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| | number = ML111110513 | | | number = ML111110513 |
| | issue date = 04/21/2011 | | | issue date = 04/21/2011 |
| | title = Watts Bar, Unit 2, Withdrawal of a Previous Comment | | | title = Withdrawal of a Previous Comment |
| | author name = Stinson D | | | author name = Stinson D |
| | author affiliation = Tennessee Valley Authority | | | author affiliation = Tennessee Valley Authority |
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| | document type = Letter | | | document type = Letter |
| | page count = 2 | | | page count = 2 |
| | | project = TAC:ME2731 |
| | | stage = Withdrawal |
| }} | | }} |
| | |
| | =Text= |
| | {{#Wiki_filter:Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381-2000 April 21, 2011 10 CFR 50.34 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 2 NRC Docket No. 50-391 |
| | |
| | ==Subject:== |
| | WATTS BAR NUCLEAR PLANT (WBN) UNIT 2 - WITHDRAWAL OF A PREVIOUS COMMITMENT |
| | |
| | ==Reference:== |
| | TVA letter dated June 28, 2010, Watts Bar Nuclear Plant (WBN) Unit 2 - |
| | Request for Additional Information (RAI) Regarding Licensees Final Safety Analysis Report Amendment Related to Section 4.2.2, Reactor Vessel Internal Components (TAC No. ME2731) |
| | The purpose of this letter is to withdraw a previous commitment made in the referenced letter. |
| | In that letter, TVA committed to replace prior to Unit 2 operation the current Unit 2 clevis insert bolts to a design which uses X-750 alloy with a high temperature heat (HTH) treatment, rolled threads, and a larger radius on the undercut of the cap screw head. Upon further evaluation, TVA has determined that this replacement is unwarranted at this time. |
| | The justification for this withdrawal stems from the fact that the bolting failure phenomenon has only known to have occurred at one unit in the industry. The phenomenon appears to be time based, and the breakage only occurs after many operating cycles. In discussions with personnel at the affected plant, TVA has learned that the cause is not yet known and that any change might be at best neutral to solving the problem. TVA has also confirmed via these discussions that bolting at the affected plants other unit does not have the same issue. In addition, WBN Unit 1 has operated with the same type bolting since 1995 with no failure of these bolts. |
| | The initial NRC RAI cited the Staff Requirements Memorandum dated July 25, 2007 (ADAMS Accession No. ML093370274) directing TVA to look for opportunities to resolve issues where the unirradiated state of WBN Unit Bar 2 makes the issue easier to resolve. At this time, the root cause of the subject issue has not been determined, an industry resolution has not been established, the problem appears to be restricted to a single unit at another utility, and WBN |
| | |
| | U.S. Nuclear Regulatory Commission Page 2 April 21, 2011 Unit 1 has operated with the X-750 bolting approximately sixteen years with no failure of these bolts. Even though WBN Unit 2 is not yet irradiated, TVA has decided to withdraw the previous commitment to replace the X-750 alloy insert bolts since replacement is not a definite solution for a near term problem. |
| | If you should have any questions, please call Bill Crouch at (423) 365-2004. |
| | Respectfully, David Stinson Watts Bar Unit 2 Vice President cc: U. S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, Georgia 30303-1257 NRC Resident Inspector Unit 2 Watts Bar Nuclear Plant 1260 Nuclear Plant Road Spring City, Tennessee 37381}} |
Letter Sequence Withdrawal |
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Results
