Technical Report No. SQN2-SGR-TR3, Revision 0 Sequoyah Unit 2 … · 2012. 12. 4. · SEQUOYAH UNIT 2 SGR ALTERNATE REBAR SPLICE - BAR-LOCK MECHANICAL SPLICES TECHNICAL REPORT (No

Attachment 2

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

Mechanical Splices Technical ReportApproved by TVA on February 15, 2011

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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 NCONTRACT PO 00075603 UNIT 2DESC. Rebar Mechanical Splice (Bar-Lock) Qual. ReportDWG/DOC NO. S0N2-SGR-TR3SHEET - OF - REV. 00DATE 02/15/11 ECN/DCN - FILE N2N-075

The Steam Generatina Team

A URS-Washington Division IAREVA NP Company

EDMS, WT CA-K

Page 1 of 56

The Steam Generating Team

SWA 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

PageslSectionsName and P, R, A PreparedlReviewed/

Title/Discipline Signature Date Approved or Comments

Mark D. Ceraldi /~ AllSGT LICENSING <01

Maria M. Hamrick / R AllSGT CIVIL ENGR ' I/L3 hiGeorge L. Comer A // AllSGT ASST PEM

Note: P designates Preparer, R designates Reviewer, and A designates Approver.

Page 2 of 56

The Steam Generating Team

KGJA URS-WashngtiMb DIvisIon/ARE VA NP Company

Document No.: SQN2-SGR-TR3

ALTERNATE REBAR SPLICE - BAR-LOCK SPLICES TECHNICAL REPORT

Record of Revision

Revision Pages/SectionslNo. 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 MECHANICALSPLICES TECHNICAL REPORT (No. SQN2-SGR-TR3)

Table of Contents1 .0 A bstra ct ............................................................................................. ; ......................................................... 52 .0 In tro d uctio n ................................................................................................................................................... 53 .0 O bje ctive s .................................................................................................................................................... 64.0 Regulatory Requirements/Criteria for Mechanical Splices ..................................................................... 74.1 NRC Regulatory Guide 1.136, Materials, Construction, and Testing of Concrete Containments ..... 74.2 ASME Section III, Division 2, Paragraph CC-4333, Mechanical Splices .............................................. 84.3 ASTM A370, Standard Test Methods and Definitions for Mechanical Testing of Steel Products ..... 94.4 ANSI N45.2.5, Supplementary Quality Assurance Requirements for Installation, Inspection, and

Testing of Structural Concrete and Structural Steel During the Construction Phase of NuclearP o w e r P la nts .............................................................................................................................................. 9

5.0 Description of Bar-Lock Couplers .......................................................................................................... 96.0 Criteria for QA/QC for Manufacturing and Use of Bar-Lock Couplers ................................................. 126 .1 C o de of R e co rd ..................................... ................................................................................................... 126.2 10 C FR 50 A ppendix B Elem ents ........................................................................................................ 127.0 Bar-Lock Coupler Prequalification Testing for Sequoyah Unit 1 and Watts Bar Unit 1 SGRs ............ 147.1 Bechtel/INEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use to Support the

Sequoyah Unit 1 SGR Project - Overview ............................................ 147.2 Bechtel/INEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use to Support the

Sequoyah Unit 1 SGR Project -Test Plan Employed ......................................................................... 157.3 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 ................ 157.4 BechtelINEEL Testing Program to Pre-Qualify Bar-Lock Couplers forUse to Support the

Sequoyah Unit 1 SGR Project - Description of Coupler Test Specimens ......................................... 187.5 Bechtel/INEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use to Support the

Sequoyah Unit 1 SGR Project - Test Results ................................................................................... 198.0 Sequoyah Unit 2 Bar-Lock Coupler Installation .................................................................................... 248.1 S plicing C rew Q ualification ....................................................................................................................... 258 .2 Inspectio n C rite ria ..... ............................................................................................................................... 2 58.3 Production / Sister Splice Testing ........................................................................................................ 258 .4 A cceptance C rite ria .................................................................................................................................... 268.5 Quality Assurance / Quality Control ........................................................ 269.0 S um m ary and C onclusions ...................................... I ............................................................................... 27

