ML11116A211

Technical Report No. SQN2-SGR-TR3, Revision 0 Sequoyah Unit 2 Steam Generator Replacement Alternate Rebar Splice - Bar-Lock Mechanical Splices Technical Report, Attachment 2

ML11116A211
Person / Time
Site:	Sequoyah
Issue date:	04/21/2011
From:	Krich R, Ceraldi M Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML11116A211 (58)

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Attachment 2 Technical Report No. SQN2-SGR-TR3, Revision 0 Sequoyah Unit 2 Steam Generator Replacement Alternate Rebar Splice - Bar-Lock Mechanical Splices Technical Report Approved by TVA on February 15, 2011 El-12

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SEQUOYAH UNIT 2 STEAM GENERATOR REPLACEMENT ALTERNATE REBAR SPLICE - BAR-LOCK MECHANICAL SPLICES TECHNICAL REPORT Document No: SQN2 - SGR - TR3 PROJECT Sequoyah DISCIPLINE N CONTRACT PO 00075603 UNIT 2 DESC. Rebar Mechanical Splice (Bar-Lock) Qual. Report DWG/DOC NO. S0N2-SGR-TR3 SHEET - OF - REV. 00 DATE 02/15/11 ECN/DCN - FILE N2N-075 The Steam Generatina Team A URS-Washington DivisionIAREVA NP Company EDMS, WT CA-K Page 1 of 56

The Steam Generating Team SW A OS.Washingtlon Division/ARF'A WP Company Document No.: SQN2-SGR-TR3 ALTERNATE REBAR SPLICE - BAR-LOCK SPLICES TECHNICAL REPORT Safety Related? [* YES n-] NO Does this document contain assumptions requiring verification? [-- YES NO Signature Block PageslSections Name and P, R, A PreparedlReviewed/

Title/Discipline Signature Date Approved or Comments Mark D. Ceraldi /~ All SGT LICENSING <01 Maria M. Hamrick / R All SGT CIVIL ENGR ' I/L3 hi George L. Comer A // All SGT ASST PEM Note: P designates Preparer, R designates Reviewer, and A designates Approver.

Page 2 of 56

The Steam Generating Team KGJ AURS-WashngtiMb DIvisIon/ARE VANPCompany Document No.: SQN2-SGR-TR3 ALTERNATE REBAR SPLICE - BAR-LOCK SPLICES TECHNICAL REPORT Record of Revision Revision Pages/Sectionsl No. Date Paragraphs Changed Brief Description I Change Authorization 0 05-Jan-2011 All Initial Issue Page 3 of 56

SEQUOYAH UNIT 2 SGR ALTERNATE REBAR SPLICE - BAR-LOCK MECHANICAL SPLICES TECHNICAL REPORT (No. SQN2-SGR-TR3)

Table of Contents 1.0 Abstra ct .............................................................................................  ;......................................................... 5 2 .0 Intro d uctio n ................................................................................................................................................... 5 3 .0 O bje ctive s .................................................................................................................................................... 6 4.0 Regulatory Requirements/Criteria for Mechanical Splices ..................................................................... 7 4.1 NRC Regulatory Guide 1.136, Materials, Construction, and Testing of Concrete Containments ..... 7 4.2 ASME Section III, Division 2, Paragraph CC-4333, Mechanical Splices .............................................. 8 4.3 ASTM A370, Standard Test Methods and Definitions for Mechanical Testing of Steel Products ..... 9 4.4 ANSI N45.2.5, Supplementary Quality Assurance Requirements for Installation, Inspection, and Testing of Structural Concrete and Structural Steel During the Construction Phase of Nuclear P owe r P la nts .............................................................................................................................................. 9 5.0 Description of Bar-Lock Couplers .......................................................................................................... 9 6.0 Criteria for QA/QC for Manufacturing and Use of Bar-Lock Couplers ................................................. 12 6 .1 Co de of Re co rd ..................................... ................................................................................................... 12 6.2 10 C FR 50 Appendix B Elem ents ........................................................................................................ 12 7.0 Bar-Lock Coupler Prequalification Testing for Sequoyah Unit 1 and Watts Bar Unit 1 SGRs ............ 14 7.1 Bechtel/INEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use to Support the Sequoyah Unit 1 SGR Project - Overview ............................................ 14 7.2 Bechtel/INEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use to Support the Sequoyah Unit 1 SGR Project - Test Plan Employed ......................................................................... 15 7.3 Bechtel/IlNEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use to Support the Sequoyah Unit I SGR Project - Mechanical Properties Test Results for Reinforcing Bar ................ 15 7.4 BechtelINEEL Testing Program to Pre-Qualify Bar-Lock Couplers forUse to Support the Sequoyah Unit 1 SGR Project - Description of Coupler Test Specimens ......................................... 18 7.5 Bechtel/INEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use to Support the Sequoyah Unit 1 SGR Project - Test Results ................................................................................... 19 8.0 Sequoyah Unit 2 Bar-Lock Coupler Installation .................................................................................... 24 8.1 S plicing Crew Q ualification ....................................................................................................................... 25 8 .2 Inspectio n C rite ria ..... ............................................................................................................................... 25 8.3 Production / Sister Splice Testing ........................................................................................................ 25 8 .4 Acceptance C rite ria .................................................................................................................................... 26 8.5 Quality Assurance / Quality Control ........................................................ 26 9.0 S um m ary and C onclusions ...................................... I............................................................................... 27 10 .0 Refe re nce s ................................................................................................................................................ 28 Appendices A Ne Signiflcant HazarI d nsid tin Determination .................... ......................

B Bar-Lock Coupler Test Reports for Sequoyah Unit 1 and Watts Bar Unit 1 SGRs ............................... 30 Tables 7-1 Bechtel/INEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use to Support the Sequoyah Unit 1 SGR Project - Mechanical Properties of Rebar Used in Test Specimens ............................. 17 7-2 Bar-Lock L-Series Coupler Specifications (Sizes 6L and 8L) ............................................................. 18 Figures 5-1 Bar-Lock C oupler C utaway ....................................................................................................................... 10 5-2 Bar-Lock Coupler L-Series (8-Bolts) .......................................... 11 5-3 Bar-Lock Coupler Installation ............................................... 11 Technical Report No. SQN2-SGR-TR3 Page 4 of 56

SEQUOYAH UNIT 2 SGR ALTERNATE REBAR SPLICE - BAR-LOCK MECHANICAL SPLICES TECHNICAL REPORT (No. SQN2-SGR-TR3) 1.0 Abstract The original construction of the Sequoyah Nuclear Plant Unit 2 concrete Shield Building employed lap splices to join concrete reinforcing steel (rebar). While such splices were able to be easily employed for original plant construction, they are difficult to perform when restoring the concrete in Shield Building openings that result from performing maintenance activities such as steam generator replacements (SGRs). Historically for SGRs, mechanical splices have been employed in reestablishing the rebar connections for restoring the temporary concrete openings that are made to allow access to containment of the old steam generators (OSGs) and replacement steam generators (RSGs). In this manner, both the Sequoyah Unit 1 and Watts Bar Unit I SGRs utilized the Bar-Lock coupler system to provide the mechanical rebar splicing necessary to restore the temporary steam generator access openings in their Shield Buildings.

Extensive prequalification of the Bar-Lock couplers actually employed for these SGRs was performed to meet ASME/ACI criteria which demonstrate the equivalency of the Bar-Lock Model 6L and Model 8L rebar connections to rebar repairs using a cadweld splice methodology. Technical Report SQN2-SGR-TR3 presents the technical justification for use of the same model Bar-Lock couplers for the restoration of the Sequoyah Unit 2 Shield Building temporary steam generator access openings as part of the Unit 2 SGR that will be performed in Fall 2012.

2.0 Introduction Technical Report SQN2-SGR-TR3 provides the technical justification for use of Model 6L and Model 8L Bar-Lock couplers in the restoration of the temporary steam generator access openings in the Sequoyah Unit 2 Shield Building as part of the Unit 2 SGR Project. Mechanical splices for reinforcing steel (rebar) used in nuclear safety-related concrete structures are subject to the stringent requirements of ASME Section III, Division 2/ACI-359 and ACI-318, which includes the requirement for the splice to develop 125% of the minimum yield strength of the reinforcing bar.

For the Sequoyah Unit 1 SGR, TVA submitted Topical Report 24370-TR-C-001, Sequoyah Unit 1 Steam Generator Replacement Alternate Rebar Splice - Bar-Lock Mechanical Splices Topical Report (Reference 1), which received NRC approval via the Letter and accompanying SER dated March 13, 2003 (Reference 2) to allow use of Bar-Lock couplers model numbers #6 and #8 (i.e., Model 6L and Model 8L) for use on non-containment (i.e., Shield Building) applications at TVA's Sequoyah Units 1 and 2.

Although use of Bar-Lock couplers for the Unit 2 Shield Building is cited in the March 13, 2003 NRC Letter, since the content of Topical Report 24370-TR-C-001 does not specifically address Unit 2 application of the Bar-Lock couplers, Technical Report SQN2-Technical Report No. SQN2-SGR-TR3 Page 5 of 56

SGR-TR3 is being written specifically to address Bar-Lock coupler use for the Sequoyah Unit 2 SGR.

For the Watts Bar Unit 1 SGR Project, TVA submitted a License Amendment Request (LAR) on December 9, 2004 asking for NRC approval to utilize the same Model 6L and Model 8L Bar-Lock Couplers in the restoration of the temporary steam generator access openings in the Watts Bar Unit 1 Shield Building (Reference 3). This LAR was supplemented with prequalification testing of the Model 6L and Model 8L Bar-Lock couplers additional to that performed as part of Topical Report 24370-TR-C-001 in order to demonstrate the acceptability of using these model Bar-Lock couplers for the Watts Bar Unit 1 SGR (References 4 and 5).

The Bar-Lock couplers were successfully used for the Sequoyah Unit 1 and Watts Bar Unit 1 SGR Projects. For these applications, the Bar-Lock coupler system demonstrated the capability to achieve efficient fitup/reconnection of the rebar assembled to enable restoration of the temporary steam generator access openings made in the roofs of the Shield Buildings of Sequoyah Unit 1 and Watts Bar Unit 1. Research with the Bar-Lock coupler system manufacturer concludes that there have been no changes in the design and manufacture of the Model 6L and Model 8L Bar-Lock couplers from the time of their procurement for use in the Sequoyah Unit 1 and Watts Bar Unit 1 SGRs (Reference 6)

The Manufacturer further confirms that for these model Bar-Lock couplers the design and manufacturing parameters will not be changed before procurement of the inventories of these Bar-Lock couplers for use in restoring the temporary steam generator access openings that will be made in the Sequoyah Unit 2 Shield Building during the Unit 2 SGR in Fall 2012. Given these facts and the extensive prequalification testing documented in the applications for use of the Model 6L and Model 8L Bar-Lock couplers for the Sequoyah Unit 1 and Watts Bar Unit 1 SGR projects, further prequalification testing of the Model 6L and Model 8L Bar-Lock couplers is concluded to be not required.

The Steam Generating Team, LLC (SGT) has been contracted by TVA to perform engineering, procurement, and construction activities for the Sequoyah Unit 2 SGR Project, which includes restoration of the temporary steam generator access openings discussed in this Technical Report.

3.0 Objectives The objectives of this report are to present the necessary data supporting the use of Model 6L and Model 8L for restoration of the temporary steam generator access openings in the Sequoyah Unit 2 Shield Building roof to support the Unit 2 SGR Project.

To achieve this objective, the following types of information have been compiled:

A description of the Bar-Lock couplers (Models 6L and 8L) is presented in sufficient detail to illustrate the advantages and benefits of this rebar reconnection system.

Technical Report No. SQN2-SGR-TR3 Page 6 of 56

Criteria for the laboratory prequalification testing of the Bar-Lock Model 6L and Model 8L couplers. Previously performed laboratory prequalification testing and processes utilized for the Model 6L and 8L Bar-Lock couplers are documented in References 1, 4, and 5, and are summarized in Technical Report SQN2-TR-003, including addressing the applicability of this prequalification testing to the future procurement of Model 6L and Model 8L Bar-Lock couplers to support the Unit 2 Sequoyah SGR Project. Discussions of this laboratory testing also include the 10 CFR 50 Appendix B requirements and a description of quality control of critical processes that were involved in the manufacture and testing of the couplers, and the application of these criteria to current manufacture of the Model 6L and Mode 8L Bar-Lock couplers. Applicable test reports of this laboratory prequalification testing are included in Appendix B of this Technical Report.

" Criteria for qualification and testing of the installation of the Model 6L and Model 8L Bar-Lock couplers to support restoration of the temporary steam generator access openings pertain to the onsite qualification testing that is performed as part of the installation process to be employed during the Sequoyah Unit 2 SGR Outage.

• Specifics of the Bar-Lock Installation to support the Sequoyah Unit 2 SGR.

