ML060870188
| ML060870188 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 04/27/2006 |
| From: | Pickett D V Plant Licensing Branch III-2 |
| To: | Singer K W Tennessee Valley Authority |
| Pickett , NRR/DLPM, 415-1364 | |
| References | |
| TAC MC5368 | |
| Download: ML060870188 (10) | |
Text
April 27, 2006Mr. Karl W. Singer Chief Nuclear Officer and Executive Vice President Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, Tennessee 37402-2801
SUBJECT:
WATTS BAR NUCLEAR PLANT, UNIT 1 - ISSUANCE OF AMENDMENTON THE USE OF A BAR-LOCK MECHANICAL COUPLER FOR SPLICING REINFORCING BARS IN THE SHIELD BUILDING (TAC NO. MC5368)
Dear Mr. Singer:
The Commission has issued the enclosed Amendment No. 60 to Facility Operating LicenseNo. NPF-90 for Watts Bar Nuclear Plant (WBN), Unit 1. This amendment is in response to your application dated December 9, 2004 (WBN-TS-04-18), as supplemented by letters dated November 18 and December 5, 2005.The amendment authorizes modification to the Updated Final Safety Analysis Report for WBN,Unit 1 to include a revision to the methodology for splicing reinforcing steel bars during restoration of the concrete shield building dome as part of the steam generator replacement project.A copy of the safety evaluation is also enclosed. Notice of issuance will be included in theCommission's biweekly Federal Register notice. Sincerely,/RA/Douglas V. Pickett, Senior Project ManagerPlant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor RegulationDocket No. 50-390
Enclosures:
- 1. Amendment No. 60 to NPF-902. Safety Evaluationcc w/encls: See next page
ML060870188*No Legal ObjectionNRR-058OFFICELPLDLPL2-2/PMBC:EGCBLPL2-2/LAOGCLPL2-2/BCNAMESCrane DPickettRKaras(via memo)RSolaAPHodgdon*MMarshallDATE4/13/064/14/063/13/064/12/064/25/064/27/06 Mr. Karl W. Singer Tennessee Valley Authority WATTS BAR NUCLEAR PLANT cc:Mr. Ashok S. Bhatnagar, Senior Vice President Nuclear Operations Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. Larry S. Bryant, Vice PresidentNuclear Engineering & Technical Services Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801Mr. Robert J. Beecken, Vice PresidentNuclear Support Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. Michael D. SkaggsSite Vice President Watts Bar Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Spring City, TN 37381General CounselTennessee Valley Authority ET 11A 400 West Summit Hill DriveKnoxville, TN 37902Mr. John C. Fornicola, ManagerNuclear Assurance and Licensing Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801Mr. Glenn W. Morris, Manager Corporate Nuclear Licensing and Industry Affairs Tennessee Valley Authority 4X Blue Ridge 1101 Market Street Chattanooga, TN 37402-2801Mr. Paul L. Pace, ManagerLicensing and Industry Affairs Watts Bar Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Spring City, TN 37381Mr. Jay Laughlin, Plant ManagerWatts Bar Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Spring City, TN 37381Senior Resident InspectorWatts Bar Nuclear Plant U.S. Nuclear Regulatory Commission 1260 Nuclear Plant Road Spring City, TN 37381County Executive 375 Church Street Suite 215 Dayton, TN 37321County Mayor P. O. Box 156 Decatur, TN 37322Mr. Lawrence E. Nanney, DirectorDivision of Radiological Health Dept. of Environment & Conservation Third Floor, L and C Annex 401 Church Street Nashville, TN 37243-1532Ms. Ann P. Harris341 Swing Loop Road Rockwood, Tennessee 37854 TENNESSEE VALLEY AUTHORITYDOCKET NO. 50-390WATTS BAR NUCLEAR PLANT, UNIT 1AMENDMENT TO FACILITY OPERATING LICENSEAmendment No. 60 License No. NPF-90 1.The Nuclear Regulatory Commission (the Commission) has found that:A.The application for amendment by Tennessee Valley Authority (the licensee) datedDecember 9, 2004, as supplemented by letters dated November 18 and December 5, 2005, complies with the standards and requirements of the Atomic Energy Act of 1954, as amended (the Act), and the Commission's rules and regulations set forth in 10 CFR Chapter I;B.The facility will operate in conformity with the application, the provisions of the Act,and the rules and regulations of the Commission;C.There is reasonable assurance (I) that the activities authorized by this amendmentcan be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commission'sregulations;D.The issuance of this amendment will not be inimical to the common defense andsecurity or to the health and safety of the public; andE.The issuance of this amendment is in accordance with 10 CFR Part 51 of theCommission's regulations and all applicable requirements have been satisfied. 