10 .0 R e fe re nce s ................................................................................................................................................ 2 8

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 SequoyahUnit 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 utaw ay ....................................................................................................................... 105-2 Bar-Lock Coupler L-Series (8-Bolts) .......................................... 115-3 Bar-Lock Coupler Installation ............................................... 11

Technical Report No. SQN2-SGR-TR3 Page 4 of 56

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

1.0 Abstract

The original construction of the Sequoyah Nuclear Plant Unit 2 concrete Shield Buildingemployed lap splices to join concrete reinforcing steel (rebar). While such splices wereable to be easily employed for original plant construction, they are difficult to performwhen restoring the concrete in Shield Building openings that result from performingmaintenance activities such as steam generator replacements (SGRs). Historically forSGRs, mechanical splices have been employed in reestablishing the rebar connectionsfor restoring the temporary concrete openings that are made to allow access tocontainment 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 utilizedthe Bar-Lock coupler system to provide the mechanical rebar splicing necessary torestore the temporary steam generator access openings in their Shield Buildings.Extensive prequalification of the Bar-Lock couplers actually employed for these SGRswas performed to meet ASME/ACI criteria which demonstrate the equivalency of theBar-Lock Model 6L and Model 8L rebar connections to rebar repairs using a cadweldsplice methodology. Technical Report SQN2-SGR-TR3 presents the technicaljustification for use of the same model Bar-Lock couplers for the restoration of theSequoyah Unit 2 Shield Building temporary steam generator access openings as part ofthe 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 6Land Model 8L Bar-Lock couplers in the restoration of the temporary steam generatoraccess openings in the Sequoyah Unit 2 Shield Building as part of the Unit 2 SGRProject. Mechanical splices for reinforcing steel (rebar) used in nuclear safety-relatedconcrete structures are subject to the stringent requirements of ASME Section III, Division2/ACI-359 and ACI-318, which includes the requirement for the splice to develop 125% ofthe 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-LockMechanical Splices Topical Report (Reference 1), which received NRC approval via theLetter 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 notspecifically address Unit 2 application of the Bar-Lock couplers, Technical Report SQN2-


SGR-TR3 is being written specifically to address Bar-Lock coupler use for the SequoyahUnit 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 accessopenings in the Watts Bar Unit 1 Shield Building (Reference 3). This LAR wassupplemented with prequalification testing of the Model 6L and Model 8L Bar-Lockcouplers additional to that performed as part of Topical Report 24370-TR-C-001 in orderto demonstrate the acceptability of using these model Bar-Lock couplers for the WattsBar Unit 1 SGR (References 4 and 5).

The Bar-Lock couplers were successfully used for the Sequoyah Unit 1 and Watts BarUnit 1 SGR Projects. For these applications, the Bar-Lock coupler system demonstratedthe capability to achieve efficient fitup/reconnection of the rebar assembled to enablerestoration of the temporary steam generator access openings made in the roofs of theShield 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 designand manufacture of the Model 6L and Model 8L Bar-Lock couplers from the time of theirprocurement 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 andmanufacturing parameters will not be changed before procurement of the inventories of

these Bar-Lock couplers for use in restoring the temporary steam generator accessopenings that will be made in the Sequoyah Unit 2 Shield Building during the Unit 2 SGRin Fall 2012. Given these facts and the extensive prequalification testing documented inthe applications for use of the Model 6L and Model 8L Bar-Lock couplers for theSequoyah Unit 1 and Watts Bar Unit 1 SGR projects, further prequalification testing of theModel 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 SGRProject, which includes restoration of the temporary steam generator access openingsdiscussed 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 insufficient detail to illustrate the advantages and benefits of this rebarreconnection system.