Other: CNL-14-077, Responses to Degraded Voltage Issue Requests for Additional Information, ML102290358, ML102290360, ML102290361, ML102290362, ML102290363, ML102290364, ML102290365, ML102290366, ML102290367, ML102290368, ML102290383, ML102290384, ML102290385, ML102290386, ML102290387, ML102290388, ML102290389, ML102290390, ML102290391, ML102290392, ML102290403, ML102290404, ML102290405, ML102290406, ML102290407, ML102290408, ML102290409, ML102290410, ML102290411, ML102290414, ML102290439, ML102290440, ML102290441, ML102290442, ML102290443, ML102290444, ML102290445, ML102290446, ML102290447, ML102290448, ML102290458, ML102290459, ML102290460, ML102290461, ML102290462, ML102290463, ML102290464, ML102290465, ML102290466... further results
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Project stage: Response to RAI ML1011303512010-05-0505 May 2010 Request for Withholding Information from Public Disclosure (Tac No. ME2731) Project stage: Withholding Request Acceptance ML1014500842010-06-23023 June 2010 Request for Additional Information Regarding Licensee'S Final Safety Analysis Report Amendment Related to Reactor Systems, Nuclear Performance and Code Review, Ansd Plant Systems Project stage: RAI ML1015402502010-06-24024 June 2010 Request for Additional Information Regarding Licensee'S Final Safety Analysis Report Amendment Related to Nuclear Performance and Code Review, Plant Systems, and Testing (Tac Nos. 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Related to Electrical Engineering Systems Project stage: RAI ML1018001562010-07-15015 July 2010 Request for Additional Information Regarding Licensee'S Final Safety Analysis Report Amendment Related to Chapter 8, Electric Power Project stage: RAI ML1023003272010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-4A (Dwg No. 1-47W845-5, R38) Project stage: Other ML1022904652010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-2 (Dwg No. 1-47W845-2, R76) Project stage: Other ML1023003282010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-4B (Dwg No. 1-47W845-7, R14) Project stage: Other ML1023003292010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-5 (Dwg No. 1-47W611-67-1, R8) Project stage: Other ML1023003302010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-6 (Dwg No. 1-47W611-67-2, R5) Project stage: Other ML1023003312010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-8 (Dwg No. 1-47W611-67-4, R5) Project stage: Other ML1023003322010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-9 (Dwg No. 1-47W611-67-5, R10) Project stage: Other ML1023003332010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-10 (Dwg No. 1-47W610-67-1, R27) Project stage: Other ML1023003342010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-10 Sh a (Dwg No. 1-47W610-67-1A, R16) Project stage: Other ML1023003352010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-11 (Dwg No. 1-47W610-67-2, R15) Project stage: Other ML1023003432010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-12 Sh a (Dwg No. 1-47W610-67-3A, R7) Project stage: Other ML1023003442010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-13 (Dwg No. 1-47W610-67-4, R17) Project stage: Other ML1023003452010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-11 Sh a (Dwg No. 1-47W610-67-2A, R8) Project stage: Other ML1023003462010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-12 (Dwg No. 1-47W610-67-3, R12) Project stage: Other ML1023003472010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-14 (Dwg No. 1-47W610-67-5, R14) Project stage: Other ML1023003482010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-14 (Dwg No. 1-47W610-67-5A, R2) Project stage: Other ML1023003492010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-16 (Dwg No. 1-47W859-4, R23) Project stage: Other ML1023003502010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-17 (Dwg No. 1-47W859-3, R18) Project stage: Other ML1023003512010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-18 (Dwg No. 1-47W859-2, R36) Project stage: Other ML1023003522010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-19 (Dwg No. 1-47W859-1, R47) Project