ML060870188

License Amendment, the Use of a Bar-Lock Mechanical Coupler for Splicing Reinforcing Bars in the Shield Building

ML060870188
Person / Time
Site:	Watts Bar
Issue date:	04/27/2006
From:	Pickett D Plant Licensing Branch III-2
To:	Singer K Tennessee Valley Authority
Pickett , NRR/DLPM, 415-1364
References
TAC MC5368
Download: ML060870188 (10)

Text

April 27, 2006 Mr. 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 AMENDMENT ON 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 License No. 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 the Commission's biweekly Federal Register notice.

Sincerely,

/RA/

Douglas V. Pickett, Senior Project Manager Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-390

Enclosures:

1. Amendment No. 60 to NPF-90

2. Safety Evaluation cc w/encls: See next page

ML060870188 *No Legal Objection NRR-058 OFFICE LPLD LPL2-2/PM BC:EGCB LPL2-2/LA OGC LPL2-2/BC NAME SCrane DPickett RKaras RSola APHodgdon* MMarshall (via memo)

DATE 4/13/06 4/14/06 3/13/06 4/12/06 4/25/06 4/27/06 Mr. Karl W. Singer Tennessee Valley Authority WATTS BAR NUCLEAR PLANT cc:

Mr. Ashok S. Bhatnagar, Senior Vice President Mr. Paul L. Pace, Manager Nuclear Operations Licensing and Industry Affairs Tennessee Valley Authority Watts Bar Nuclear Plant 6A Lookout Place Tennessee Valley Authority 1101 Market Street P.O. Box 2000 Chattanooga, TN 37402-2801 Spring City, TN 37381 Mr. Larry S. Bryant, Vice President Mr. Jay Laughlin, Plant Manager Nuclear Engineering & Technical Services Watts Bar Nuclear Plant Tennessee Valley Authority Tennessee Valley Authority 6A Lookout Place P.O. Box 2000 1101 Market Street Spring City, TN 37381 Chattanooga, TN 37402-2801 Senior Resident Inspector Mr. Robert J. Beecken, Vice President Watts Bar Nuclear Plant Nuclear Support U.S. Nuclear Regulatory Commission Tennessee Valley Authority 1260 Nuclear Plant Road 6A Lookout Place Spring City, TN 37381 1101 Market Street Chattanooga, TN 37402-2801 County Executive 375 Church Street Mr. Michael D. Skaggs Suite 215 Site Vice President Dayton, TN 37321 Watts Bar Nuclear Plant Tennessee Valley Authority County Mayor P.O. Box 2000 P. O. Box 156 Spring City, TN 37381 Decatur, TN 37322 General Counsel Mr. Lawrence E. Nanney, Director Tennessee Valley Authority Division of Radiological Health ET 11A Dept. of Environment & Conservation 400 West Summit Hill Drive Third Floor, L and C Annex Knoxville, TN 37902 401 Church Street Nashville, TN 37243-1532 Mr. John C. Fornicola, Manager Nuclear Assurance and Licensing Ms. Ann P. Harris Tennessee Valley Authority 341 Swing Loop Road 6A Lookout Place Rockwood, Tennessee 37854 1101 Market Street Chattanooga, TN 37402-2801 Mr. Glenn W. Morris, Manager Corporate Nuclear Licensing and Industry Affairs Tennessee Valley Authority 4X Blue Ridge 1101 Market Street Chattanooga, TN 37402-2801

TENNESSEE VALLEY AUTHORITY DOCKET NO. 50-390 WATTS BAR NUCLEAR PLANT, UNIT 1 AMENDMENT TO FACILITY OPERATING LICENSE Amendment 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) dated December 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 amendment can be conducted without endangering the health and safety of the public, and (ii) that such activities will be conducted in compliance with the Commission's regulations; D. The issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public; and E. The issuance of this amendment is in accordance with 10 CFR Part 51 of the Commission's regulations and all applicable requirements have been satisfied.

2. Accordingly, the license is amended to authorize revision of the Updated Final Safety Analysis 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 the amendment 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 TVAs application dated December 9, 2004, as supplemented by letters dated November 18 and December 5, 2005, and evaluated in the staffs Safety Evaluation attached to this amendment.

FOR THE NUCLEAR REGULATORY COMMISSION

/RA/

Michael L. Marshall, Jr., Chief Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Date of Issuance: April 27, 2006

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 60 TO FACILITY OPERATING LICENSE NO. NPF-90 TENNESSEE VALLEY AUTHORITY WATTS BAR NUCLEAR PLANT, UNIT 1 DOCKET NO. 50-390

1.0 INTRODUCTION

By application dated December 9, 2004, as supplemented by letters dated November 18 and December 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 consideration determination.