Criteria for the laboratory prequalification testing of the Bar-Lock Model 6L and

Model 8L couplers. Previously performed laboratory prequalification testing andprocesses 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 futureprocurement of Model 6L and Model 8L Bar-Lock couplers to support the Unit 2Sequoyah SGR Project. Discussions of this laboratory testing also include the

10 CFR 50 Appendix B requirements and a description of quality control ofcritical processes that were involved in the manufacture and testing of thecouplers, and the application of these criteria to current manufacture of theModel 6L and Mode 8L Bar-Lock couplers. Applicable test reports of thislaboratory prequalification testing are included in Appendix B of this TechnicalReport.

" Criteria for qualification and testing of the installation of the Model 6L and Model8L Bar-Lock couplers to support restoration of the temporary steam generatoraccess openings pertain to the onsite qualification testing that is performed aspart of the installation process to be employed during the Sequoyah Unit 2 SGROutage.

* 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 mechanicalsplices. Following each requirement/criterion is an italicized reference to where therequirement/criteria are addressed within this Technical Report.

4.1 NRC Regulatory Guide 1.136, Materials, Construction, and Testing ofConcrete 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 discussed in Section 8.3, all splice samples will be sister splices.

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 seriesof performance tests in order to qualify his splice system for use.

Previous testing which meets the requirements of Paragraph CC-4333.2.1 has beenperformed for the Model 6L and Model 8L Bar-Lock couplers that will be employed inrestoring the temporary Shield Building access openings that will be made to performthe Sequoyah Unit 2 SGR. As described above, this extensive prequalification testingwas performed for these model Bar-Lock couplers for their use in the same applicationas part of the Sequoyah Unit 1 and Watts Bar Unit I SGRs. Specifically, as presentedin Appendix B of this Technical Report, this testing was performed in 2001 forSequoyah Unit I and 2005 for Watts Bar Unit 1. Research with the Bar-Lock couplersystem manufacturer concludes that there have been no changes in the design andmanufacture of the Model 6L and Model 8L Bar-Lock couplers from the time of theirprocurement for use in the Sequoyah Unit I and Watts Bar Unit I SGRs (and the abovecited performance of prequalification testing) to the present day (Reference 6). The Bar-Lock manufacturer further confirms that for these model Bar-Lock couplers the designand manufacturing parameters will not be changed before procurement of the inventoriesof these Bar-Lock couplers for use in restoring the temporary steam generator accessopenings that will be made in the Sequoyah Unit 2 Shield Building during the Unit 2 SGRin Fall 2012. Therefore, the test reports contained in Appendix B serve to demonstratefrom a prequalification testing standpoint that the Bar-Lock Model 6L and Model 8Lcouplers are appropriate for use in restoring the temporary Shield Building accessopenings for the Sequoyah Unit 2 SGR and that the requirements of Paragraph CC-4333.2.1 have been satisfied.

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

Splicing crew qualification is described in Section 8.1.

Paragraph CC-4333.5.4 requires that splice samples be tensile tested using the loadingrates 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.


(b) The average tensile strength of each group of 15 consecutive samples shallequal 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 Testingof Steel Products

Section 10 of the standard specifies the requirements for gage marks to determinepercent elongation.

A discussion of the determination of the mechanical properties of the rebar used in theBechtel/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 tensileproperties.

A discussion of the determination of the mechanical properties of the rebar used in theBechtel/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 forInstallation, Inspection, and Testing of Structural Concrete and StructuralSteel 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 plantconstruction.

Sections 6.2 and 8.5 describe the conformance to quality requirements for the Bar-Lockcouplers 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 toASTM A-519, with a minimum tensile strength exceeding 100 ksi. The couplers utilize acombination of lockshear bolts and heat-treated internal serrated rails to create amechanical connection that exceeds the ASME and ACI requirements. A cutaway viewof a typical Bar-Lock coupler is provided in Figure 5-1. The serrated rails extend thelength of the tube to cradle and grip the rebar. As the six bolts in the illustration aretightened, 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 ofthe rebar to be spliced. Unlike the 6 bolts shown on Figure 5-1, the Bar-Lock couplersfor 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, A.a-C -D .