stage: Other ML1023003602010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-23 (Dwg No. 1-47W611-70-1, R9) Project stage: Other ML1023003612010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-20 (Dwg No. 1-47W610-70-1, R23) Project stage: Other ML1023003622010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-21 (Dwg No. 1-47W610-70-2, R29) Project stage: Other ML1023003632010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-21A (Dwg No. 1-47W610-70-2A, R15) Project stage: Other ML1023003642010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-22 (Dwg No. 1-47W610-70-3, R17) Project stage: Other ML1023003652010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-24 (Dwg No. 1-47W611-70-2, R11) Project stage: Other ML1023003672010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-25 (Dwg No. 1-47W611-70-3, R4) Project stage: Other ML1023003682010-08-0505 August 2010 Final Safety Analysis Report Figure 9.2-25A (Dwg No. 1-47W611-70-4, R4) Project stage: Other ML1023003692010-08-0505 August 2010 Final Safety Analysis Report Figure 9.3-1 (Dwg No. 1-47W610-32-1, R15) Project stage: Other ML1022903652010-08-0505 August 2010 Final Safety Analysis Report Figure 8.3-7 (Dwg No. 1-45W760-211-9, R16) Project stage: Other ML1023003972010-08-0505 August 2010 Final Safety Analysis Report Figure 9.5-25A (Dwg No. 1-47W610-82-2, R7) Project stage: Other ML1023003982010-08-0505 August 2010 Final Safety Analysis Report Figure 9.5-25B (Dwg No. 1-47W610-82-3, R7) Project stage: Other ML1023003992010-08-0505 August 2010 Final Safety Analysis Report Figure 9.5-25C (Dwg No. 1-47W610-82-4, R7) Project stage: Other ML1022903682010-08-0505 August 2010 Final Safety Analysis Report Figure 8.3-14B (Dwg No. 1-45W760-82-1, R17) Project stage: Other ML1022903672010-08-0505 August 2010 Final Safety Analysis Report Figure 8.3-9 (Dwg No. 1-45W760-211-11, R13) Project stage: Other ML1022903662010-08-0505 August 2010 Final Safety Analysis Report Figure 8.3-8 (Dwg No. 1-45W760-211-10, R12) Project stage: Other ML1022903622010-08-0505 August 2010 Final Safety Analysis Report Figure 8.1-3 (Dwg No. 1-45W700-1, R28) Project stage: Other ML1022903582010-08-0505 August 2010 Final Safety Analysis Report Figure 8.1.2 (Dwg No. 1-15E500-1, R31) Project stage: Other 2010-06-28
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Category:Letter
MONTHYEARML24219A0262024-08-12012 August 2024 Request for Withholding Information from Public Disclosure IR 05000390/20240022024-08-0707 August 2024 Integrated Inspection Report 05000390/2024002 and 05000391/2024002 Rev ML24204A2652024-07-25025 July 2024 Regulatory Audit Summary Related to Request to Revise Technical Specification Surveillance Requirement 3.9.5.1 to Reduce the Residual Heat Removal Flow Rate ML24199A0012024-07-22022 July 2024 Clarification and Correction to Exemption from Requirement of 10 CFR 37.11(c)(2) ML24172A1342024-07-15015 July 2024 Exemptions from 10 CFR 37.11(C)(2) (EPID L-2023-LLE-0024) - Letter ML24170A8002024-07-15015 July 2024 Issuance of Amendment Nos. 168 and 74 Regarding Revision to Technical Specification Table 1.1-1 for Required Number of Fully Tensioned Reactor Pressure Vessel Head Closure Bolts IR 05000390/20244402024-07-12012 July 2024 95001 Supplemental Inspection Supplemental Report 05000390-2024440 and 05000391-2024440 and Follow-Up Assessment Letter ML24131A0012024-07-0202 July 2024 Issuance of Amendment Nos. 167 and 73 Regarding Adoption of Technical Specification Task Force Traveler TSTF-427-A, Revision 2 CNL-24-052, Response to Request for Additional Information Regarding Application to Modify the Technical Specification Surveillance Requirement 3.9.5.1 (WBN-TS-21-14)2024-06-27027 June 2024 Response to Request for Additional Information Regarding Application to Modify the Technical Specification Surveillance Requirement 3.9.5.1 (WBN-TS-21-14) CNL-24-018, License Amendment Request for