4.0 Regulatory Requirements/Criteria for Mechanical Splices Detailed below are regulatory requirements/criteria that are relevant to mechanical splices. Following each requirement/criterion is an italicized reference to where the requirement/criteria are addressed within this Technical Report.

4.1 NRC Regulatory Guide 1.136, Materials, Construction, and Testing of Concrete Containments Regulatory Guide 1.136 states in part that the requirements specified in Article CC-4000 of ASME Section III, Division 2, 1980 Edition (also known as ACI 359-80), are acceptable to the NRC staff subject to the following:

• Instead of the requirements in subparagraph CC-4333.4.2, splice samples shall be production splices (cut directly from in-place reinforcement).

As discussedin Section 8.3, all splice samples will be sistersplices.

Technical Report No. SQN2-SGR-TR3 Page 7 of. 56

4.2 ASME Section III, Division 2, Paragraph CC-4333, Mechanical Splices This section of the ASME Code addresses the requirements for mechanical splices.

Paragraph CC-4333.2.1 requires each splice system manufacturer to conduct a series of performance tests in order to qualify his splice system for use.

Previous testing which meets the requirements of Paragraph CC-4333.2.1 has been performed for the Model 6L and Model 8L Bar-Lock couplers that will be employed in restoring the temporary Shield Building access openings that will be made to perform the Sequoyah Unit 2 SGR. As described above, this extensive prequalificationtesting was performed for these model Bar-Lock couplers for their use in the same application as part of the Sequoyah Unit 1 and Watts Bar Unit I SGRs. Specifically, as presented in Appendix B of this Technical Report, this testing was performed in 2001 for Sequoyah Unit I and 2005 for Watts Bar Unit 1. Research with the Bar-Lock coupler system manufacturer concludes that there have been no changes in the design and manufacture of the Model 6L and Model 8L Bar-Lock couplers from the time of their procurement for use in the Sequoyah Unit I and Watts Bar Unit I SGRs (and the above cited performance of prequalificationtesting) to the present day (Reference 6). The Bar-Lock manufacturerfurther confirms that for these model Bar-Lock couplers the design and manufacturingparameterswill not be changed before procurementof the inventories of these Bar-Lock couplers for use in restoring the temporary steam generator access openings that will be made in the Sequoyah Unit 2 Shield Building during the Unit 2 SGR in Fall 2012. Therefore, the test reports contained in Appendix B serve to demonstrate from a prequalification testing standpoint that the Bar-Lock Model 6L and Model 8L couplers are appropriate for use in restoring the temporary Shield Building access openings for the Sequoyah Unit 2 SGR and that the requirements of ParagraphCC-4333.2.1 have been satisfied.

Paragraph CC-4333.4 requires that each splicer prepare two qualification splices on the largest size bar to be used. The qualification splices shall be made using reinforcing bar identical to that to be used in the structure. The completed qualification splices shall be tensile tested using the loading rates set forth in SA-370, and the tensile results shall meet those specified in Table CC-4333.1.

Splicing crew qualificationis describedin Section 8.1.

Paragraph CC-4333.5.4 requires that splice samples be tensile tested using the loading rates set forth in SA-370 and meet the following acceptance standards:

(a) The tensile strength of each sample shall equal or exceed 125% of the specified yield strength as shown on Table CC-4333-1.

Technical Report No. SQN2-SGR-TR3 Page 8 of 56

(b) The average tensile strength of each group of 15 consecutive samples shall equal or exceed the specified minimum strength as shown in Table CC-4333-1.

The acceptance criteria that will be used for testing of splice samples are described in Section 8.4.

4.3 ASTM A370, Standard Test Methods and Definitions for Mechanical Testing of Steel Products Section 10 of the standard specifies the requirements for gage marks to determine percent elongation.

A discussion of the determination of the mechanical properties of the rebar used in the Bechtel/INEEL coupler testing presented in Appendix B is described in Section 7.3, which includes information on the gage lengths used.

Section 13 of the standard specifies acceptable methods for determining tensile properties.

A discussion of the determination of the mechanicalproperties of the rebarused in the Bechtel/INEEL coupler testing presented in Appendix B is described in Section 7.3.

The results of the testing of these coupler assemblies are provided in Section 7.5.

4.4 ANSI N45.2.5-1974, Supplementary Quality Assurance Requirements for Installation, Inspection, and Testing of Structural Concrete and Structural Steel During the Construction Phase of Nuclear Power Plants ANSI N45.2.5 specifies supplementary quality assurance requirements for installation, inspection, and testing of structural concrete and structural steel for nuclear power plant construction.

Sections 6.2 and 8.5 describe the conformance to quality requirementsfor the Bar-Lock couplers and installation of the couplers at Sequoyah Unit 2.

5.0 Description of Bar-Lock Couplers Bar-Lock couplers are manufactured of seamless hot-rolled steel tube conforming to ASTM A-519, with a minimum tensile strength exceeding 100 ksi. The couplers utilize a combination of lockshear bolts and heat-treated internal serrated rails to create a mechanical connection that exceeds the ASME and ACI requirements. A cutaway view of a typical Bar-Lock coupler is provided in Figure 5-1. The serrated rails extend the length of the tube to cradle and grip the rebar. As the six bolts in the illustration are tightened, they embed into the rebar. The serrated rails also embed into the rebar and Technical Report No. SQN2-SGR-TR3 Page 9 Of 56

the interior wall of the tube. The number of bolts required is dependent on the size of the rebar to be spliced. Unlike the 6 bolts shown on Figure 5-1, the Bar-Lock couplers for the 6L and 8L rebar to be used at Sequoyah Unit 2 utilize 8 and 10 bolts, respectively. The 8-bolt Bar-Lock Model 6L coupler is represented on Figure 5-2.

A, Coupler Bcirral A.

a- Lockshtor Bolts C- Sefroted RoArs D. Cen~ter Pin Figure 5 Bar-Lock Coupler Cutaway Installation of the Bar-Lock coupler is as follows:

" Insert the first rebar halfway into the coupler to the center pin (D).

" Tighten the bolts (B) to snug (finger-tight) fit.

• Insert the second piece of rebar halfway into the other end of the coupler to the center pin (D).

" Tighten the remaining bolts (B) to snug (finger-tight) fit.

" Tighten all bolts (B) in a random alternating pattern, making a minimum of two passes of tightening each bolt prior to shearing the bolt heads.

The installation process is depicted in Figure 5-3.,

Technical Report No. SQN2-SGR-TR3 Page 10 of 56

I' kl-n F-Figure 5 Bar-Lock Coupler L-Series (8-Bolts)

Figure 5 Bar-Lock Coupler Installation Technical Report No. SQN2-SGR-TR3 Page.11 of 56

The couplers are easy to install, normally requiring no special equipment and minimal operator training, and do not require special nrebar preparation. Each coupler uses lockshear bolts that require a specified minimum torque to shear the bolt heads off. Most coupler sizes can be installed with a standard impact wrench, and smaller sizes require only a manual socket wrench. No heavy crimping equipment or threading devices are required. The couplers can be used when rebar is fixed in a position (positional) as well as when the rebar is free to rotate (standard).

The susceptibility of the Bar-Lock splice bolt tip materials to stress corrosion cracking (SCC) has been considered. For SCC to occur, three elements are required: (1) a susceptible material, (2) a corrosive environment, and (3) tensile stress. High hardness, low alloy steels are susceptible to stress corrosion under some circumstances. However, the alkaline environment of properly specified and placed concrete is normally not corrosive to steel. The concrete at Sequoyah is formulated to industry standards and should provide a non-corrosive environment for the reinforcing bar and other steel components. In addition, the bolts in the Bar-Lock splice are tightened against the reinforcing bar so that they are in compression, not tension. Therefore, the three necessary conditions for stress corrosion do not occur in the application of Bar-Lock splice bolt tips at Sequoyah Unit 2 in the performance of the restoration of the temporary steam generator access openings made in the Unit 2 Shield Building dome.

6.0 Criteria for Quality Assurance I Quality Control for Manufacturing and Use of Bar-Lock Couplers Regulatory requirements/criteria for the manufacturing and use of mechanical splices are detailed in Section 4 of this Technical Report.

6.1 Code of Record As indicated in Section 3.8.1.2 of the Sequoyah UFSAR, the structural design of the Shield Building is in compliance with the American Concrete Institute (ACI) 318-63 building code working stress requirements. The reinforcing steel conforms to the requirements of ASTM Designation A 615, Grade 60. Original construction was carried out under the requirements of TVA Construction Specification G-2. UFSAR Section 3.8.1.1 states that reinforcing bars were lap spliced in accordance with ACI 318-63 requirements for Strength Design.

6.2 10 CFR 50 Appendix B Elements 10 CFR 50, Appendix B establishes quality assurance requirements for the design, construction, and operation of structures, systems, and components (SSCs) that prevent or mitigate the consequences of postulated accidents that could cause undue risk to the health and safety of the public. The pertinent requirements of 10 CFR 50, Appendix B apply to activities affecting the safety-related functions of those SSCs.

Since the planned use of Bar-Lock couplers at Sequoyah Unit 2 will be to restore the Technical Report No. SQN2-SGR-TR3 Page 12 of 56

safety-related shield building, 10 CFR 50, Appendix B requirements are applicable to the design, purchase, fabrication, handling, shipping, storage, inspection, testing, and installation of the couplers. Specifics on conformance to the 10 CFR 50, Appendix B requirements relative to the use of Bar-Lock couplers are provided in the quality assurance manuals, plans, procedures, and specification described below.

As indicated in Chapter 17 of the Sequoyah UFSAR, design and construction activities at the Sequoyah plant will be in accordance with the latest approved revision of the TVA Nuclear Quality Assurance Plan (TVA-NQA-PLN89-A). Steam Generating Team (SGT) activities related to the Unit 2 SGR Project will be in accordance with the latest revision of the SGT Quality Assurance Manual which has been approved by TVA. SGT specifications issued to purchase the reinforcing bar and Bar-Lock couplers that will be used to restore the temporary steam generator access openings in the Unit 2 Shield Building dome include:

1. Specification 39866-SPEC-C-006, "Purchase of Bar-Lock Rebar Couplers"

2. Specification 39866-SPEC-C-007, "Technical Specification for Purchase of Reinforcing Steel" As described in Section 8 of this Technical Report, installation of reinforcing bar and the Bar-Lock couplers will be addressed through standard TVA work controlling processes.

Bar-Lock couplers are not currently manufactured as nuclear safety-related. Since the Bar-Lock couplers will be used in a nuclear safety-related application, they are subject to a commercial grade dedication program by SGT. To support this dedication, SGT will witness and verify implementation of the Bar-Lock manufacturing and quality control processes and procedures for compliance with the provisions of SGT Specification 39866-SPEC-C-006.

The following processes and critical parameters will be observed and checked by SGT in accordance with a Commercial Grade Dedication Plan to ensure that the final product meets the technical requirements:

" Processes

- Verification of material identification for the tube, serrated rail, and bolt materials

- Item packaging and shipping preparation

• Critical Parameters

- Length of tube

- Inside diameter and wall thickness of tube

- Serrated rail location

- Number of bolts Technical Report No. SQN2-SGR-TR3 Page 13 of 56

- Bolt spacing

- Bolt edge distance

- Bolt threads

- Bolt tip hardness

- Diameter of bolt shear plane

- Actual bolt break-point torque values The following records will also be examined:

" Certified material test reports for tube, serrated rail, and bolt materials from each heat/lot of each of these items

" Bolt heat treatment reports

" Bolt tip hardness test results

• Bolt shear test results

• Serrated rail heat treatment reports 7.0 Bar-Lock Coupler Prequalification Testing for Sequoyah Unit 1 and Watts Bar Unit I SGRs For the preparation of Topical Report 24370-TR-C-001-A to gain NRC approval to use Bar-Lock couplers to support the Shield Building dome restoration activities of the Sequoyah Unit 1 SGR Project, extensive laboratory testing was performed of specimens of the Model 6L and Model 8L Bar-Lock couplers by Idaho National Engineering and Environmental Laboratory (INEEL). The test report which resulted from this testing is presented in Appendix B of this Technical Report (No. SQN2-SGR-TR3). Also included in Appendix B are the test results from the abbreviated laboratory-type testing that was performed to pre-qualify Bar-Lock couplers for use in the similar Shield Building dome temporary access opening restoration activities that were planned for the Watts Bar Unit 1 SGR Project. Sections 7.1 through 7.5 (and associated subsections) describe the Bechtel and INEEL collaborative effort to perform the laboratory testing of the Bar-Lock couplers for use to support the Sequoyah Unit 1 SGR Project. This presentation is reflective of the similar content contained in Sections 8.1 through 8.5 (and associated subsections) of Topical Report 24370-TR-C-001-A (Reference 1).