Coupler BcirralLockshtor BoltsSefroted RoArsCen~ter Pin

Figure 5-1 - 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 thecenter 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 twopasses of tightening each bolt prior to shearing the bolt heads.

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


I'

F-kl-n

Figure 5-2 - Bar-Lock Coupler L-Series (8-Bolts)

Figure 5-3 - 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 minimaloperator training, and do not require special nrebar preparation. Each coupler useslockshear bolts that require a specified minimum torque to shear the bolt heads off. Mostcoupler sizes can be installed with a standard impact wrench, and smaller sizes requireonly a manual socket wrench. No heavy crimping equipment or threading devices arerequired. The couplers can be used when rebar is fixed in a position (positional) as wellas 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) asusceptible 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 notcorrosive to steel. The concrete at Sequoyah is formulated to industry standards andshould provide a non-corrosive environment for the reinforcing bar and other steelcomponents. In addition, the bolts in the Bar-Lock splice are tightened against thereinforcing bar so that they are in compression, not tension. Therefore, the threenecessary conditions for stress corrosion do not occur in the application of Bar-Locksplice bolt tips at Sequoyah Unit 2 in the performance of the restoration of the temporarysteam generator access openings made in the Unit 2 Shield Building dome.

6.0 Criteria for Quality Assurance I Quality Control for Manufacturing and Use ofBar-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 theShield Building is in compliance with the American Concrete Institute (ACI) 318-63building code working stress requirements. The reinforcing steel conforms to therequirements of ASTM Designation A 615, Grade 60. Original construction was carriedout under the requirements of TVA Construction Specification G-2. UFSAR Section3.8.1.1 states that reinforcing bars were lap spliced in accordance with ACI 318-63requirements 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) thatprevent or mitigate the consequences of postulated accidents that could cause unduerisk 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


safety-related shield building, 10 CFR 50, Appendix B requirements are applicable tothe design, purchase, fabrication, handling, shipping, storage, inspection, testing, andinstallation of the couplers. Specifics on conformance to the 10 CFR 50, Appendix Brequirements 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 activitiesat the Sequoyah plant will be in accordance with the latest approved revision of the TVANuclear 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 revisionof 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 beused to restore the temporary steam generator access openings in the Unit 2 ShieldBuilding dome include:

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

2. Specification 39866-SPEC-C-007, "Technical Specification for Purchase ofReinforcing Steel"

As described in Section 8 of this Technical Report, installation of reinforcing bar and theBar-Lock couplers will be addressed through standard TVA work controlling processes.

Bar-Lock couplers are not currently manufactured as nuclear safety-related. Since theBar-Lock couplers will be used in a nuclear safety-related application, they are subjectto a commercial grade dedication program by SGT. To support this dedication, SGTwill witness and verify implementation of the Bar-Lock manufacturing and quality controlprocesses and procedures for compliance with the provisions of SGT Specification39866-SPEC-C-006.

The following processes and critical parameters will be observed and checked by SGTin accordance with a Commercial Grade Dedication Plan to ensure that the finalproduct 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


- 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 eachheat/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 WattsBar Unit I SGRs

For the preparation of Topical Report 24370-TR-C-001-A to gain NRC approval to useBar-Lock couplers to support the Shield Building dome restoration activities of theSequoyah Unit 1 SGR Project, extensive laboratory testing was performed ofspecimens of the Model 6L and Model 8L Bar-Lock couplers by Idaho NationalEngineering and Environmental Laboratory (INEEL). The test report which resultedfrom 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 similarShield Building dome temporary access opening restoration activities that were plannedfor the Watts Bar Unit 1 SGR Project. Sections 7.1 through 7.5 (and associatedsubsections) describe the Bechtel and INEEL collaborative effort to perform thelaboratory testing of the Bar-Lock couplers for use to support the Sequoyah Unit 1 SGRProject. This presentation is reflective of the similar content contained in Sections 8.1through 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 useBar-Lock couplers, Bechtel Corporation and INEEL developed and performed an