Adoption of Technical Specification Task Force Traveler TSTF-276-A, Revision 2, Regarding TS 3.8.1 AC Sources – Operating to Clarify Requirements for Diesel Generator Testing (WBN-TS2024-06-25025 June 2024 License Amendment Request for Adoption of Technical Specification Task Force Traveler TSTF-276-A, Revision 2, Regarding TS 3.8.1 AC Sources – Operating to Clarify Requirements for Diesel Generator Testing (WBN-TS ML24089A1152024-06-21021 June 2024 Transmittal Letter, Environmental Assessments and Findings of No Significant Impact Related to Exemption Requests from 10 CFR 37.11(c)(2) ML24141A0482024-05-17017 May 2024 EN 56958_1 Ametek Solidstate Controls, Inc ML24100A7642024-05-16016 May 2024 Issuance of Amendment No. 166 Regarding Revision to Technical Specification 3.8.2, AC Sources-Shutdown, to Remove Reference to C-S Diesel Generator (CNL-23-062) IR 05000390/20240012024-05-14014 May 2024 Integrated Inspection Report 05000390/2024001 and 05000391/2024001 CNL-24-040, Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure Revisions2024-05-0808 May 2024 Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure Revisions IR 05000391/20240072024-04-30030 April 2024 Assessment Follow-up Letter for Watts Bar Nuclear Plant, Unit 2 – Report 05000391/2024007 ML24120A1182024-04-29029 April 2024 – Notification of NRC Supplemental Inspection (95001) and Request for Information CNL-24-037, Clinch River, Sequoyah, Units 1 and 2, Watts Bar, Unit 1 and 2, Nuclear Quality Assurance Plan, TVA-NQA-PLN89-A, Revision 422024-04-22022 April 2024 Clinch River, Sequoyah, Units 1 and 2, Watts Bar, Unit 1 and 2, Nuclear Quality Assurance Plan, TVA-NQA-PLN89-A, Revision 42 ML24087A1912024-04-18018 April 2024 Exemption from Select Requirements of 10 CFR Part 73, Security Notifications, Reports, and Recordkeeping and Suspicious Activity Reporting CNL-24-033, Central Emergency Control Center Emergency Plan Implementing Procedure Revisions2024-04-17017 April 2024 Central Emergency Control Center Emergency Plan Implementing Procedure Revisions CNL-24-010, License Amendment Request to Recapture Low-Power Testing Time (WBN-TS-23-19)2024-04-17017 April 2024 License Amendment Request to Recapture Low-Power Testing Time (WBN-TS-23-19) CNL-24-024, Hydrologic Engineering Center River Analysis System Project Milestone Status Update2024-04-17017 April 2024 Hydrologic Engineering Center River Analysis System Project Milestone Status Update ML24072A0052024-04-15015 April 2024 Issuance of Amendment Nos. 165 and 72 Regarding Increase in the Maximum Number of Tritium Producing Burnable Absorber Rods and Supporting Changes, and Revision to the Updated Final Safety Analysis Report CNL-24-004, Application to Modify the Watts Bar Nuclear Plant, Unit 1 and Unit 2 Technical Specifications for Main Control Room Chiller Completion Time Extension (WBN-TS-23-13)2024-04-0404 April 2024 Application to Modify the Watts Bar Nuclear Plant, Unit 1 and Unit 2 Technical Specifications for Main Control Room Chiller Completion Time Extension (WBN-TS-23-13) IR 05000390/20244012024-04-0202 April 2024 – Security Baseline Inspection Report 05000390/2024401 and 05000391/2024401 - (Public) CNL-24-020, Clinch River, Sequoyah, Units 1 and 2, Watts Bar, Units 1 and 2, Request for Approval of Quality Assurance Program Description and Application to Revise the Technical Specifications Associated with QAPD Requirements2024-04-0101 April 2024 Clinch River, Sequoyah, Units 1 and 2, Watts Bar, Units 1 and 2, Request for Approval of Quality Assurance Program Description and Application to Revise the Technical Specifications Associated with QAPD Requirements CNL-24-008, Guarantee of Payment of Deferred Premiums - 2023 Annual Report2024-03-27027 March 2024 Guarantee of Payment of Deferred Premiums - 2023 Annual Report CNL-24-007, Annual Insurance Status Report2024-03-27027 March 2024 Annual Insurance Status Report