7.1 Bechtel/INEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use to Support the Sequoyah Unit 1 SGR Project - Overview For the preparation of Topical Report 24370-TR-C-001-A to gain NRC approval to use Bar-Lock couplers, Bechtel Corporation and INEEL developed and performed an Technical Report No. SQN2-SGR-TR3 Page 14 of 56

independent mechanical testing and analysis program to assess the mechanical performance characteristics of the Bar-Lock L-Series rebar coupler system. By design, this program provided a rigorous test of coupler design mechanical performance, using the qualification criteria of ASME Section III, Division 2, CC-4333 as a standard of reference.

The Bechtel/INEEL test program tested and demonstrated that the mechanical properties of the L-Series Bar-Lock mechanical splices meet the existing Codes and NRC requirements and are an acceptable method of connecting reinforcing bar in nuclear power plant safety-related applications.

Work performed by INEEL was conducted in accordance with INEEL's Quality Assurance Project Plan and was reviewed by Bechtel and determined to meet the applicable requirements of 10 CFR 50, Appendix B, and in addition conformed to the provisions of ASME/ANSI N45.2 and the applicable ANSI N45.2 series standards.

7.2 Bechtel/INEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use to Support the Sequoyah Unit 1 SGR Project - Test Plan Employed ASME Section CC-4333 specifies performance criteria to qualify rebar splicing devices for use in nuclear safety-related applications. While the strength specifications are moderately high, the quantity of test specimens is relatively low. To achieve high statistical confidence in measured sample parameters, e.g., ultimate strength, the Bechtel/INEEL testing purposely increased the quantity of test specimens (the sample set - n). For the static strength assessment, the ASME Code requires that six (6) specimens be tested, and that all six (6) must pass. In the Bechtel/INEEL test plan, the quantity was increased to n = 40 for each size tested. For the cyclic durability test, the ASME code requires three (3) specimens to survive the 100-cycle test, and the Bechtel/INEEL testing conservatively increased the number of samples to n = 40 for each size for that testing. Increasing the statistical sample size from six (6) or three (3) to forty (40) allowed a great improvement in the confidence levels (especially for the binomial distribution of the cyclic test) associated with lower bound strength and cyclic durability requirements specified in the Code.

The Bechtel/INEEL Bar-Lock testing was monitored by Bechtel QAIQC personnel to ensure that it was performed in accordance with the Bechtel Quality requirements.

7.3 Bechtel/INEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use to Support the Sequoyah Unit 1 SGR Project - Mechanical Properties Test Results for Reinforcing Bar In performing the Bechtel/INEEL testing, mechanical properties used in these tests were determined in accordance with project test procedures, incorporating relevant ASTM standards and procedures (ASTM A 370 and ASTM E 8). Mechanical properties tests were performed on the same universal test machine, using the same Technical Report No. SQN2-SGR-TR3 Page 15 of 56

measurement transducers. The same test machine, load cell, and extensometer were used in the coupler assembly tests as well. Representative stress-strain curves for both heats of rebars are documented in Figures 1 and 2 of the Bechtel/INEEL Test Report included in Appendix B of this Technical Report.

The reinforcing bar used in the Bechtel/INEEL Bar-Lock coupler testing program was ASTM A615 Grade 60 material #6 (3/4 inch nominal diameter) and #8 (1 inch nominal diameter) sizes. Consolidated Power Supply, the vendor of the rebar, provided certified material test reports (CMTRs). The values reported in these CMTRs were based on the results of a single tensile test. The CMTR value, while confirming the nominal material performance, was inadequate to determine "actual" material properties. The ASTM test standard recommends a minimum of three specimens be tested and the results averaged. Additional verification testing was performed as part of this test program to determine the "actual" of measured mechanical properties of the different heats of rebar employed in specimen assembly.

For the Bechtel/INEEL testing, a common heat rebar (CPS #589812899) was used in making up the 6L size coupler test assemblies. Seven #6 size plain bar sections from this heat were tested to determine actual tensile properties of this lot of material (See Appendix B, Table 3). Per ASME Section II, Division 2 requirements, the same 10 inch extensometer gage length as was used in the 6L coupler assembly tests was used to measure strain in the tensile properties tests. The test results are summarized in Table 7-1. Material properties obtained from the Consolidated Power Supply CMTR are provided for comparison.

Table 7-1 illustrates that the differences in yield strength value as determined by three different definitions of yield are minimal. For this type of steel, the yield point is the appropriate measurement and provides the most consistent value (smallest standard deviation). Where "measured" or "actual" yield strength was required in the analyses, 67.7 ksi was used for the 6L coupler tests performed by Bechtel/INEEL. Where "measured" or "actual" ultimate tensile strength (UTS, or Fu) was required in the analyses, 107.5 ksi was used for the 6L tests.

Technical Report No. SQN2-SGR-TR3 Page 16 of 56

Table 7 Bechtel/IlNEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use to Support the Sequoyah Unit I SGR Project - Mechanical Properties of Rebar Used in Test Specimens Yield Point 0.2% OS 0.5% EUL UTS (ksi) Elongation E (MSi)e (ksi)ý Yield (ksi)b Yield (ksi)c (%)d 6L Average 67.7 67.9 68.2 107.5 13.2 27.8 6L Std Dev 1.03 1.19 1.14 1.12 1.26 0.89 6L CMTR 1.0 67.6 107.4 15 8L Average 72.6 72.4 72.5 110.1 11.5 29.2 8L Std Dev 0.45 0.57 0.47 0.74 0.98 0.46 8L CMTR -- -- 73.1 112.0 14 8L CMTR 69.0 -- 112.8 16 (C-series only)

NOTES:

a The "upper yield point" as observed in most carbon steels.

b Yield strength determined using the offset method.

c EUL = "extension under load," the stress at a fixed strain offset from the strain point at the onset of loading.

d CMTR reports elongation based on the standard 8 inches gage length. By test requirements, the gage lengths used in these tests were 10.0 inches for #6 rebar and 14.5 inches for #8 rebar. There is no requirement or point of comparison in the ASME Code related to the ductility (percent uniform elongation) of the rebar material. Itwas measured and reported for the plain bar because itwas a result of the plain bar test method data analysis of ASTM A370. The measured elongation of the plain bar was not comparable to the elongation measured in the coupler tests.

e Modulus of elasticity in 106 psi.

For the Bechtel/INEEL testing, a common heat of rebar (CPS #589813260) was used in making up the 8L size coupler test assemblies used in the tensile strength tests. Seven

1. 8 size plain bar sections from this heat were tested to determine actual tensile properties of this lot of material (see Appendix B, Table 4). Per ASME requirements, the same 14.5 inch extensometer gage length was used in the tensile properties test as was used in the 8L coupler assembly tests. The test results are summarized in Table 7-1. Material properties obtained from the Consolidated Power Supply CMTR are also provided for comparison. Again, the yield point strength was selected for the material yield- strength value. Where "measured" or "actual" ultimate strength (UTS) was required in the analyses, 110.1 ksi was used for the 8L tests.

A separate heat of rebar material (CPS #123741) was used to fabricate the 8L size cyclic test coupler assemblies. There were no measured strength parameters (only specified minimums) associated with the cyclic test procedures, so no verification Technical Report No. SQN2-SGR-TR3 Page 17 Of 56

testing of this material was performed. The CMTR-reported values for this heat are provided at the bottom of Table 7-1 for reference.

7.4 Bechtel/INEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use to Support the Sequoyah Unit I SGR Project - Description of Coupler Test Specimens The Bar-Lock couplers used by Bechtel/INEEL in the test and which were used at Sequoyah were Bar-Lock's "L-Series" (coupler designations 6L and 8L), which are higher strength rebar couplers for use in tension/compression, seismic and other cyclic loading conditions. The specifications for these couplers are provided in Table 7-2.

Table 7 Bar-Lock L-Series Coupler Specifications (Sizes 6L and 8L)

For Coupler Specifications Bolt Specifications Coupler Use Designation on Outside Length Nominal Quantity Size Nominal Rebar Diameter (inch) Weight per Bar (inch) Shear Size (inch) (inch) WTorque I(bs.) (ft.-lb.)

6L #6 1.9 8.0 4.5 4 1/2 80 8L #8 2.2 12.3 9.5 5 5/8 180 For the Bechtel/INEEL testing, the component parts of each Bar-Lock coupler consisted of a steel tube, "lockshear" bolts, and serrated rails. Figure 5-1 shows a schematic diagram of the coupler design (which will be. the same design employed for the Sequoyah Unit 2 SGR). The seamless, hot-rolled steel tube conforms to ASTM A-519, with a minimum tensile strength in excess of 100 ksi. The lockshear bolt material is AISI 41 L40. The bolts are through-hardened over the entire bolt length and induction hardened at the conical bolt tip. The serrated rails are made of ASTM CD19188 material. They are machined and then carburized to a depth of 0.032 inches.

For the Bechtel/INEEL testing, an equivalent testing program was performed for each of the two coupler/rebar sizes tested. For each size, forty (40) test specimen assemblies were made up for tensile strength tests, and forty (40) assemblies were made up for the cyclic durability tests. The test specimens were assembled by construction craft personnel using Bar-Lock's assembly instructions in a normal field environment.

Assembly of the test specimens was monitored by Bechtel QC personnel.

Technical Report No. SQN2-SGR-TR3 Page 18 of 56

7.5 BechtelllNEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use to Support the Sequoyah Unit 1 SGR Project - Test Results The 160 individual coupler specimens tested by the Bechtel/INEEL testing program, and the relevant specimen sample set averages and individual coupler strengths, exceeded the requirements set forth in ASME Code, Section CC-4333.2.3(a).

Eighty (80) tensile strength -tests (forty (40) of each size) were performed on coupler assembly specimens according to relevant sections of ASMT A 3700 and E8, and ASTM CC-4333.2.3(a). A representative stress-strain curve for a coupler strength test is provided in Figure 4 of the Bechtel/INEEL Test Report included as Appendix B of this Technical Report. No practical differences were observed in the general character of the stress-strain curve of the 80 specimens tested. Test data collected included stress, strain, crosshead displacement, applied force, and elapsed time. Crosshead displacement, as utilized here, refers to the relative separation between the test machine grips (i.e., the displacement of the test machine's moving crosshead relative to its fixed one).

The mechanical properties from individual specimen tests, extracted from raw test data using .standard analysis methods provided in ASTM E 8, are tabulated in Table 5 of the Bechtel/INEEL Test Report presented in Appendix B of this Technical Report.

Representative stress-strain plots for a strength test and a cyclic test for each size are also provided in Appendix B.

In addition, for the Bechtel/INEEL testing, several specimens of each size were randomly selected to receive an initial slip test prior to the normal strength test. Virgin test specimens were installed in the test machine and instrumented as for a normal strength test. The applied stress was increased from 0, through 3 ksi, up to 30 ksi, and the reduced to 3 ksi. The change in displacement across the coupler between the two 3 ksi stress levels was measured with an extensometer. Figure 5 in the Bechtel/INEEL Test Report presented in Appendix B shows the traces of applied stress and resultant displacement for the six specimens. In each case, no measurable slip was detected, i.e., the recorded slip displacements, equivalent to less than 0.001 inch over the length of the coupler, were much less than observed hysteresis error in the extensometer.

The Bechtel/INEEL Test Report concludes that this was expected due to the mechanical interlocking of coupler and bar in the Bar-Lock coupler design. The observation of no bar slip within the coupler on initial loading meant that the coupler would develop full strength without excessive deformation upon initial loading.

Technical Report No. SQN2-SGR-TR3 Page 19 of 56

7.5.1 Bechtel/INEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use to Support the Sequoyah Unit I SGR Project - Tensile Test Results The ASME Code, Section CC-4333.2.3, has several criteria with which the coupler performance is compared. The two pertinent criteria for the tensile strength test results of the Bechtel/INEEL Testing Program were as follows:

1. "...The average tensile strength of the splices shall not be less than 90% of the actual tensile strength of the reinforcing bar being tested, nor less than 100% of the specified minimum tensile strength." Average tensile strength is a single average value that is calculated from the entire group (sample set) of replicate test specimens, i.e., from one heat of material, in one size.

As it turns out, the 90% of the actual tensile strength is the governing criteria. For the size 6L group, the specified minimum average strength value is 96.8 ksi. For the size 8L group, the specified minimum average strength value is 99.1 ksi.

Coupler/Bar Size 6L The sample set of strength data from the coupler/bar size 6L was evaluated for normal (Gaussian) probability distribution using the Wilk-Shapiro W-test and graphical analysis methods. The results showed a near normal distribution, i.e.,

only slight departure from normality. Where necessary in the assignment of confidence limits, the assumption of normality is justified.

The size 6L group (sample set, n = 40) average tensile strength was 106.2 ksi (98.8% of the average 6L bar actual tensile strength), with a standard deviation of only 1.87 ksi. The code-required average strength value of 96.8 ksi (90% of actual tensile strength) was 5.0 standard deviations below the sample average. This corresponded to a probability that less than 3 in 10 million couplers would have strength less than the required 96.88 ksi minimum value. Further, a one-sided test for lower bound was also performed. This test provided a practical lower limit strength value for the 6L coupler assembly. Based upon this data set, 99% of the couplers of this type will have a tensile strength greater than 100.13 ksi (with a 99%

confidence level). This was a very strong indication that the size 6L coupler design will achieve the required minimum strength.