2. Accordingly, the license is amended to authorize revision of the Updated Final SafetyAnalysis Report (UFSAR) as set forth in the application for amendment by the licensee dated December 9, 2004, as supplemented by letters dated November 18 and December 5, 2005.3. This license amendment is effective as of its date of issuance. Implementation of theamendment is the incorporation into the next UFSAR update made in accordance with 10 CFR 50.71(e), of the changes to the description of the facility as described in TVA'sapplication dated December 9, 2004, as supplemented by letters dated November 18 and December 5, 2005, and evaluated in the staff's Safety Evaluation attached to this amendment.FOR THE NUCLEAR REGULATORY COMMISSION/RA/Michael L. Marshall, Jr., ChiefPlant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor RegulationDate of Issuance: April 27, 2006 EnclosureSAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATIONRELATED TO AMENDMENT NO. 60 TO FACILITY OPERATING LICENSE NO. NPF-90TENNESSEE VALLEY AUTHORITYWATTS BAR NUCLEAR PLANT, UNIT 1DOCKET NO. 50-39
01.0 INTRODUCTION
By application dated December 9, 2004, as supplemented by letters dated November 18 andDecember 5, 2005, Tennessee Valley Authority (TVA, the licensee) requested changes to the license of Watts Bar Nuclear Plant (WBN) Unit 1. The supplemental letters provided clarifying information that did not change the initial proposed no significant hazards considerationdetermination. The requested change provides a revision to the WBN Updated Final Safety Analysis Report(UFSAR) to permit the use of an alternate methodology for reinforcing bar (rebar) splicing. The change in methodology applies to the restoration of the concrete shield building dome as part of the steam generator replacement project for Unit 1 scheduled for Fall 2006. The alternate methodology uses a Bar-Lock mechanical coupler for splicing rebar in lieu of the Cadweld splice used for the original design and construction of the plant.In its application, TVA stated that it would use Bar-Lock couplers to connect the new andexisting shield building concrete reinforcement as described in Bechtel Report No. 24370-TR-C-001-A "Alternate Rebar Splice - Bar-Lock Mechanical Splices." TVA indicated its preference to use the Bar-Lock mechanical splice over the Cadweld splice because it is easier to install, and requires no special equipment and rebar preparation, and minimal operator training. TVA also requested that the Nuclear Regulatory Commission (NRC) staff allow theuse of the Bar-Lock coupler system without a prequalification test program bec ause t he syst emhad been qualified for use in the shield building at Sequoyah Nuclear Plant (SQN). The NRC approved the Bar-Lock coupler system for use in the shield building restoration atSQN, and the approval was based on the licensee's submittal dated March 18, 2002, assupplemented by a letter dated December 10, 2002. The approval was limited to SQN's specific request and was not applicable to other plants. Based on the staff's review of the license amendment application and subsequent discussionswith the licensee, the staff concluded that the essential variables in the Bar-Lock coupler system to be used at WBN were not identical to those used at SQN; therefore, the licensee'srequest to use the Bar-Lock coupler system could not be approved without a prequalificationtest program. During the staff's discussion with the licensee, TVA stated that it planned to use the leftover couplers from SQN at WBN. The staff stated that it did not object to the use of theleftover couplers, but that these couplers would need to be requalified as a new system. Thestaff's positions were stated in a letter to the licensee dated March 7, 2005.In its letter dated December 5, 2005, the licensee stated that qualification testing wasperformed on the remaining couplers used at TVA's SQN, as well as the newly manufactured couplers, and that the test results showed that these couplers were qualified for use to repairthe opening in the dome of the WBN shield building.
