-0101 July 2014 Issuance of Amendment No. 208, Adopt TSTF-522-A, Revision 0, Revise Ventilation System to Operate for 10 Hours Per Month, Using Consolidated Line Item Improvement Process ML13282A5342013-12-0606 December 2013 Issuance of Amendment No. 207, Revise Technical Specification 3.4.12, Low Temperature Overpressure Protection (LTOP) System, to Reflect Mass Input Transient Analysis ML13282A1472013-12-0202 December 2013 Issuance of Amendment No. 206, Revise Technical Specification 3.8.1, AC Sources - Operating, Surveillance Requirement 3.8.1.10 to Increase Voltage Limit for Diesel Generator Load Rejection Test ML13197A2102013-08-23023 August 2013 Issuance of Amendment No. 205, Revise Fire Protection License Condition and the Updated Safety Analysis Report for a Deviation from Appendix R for Volume Control Tank Outlet Valves ML13109A2342013-07-12012 July 2013 Safety Evaluation Regarding Wolf Creek Generating Station - Loss of Offsite Power and Augmented Inspection, Issue for Resolution 2012-004 ML13149A1712013-06-0303 June 2013 Safety Assessment in Response to Information Request Pursuant to 10 CFR 50.54(f) - Recommendation 9.3 Communications Assessment ML13078A1552013-03-20020 March 2013 License Amendment Request to Change Diesel Generator Surveillance Requirements ML12353A2412013-01-0404 January 2013 Relief Request I3R-07 from ASME Code Case N-729-1 for Examination of Reactor Vessel Head Penetration Welds, for Remainder of Third 10-Year Inservice Inspection Interval 2023-09-20
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 November 18, 2010 Mr. Matthew W. Sunseri President and Chief Executive Officer Wolf Creek Nuclear Operating Corporation Post Office Box 411 Burlington, KS 66839
SUBJECT:
WOLF CREEK GENERATING STATION - REQUEST FOR ALTERNATIVE TO ASME CODE CASE N-579 ON USE OF NONSTANDARD HYDRAULIC NUTS ON THE EXCESS LETDOWN HEAT EXCHANGER (TAC NO. ME4075)
Dear Mr. Sunseri:
By letter dated June 10, 2010, Wolf Creek Nuclear Operating Corporation (the licensee) proposed an alternative to the requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section III, Code Case N-579, "Use of Nonstandard Nuts, Class 1, 2, and 3, MC, CS Components and Supports Construction,Section III, Division 1." The licensee plans to replace the channel head flange bolting of the Excess Letdown Heat Exchanger under the ASME Code,Section XI in the third 10-year inservice inspection interval (lSI) during the refueling outage 18 at Wolf Creek Generating Station (WCGS). The licensee has requested relief from use of the material specified in Code Case N-579 for the hydraulic nuts and conformance of thread configuration to ASME B1.1.
The U.S. Nuclear Regulatory Commission (NRC) staff has completed its review of the subject relief request. Based on the enclosed safety evaluation, the NRC staff concludes that the proposed alternative to Code Case N-579 stated in licensee's request for relief provides an acceptable level of quality and safety. Therefore, the proposed alternative is authorized pursuant to paragraph 50.55a(a)(3)(i) of Title 10 of the Code of Federal Regulations for the third 10-year lSI interval of WCGS. 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.
M. Sunseri -2 If you have any questions regarding the safety evaluation, please contact Balwant K. Singal at (301) 415-3016.
Sincerely, Michael T. Markley, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-482 Enclosure As stated cc w/encl: Distribution via Listserv
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REQUEST FOR RELIEF ON USE OF NONSTANDARD HYDRAULIC NUTS ON THE EXCESS LETDOWN HEAT EXCHANGER DURING THIRD 10-YEAR INSERVICE INSPECTION INTERVAL WOLF CREEK GENERATING STATION WOLF CREEK NUCLEAR OPERATING CORPORATION DOCKET NO. 50-482
1.0 INTRODUCTION
By letter dated June 10, 2010 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML101730557), Wolf Creek Nuclear Operating Corporation (the licensee) proposed an alternative to the requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section III, Code Case N-579, "Use of Nonstandard Nuts, Class 1, 2, and 3, MC, CS Components and Supports Construction,Section III, Division 1." The licensee plans to replace the channel head flange bolting of the Excess Letdown Heat Exchanger under the ASME Code,Section XI in the third 10-year inservice inspection (lSI) interval during refueling outage number 18 at Wolf Creek Generating Station (WCGS). Code Case N-579 has been approved by the U.S. Nuclear Regulatory Commission (NRC) and is documented in NRC Regulatory Guide 1.84, "Design, Fabrication, and Materials Code Case Acceptability, ASME Section III," Revision 35, dated October 2010.
The licensee has requested relief from use of the material specified in Code Case N-579 for the hydraulic nuts and conformance of thread configuration to ASME B1.1.
2.0 REGULATORY EVALUATION
The lSI of the ASME Code Class 1, 2, and 3 components is to be performed in accordance with Section XI of the ASME Code and applicable addenda as required by Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(g), "Inservice inspection requirements," except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i).
The regulations in 10 CFR 50.55a(a)(3) state 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.
Enclosure
-2 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 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 1O-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 applicable lSI Code of record for the third 1O-year lSI interval of WCGS is the 1998 Edition through the 2000 Addenda of the ASME Code,Section XI.