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 and existing 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 the use of the Bar-Lock coupler system without a prequalification test program because the system had 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 at SQN, and the approval was based on the licensees submittal dated March 18, 2002, as supplemented by a letter dated December 10, 2002. The approval was limited to SQNs specific request and was not applicable to other plants.

Based on the staffs review of the license amendment application and subsequent discussions with the licensee, the staff concluded that the essential variables in the Bar-Lock coupler Enclosure

system to be used at WBN were not identical to those used at SQN; therefore, the licensees request to use the Bar-Lock coupler system could not be approved without a prequalification test program. During the staffs 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 the leftover couplers, but that these couplers would need to be requalified as a new system. The staffs 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 was performed on the remaining couplers used at TVAs SQN, as well as the newly manufactured couplers, and that the test results showed that these couplers were qualified for use to repair the 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, the licensee 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 test procedures that incorporate the requirements and acceptance limits contained in applicable design documents. According to 10 CFR 50.55a(a)(2), systems and components of boiling and pressurized 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-4333.2.1 requires that each splice system manufacturer conduct a series of performance tests in order to qualify a splice system for use.

Section CC-4333.2.3(a) of the Code, Static Tensile Tests for Mechanical Splices, requires that six 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 actual tensile strength of the reinforcing bar being tested, nor less than 100 percent of the specified minimum tensile strength. Additionally, the tensile strength of any individual splice system shall not 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, requires that 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 strength of the reinforcing bar.

3.0 TECHNICAL EVALUATION

The Bar-Lock coupler system consists of two pieces of rebar joined by a coupler barrel and tightened by lockshear bolts through torque and with serrated rails as inserts between the rebar and the barrel. The coupler barrel, lockshear bolts, serrated rails, and rebar are elements that influence and contribute to the performance of the Bar-Lock coupler system. The purpose of the qualification test for the Bar-Lock coupler system is to demonstrate that the entire assembly containing 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 be used in the shield building at WBN would not be identical to those used at SQN, the Bar-Lock coupler 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 essential variables for the Bar-Lock coupler system. Therefore, any change in one of the essential variables prompts a need for a requalification of the Bar-Lock coupler system.

3.1 Requalification Testing The staff reviewed the Test Report for Bar-Lock Qualification, which was attached to the licensees letter dated December 5, 2005. The report stated that the Code required six splice specimens 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 rebar specimens tested under static loading shall be no less than 90 percent of the actual tensile strength of the reinforcing bar being tested, nor less than 100 percent of the specified minimum tensile 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 the specified 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-lock couplers. 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. The average tensile strength of the six #6 static tensile specimens with SQN leftover couplers was 104,350 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 Code requirement of 1.25 x 60,000 psi = 75,000 psi.

The average tensile strength of the eight #6 static tensile specimens with new couplers was 107,730 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 Code requirement 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 tensile strength 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 of 102,306 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 code requirement of 1.25 x 60,000 psi = 75,000 psi.

The average tensile strength of the six #8 static tensile specimens with new couplers was 99,951 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 Code requirement 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 for each 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 #6 and 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 licensees conclusion.

The staffs approval of the Bar-Lock assemblies at the SQN facility included a detailed review of Bechtel Report No. 24370-TR-C-001. This report, which will be referenced in the WBN UFSAR, 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 Bechtels control of quality assurance and operations will be equivalent to that conducted during the SQN steam generator replacement project. The Bechtel 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, and installation of the Bar-Lock mechanical couplers.

2. TVA has reviewed and approved Bechtels Watts Bar Steam Generator Replacement 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 Part 50, 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 manufacturing quality control process and procedures for compliance with the applicable provisions of ANSI/ASME N45.2.

4. Bechtel developed and performed an independent mechanical testing and analysis program to assess the mechanical performance characteristics of the Bar-Lock coupler system, using the qualification criteria of ASME Code Section III, Division 2, CC-4333, Mechanical Splices, as a standard of reference. 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 Conclusion The staff concludes that the licensees test results meet the requirements specified in ASME

Code,Section III, Division 2, CC-4333, Mechanical Splices. Therefore, the staff concurs with the 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 applicable to the design, purchase, fabrication, handling, shipping, storage, inspection, testing, and installation of the Bar-Lock mechanical couplers.

4.0 STATE CONSULTATION

In accordance with the Commission's regulations, the Tennessee State official was notified of the 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 facility component located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no 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 for categorical 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 is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributor: John Ma Samantha Crane Date: April 27, 2006