Coupler/Bar Size 8L The sample set of strength data from the coupler/bar size 8L was also evaluated for normal (Gaussian) probability distribution using the W-test and graphical analysis methods. The results showed only slight departure from normality.

The size 8L group (sample set, n = 40) average tensile strength was 109.0 ksi (99%

of the average 8L bar actual tensile strength), with a standard deviation of only 2.78 Technical Report No. SQN2-SGR-TR3 Page 20 Of 56

ksi. The required average strength value of 99.1 ksi was 3.6 standard deviations below the sample average. This corresponded to a probability that less than 2 in 10,000 couplers would have a strength less than the required 99.1 ksi minimum value. Further, a one-sided test for lower bound based upon this data set indicated that, with 99% confidence, 99% of the couplers of this type will have a tensile strength greater than 99.94 ksi. This was a very strong indication that the size 8L coupler design will achieve the required minimum strength.

To assess the general capabilities of the overall coupler design, the results from both sizes can be normalized by their respective bar lot (mill heat) tensile strengths and combined into one sample set. In so doing, the conclusion is that the Bar-Lock coupler design produces a splice that will achieve an average strength that is 98.9%

as strong as the rebar itself. It is obvious that this greatly exceeds the ASME Code-required 90% value. The cumulative standard deviation for this combined/normalized sample set was 2.2% of the bar strength, making the required minimum strength 4.0 standard deviations below the sample average. The equivalent likelihood was that only 3 in 100,000 would fail to achieve a strength level equivalent to the rebar ultimate strength.

2. "...The tensile strength of an individual splice system (test specimen) shall not be less than 125% of the specified minimum yield strength of the spliced bar." This is the strength value of each individual test specimen (coupler assembly) consisting of one coupler unit and two attached sections of rebar.

This requirement for each individual coupler tested provided additional assurance that the occasional sample tested that may have a relatively low strength value, as compared to the sample set average, at least had an absolute minimum necessary strength for structural considerations. For the Grade 60 rebar used in the Bechtel/INEEL Testing Program, this required value was 75.0 ksi, and was the same for all specimens tested. All specimens tested in the Bechtel/INEEL Testing Program passed this test, and by a very large margin.

In the simplest case, the pass/fail criteria could be applied directly. For the combined sample size of 80, with no observed failures (strength below 75.0 ksi), the statement could be made with 90% confidence, that no more than 2.8% of couplers would fail this test. By the nature of this type of binomial probability distribution (pass/fail), it was difficult to state reliabilities with a higher level of confidence until many hundreds of samples were assessed. However, by normalizing the measured individual coupler strengths by the required value, an analysis of the amount of deviation on those values could provide a yet stronger comparison and corresponding statement of reliability.

This distribution of normalized strengths showed that the average coupler strength was 144% of the minimum required level for individual couplers, with a standard Technical Report No. SQN2-SGR-TR3 Page 21 of- 56

deviation of less than 4%. Within this distribution, the probability that the strength of an individual coupler assembly would be lower than the requirement was negligible.

However, in the development of Topical Report 24370-TR-C-001-A, the NRC commented that the minimum strength criterion for individual test specimens should be based upon the actual, measured yield strength of the bar material, rather than the specified minimum value described here. This makes more sense from a practical viewpoint, and it removes one variable (the specified material yield strength) from the comparison. This approach does, however, apply a more stringent test of the coupler capability, since the actual yield strength will always be higher than the minimum allowable. To apply this criterion, the size 6L and 8L specimens must be treated separately since the measured yield strengths of the two bar sizes are significantly different.

Size 6L Coupler Using the appropriately normalized test results from the 6L specimens, the same analysis described above was carried out. The size 6L coupler specimen tensile strengths averaged 106.2 ksi, 25.4% above the proposed strength level of 84.6 ksi (125%

• 67.7 ksi) with a standard deviation of 1.86 ksi.

Size 8L Coupler Analyzing the normalized test results from the 8L test specimens showed that their tensile strengths averaged 109.0 ksi, 20.1% above the proposed strength level of 90.8 ksi (125%

• 72.6 ksi) with a standard deviation of 2.81 ksi.

The overall strength performance of the Bar-Lock coupler design can be summarized as excellent, based on this comprehensive test program of different size couplers by performed by Bechtel/INEEL. There were no failures to meet the specified or proposed strength criteria. As the various failure probability values indicated, the likelihood of an individual Type 6L or 8L coupler assembly failing to achieve the ASME required strength levels was very low.

7.5.2 Bechtel/INEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use to Support the Sequoyah Unit 1 SGR Project - Cyclic Test Results Coupler assemblies were cyclically tested by the Bechtel/INEEL Testing Program according to the requirements of ASME CC-4333.2.3(b). Forty specimens of each of the two types (6L and 8L) received 100 load cycles between 5 and 90% of specified minimum bar yield strength (60 ksi). None of the specimens failed (e.g., bar break or bar slip) within the coupler.

Applied stress and specimen extension data were digitized during the cyclic tests in order to provide additional insight into the coupler performance under cyclic load conditions. Figure 6 of the Bechtel/INEEL Test Report included in Appendix B shows a Technical Report No. SQN2-SGR-TR3 Page 22 of 56

representative plot of stress versus displacement. For clarity, only every tenth cycle is presented. It shows the accumulated slip over 100 cycles to be less than 0.0015 inch.

This is less than 10% of the elastic deformation that occurs during a single load cycle.

The same behavior was observed in all of the tests of both coupler sizes. The couplers showed no significant deterioration (visible, or evidenced by deviations in test data) during the tests.

Based on the binomial probability function (pass/fail testing), and no observed failures in 80 tests, it can be stated with 90% confidence that less than 2.8% of the couplers would fail prior to the completion of 100 loading cycles.

Higher Count Cyclic Tests In an effort to improve the cyclic durability performance assessment, several of the specimens in each size were selected at random to receive additional cyclic loading.

Each selected specimen was subjected to an additional 1000 cycles. None of the specimens failed, and none of them showed signs of deterioration through excessive strain accumulation or physical deformation. While this did not provide a verifiable improvement in the statistical probability of failure (the confidence level was too low to be useful), it did provide an engineering indication that the cyclic durability of the couplers will far exceed 100 cycles.

Residual Strength Tests Another test was also performed on randomly selected couplers to provide additional information regarding cyclic durability and residual strength. The selected couplers, each having been subjected to 100 loading cycles, were subsequently loaded to failure monotonically. This is the standard "tensile strength test" described in the previous section. The concept here was to determine if the prescribed cyclic loading substantially damaged the integrity of the splice assembly. The eight specimens tested achieved the same nominal strength as the corresponding specimens receiving no cyclic loading. Table 6 of the Bechtel/INEEL Test Report included in Appendix B summarizes these test results. These observations suggest that cyclic loading in the stress range from 3 to 54 ksi did very little, if anything, to reduce the strength capacity of a spliced joint made using the Bar-Lock L-Series coupler.

7.5.3 BechtelllNEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use to Support the Sequoyah Unit I SGR Project - Coupler Test Program Conclusions The Bar-Lock coupler qualification testing program was carried out on two representative sizes - the Model 6L and Model 8L couplers. A total of 160 coupler assemblies were tested. Fourteen pieces of rebar were tested to determine the actual, or measured, mechanical properties of the two heats of bar material used in the test specimens.

Technical Report No. SQN2-SGR-TR3 Page 23 of 56

The tensile strength on 80 samples exceeded the two ASME requirements by a large margin. Statistical analyses of the test results determined several important performance indicators. The overall probability of a coupler assembly (Models 6L and 8L) failing to meet the minimum qualification criterion is less than 3 in 100,000.

In performing the Bechtel/INEEL laboratory testing documented in Topical Report 24370-TR-C-001-A, there was some variation in strength between the two heats of rebar used in the strength tests. Comparing and correlating these results showed that Bar-Lock L-Series (Models 6L and 8L) coupler splices can be expected to achieve a tensile strength greater than 96% of the actual bar strength. While there were not enough different combinations of bar material and coupler size data, the combined test results from this program appeared similar when normalized by the actual bar strength.

Slip tests performed on selected specimens of the Model 6L and Model 8L couplers showed a solid mechanical connection between the coupler and the rebar. There was no tendency for the rebar to move within the coupler prior to developing full splice strength. This was expected since the conical-tipped lock bolts physically embed into the bar material to provide a physical shear force transfer from bar to coupler.

Each of the 80 splice specimens that underwent the cyclic loading durability test passed the 100-cycle test, with no obvious physical degradation of the spliced joint. To provide an additional degree of assurance of adequate cyclic durability, selected specimens received 1000 cycles of loading, again with no noticeable physical degradation. Some of the specimens that passed the 100 cycle test were subsequently tested by monotonic loading to failure. The resultant measured strengths were essentially the same as the virgin strength specimens (no cyclic loading applied). These results suggested that the design of the Bar-Lock coupler is essentially insensitive to cyclic loading to levels below 90% of the minimum bar yield strength.

The results of these tests, compared to the ASME splice system qualification requirements, indicated that the Bar-Lock coupler design for rebar splicing was entirely adequate from a strength point of view for use in nuclear safety-related construction.

The additional quantity of couplers tested provided higher confidence that the couplers do meet, and indeed far exceed, those ASME-specified requirements.

8.0 Sequoyah Unit 2 Bar-Lock Coupler Installation The Model 6L and Model 8L Bar-Lock couplers will be installed in connecting the new rebar to the existing rebar to prepare the temporary access openings in the Sequoyah Unit 2 Shield Building dome for concrete placement. The 6L and 8L couplers will be installed in accordance with the manufacturer's instructions presented in Section 5.0 of this Technical Report. Installation will be implemented through standard TVA work controlling processes.

Technical Report No. SQN2-SGR-TR3 Page 24 of 56

8.1 Splicing Crew Qualification At least one member of each splicing crew will be trained to install the Model 6L and Model 8L couplers. Splicing crew qualification will be demonstrated by preparing two qualification (test) splices using the largest bar size to be used. On successful inspection and testing of the qualification splices, the crew will be considered to be qualified to perform production splices. Each qualified splicing crew shall be assigned an identification mark to be placed on each completed splice. Splicing crew qualification records shall be retained as permanent records.

8.2 Inspection Criteria Inspection of splices shall be in accordance with the manufacturer's instructions and will be implemented through standard TVA work controlling processes. Completed splices will be visually inspected for defects. In addition, it will be verified that bolt heads are either sheared off or torqued to specified values and that the Splicer Crew's identification mark is placed on each splice. Results of splice inspections will be documented and retained as permanent records.

8.3 Production I Sister Splice Testing During the original construction, both rebar production splices and sister splices were used as samples for tensile testing. Sampling of production splices during the restoration of the temporary steam generator access openings in the Unit 2 Shield Building during the SGR would increase the amount of concrete chipback and the potential for reinforcing bar damage. In addition to increased concrete chipback, there would be geometric constraints associated with replacing production splices taken for tensile testing.

ANSI N45.2.5-74 takes exception to taking production splice samples when the splicing sleeve is a leak tight barrier (embedded structural steel sections or liner plate) and instead requires a representative sister splice sample to be taken. For the Sequoyah Unit 2 SGR Project reinforcing bar splice testing program a similar approach will be used. Production splices will not be removed for tensile testing, and sister splices will be used exclusively. With the exception of substituting a sister splice for a production splices on a one-to-one basis, the splice tensile testing using this sampling scheme is consistent with the sampling in ANSI N45.2.5-74 when testing both sister and production splices. The proposed testing scheme also substitutes a sister splice for a production splice on a one-to-one basis for handling of substandard tensile test results.

This proposed testing scheme is conservative when compared with the current edition of ASME Section III, Division 2, which requires tensile testing only one splice (sister or production) for every 100 production splices for ferrous filler metal splices.

Technical Report No. SQN2-SGR-TR3 Page 25 of 56

8.4 Acceptance Criteria Criteria for the acceptability of Model 6L and Model 8L Bar-Lock splices used during the Sequoyah Unit 2 SGR Project are summarized below:

1) Sister splices will be tensile-tested using the loading rates set forth in ASTM Specification A-370. Testing will determine conformance to the following standards:

a) The strength of each sample tested shall equal or exceed 125% of the minimum yield strength (i.e., 75,000 psi).

b) The average strength of 15 consecutive samples shall equal or exceed the minimum ultimate tensile strength (i.e., 90,000 psi).

2) If any sample splice used for testing fails to meet the above tensile test requirements and the failure occurs in the rebar, any necessary corrective actions will be determined prior to continuing the testing frequency.