3.0 TECHNICAL EVALUATION
3.1 Applicable Code Edition and Addenda (as stated by the licensee)
The bolting replacement will be performed as a repair/replacement activity under the jurisdiction of the ASME Boiler and Pressure Vessel Code,Section XI. The 1998 Edition through the 2000 Addenda is the applicable Section XI edition and addenda for Wolf Creek Nuclear Operating Corporation's (WCNOC's) third inservice inspection interval.Section XI IWA-4000 requires use of portions of the original Construction Code and allows use of Construction Code, Code Cases.
For the Excess Letdown Heat Exchanger, the applicable Construction Code is ASME Section III, 1974 Edition including Summer 1975 Addendum.
Code Case N-579, "Use of Nonstandard Nuts, Class 1, 2, and 3, MC, CS Components and Supports Construction Section III, Division 1," is approved for use by the [NRC] as documented in Regulatory Guide 1.84, "Design, Fabrication, and Materials Code Case Acceptability, ASME Section III," Revision [35], dated October [2007].
3.2 System/Component(s) for Which Relief is Requested (as stated by the licensee)
The Excess Letdown Heat Exchanger (EBG02) channel head joint flange replacement bolting (ASME Class 2).
3.3 Code Relief Request (as stated by the licensee)
Relief is requested from the ASME Section XI repair/replacement activity requirements for the replacement bolting in accordance with Code Case N-579.
The specific requirements in Code Case N-579 for which relief is requested are the use of SA-194 material specified in Code Case N-579 for the nonstandard hydraulic nuts and conformance of thread configuration to ASME B1.1.
-3 3.4 Proposed Alternative (as stated by the licensee)
SA-540 Grade B23 material meeting the requirements for bolting material in
[ASME] Section III, paragraph NC-2127(a), will be used to fabricate the hydraulic nuts for the excess letdown heat exchanger flange instead of the SA-194 material specified in Code Case N-579. No torque wrench is required for installation of bolting since HydraNuts employ a stud tensioning process that tensions all twelve (12) studs simultaneously. The hydraulic nuts will incorporate a proprietary outside thread design providing minimized thread deflection to maximize retained load and allow lower preload to be used in contrast to standard threads manufactured in accordance with ASME B1.1 .
... While the inside threads of the hydraulic nuts conform to ASME B1.1, the outside threads have a proprietary thread design developed by the vendor, Nova-Technofast, which minimizes thread deflection between the nut and lock ring and thereby minimizes loss of pre-load.
3.5 Basis for Alternative (as stated by the licensee)
Use of [ASME] Section III approved SA-540 Grade B23 material in lieu of SA-194 material specified in Code Case N-579 will assure adequate strength in the joint.
The special thread design of the outside threads of the hydraulic nuts minimizes thread deflection and loss of preload. Use of these nonstandard nuts is expected to eliminate leakage from the joint while reducing radiation exposure to maintenance personnel by reducing maintenance time in the area.
3.6 NRC Staff Evaluation The NRC staff has reviewed the information related to the request for relief from Code Case N-579 for replacement of bolting in the channel head joint flange of the Excess Letdown Heat Exchanger. The component is located in a high-radiation area in the vicinity of reactor coolant loop 4 inside the secondary shield wall of the reactor building. The Excess Letdown Heat Exchanger flange has had chronic boric acid leakage at various times. Prior efforts to stop the leakage by replacement of the gasket along with adjustment of bolt torque have not been successful and have exposed maintenance personnel to increased occupational radiation exposure. Typical joint design incorporates a tapered geometry and a series of spacer washers that are difficult to maintain. The joint is being redesigned to eliminate the tapered geometry and spacer washer configuration with the use of hydraulic tensioning nuts (HydraNuts) to assure consistent loading around the joint. The new design would provide a safety benefit in reducing occupational radiation exposure by limiting maintenance stay times in the area.
As an alternative to Code Case N-579, SA-540 Grade B23 material was used instead of SA-194 for the manufacture of the hydraulic nuts. The licensee has determined that SA-540 Grade B23 material has sufficient strength for this application. The NRC staff concludes that SA-540 Grade B23 is acceptable for this application because this material is listed as an acceptable material for Class 2 bolting in ASME Code,Section III.
-4 Code Case N-579 requires that the screw threads of nonstandard nuts be manufactured to meet the requirements for threads in ASME B1.1. The hydraulic nuts used by the licensee have a proprietary outside thread design developed by the nut manufacturer which minimizes thread deflection between the nut and the lock ring and thereby minimizes loss of preload. The inside threads of the hydraulic nuts conform to ASME B1.1. The NRC staff concludes the use of the proprietary outside thread design is acceptable because the design would result in minimizing thread deflection between the nut and the lock ring, which would result in reducing the loss of preload.
Therefore, the NRC staff concludes that the use of hydraulic nonstandard nuts provides an equivalent level of quality and safety pursuant to 10 CFR 50.55a(a)(3)(i).
4.0 CONCLUSION
Based on the above evaluation, the NRC staff concludes that the proposed alternative to Code Case N-579 stated in licensee's request for relief provides an acceptable level of quality and safety. Therefore, the proposed alternative is authorized pursuant to 10 CFR 50.55a(a)(3)(i) for the third 10-year lSI interval of WCGS. All other requirements of the ASME Code,Section XI for which relief has not been specifically requested remain applicable, including a third-party review by the Authorized Nuclear Inservice Inspector.
Principal Contributor: Pat Patnaik Date: November 18, 2010
ML102990132 *SE memo dated October 8 , 2010 OFFICE I'JRR/LPL4/PM NRR/LPL4/LA DCI/CSGB/BC NRR/LPL4/BC NAME BSingal JBurkhardt RTaylor* MMarkley DATE 11/15/10 11/12/10 10/8/10 11118/10