CNL-24-025, Notice of Intent to Pursue License Renewal for Watts Bar Nuclear Plant, Unit 1 - Submittal Schedule2024-03-25025 March 2024 Notice of Intent to Pursue License Renewal for Watts Bar Nuclear Plant, Unit 1 - Submittal Schedule ML24081A0262024-03-21021 March 2024 Emergency Plan Implementing Procedure Revisions ML24079A0312024-03-19019 March 2024 Wb 2024-301, Corporate Notification Letter (210-day Ltr) CNL-24-031, Supplement to Request for Exemption from Various Part 72 Regulations Resulting from Fuel Basket Design Control Compliance2024-03-18018 March 2024 Supplement to Request for Exemption from Various Part 72 Regulations Resulting from Fuel Basket Design Control Compliance CNL-24-029, Response to Request for Additional Information Regarding Tennessee Valley Authority - Request for Exemption from Specific Requirements of 10 CFR Part 372024-03-14014 March 2024 Response to Request for Additional Information Regarding Tennessee Valley Authority - Request for Exemption from Specific Requirements of 10 CFR Part 37 CNL-24-028, Response to Request for Additional Information Regarding Watts Bar Nuclear Plant, Units 1 and 2, Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation2024-03-14014 March 2024 Response to Request for Additional Information Regarding Watts Bar Nuclear Plant, Units 1 and 2, Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation IR 05000390/20240102024-03-0808 March 2024 Age-Related Degradation Inspection Report 05000390/2024010 and 05000391/2024010 CNL-24-012, Request for Exemption from Various Part 72 Regulations Resulting from Fuel Basket Design Control Compliance2024-02-28028 February 2024 Request for Exemption from Various Part 72 Regulations Resulting from Fuel Basket Design Control Compliance IR 05000390/20230062024-02-28028 February 2024 Annual Assessment Letter for Watts Bar Nuclear Plant Units 1 and 2 - Report 05000390/2023006 and 05000391/2023006 CNL-24-023, Central Emergency Control Center Emergency Plan Implementing Procedure Revision. Includes CECC EPIP-17, Revision 252024-02-20020 February 2024 Central Emergency Control Center Emergency Plan Implementing Procedure Revision. Includes CECC EPIP-17, Revision 25 IR 05000390/20230042024-02-13013 February 2024 Integrated Inspection Report 05000390/2023004 and 05000391/2023004 and Apparent Violation ML24038A3342024-02-0707 February 2024 Change to South Texas Project Electric Generating Station (Stepgs) Emergency Plan ML23319A2452024-01-29029 January 2024 Issuance of Amendment Nos. 366 and 360; 164 and 71 Regarding the Adoption of TSTF-567, Revision 1, Add Containment Sump TS to Address GSI-191 Issues ML24008A2462024-01-18018 January 2024 Revision to the Reactor Vessel Material Surveillance Capsule Withdrawal Schedule CNL-24-017, Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure and Emergency Preparedness Department Procedure Revisions2024-01-17017 January 2024 Tennessee Valley Authority - Central Emergency Control Center Emergency Plan Implementing Procedure and Emergency Preparedness Department Procedure Revisions CNL-24-016, Supplement to Application to Modify the Technical Specification Surveillance Requirement 3.9.5.1 (WBN-TS-21-14)2024-01-10010 January 2024 Supplement to Application to Modify the Technical Specification Surveillance Requirement 3.9.5.1 (WBN-TS-21-14) CNL-23-052, Application to Adopt TSTF-427-A, Revision 2, Allowance for Non-Technical Specification Barrier Degradation on Supported System Operability2024-01-0909 January 2024 Application to Adopt TSTF-427-A, Revision 2, Allowance for Non-Technical Specification Barrier Degradation on Supported System Operability CNL-23-062, Application to Revise the Technical Specifications Section 3.8.2, AC Sources-Shutdown, to Remove Reference to the C-S Diesel Generator (WBN-TS-23-018)2024-01-0808 January 2024 Application to Revise the Technical Specifications Section 3.8.2, AC Sources-Shutdown, to