If a sample splice used for testing fails to meet the above tensile test requirements and the failure occurs in the splice, two additional sister splices made under the same conditions and in the same position shall be produced. If either of these retests fails to achieve 90,000 psi, splicing shall be halted until the cause of the failures has been evaluated and resolved.

3) For any failures, if the rate of failure does not exceed 1 in 15 consecutive samples, the sampling procedure shall be started anew. If the failure rate exceeds 1 in 15 consecutive samples, splicing shall be halted until the cause of the failures has been evaluated and resolved.

4) When splicing is resumed (after being halted for corrective action), the sampling procedure shall be started anew.

5) Material, installation, inspection and testing of Bar-Lock splices, including qualification of installers, are classified as safety-related. Safety-related work will comply with Steam Generating Team's Quality Assurance Program, which demonstrates compliance of quality controlled activities to TVA's Quality Assurance Program and ANSI N45.2. Qualification of inspection personnel will be in accordance with ANSI N45.2.6.

8.5 Quality Assurance / Quality Control Material, installation, inspection and testing of Model 6L and Model 8L Bar-Lock Splices, including qualification of installers, are classified as safety-related. Safety-related work will comply with Steam Generating Team's Quality Assurance Program for the Sequoyah Nuclear Plant - Unit 2 SGR Project and ANSI N45.2. Qualification of inspection personnel will be in accordance with ANSI N45.2.6.

Technical Report No. SQN2-SGR-TR3 Page 26 Of 56

9.0 Summary and Conclusions The prequalification test results presented in Appendix B for Sequoyah Unit 1 and Watts Bar Unit 1 demonstrate that, when compared to the ASME splice system qualification requirements, the Bar-Lock coupler design for rebar splicing is more than sufficient from a strength point of view for use in nuclear safety-related construction. As discussed in Section 7 of this Technical Report, no failures occurred in any of the specimens tested. The additional couplers tested provide higher confidence that the couplers do meet, and indeed far exceed, those ASME-specified requirements. The testing referenced in Appendix B of this Technical Report is applicable to the Bar-Lock Model 6L and Model 8L couplers that will be procured for the Sequoyah Unit 2 SGR Project. Therefore, use of the Model 6L and Model 8L Bar-Lock couplers for nuclear safety-related applications at Sequoyah Unit 2 to support the SGR for that unit is considered acceptable. These Model 6L and Model 8L Bar-Lock couplers will be procured as commercially dedicated equipment for use in the Sequoyah Unit 2 SGR in accordance with the quality requirements described in Section 6 for installation and installation testing described in respective Sections 5 and 8 of this Technical Report.

Technical Repeot No. SQN2-SGR-TR3 Page 27 of 5f)

10.0 References

1. Topical Report No. 24370-TR-C-001-A, Sequoyah Unit I Steam Generator Replacement Alternate Rebar Splice - Bar-Lock Mechanical Splices Topical Report, Revision 0

2. NRC Letter to Mr. J. A. Scalice, CNO and Executive V.P. of TVA, dated March 13, 2003.

Subject:

Sequoyah Nuclear Plant, Unit 1, Safety Evaluation of Topical Report No. 24370-TR-C-001, "Alternate Rebar Splice - Bar-Lock Mechanical Splices" (TAC No. MB5371)

3. TVA Letter to NRC Concerning WBN License Amendment Request No. WBN-TS-04-18, dated December 9, 2004,

SUBJECT:

Watts Bar Nuclear Plant (WBN)

Unit 1 - License Amendment (TS-04-18) to Utilize Methodology Described in Topical Report No. 24370-TR-C-001-A, Alternate Reinforcement Bar (Rebar)

Splice - Bar-Lock Mechanical Splices

4. TVA Letter to NRC Concerning WBN License Amendment Request No. WBN-TS-04-18, dated November 18, 2005,

SUBJECT:

Watts Bar Nuclear Plant (WBN) Unit I - License Amendment (WBN-TS-04-18) Use of Bar Lock Mechanical Couplers for Splicing Reinforcing Bars in the Shield Building Restoration - Test Results (TAC No. MC5368)

5. TVA Letter to NRC Concerning WBN License Amendment Request No. WBN-TS-04-18, dated December 5, 2005,

SUBJECT:

Watts Bar Nuclear Plant (WBN)

Unit 1 - License Amendment (WBN-TS-04-18) Use of Bar Lock Mechanical Couplers for Splicing Reinforcing Bars in the Shield Building Restoration - Test Results Revision 1 (TAC No. MC5368)

6. Letter from Sean Hirka and Joshua Ison of Dayton Superior to Mark Ceraldi (SGT/AREVA), RE: Qualifications of the Dayton Superior Bar Locke Coupler System, dated August 2, 2010

7. ASME Boiler and Pressure Vessel Code,Section III, Division 2, Article CC-4333, Mechanical Splices, 2004 (ACI 359)

8. ASME NQA-1, Subpart 2.5, Quality Assurance Requirements for Installation, Inspection, and Testing of Structural Concrete, Structural Steel, Soils, and Foundations for Nuclear Power Plants, 2008

9. ASTM A 370-97a, Standard Test Methods and Definitions for Mechanical Testing of Steel Products

10. NRC Regulatory Guide 1.136, "Materials, Construction, and Testing of Concrete Containments," Revision 2

11. ACI 318-63, Building Code Requirements for Reinforced Concrete Technical Report No. SQN2-SGR-TR3 Page 28 of 56

12. TVA-NQA-PLN89-A, Nuclear Quality Assurance Plan, Revision 23

13. Steam Generating Team (SGT) Quality Assurance Manual

14. INEEL Report No. INEEL/EXT-02-01387, Qualification of the Bar-Lock Rebar

.Coupler For Use in Nuclear Safety-Related Applications Mechanical Testing Program and Performance Analysis, December 2001

15. TVA General Engineering Specification G-2, Plain and Reinforced Concrete, Revision 7

16. Sequoyah Updated Final Safety Analysis Report, Amendment 22

17. ASTM A 615, Standard Specification for Deformed and Plain Billet-Steel Bars for Reinforced Concrete

18. 10 CFR 50, Appendix B, quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants

19. SGT Specification 39866-SPEC-C-006, Purchase and Installation of Bar-Lock Rebar Splices, Revision 0

20. SGT Specification 39866-SPEC-C-007, Technical Specification for Purchase of Reinforcing Steel, Revision 0

21. ASTM E 8, Standard Test Methods for Tension Testing of Metallic Materials Technical Report No. SQN2-SGR-TR3 Page 29 of 56

Appendix B Test Reports for Sequoyah Unit I and Watts Bar Unit I Bar-Lock Rebar Coupler Prequalification Testing Appendix B Table of Contents INEELIEXT-02-01387, Qualification of the Bar-Lock Rebar Coupler For Use In Nuclear Safety-Related Applications Mechanical Testing Program and Performance Analysist ......................................... 36 Watts Bar Nuclear Plant (WBN) Unit I Excerpts from the Engineering Test Report 24900-ETR-001, Revision 1, for Bar-Lock Mechanical Coupler Qualification ........................................................................ 57 Technical Report No. SQN2-SGR-TR3 Page 30 of 96

INEEUEXT-02-01387.

Dec 2001 Qualification of the Bar-Lock Rebar Coupler For Use in Nuclear Safety-Related Applications Mechanical Testing Program and Performance Analysis W. R. Lloyd Technical Report No. SQN2-SGR-TR3 Page 31 of 56

INEEL/EXT-02-01387 Qualification of the Bar-Lock Rebar Coupler For Use in Nuclear Safety-Related Applications Mechanical Testing Program and Performance Analysis W. R. Lloyd Published Dec 2001 Idaho National Engineering and Environmental Laboratory Materials Department Idaho Falls, Idaho 83415-2218 Technical Report No. SQN2-SGR-TR3 Page 32 of 56

Summary Bechtel Corporation and INEEL developed and performed an independent mechanical testing and analysis program to assess the mechanical performance characteristics of the Bar-Lock L-Series rebar coupler system. A test plan that exceeded the assessment requirements given in ASME Section CC -4333 was developed. To achieve high statistical confidence in measured sample parameters, e.g. ultimate strength, the number of specimens tested was increased to forty (40) from the ASME Code-required quantity of six (6). Bechtel QA/QC personnel monitored the testing program to ensure that it was performed in accordance with the requirements in Specification 24370-C-602.

Static strength tests of two sizes, #6 and #8, of Bar-Lock coupler assemblies showed that they exceeded the ASME-specified minimum strength levels by large margins. Statistical analysis of the results showed a 99.998% probability that the average strength of a group of coupler assemblies would exceed the ASME static strength requirement of 90% of the joined rebar tensile strength. Assessing the performance of individual coupler assemblies against the ASME-specified minimum strength (75 ksi for the Grade 60 rebar used in the tests) for individual assemblies showed that the average strength of an individual assembly was more than 8 standard deviations above the specified minimum. This corresponds to the probability that essentially 100% of all coupler assemblies would exceed the specified minimum strength.

Forty specimens of each of the two sizes (6L and 8L) of coupler/rebar assembly were tested to determine their cyclic loading durability. The test procedure cycled each assembly between 5 and 90% of specified minimum bar yield strength (60 ksi) 100 times. None of the specimens failed in any manner, e.g. bar break, or bar slip within the coupler.

In an effort to improve the cyclic durability performance assessment, several randomly selected specimens received additional cyclic loading. Each selected specimen had an additional 1000 loading cycles imposed. None of the specimens failed, and none of them showed signs of deterioration through excessive strain accumulation or physical deformation. This provides an empirical indication that the cyclic durability of the couplers will far exceed 100 cycles.

Further, some coupler assemblies randomly selected from those already receiving 100 loading cycles were subsequently loaded to failure monotonically (static strength test). This test determined if the prescribed cyclic loading substantially damages the integrity or strength of the coupler splice assembly.

The eight specimens tested all achieved the same nominal strength as like specimens receiving no cyclic loading.

The BechtelINEEL test program tested and demonstrated that the mechanical properties of the L-Series Bar-Lock mechanical splices meet the existing Codes and NRC requirements and are an acceptable method of connecting reinforcing bar in nuclear power plant safety-related applications. The large quantity of couplers tested provides a higher confidence that the couplers do meet, and indeed far exceed, those ASME-specified requirements.

iii Technical Report No. SQN2-SGR-TR3 Page 33 of 56

CONTENTS Summary ................................................... .............. ........ . ............................... Iv I. O verview ............................... ...... ................... 44................................................................

2. Test Plan .......................................................................................... .......................... 4

3. Reinforcing Bar Mechanical Properties Tesls ................................................................. 4 3.1 #6 Re-Bar Material .......................................... .4 3.2 48 Re-Bar M aterial ................................................................ ................................. 4 3.3 Material for #8 Coupler Size Cyclic Durability Tests ......................... 4

4. Description of Coupler Test Specimens ........................................................................... 4

5. Test Results ...................................................... . .......................... ................. 4 5.1 Tensile Test Results .......................................... 4 5.1.1 Minimum Average Tensile Strength Comparison ........................... 4 5.1.2 Minimum Tensile Strength of Individual Specimens ....................... 4 5.1.3 Tensile Strength Performance Exceeds Requirements . ........... 4 5.2 Cyclic Test Results .......................................... .4 5.2.1 Higher Count Cyclic Tests ............................................................ 4 5.2.2 Residual Strength Tests ................................................................... 4

6. Coupler Test Program Conclusions 4 6.1 Tensile Strength ............................................. 4 6.2 Mechanical Slippage in the Couplers ................................................................. 4 6.3 Cyclic Loading Durability ...................................... 4 6.4 Overall Coupler Performance ........................................ 4 v

Technical Report No. SQN2-SGR-TR3 Page 34 of 56

FIGURES Figure 1. Representative Stress-Strain Curve from #6 Rebar Material ...................... 4 Figure 2. Representative Stress-Strain Curve from #8 Rebar Material ...................... 4 Figure 3. Bar-Lock Coupler Cutaway View Showing Internal Details ...................... 4 Figure 4. Representative Test Data from a Coupler Assembly Strength Test ........................... 4 Figure 5. Data Curves Showing Load-Unload Cycle to Assess Bar Slip in Couplers ............... 4 Figure 6. Cyclic Stress-Displacement History for a Typical Test ........................ 4 TABLES Table 1. Mechanical Properties of Rebar Used in Test Specimens ........................ 4 Table 2. Bar-Lock L.Series Coupler Specifications (Sizes #6 and #8) ...................... 4 Table 3. Tensile Properties for #6 Rebar (Heat ID: 589812899) ......................... 4 Table 4. Tensile Properties for #6 Rebar Heat ID: 589812899 ................................................ 4 Table 5. Re-Bar Splice Assemblies Strength Test Results ...................................................... 4 Table 7. Results of Residual Strength Tests on Load-Cycled Specimen Assemblies ............... 4 vi Technical Report No. SQN2-SGR-TR3 Page 35 of 56

Qualification of the Bar-Lock Rebar Coupler for Use in Nuclear Safety-Related Applications:

Mechanical Testing Program and Performance Analysis.