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

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

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


Support the Sequoyah Unit 1 SGR Project - Test Plan Employed

ASME Section CC-4333 specifies performance criteria to qualify rebar splicing devicesfor use in nuclear safety-related applications. While the strength specifications aremoderately high, the quantity of test specimens is relatively low. To achieve highstatistical confidence in measured sample parameters, e.g., ultimate strength, theBechtel/INEEL testing purposely increased the quantity of test specimens (the sampleset - 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, thequantity was increased to n = 40 for each size tested. For the cyclic durability test, theASME code requires three (3) specimens to survive the 100-cycle test, and theBechtel/INEEL testing conservatively increased the number of samples to n = 40 foreach 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 thebinomial distribution of the cyclic test) associated with lower bound strength and cyclicdurability requirements specified in the Code.

The Bechtel/INEEL Bar-Lock testing was monitored by Bechtel QAIQC personnel toensure 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 toSupport the Sequoyah Unit 1 SGR Project - Mechanical Properties Test

Results for Reinforcing Bar

In performing the Bechtel/INEEL testing, mechanical properties used in these testswere determined in accordance with project test procedures, incorporating relevantASTM standards and procedures (ASTM A 370 and ASTM E 8). Mechanical propertiestests were performed on the same universal test machine, using the same


measurement transducers. The same test machine, load cell, and extensometer wereused 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 Reportincluded 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 nominaldiameter) sizes. Consolidated Power Supply, the vendor of the rebar, provided certified

material test reports (CMTRs). The values reported in these CMTRs were based on theresults of a single tensile test. The CMTR value, while confirming the nominal materialperformance, was inadequate to determine "actual" material properties. The ASTM teststandard recommends a minimum of three specimens be tested and the resultsaveraged. Additional verification testing was performed as part of this test program todetermine the "actual" of measured mechanical properties of the different heats of rebaremployed 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 (SeeAppendix B, Table 3). Per ASME Section II, Division 2 requirements, the same 10 inchextensometer gage length as was used in the 6L coupler assembly tests was used tomeasure strain in the tensile properties tests. The test results are summarized in Table7-1. Material properties obtained from the Consolidated Power Supply CMTR areprovided for comparison.

Table 7-1 illustrates that the differences in yield strength value as determined by threedifferent definitions of yield are minimal. For this type of steel, the yield point is theappropriate measurement and provides the most consistent value (smallest standarddeviation). 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 theanalyses, 107.5 ksi was used for the 6L tests.


Table 7-1 - Bechtel/IlNEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use toSupport the Sequoyah Unit I SGR Project - Mechanical Properties of Rebar Used in TestSpecimens

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 norequirement or point of comparison in the ASME Code related to the ductility (percent uniformelongation) of the rebar material. It was measured and reported for the plain bar because it was a resultof the plain bar test method data analysis of ASTM A370. The measured elongation of the plain bar wasnot 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 inmaking up the 8L size coupler test assemblies used in the tensile strength tests. Seven

#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 materialyield- 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 (onlyspecified minimums) associated with the cyclic test procedures, so no verification


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


Support the Sequoyah Unit I SGR Project - Description of Coupler TestSpecimens

The Bar-Lock couplers used by Bechtel/INEEL in the test and which were used atSequoyah were Bar-Lock's "L-Series" (coupler designations 6L and 8L), which arehigher strength rebar couplers for use in tension/compression, seismic and other cyclicloading conditions. The specifications for these couplers are provided in Table 7-2.