Remove Reference to the C-S Diesel Generator (WBN-TS-23-018) ML23346A1382024-01-0303 January 2024 Regulatory Audit Summary Related to Request to Increase the Number of Tritium Producing Burnable Absorber Rods CNL-23-069, Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation2023-12-21021 December 2023 Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation IR 05000390/20234412023-12-21021 December 2023 Plantfinal Significance Determination for a Security-Related Greater than Green Finding, Nov, and Assessment Follow-up, 05000390-2023441 and 05000391-2023441-Public CNL-23-036, Application to Revise Function 5 of Technical Specification Table 3.3.2-1, Engineered Safety Feature Actuation System Instrumentation, for the Sequoyah Nuclear Plant and Watts Bar Nuclear Plant (SQN-TS-23-02 and WBN-TS-23-08)2023-12-18018 December 2023 Application to Revise Function 5 of Technical Specification Table 3.3.2-1, Engineered Safety Feature Actuation System Instrumentation, for the Sequoyah Nuclear Plant and Watts Bar Nuclear Plant (SQN-TS-23-02 and WBN-TS-23-08) 2024-08-07
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Text
Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381-2000 April 21, 2011 10 CFR 50.34 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 2 NRC Docket No. 50-391
Subject:
WATTS BAR NUCLEAR PLANT (WBN) UNIT 2 - WITHDRAWAL OF A PREVIOUS COMMITMENT
Reference:
TVA letter dated June 28, 2010, Watts Bar Nuclear Plant (WBN) Unit 2 -
Request for Additional Information (RAI) Regarding Licensees Final Safety Analysis Report Amendment Related to Section 4.2.2, Reactor Vessel Internal Components (TAC No. ME2731)
The purpose of this letter is to withdraw a previous commitment made in the referenced letter.
In that letter, TVA committed to replace prior to Unit 2 operation the current Unit 2 clevis insert bolts to a design which uses X-750 alloy with a high temperature heat (HTH) treatment, rolled threads, and a larger radius on the undercut of the cap screw head. Upon further evaluation, TVA has determined that this replacement is unwarranted at this time.
The justification for this withdrawal stems from the fact that the bolting failure phenomenon has only known to have occurred at one unit in the industry. The phenomenon appears to be time based, and the breakage only occurs after many operating cycles. In discussions with personnel at the affected plant, TVA has learned that the cause is not yet known and that any change might be at best neutral to solving the problem. TVA has also confirmed via these discussions that bolting at the affected plants other unit does not have the same issue. In addition, WBN Unit 1 has operated with the same type bolting since 1995 with no failure of these bolts.
The initial NRC RAI cited the Staff Requirements Memorandum dated July 25, 2007 (ADAMS Accession No. ML093370274) directing TVA to look for opportunities to resolve issues where the unirradiated state of WBN Unit Bar 2 makes the issue easier to resolve. At this time, the root cause of the subject issue has not been determined, an industry resolution has not been established, the problem appears to be restricted to a single unit at another utility, and WBN
U.S. Nuclear Regulatory Commission Page 2 April 21, 2011 Unit 1 has operated with the X-750 bolting approximately sixteen years with no failure of these bolts. Even though WBN Unit 2 is not yet irradiated, TVA has decided to withdraw the previous commitment to replace the X-750 alloy insert bolts since replacement is not a definite solution for a near term problem.
If you should have any questions, please call Bill Crouch at (423) 365-2004.
Respectfully, David Stinson Watts Bar Unit 2 Vice President cc: U. S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, Georgia 30303-1257 NRC Resident Inspector Unit 2 Watts Bar Nuclear Plant 1260 Nuclear Plant Road Spring City, Tennessee 37381