2.0 REGULATORY EVALUATION
Pursuant to Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix B, thelicensee is required to establish and perform a testing program that assures that structures, systems, and components will perform satisfactorily in service in accordance with written testprocedures that incorporate the requirements and acceptance limits contained in applicabledesign documents. According to 10 CFR 50.55a(a)(2), systems and components of boiling andpressurized water-cooled nuclear reactors must meet the requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code). ASME Code,Section III, Division 2, "Code for Concrete Containments" (the Code), Paragraph CC-4333.2.1requires that each splice system manufacturer conduct a series of performance tests in order toqualify a splice system for use.Section CC-4333.2.3(a) of the Code, "Static Tensile Tests for Mechanical Splices," requires thatsix splice specimens for each bar size shall be tensile tested to failure. The average tensile strength of the reinforcing bar being tested shall not be less than 90 percent of the actualtensile strength of the reinforcing bar being tested, nor less than 100 percent of the specifiedminimum tensile strength. Additionally, the tensile strength of any individual splice system shallnot be less than 125 percent of the specified minimum yield strength of the spliced bar.Section CC-4333.2.3(b) of the Code, "Cyclic Tensile Tests for Mechanical Splices," requiresthat three specimens of the bar-to-bar splice for each reinforcing bar size shall withstand 100 cycles of stress variation from 5 percent to 90 percent of the specified minimum yield strengthof the reinforcing bar.
3.0TECHNICAL EVALUATION
The Bar-Lock coupler system consists of two pieces of rebar joined by a coupler barrel andtightened by lockshear bolts through torque and with serrated rails as inserts between the rebarand the barrel. The coupler barrel, lockshear bolts, serrated rails, and rebar are elements thatinfluence and contribute to the performance of the Bar-Lock coupler system. The purpose ofthe qualification test for the Bar-Lock coupler system is to demonstrate that the entire assemblycontaining these elements can transfer the force from one rebar to the other, through the coupler, in a desirable manner as specified in the Paragraph CC-4333.2.3 of the Code. Since the material and geometry of the rebar, coupler barrels, lockshear bolts, and serrated rails to beused in the shield building at WBN would not be identical to those used at SQN, the Bar-Lockcoupler system to be used at the WBN would require a new qualification test program. The staff considers the rebar, coupler, lockshear bolt, serrated rail, and torque to be essentialvariables for the Bar-Lock coupler system. Therefore, any change in one of the essentialvariables prompts a need for a requalification of the Bar-Lock coupler system.3.1Requalification TestingThe staff reviewed the "Test Report for Bar-Lock Qualification," which was attached to thelicensee's letter dated December 5, 2005. The report stated that the Code required six splicespecimens for each bar size to be tensile tested statically to failure and three to be tested cyclically for 100 cycles, and provided the test results.Section CC-4333.2.3(a) of the Code requires the average tensile strength of the six rebarspecimens tested under static loading shall be no less than 90 percent of the actual tensilestrength of the reinforcing bar being tested, nor less than 100 percent of the specified minimumtensile strength, which is 90,000 pounds per square inch (psi) for Grade 60 rebar. Furthermore, the tensile strength of any individual splice system shall not be less than 125 percent of thespecified minimum yield strength of the spliced bar, which is 60,000 psi for Grade 60 rebar.The static tensile tests were performed for both the new and SQN leftover #6 and #8 Bar-lockcouplers. The average tensile strength of the six unspliced #6 bars was 111,902 psi. The 111,902 psi value was used as the actual tensile strength of the rebar being tested. Theaverage tensile strength of the six #6 static tensile specimens with SQN leftover couplers was104,350 psi, which was greater than the Code requirement of 0.9 x 111,902 psi = 100,712 psi. The value of 104,350 psi was also greater than the Code-specified minimum strength of 90,000 psi. Each of the six specimens had a tensile strength greater than the Coderequirement of 1.25 x 60,000 psi = 75,000 psi. The average tensile strength of the eight #6 static tensile specimens with new couplers was107,730 psi, which was greater than the Code requirement of 0.9 x 111,902 psi = 100,712 psi. The value of 107,730 psi was also greater than the Code-specified minimum strength of 90,000 psi. Each of the six specimens had a tensile strength greater than the Coderequirement of 1.25 x 60,000 psi = 75,000 psi. The average tensile strength of six unspliced #8 bars was 105,066 psi. The average tensilestrength of the six #8 static tensile specimens with SQN leftover couplers was 102,306 psi,which was greater than the Code requirement of 0.9 x 105,066 psi = 94,560 psi. The value of102,306 psi was also greater than the Code-specified minimum strength of 90,000 psi. Each ofthe six specimens had a tensile strength greater than the code requirement of1.25 x 60,000 psi = 75,000 psi.The average tensile strength of the six #8 static tensile specimens with new couplers was99,951 psi, which was greater than the Code requirement of 0.9 x 105,066 psi = 94,560 psi. The value of 99,951 psi was also greater than the Code-specified minimum strength of 90,000 psi. Each of the eight specimens had a tensile strength greater than the Coderequirement of 1.25 x 60,000 psi = 75,000 psi.Section CC-4333.2.3(b) of the Code requires that three specimens of the bar-to-bar splice foreach reinforcing bar size shall withstand 100 cycles of stress variation from 5 percent to 90 percent of the specified minimum yield strength of the reinforcing bar. All of the three #6and three #8 Bar-Lock couplers completed the Code requirement of 100 cycles without failure. The licensee concluded that the #6 and #8 Bar-Lock couplers are qualified for use for the shield building at WBN in accordance with Paragraph CC-4333.2.1 of the Code. The staff reviewed the test data for all Bar-Lock couplers and concurs with the licensee's conclusion. The staff's approval of the Bar-Lock assemblies at the SQN facility included a detailed review ofBechtel Report No. 24370-TR-C-001. This report, which will be referenced in the WBNUFSAR, discusses quality assurance programs, quality control processes, and procedures for compliance with applicable regulatory and ASME Code requirements, and the testing program.