Table 7-2 - Bar-Lock L-Series Coupler Specifications (Sizes 6L and 8L)

For Coupler Specifications Bolt SpecificationsCoupler UseDesignation on Outside Length Nominal Quantity Size Nominal

Rebar Diameter (inch) Weight per Bar (inch) ShearSize (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 consistedof a steel tube, "lockshear" bolts, and serrated rails. Figure 5-1 shows a schematicdiagram of the coupler design (which will be. the same design employed for theSequoyah 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 isAISI 41 L40. The bolts are through-hardened over the entire bolt length and inductionhardened at the conical bolt tip. The serrated rails are made of ASTM CD19188material. 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 ofthe two coupler/rebar sizes tested. For each size, forty (40) test specimen assemblieswere made up for tensile strength tests, and forty (40) assemblies were made up for thecyclic durability tests. The test specimens were assembled by construction craftpersonnel using Bar-Lock's assembly instructions in a normal field environment.Assembly of the test specimens was monitored by Bechtel QC personnel.


7.5 BechtelllNEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Use toSupport 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 couplerassembly specimens according to relevant sections of ASMT A 3700 and E8, andASTM CC-4333.2.3(a). A representative stress-strain curve for a coupler strength testis provided in Figure 4 of the Bechtel/INEEL Test Report included as Appendix B of thisTechnical Report. No practical differences were observed in the general character ofthe stress-strain curve of the 80 specimens tested. Test data collected included stress,strain, crosshead displacement, applied force, and elapsed time. Crossheaddisplacement, as utilized here, refers to the relative separation between the testmachine grips (i.e., the displacement of the test machine's moving crosshead relative toits fixed one).

The mechanical properties from individual specimen tests, extracted from raw test datausing .standard analysis methods provided in ASTM E 8, are tabulated in Table 5 of theBechtel/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 arealso provided in Appendix B.

In addition, for the Bechtel/INEEL testing, several specimens of each size wererandomly selected to receive an initial slip test prior to the normal strength test. Virgintest specimens were installed in the test machine and instrumented as for a normalstrength test. The applied stress was increased from 0, through 3 ksi, up to 30 ksi, andthe reduced to 3 ksi. The change in displacement across the coupler between the two3 ksi stress levels was measured with an extensometer. Figure 5 in the Bechtel/INEELTest Report presented in Appendix B shows the traces of applied stress and resultantdisplacement 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 lengthof the coupler, were much less than observed hysteresis error in the extensometer.The Bechtel/INEEL Test Report concludes that this was expected due to themechanical interlocking of coupler and bar in the Bar-Lock coupler design. Theobservation of no bar slip within the coupler on initial loading meant that the couplerwould develop full strength without excessive deformation upon initial loading.


7.5.1 Bechtel/INEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Useto Support the Sequoyah Unit I SGR Project - Tensile Test Results

The ASME Code, Section CC-4333.2.3, has several criteria with which the couplerperformance is compared. The two pertinent criteria for the tensile strength test resultsof the Bechtel/INEEL Testing Program were as follows:

1. "...The average tensile strength of the splices shall not be less than 90% of theactual tensile strength of the reinforcing bar being tested, nor less than 100% of thespecified minimum tensile strength." Average tensile strength is a single averagevalue that is calculated from the entire group (sample set) of replicate testspecimens, 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. Forthe size 6L group, the specified minimum average strength value is 96.8 ksi. For thesize 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 fornormal (Gaussian) probability distribution using the Wilk-Shapiro W-test andgraphical analysis methods. The results showed a near normal distribution, i.e.,only slight departure from normality. Where necessary in the assignment ofconfidence 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 ofonly 1.87 ksi. The code-required average strength value of 96.8 ksi (90% of actualtensile strength) was 5.0 standard deviations below the sample average. Thiscorresponded to a probability that less than 3 in 10 million couplers would havestrength less than the required 96.88 ksi minimum value. Further, a one-sided testfor lower bound was also performed. This test provided a practical lower limitstrength value for the 6L coupler assembly. Based upon this data set, 99% of thecouplers 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 designwill achieve the required minimum strength.