1. OVERVIEW Bechtel Corporation and INEEL developed and performed an independent mechanical testing and analysis program to assess the mechanical performance characteristics of the Bar-Lock I-Series rebar coupler system. By design, this program provided a very rigorous test of coupler design mechanical performance, using the qualification criteria of ASME Section 11, Division 2, CC-4333 as a standard of reference.

The Bechtel/INEEL test program tested and demonstrated that the mechanical properties of the L -Series Bar-Lock mechanical splices meet the existing Codes and NRC requirements and are an acceptable method of connecting reinforcing bar in nuclear power plant safety-related applications. -

2. TEST PLAN ASME Section CC-4333 specifies performance criteria to qualify rebar splicing devices for use in nuclear safety-related applications. While the strength specifications are moderately high, the quantity of test specimens required is relatively low. To achieve high statistical confidence in measured sample parameters, e.g. ultimate strength, a larger sample size (n) is required. To achieve the desired level of confidence that any installation of these couplers will have the requisite performance characteristics, the quantity of verification test specimens (the sample set) was increased. For the static strength assessment, the ASME Coda requires six specimens be tested, and all six must pass. In this test plan, the quantity was increased to n = 40 for each size tested. For the cyclic durability test, the ASME Code requires three specimens to survive the 100-cycle test. This was increased to n = 40 for each size. Increasing the statistical sample size from six or three to 40 allows a great improvement in the confidence levels (especially for the binomial distribution of the cyclic test) associated with lower bound strength and cyclic durability requirements specified in the Code.

The Bar-Lock testing was monitored by Bechtel QA/QC personnel to ensure that it was performed in accordance with the requirements in Specification 24370-C-602.

3. REINFORCING BAR MECHANICAL PROPERTIES TESTS Mechanical properties for the rebar material used in these tests were determined in accordance with project test procedures, incorporating relevant American Society for Testing and Materials (ASTM) test standards and procedures (ASTM Designation A 370-96, Standard Test Methods and Definitions fot Mechanical Testing of Steel Products; and ASTM Designation E 8-99, Standard Test Methods for Tension Testing of Metallic Materials). All mechanical properties tests were performed on the same universal test machine, using the same measurement transducers. The same test machine, load cell, and extensometer were used in all of the coupler assembly tests as well. Bechtel Quality Assurance Department retains all calibration certification and records for this equipment and these devices.

Technical Report No. SQN2-SGR-TR3 Page 36 of 56

The reinforcing bar used in the Bar -Lock coupler testing program was ASTM A615 Grade 60 material in

1. 6 (C/ in. nominal diameter) and #8 (1 in. nominal diameter) sizes. Consolidated Power Supply, the vendor of the rebar, provided ce-tified material test reports (CMTRs). The values reported in the CMTRs are based on the results of a single tensile test. The CMTR value, while confirming the nominal material performance, is inadequate to determine "actual" material properties. The ASTM test standard recommends a minimum of three specimens be tested and the results averaged. Additional verification testing was performed as part of this test program to determine the '"ctual"or m easured mechanical properties of the different heats of rebar employed in specimen assembly. Figures I and 2 show representative stress-strain curves for both heats of re-bar used in this test program.

3.1 #6 Re-Bar Material A common heat of rebar (CPS #589812899) was used in making up all #6-size coupler test assemblies.

Per ASME Section II, Division 2 requirements, the same 10 inch extensometer gage length, as would be used in the #6 coupler assembly tests, was used to measure strain in the tensile properties tests. Seven #6-size plain bar sections from this heat were tested to determine actual tensile properties of this lot of material. Table I summarizes the test results. Material properties obtained from Consolidated Power Supply CMTR are provided for comparison.

It is apparent that the differences in yield strength as determined by three different definitions are minimal. For this type of steel, the yield point is the appropriate measurement and provides the most consistent value (smallest standard deviation). Where "measured" or 'actual" yield strength is required in the analyses, 67.7 ksi is used for the #6L coupler tests. Where "measured"or "actual"ultimate tensile strength (UTS, or F,) is required in the analyses, 107.5 ksi is used for the #6 tests.

Table 1. Mechanical Properties of Rebar Used in Test Specimens Yield Point 0.2%OS 0.5% EUL UTS (ksi) Elongation E (Msi) 0 (ksi) Yield (ksi) Yield (ksi) ( /)

1. 6 Average 99M67.9 67.9 68.2 13.2 27.8

1. 6 Std Dev 1.03 1.19 1.14 1.12 1.26 0.89

1. 6CMTR - -- 67.6 107.4 15 --

1. 8 Average U 72.4 72.5 ___I- 11.5 29.2

1. 8 Std Dev 0.45 0.57 0.47 0.74 0.98 0.46

1. 8 CMTR -- - 73.1 112.0 14 -

1. 8 CMTR - 69.0 - 112.8 16 -

(C-series only) 3.2 #8 Re-Bar Material A common heat of rebar (CPS #589813260) was used in making up all of the #8-size coupler test assemblies used in the tensile strength tests. Per ASME requirements, the same 14.5 inch extensometer 2

Technical Report No. SQN2-SGR-TR3 Page 37 of 56

gage length was used in the tensile properties test as would be used in the #8 coupler assembly tests.

Seven #8-size plain bar sections from this heat were tested to determine actual tensile properties of this lot of material. Table I summarizes the results of those tests. Material properties obtained from Consolidated Power SupplyCMTR are also provided for comparison. Again, the yield point strength is selected for the material yield strength value. Where "measured"or "actual"yicld strength is required in the analyses, 72.6 ksi is used for the #8 tests. Where "measured'or "a ctual"ultimate strength (UyTS) is required in the analyses, 110.1 ksi is used for the #8 tests.

3.3 Material for #8 Coupler Size Cyclic Durability Tests A separate heat of rebar material (CPS #123741) was used to fabricate the size #8 cyclic test coupler assemblies. There are no measured strength parameters (only specified minimums) associated with the cyclic test procedures, so no verification testing of this material was performed. The CMTR-reported values for this heat are provided at the bottom of Table 1 for reference.

4. DESCRIPTION OF COUPLER TEST SPECIMENS The Bar-Lock couplers used are Bar-Lockh ', -Series" (coupler designations 6L and 8L), which are higher strength rebar couplers for use in tension/compression, seismic and other cyclic load conditions.

The specifications for these couplers are provided in Table 2.

Table 2. Bar-Lock L-Series Coupler Specifications (Sizes #6 and #8)

For Coupler Specifications Bolt Specifications Coupler Use Outside Length Nominal Quantity Size Nominal Designation on Diameter (inch) Weight per Bar (inch) Shear Size (inch) (bs.) Torque (f.-lb.)

6L #6 1.9 8.0 4.5 4 1/2 80 8L #8 2.2 12.3 9.5 5 5/8 180 The component parts of each Bar-Lock coupler consist of a steel tube, 'lock-shear"bolts, and serrated rails. Figure 3 (4-1) shows a schematic diagram of the coupler design. The seamless, hot-rolled steel tube conforms to ASTM A-519, with a minimum tensile strength in excess of 100 ksi. The lockshear bolt material is AISI 41L40. The bolts are through-hardened over the entire bolt length and further induction -

hardened at the conical bolt tip. The serrated rails are made of ASTM CD1018. They are machined and.

then carburized to a depth of 0.032 in.

An equivalent testing program was performed for each of the two coupler/rebar sizes tested. For each size, forty test specimen assemblies were made up for tensile strength tests, and forty assemblies were made up for the cyclic durability tests. The test specimen assemblies were made up by stel construction workers using Bar-Lockk assembly instructions in a normal field environment. Assembly of the test specimens was monitored by Bechtel QC personnel.

3 Technical Report No. SQN2-SGR-TR3 Page, 38 of 56

5. TEST RESULTS All of the 160 individual coupler specimens tested in this pro;-am, and all relevant specimen sample set averages and individual coupler strengths, exceeded the requirements set forth in the ASME Code, Section CC-4333.2.3(a).

Eighty tensile strength tests (forty of each size) were performed on coupler assembly specimens according to relevant sections of ASTM A 370 and E 8, and ASME CC-4333.2.3(a). A representative stress-strain curve for a coupler strength test is provided in Figure 4. No practical differences were observed in the general character of the stress-strain curve of any of the 80 specimens tested. All test data collected included stress, strain, crosshead displacement, applied force, and elapsed time. The actual individual test specimen results obtained through standard analysis methods provided in ASTM E 8 are tabulated in Tables 3 and 4. A representative stress-strain plot for a cyclic test is provided in Figure 5.

Table 3. Tensile Properties for #6 Rebar (Heat ID: 589812899)

Specimen HOF Yield UTS Er E MD (ksi) (ksi) (%) 0)

U6-2 67.7 106.9 14.0 28.7 U6-5 66.8 106.6 13.5 27.4 U6-9 67.0 107.0 12.9 28.1 U6-11 67.6 107.8 14.2 28.6 U6-12 69.9 109.7 10.6 27.3 U6-14 67.9 107.9 12.9 28.3 U6-1 8 67.3 106.5 14.1 26.2 Averages . 'd 13.2 27.8 Table 4. Tensile Properties for #6 Rebar Heat ID: 589812899 Specimen HOF Yield UTS E Bf IV (ksi) (ksi) (%) (Msi)

US-I 1 72.5 110.3 12.9 30.1 US-12 72.4 108.8 11.2 28.7 U8-13 71.7 109.5 12.2 29.3 U8-14 73.0 111.0 9.8 28.8 U8-16 72.8 110.2 11.0 29.1 Us-i8 72,5 110.4 11.I 29.2 U8-20 73.0 110.6 11.5 29.1 Averages SA 11**

11.5 29.2 4

Technical Report No. SQN2-SGR-TR3 Page 39 of 56

In addition, several specimens of each size were randomly selected to receive an initial slip test prior to the normal strength test. A statistically -legitimate random selection process, using a random number generation algorithm on a computer, was applied to make the selections. Virgin test specimens were installed in the test machine, and instrumented as for a normal strength test. The applied stress was increased from 0, through 3 ksi, up to 30 ksi, and then reduced to 3 ksi. The change in displacement across the coupler between the two 3 ksi stress levels was measured with an extensometer. Figure 5 shows the traces of applied stress and resultant displacement for the six specimens. In all cases, no measurable slip was detected.' The observation of no bar slip within the coupler on initial loading means the coupler will develop full strength without excessive deformation upon initial loading.

5.1 Tensile Test Results The ASME Code, Section CC-4333.2.3, has several criteria with which coupler performance is compared.

The two pertinent criteria for the tensile strength test results are:

1. "... Theaverage tensile strength' of the splices shall not be less than 90% of the actual tensile strength of the reinforcing bar being tested, nor less than 100% of the specified minimum tensile strength."

2. "... Thetenslle strength of an individualsplice system (test specimen)s shall not be less than 125% of the specified minimum yield strength of the spliced bar."

The coupler assembly performance for both sizes evaluated exceeded both of these criteria. Table 5 tabulates the results of the individual strength tests. Discussion of the comparisons of test results to ASME specified minimum values follow:

5.1.1 Minimum Average Tensile Strength Comparison For the lots of rebar tested, the '90% of the actual tensile strength" is the governing criteria.

For the size #6 group, the specified minimum average strength value is 96.8 ksi. For the size

1. 8 group, the specified minimum average strength value is 99.1 ksi.

5.1.1.1 Couplerlbarsize #6 The sample set of strength data from the coupler/bar size #6 was evaluated for normal (Gaussian) probability distribution using the Wilk-Shapiro W-test and graphical analysis methods. The results show a near normal distribution, i.e. only slight departure from normality. Where necessary in the assignment of confidence limits, the assumption of normality is justified.

The size #6 group (sample set, n = 40) average tensile strength is 106.2 ksi (98.8% of the average #6 bar actual tensile strength), with a standard deviation of only 1.87 ksi. The Code-

' the measured slip displacements, equivalent to less than 0.001 in. over the length of the coupler, were much less than observed hysteresis error Inthe extensometer.

2 This is a single average value, calculated from the entire group (sample set) of replicate test specimens, i.e. from one heat of matenal, inone size.

3This is the strength value of each individual test speeimen (coupler assembly) consisting of one coupler unit and two attached sections of rebar.

5 Technical Report No. SQN2-SGR-TR3 Page,40 of 56

required average strength value of 96.8 ksi (90% of actual tensile strength) is 5.0 standard deviations below the sample average. This corresponds to a probability of less than 3 in 10 million couplers would have strength less than the required 96.8 ksi minimum value. Further, a one-sided test for lower bound was also performed. This test provides a practical lower limit strength value for any #6L coupler assembly. Based upon this data set 99% of all couplers of this type will have a tensile strength greater than 100.13 ksi (with a 99%

confidence level). This is a very strong indication that the size #6 coupler design will achieve the required minimum strength. These results are confirmed in a letter report (see Appendix F) from INEEL statistician JJ. Einerson. Mr. Einerson reviewed the statistical analyses of the mechanical test data.