The staff understands that Bechtel's control of quality assurance and operations will beequivalent to that conducted during the SQN steam generator replacement project. TheBechtel Quality Assurance Manual used at WBN has been approved by TVA and is equivalent to the SQN Quality Assurance Manual that was used for that application. In addition, the WBN implementation of Bar-Lock assemblies includes the following attributes:1.The requirements of 10 CFR Part 50, Appendix B are applicable to the design,purchase, fabrication, handling, shipping, storage, inspection, testing, andinstallation of the Bar-Lock mechanical couplers.2.TVA has reviewed and approved Bechtel's Watts Bar Steam GeneratorReplacement Project Nuclear Quality Assurance Manual. The policies in this manual correspond to each of the 18 criteria of 10 CFR Part 50, Appendix B and meet the requirements of the American National Standards Institute (ANSI)/ASME N45.2 and ANSI/ASME N45.2 series standards and quality assurance-related NRC regulatory guides.Bechtel, in its roles as a contractor to TVA, imposed the applicable 10 CFR Part50, Appendix B, requirements along with the technical and document submittal requirements on the subcontractors involved in the material supply, fabrication, and testing of the rebar and Bar-Lock couplers. Bechtel reviewed the quality programs for the rebar supplier, the manufacturer of the Bar-Lock couplers, and where appropriate, required changes to these programs to bring them into compliance with the requirements of 10 CFR Part 50, Appendix B.3.Bechtel witnessed and verified implementation of the Bar-Lock manufacturingquality control process and procedures for compliance with the applicable provisions of ANSI/ASME N45.2.4.Bechtel developed and performed an independent mechanical testing andanalysis program to assess the mechanical performance characteristics of the Bar-Lock coupler system, using the qualification criteria of ASME CodeSection III, Division 2, CC-4333, "Mechanical Splices," as a standard ofreference. The test program demonstrated that the mechanical properties of the Bar-Lock coupler system met the ASME Code and NRC requirements.3.2 Technical Evaluation ConclusionThe staff concludes that the licensee's test results meet the requirements specified in ASME Code,Section III, Division 2, CC-4333, "Mechanical Splices." Therefore, the staff concurs withthe licensee that the qualified Bar-Lock coupler assembly can be used for splicing rebar at the WBN shield building. The staff notes that 10 CFR 50, Appendix B requirements are applicableto the design, purchase, fabrication, handling, shipping, storage, inspection, testing, andinstallation of the Bar-Lock mechanical couplers.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Tennessee State official was notified ofthe proposed issuance of the amendment. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a facilitycomponent located within the restricted area as defined in 10 CFR Part 20. The NRC staff hasdetermined that the amendment involves no significant increase in the amounts, and nosignificant change in the types, of any effluents that may be released offsite, and that there isno significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (70 FR 405, January 4, 2005). Accordingly, the amendment meets the eligibility criteria forcategorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
6.0 CONCLUSION
Based on the considerations discussed above, the Commission concludes that: (1) there isreasonable assurance that the health and safety of the public will not be endangered byoperation in the proposed manner, (2) such activities will be conducted in compliance with theCommission's regulations, and (3) the issuance of this amendment will not be inimical to thecommon defense and security or to the health and safety of the public.Principal Contributor:John MaSamantha CraneDate: April 27, 2006