&1.t1.2 Coupleribarsize #8 The sample set of strength data from the coupler/bar size #8 was also evaluated for normal (Gaussian) probability distribution using the W-test and graphical analysis methods. Again, results show only slight departure from normality.

The size #8 group (sample set, n = 40) average tensile strength is 109.0 ksi (99.0% of the average #8 bar actual tensile strength), with a standard deviation of only 2.78 ksi. The required average strength value of 99.1 ksi is 3.6 standard deviations below the sample average. This corresponds to a probability of less than 2 in 10,000 couplers Would have a strength less than the required 99.1 ksi minimum value. Further, the one -sided test for lower bound (described above) based upon this data set indicates that, with 99% confidence, 99% of all couplers of this type will have a tensile strength greater than 99.94 ksi (see letter report included in the Appendix). This is a very strong indication that the size #8 coupler design will achieve the required minimum strength.

To assess the general capabilities of the overall coupler design, the results from both sizes tested can be normalized by their respective bar lot (mill heat) tensile strengths and combined into one sample set. In so doing, the conclusion is that the Bar -Lock coupler design produces a splice that will achieve an average strength that is 98.9% as strong as the rebar itself. It is obvious that this greatly exceeds the ASME Code-required 90% value. The cumulative standard deviation is 2.2%A of the bar strength, making the required minimum strength 4.0 standard deviations below the sample average. The equivalent likelihood is that only 3 in 100,000 would fail to achieve a strength level equivalent to 90% of the bar ultimate strength.

5.1.2 Minimum Tensile Strength of Individual Specimens This requirement for each individual coupler tested provides additional assurance that the occasional sample tested that may have a relatively low strength value, as compared to the sample set average, at least has an absolute minimum necessary strength for structural considerations. For the Grade 60 rebar used in this study, this required value is 75.0 ksi, and is the same for all specimens tested. All specimens tested in this test program passed this test, and by a very large margin.

5.1.2.1 Binomial (PasslFall)Assessment In the simplest case, the pass/fail criteria can be applied directly. For the combined sample size of 80, with no observed failures (strength below 75.0 ksi), the statement can be made that with 90% confidence, no more than 2.8% of couplers would fail this test. By the nature of this type of binomial probability distribution (pass/fail), it is difficult to state reliabilities with 6

Technical Report No. SQN2-SGR-TR3 Page 41 of 56

a higher level of confidence without assessing many hundreds of samples. However, by normalizing the measured individual coupler strengths by the required value, an analysis of the amount of deviation on those values can provide a yet stronger comparison and corresponding statement of reliability.

5.1.2.2 Assessment Using Normalized CouplerStrength Distribution This distribution of normalized strengths shows that the average coupler strength is 144% of the minimum required level for individual couplers, with a standard deviation of less than 4%. So the required strength value is 11 standard deviations below the sample average. The probability tables do not show probabilities below 8 standard deviations from the mean, but at that value, the probability is less than 2x10-15 that the strength of an individual assembly would be lower than the requirement, i.e. practically impossible.

5.1.2.3 Assessment UsingAlternative Strength Criterion A comment by the US Nuclear Regulatory Commission (USNRC), during a presentation on the Bar-Lock couplers on August 9, 2001, was that the minimum strength criterion for individual test specimens should be based upon the actual, measured yield strength of the bar material, rather than the specified minimum value (as done above, per the ASME qualification specification). This makes more sense from a practical view, and it removes one variable (the specified material yield strength) from the comparison. However, this approach does apply a more stringent test of the coupler capability, since the actual yield strength will always be higher than the minimum allowable. To apply this criterion, the size

1. 6-and size #8 specimens must be treated separately since the measured yield strengths of the two bar sizes are significantly different.

Size #6 Couplers Using the appropriately normalized test results from the #6 test specimens, the same analysis described above was carried out. The size #6 coupler specimen tensile strengths averaged 106.2 ksi, 25.4% above the USNRC-proposed strength level of 84.6 ksi (125%

• 67.7 ksi) with a standard deviation of 1.86 ksi. The proposed minimum strength here i s still more than II standard deviations above the proposed minimum level, with the probability being essentially zero that any coupler would fail to achieve this strength level.

Size #8 Couplers Analyzing the normalized test results from the #8 test specimens show their tensile strengths averaged 109.0, 20.1% above the USNRC-proposed strength level of 90.8 ksi (125%

• 72.6 ksi) with a standard deviation of2.81 ksi. The proposed minimum strength here is still 6.5 standard deviations above the proposed minimum level. The resultant failure probability is still less than Ix1O-10.

5.1.3 Tensile Strength Performance Exceeds Requirements The overall strength performance of the Bar-Lock coupler design can be summarized as excellent, based on this comprehensive test program of different size couplers. There were no failures to meet any of the specified or proposed strength criteria in any case. As the various failure probability values indicate, the likelihood of any individual Type 6L or 8L coupler assembly failingto achieve the ASME required strength levels is very low.

7 Technical Report No. SQN2-SGR-TR3 Page 42 of 56

Table 5. Re-Bar Splice Assemblies Strength Test Results Specimen Failure Final UTS Specimen Failure Final UTS ID (#6) Type' Strain (%) (ksi) ID (#8) Type Strain (%) (ksi)

Average -- NA5 .'06.2-*,: Average -= NAb ti.,

S6-01 0 3.8 107.9 $8-01 0 3.7 109.6 S6-02 P 15.2 108.0 S8-02 T 1.4 96.8 S6-03 P 14.4 98.9 58-03 0 4.9 109.8 S6-04 P 15.2 106.4 S8-04 0 3.7 110.1 S6-05 0 4.9 107.3 S8-05 P 10.4 108.4 S6-06 0 4.1 107.8 S8-06 T 4.9 109.7 S6-07 0 4.2 107.6 S8-07 T 4.4 1104A S6-08 P 13.1 106.9 S8-08 T 3.6 109.4 S6-09 T 2.7 103.2 S8-09 0 3.6 110.5 S6-10 0 4.6 107.6 S8-10 T 1.8 102.1 S6-11 P 13.0 107.3 $8-11 T 2.1 106.0 S6-12 0 4.4 105.6 S8-12

• 3.8 108.0 S6-13 T 2.7 103.4 S8-13 0 3.4 110.5 S6-14 P 10.8 105.8 S8-14 T 3.2 110.1 S6-15 P 12.3 104.0 S8-15

• 3.7 106.7 S6-16 0 3.8 108.0 S8-16 T 4.0 111.0 S6-17 P 9.8 103.7 S8-17 T 2.1 104.5 S6-18 P 11.5 106.3 S8-18 T 4.5 109.3 S6-19 P 19.1 106.1 S8-19 T 4.0 109.4 S6-20 P 15.4 107.6 S8-20 0 4.6 110.1 56-21 P 11.0 106.0 S8-21 T 3.5 109.7 S6-22 P 11.6 105.0 S8-22 T 4.3 109.4 S6-23 T 2.7 103.1 S8-23 T 3.8 109.8 S6-24 0 4.1 107.8 S8-24 T 3.3 108.5

'B = bar break outside coupler but within extensometer gage length, 0 -bar break outside coupler and outside extensometer gage length, T- bar break at tip of first lock bolt, P - bar pulled out of coupler without breaking,

• bar break in interior of coupler Ile final stramis d ependent on several factors, including mode of failure An average value for all tests hasno significance.

For example, m a pull-out failure the final strain is detennined by the length of time the operator chooses to continue the test once pull-out is observed.

8 Technical Report No. SQN2-SGR-TR3 Page .43 of 56

Specimen Failure Final UTS Specimen Failure Final UTS ID (#6) Type' Strain (/o) -1ý(ksi)

.' ": " ID (#8) Type Strain (%)

b "-'

(ksi) 5 Average -- NA '11062 4 Average -- NAb ,'1 9."

S6-25 P 11.5 105.1 S8-25 P 10.4 110.0 S6-26 P 11.3 107.9 S8-26 T 4.2 109.9 S6-27 P 12.2 106.4 S8-27 *P 7.0 109.7 S6-28 0 3.9 107.8 S8-28 T 4.1 109.0 S6-29 B 4.8 107.0 S8-29 0 3.8 109.7 S6-30 0 4.3 107.6 S8-30 0 3.5 110.3 S6-31 0 4.4 107.4 S8-31 T 3.9 110.5 S6-32 T 3.8 107.2 S8-32 T 2.5 109.0 S6-33 T 2.9 105.7 S8-33 0 4.4 110.3 S6-34 P 12.6 105.7 S8-34 T 3.5 109.7 S6-35 T 4.4 107.2 S8-35 T 2.5 105.4 S6-36 T 2.8 104.2 S8-36 T 4.1 110.5 S6-37 0 3.8 107.2 S8-37

• 5.0 110.2 S6-38 P 11.5 107.4 58-38 P 10.3 109.9 S6-39 P 12.9 107.0 S8-39 T 3.9 111.2 S6-40 P 11.3 106.3 S8-40 P 10.2 113.6 5.2 Cyclic Test Results Coupler assemblies were cyclically tested according to the requirements of ASMECC-4333.2.3(b). Forty specimens of each of the two types (6L and 8L) received 100 load cycles between 5 and 90% of specified minimum bar yield strength (60 ksi). None of the specimens failed in any manner, e.g. bar break, or bar slip within the coupler.

Applied stress and specimen extension data were digitized during the cyclic tests to provided additional insight into the coupler performance under cyclic load conditions. Figure 6 shows a representative plot of stress versus displacement. For clarity, only every tenth cycle is presented. It shows the accumulated slip over 100 cycles to be less than 0.0015 in. This is less than 10% of the elastic deformation that occurs during a single load cycle. The same behavior was observed in all of the tests of both coupler sizes. The couplers showed no significant deterioration (visible, or evidenced by deviation is test data) during the tests.

Based on the binomial probability function (pass/fail testing), and no observed failures in 80 tests, it can be stated with 90% confidence that less than 2.8% of all couplers would fail prior to the completion of 100 loading cycles.

9 Technical Report No. SQN2-SGR-TR3 Page -44 of 56

5.2.1 Higher Count Cyclic Tests In an effort to improve the cyclic durability performance assessment, several of the specimens in each size were selected at random to receive additional cyclic loading. Each selected specimen was subjected to an additional 1000 cycles. None of the specimens failed, and none of them showed signs of deterioration through excessive strain accumulation or physical deformation. While this does not provide a verifiable improvement in the statistical probability of failure (the confidence level is too low to be useful), it does provide an engineering indication that the cyclic durability of the couplers will far exceed 100 cycles.

5.2.2 Residual Strength Tests Another test was also performed on randomly selected couplers to provide additional information regarding cyclic durability and residual strength. The selected couplers, all having been subjected to 100 loading cycles, were subsequently loaded to failure monotonically. This is the standard 'tensile strength test"described in the previous section. The concept here i s to determine if the prescribed cyclic loading substantially damages the integrity ofthe splice assembly. The eight specimens tested all achieved the same nominal strength as the corresponding specimens receiving no cyclic loading. Table 6 summarizes these test results. These observations suggest that cyclic loading in the stress range from 3 to 54 ksi does very little, if anything, to reduce the strength capacity of a spliced joint made using the Bar-Lock L-series coupler.

Table 6. Results of Residual Strength Tests on Load-Cycled Specimen Assemblies Specimen Failure Final UTS Specimen Failure Final UTS ID (#6) Type Strain (%) (ksi) ID (#8) Type Stra;n (%) (ksi)

Average -- NA 104.9 Average -- NA 106.7 C6-2 P 3.8 104.3 C8-15 106.6 C6-3 p 3.7 106.3 C8-21 106.0 C6-7 P 5.0 106.2 C8-27 107.6 C6-14 P 7.0 103.3 C6-15 P 3.7 104.5

6. COUPLER TEST PROGRAM CONCLUSIONS The Bar-Lock coupler qualification testing program was carried out on two representative sizes - #6 and

1. 8 -of their L-Series couplers. One hundred-sixty (160) coupler assemblies were tested. Fourteen(14) pieces of plain rebar were tested to determine the actual, or measured, mechanical properties of the two heats of bar material used in the test specimens.

6.1 Tensile Strength The tensile strength tests on 80 samples from each of the two sizes all exceeded the two ASME requirements by a large margin. Statistical analyses of the test results determined several important performance indicators, all of which suggested that any given coupler assembly would far exceed the 10 Technical Report No. SQN2-SGR-TR3 Page 45 of 56

ASME-specified strength requirements. The overallprobabilityof any coupler assembly (in size #6 or

1. 8)failing to meet the minimum qualificationstrength criterion is less than 3 in 100,000.

There was some variation in strength between the two heats of rebar used in the strength tests.

Comparing and correlating these results show that Bar -Lock L-Series coupler splices can be expected to achieve a tensile strength greater than 96% of the actua l.strength ofthe bar material that is connected using the coupler device. While there are not enough different combinations of bar material and coupler size data to make this statement with high probabilistic certainty, the combined test results from this program appear similar when normalized by the actual bar strength. Therefore, it is likely these test results are representative of the performance of other sizes of Bar-Lock L-Series couplers. In other words, the mechanical design of the Bar-Lock L-Series coupler is such that spliced joints can be expected to develop over 96% of the actual bar strength.

6.2 Mechanical Slippage In the Couplers Slip tests performed on selected specimens of both sizes showed a solid mechanical connection between the coupler and the rebar. There was no tendency for the rebar to move within the coupler prior to developing full splice strength. This was expected since the conical-tipped lock bolts physically embed into the bar material providing a physical shear force transfer from bar to coupler.

6.3 Cyclic Loading Durability All 80 splice specimens that underwent the cyclic loading durability test passed the 100-cycle test, with no obvious physical degradation of the spliced joint. To provide an additional degree of assurance of adequate cyclic durability, selected specimens received 1000 cycles of loading, again with no noticeable physical degradation. Some of the specimens that passed the 100 cycle test were subsequently tested by monotonic loading to failure. The resultant measured strengths were essentially the same as the virgin strength test specimens (no cyclic loading applied). These results suggest that the design of the Bar-Lock coupler is essentially insensitive to cyclic loading to levels below 90% of the minimum bar yield strength.

6.4 Overall Coupler Performance All of these test results, compared to the ASME splice system qualification requirements, indicate that the Bar-Lock coupler design for rebar splicing is entirely adequate from a strength point of view for use in nuclear safety-related construction. The large quantity of couplers tested provides higher confidence that the couplers do meet, and indeed far exceed, those ASME-specified requirement.

Technical Report No. SQN2-SGR-TR3 Page 46 of 56

120 100

1. Ur6-18 Size #6 Rebar so IHeat #589 812 8 99 60 40 20 0

0 4 8 12 16 Engineering Strain (%)

Figure 1. Representative Stress-Strain Curve from #6 Rebar Material 12 Technical Report No. SQN2-SGR-TR3 Page 47 of 56

120 100 so 60 40 20 0

8 12 16 Engimenng Strain (OA)

Figure 2. Representalive Stress-Strain Curve from #8 Rebar Material Figure 3. Bar-Lock Coupler Cutaway View Showing Internal Details 13 Technical Report No. SQN2-SGR-TR3 Page 48 of 56

Crosshead Displacement (in.)

0 0.5 1 1.5 2 120 100 Extensometer removed 80 at 2% strain level I

-10" G.L. Strain 40 Crosshcad Position 0 I 0 12 3 4 Strain (1.)

Figure 4. Representative Test Data from a Coupler Assembly Strength Test 14 Technical Report No. SQN2-SGR-TR3 Page 49 of 56

40 30 .. / )

20 Found knife edges on extensomete 0/ * , , , , I,,,. , to1 beloose I following theItest . ,

0000 0002 00o4 0006 0o0a 0012 Displacement across Coupler (in)

Figure 5. Data Curves Showing Load-Unload Cycle to Assess Bar Slip in Couplers 15 Technical Report No. SQN2-SGR-TR3 Page 50 of 56

0.000 0.005 0.010 0.015 0.020 0.025 Displacement across Coupler (in.)

Figure 6. Cyclic Stress-Displacement History for a Typical Test 16 Technical Report No. SQN2-SGR-TR3 Page 51 of 56

ENCLOSURE WATTS BAR NUCLEAR PLANT (WEN) UNIT I EXCERPTS FROM THE ENGINEERING TEST REPORT 24900-ETR-001, REVISION 1 FOR BAR-LOCK MECEANICAL COUPLER QUALIFICATION Technical Report No. SQN2-SGR-TR3 Page 52 of 56

24900-ETR-001. Rev. 1 ENGINEERING TEST REPORT FOR BAR-LOCK QUALIFICATION 1.0 GENERAL 1.1 Watts Bar Nuclear Power Plant Is a two-unit power plant located approximately 50 miles northeast of Chattanooga at the Watts Bar Site In Rhea County, Tennessee, which Is operated by Tennessee Valley Authority (TVA, hereafter referred to as 'OWNER'). Bechtel (hereafter referred to as the CONTRACTOR) has the overall responsibility for execution of the Unit 1 Steam Generator Replacement (SGR) Project. The SGR project requires that openings be created In the concrete dome of the Shield Building to remove the generators.. The Bar-lock couplers are to be used in the repair of these openings.

1.2 This test report documents the qualification of the Bar-lock couplers to be used In the repair of the opening in the Unit 1 Shield Building dome made during the steam generator replacement project.

1.3 The purpose of these tests Is to provide the required documentation for the qualification of the Badlock couplers to the requirements of ASME Section III Division 2 Article CC 4330, "Splicing of Reinforcing Bars" for use In the repair. of the construction opening In the concrete Shield Building Dome made during the steam generator replacement project outage.

2.0 CODES, STANDARDS AND REFERENCE DOCUMENTS 2.1 General The edition of the codes and standards referred to In this report are those noted below.

2.2 American Society for Testing and Materials (ASTM)

A 370- 97a Standard Test Methods and Definitions for Mechanical Testing of Steel Products A 615- 96a Standard Specification for Deformed and Plain Billet-Steel Bars for Concrete Reinforcement 2.3 American Society of Mechanical Engineers Boiler and Pressure Vessel Code,-!$92,Section III, Division 2 2.4 American National Standards Institute (ANSI N45.2-1977 Quality Assurance Program Requirements for Nuclear Facilities.

ANSI N45.2.2-72 Packaging, Shipping, Receiving, Storage, and Handling of items for Nuclear Power Plants ANSI N45.2.5-74 Supplementary Quality Assurance Requirements for Installation, Inspection, and Testing of Structural Concrete and Structural Steel During the Construction Phase of Nuclear Power Plants N45.2.6-1978 Qualifications of Inspection, Examination, and Testing Personnel for Nuclear Power Plants Confldentlalc Bechtel Power Corporation2005. All rights reserved. Page 3 of 6 Technical Report No. SQN2-SGR-TR3 Page 53 of 56

24900-ETR-001. Rev. 1 2.5 Reference Documents 24900-C-312, "Technical Specification for Installation of Bar-Lock Rebar Splices" 24900-BL, "Bar-Lock Installation Guidelines" 24900-0-602, "Testing of Bar-lock Splices" Satec Test Machine Operation Manual 3.0 TESTING 3.1 The testing of the couplers (remaining Sequoyah couplers as well as the newly manufactured couplers) was per the requirements of Specification 24900-C0602, "Technical Specification for Qualification Testing of Bar-Lock Mechanical Rebar Splices." The testing occurred during the week of August 29, 2005. The testing was performed using Bechtel's SATEC machine located at Palo Verde Nuclear Station In Arizona. The calibration data Is attached to this report.

32 Rebar from the same lot was used In the tests.

3.3 Six 36" long sections of rebar were prepared for static tensile testing for each rebar size (spares were also prepared).

3.4 Eighteen coupler rebar assemblies were manufactured for each rebar size for testing (12 static tensile tests and 6 cyclic tensile tests). Spares were also prepared.

3.5 Static Tensile Test Acceptance Criteria 3.5.1 The average tensile strength of the splices shall not be less than 90% of the actual tensile strength of the unspliced rebar being tested, nor less than 100% of the specified minimum tensile strength of the rebar. For Grade 60 rebar, the minimum specified tensile strength is 90 ksl.

3.5.2 The tensile strength of an Individual splice shall not be less than 125% of the specified minimum yield strength of the rebar. For Grade 60 rebar, the minimum specified yield strength Is 60 ksl.

3.6 Cyclic Tensile Test Acceptance Criteria 3.6.1 The spliced rebar shall be able to withstand 100 cycles of stress variation from 5% to 90% of the specified minimum yield strength of the rebar. For Grade 60 rebar, 5% minimum specified yield strength Is 3 ksi, and 90% minimum specified yield strength Is 54 ksi.

4.0 RESULTS 4.1 Static Tensile Tests 4.2 Qualification of #6 Bar-Lock Couplers 4.2.1 The average tensile strength (stress) of the 6 rebar samples Is as follows:

4.2.2 Average Ultimate Strength (Fu aw(a)) of #6 Rebar 111,901 psi Confidentlald Bechtel Power Corporation2005. All rights reserved. Page 4 of 6 Technical Report No. SQN2-SGR-TR3 Page 54 of 56

24900-ETR-001, Rev. 1 4.3 Sequoyah Bar-Lock Couplers #6 4.3.1 Average Ultimate Strength (Fua,(s awou) of #6 Bar-Lock Coupler (Sequoyah):

.104,350 psi 4.3.2 Acceptance Criteria:

A. Fu &%ies owck) >.9 Fu w(b) and B. Fumvem( BerIu > F.(specfled minmum)

C. F,-(.0h, o.)> 1.25 Fy 4.3.3 Test Result:

A. 104,350 psi > .9(111,901) = 100,712 psi Therefore, Pass B. 104,350 psi > 90,000 psi Therefore, Pass C. All Individual couplers Fu > 1.25 (60 kesii) = 75 kksl (See Appendix C, "Test Checklist.Summary'/) Therefore, Pass 4.4 New Bar-Lock Couplers #6 4.4.1 Average Ultimate Strength (FPuav(#ea~ ) of #6 Bar-Lock Coupler (New): 107,730 psi 4.4.2 Acceptance Criteria:

A. F,(.gm wki*) > .9 Fu ,o(ba) and B. Fuag(#6EeiuoWO > Fu(spapeffd minimum)

C. F,(.w.pu.) > 1.25 Fy 4.4.3 Test Result:

A. 107,730 > .9(111,901) = 100,712 psi Therefore, Pass B. 107,730 psi > 90,000 psi Therefore, Pass C. All Individual couplers Fu > 1.25 (60 kpsi) = 75 kpsl (See Appendix C, "Test Checldlst Summary") Therefore, Pass 4.5 Qualification of #8 Bar-Lock Couplers 4.5.1 The average tensile strength (stress) of the 6 rebar samples Is as follows:

4.5.2 Average Ultimate Strength (F, ,)) of #8 Rebar 105,066 psi 4.6 Sequoyah Bar-Lock Couplers #8 4.6.1 Average Ultimate Strength (F, a(fan*ouk) of #8 Bar-Lock Coupler (Sequoyah):

102,306 psi 4.6.2 Acceptance Criteria:

A. Fuw(eafntk) > .9 Fu,,vab.) and B. Fu awo( Barwk) > Fu(ap.lkd minbum)

C. Fu(each apflu)> 1.25 Fy 4.6.3 Test Result A. 102,306 psi > .9(105,066) = 94,560 psi Therefore, Pass B. 102,306 psi > 90,000 psi Therefore, Pass Confidentiala Bechtel PowerCorporation2005. All rights reserved. Page 5 of 6 Technical Report No. SQN2-SGR-TR3 Page 155 of 56

24900-ETR-001. Rev. 1 C. All Individual couplers Fu >.1.25 (60 kpsi) =75 kpsl (See Appendix .C,"Test I Checklist Summary") Therefore, Pass 4.7 New Bar-Lock Couplers 4.7.1 Average Ultimate Strength (Fuv(#a snj,4) of #8 bar-Lock Coupler (New): 99,951 psi 4.7.2 Acceptance Criteria:

A. Fua*(#aeswja) > .9 F,,,,*tw) and B. Fu *a(o bIok) > Fu(spefed mlnimum)

C. Fu(eahslo)> 1.25 Fy 4.7.3 Test Result:

A. 99,951 psi > .9(105,066) = 94,560 psi Therefore, Pass B. 99,951'psi > 90,000 psi Therefore, Pass C. All Individual couplers Fu > 1.25 (60 kpsl) = 75 kpsi (See Appendix C, "Test I Checklist Summary") Therefore, Pass 4.8 Cyclic Tensile Tests 4.8.1 All #6 and #8 rebar assembles completed the required number of cycles without failure.

5.0 CONCLUSION

5.1 The test results, as shown above and attached to this report, show that the Bar-lock couplers are qualified for use to repair the construction opening In the dome of the Shield Building at Watts Bar Nuclear Plant This qualification applies to the new couplers manufactured In 2005 as well as the remaining Sequoyah couplers.

Confidentlal@Bechtel PowerCorporation2005. AI fights reserved. Page 6 of 6 Technical Report No. SQN2-SGR-TR3 Page 56 of 56

w Enclosure 2 Commitment Listing Commitment Statement Committed Date As part of the dedication process to be performed to qualify the Model 6L and Model 8L Bar-Lock couplers for use in restoring the U2C18 Refueling SQN, Unit 2, Shield Building, TVA will confirm that there have been no changes in the design and manufacturing parameters from those Model 6L and Model 8L Bar-Lock couplers used at SQN, Unit 1, and WBN, Unit 1.

E2-1