Coupler/Bar Size 8L

The sample set of strength data from the coupler/bar size 8L was also evaluated fornormal (Gaussian) probability distribution using the W-test and graphical analysismethods. 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


ksi. The required average strength value of 99.1 ksi was 3.6 standard deviationsbelow the sample average. This corresponded to a probability that less than 2 in10,000 couplers would have a strength less than the required 99.1 ksi minimumvalue. Further, a one-sided test for lower bound based upon this data set indicatedthat, with 99% confidence, 99% of the couplers of this type will have a tensilestrength greater than 99.94 ksi. This was a very strong indication that the size 8Lcoupler design will achieve the required minimum strength.

To assess the general capabilities of the overall coupler design, the results fromboth sizes can be normalized by their respective bar lot (mill heat) tensile strengthsand combined into one sample set. In so doing, the conclusion is that the Bar-Lockcoupler 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 thiscombined/normalized sample set was 2.2% of the bar strength, making the requiredminimum strength 4.0 standard deviations below the sample average. Theequivalent likelihood was that only 3 in 100,000 would fail to achieve a strength levelequivalent to the rebar ultimate strength.

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

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

In the simplest case, the pass/fail criteria could be applied directly. For thecombined sample size of 80, with no observed failures (strength below 75.0 ksi), thestatement could be made with 90% confidence, that no more than 2.8% of couplerswould 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 untilmany hundreds of samples were assessed. However, by normalizing the measuredindividual coupler strengths by the required value, an analysis of the amount ofdeviation on those values could provide a yet stronger comparison andcorresponding statement of reliability.

This distribution of normalized strengths showed that the average coupler strengthwas 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 ofan individual coupler assembly would be lower than the requirement was negligible.However, in the development of Topical Report 24370-TR-C-001-A, the NRCcommented that the minimum strength criterion for individual test specimens shouldbe based upon the actual, measured yield strength of the bar material, rather thanthe specified minimum value described here. This makes more sense from apractical viewpoint, and it removes one variable (the specified material yieldstrength) from the comparison. This approach does, however, apply a morestringent test of the coupler capability, since the actual yield strength will always behigher than the minimum allowable. To apply this criterion, the size 6L and 8Lspecimens must be treated separately since the measured yield strengths of the twobar sizes are significantly different.

Size 6L Coupler

Using the appropriately normalized test results from the 6L specimens, the sameanalysis described above was carried out. The size 6L coupler specimen tensilestrengths 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 theirtensile strengths averaged 109.0 ksi, 20.1% above the proposed strength level of90.8 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 summarizedas excellent, based on this comprehensive test program of different size couplers byperformed by Bechtel/INEEL. There were no failures to meet the specified or proposedstrength criteria. As the various failure probability values indicated, the likelihood of anindividual Type 6L or 8L coupler assembly failing to achieve the ASME requiredstrength levels was very low.

7.5.2 Bechtel/INEEL Testing Program to Pre-Qualify Bar-Lock Couplers for Useto Support the Sequoyah Unit 1 SGR Project - Cyclic Test Results

Coupler assemblies were cyclically tested by the Bechtel/INEEL Testing Programaccording to the requirements of ASME CC-4333.2.3(b). Forty specimens of each ofthe two types (6L and 8L) received 100 load cycles between 5 and 90% of specifiedminimum bar yield strength (60 ksi). None of the specimens failed (e.g., bar break orbar slip) within the coupler.

Applied stress and specimen extension data were digitized during the cyclic tests inorder to provide additional insight into the coupler performance under cyclic loadconditions. Figure 6 of the Bechtel/INEEL Test Report included in Appendix B shows a


representative plot of stress versus displacement. For clarity, only every tenth cycle ispresented. 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 couplersshowed 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 failuresin 80 tests, it can be stated with 90% confidence that less than 2.8% of the couplerswould 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 thespecimens in each size were selected at random to receive additional cyclic loading.Each selected specimen was subjected to an additional 1000 cycles. None of thespecimens failed, and none of them showed signs of deterioration through excessivestrain accumulation or physical deformation. While this did not provide a verifiableimprovement in the statistical probability of failure (the confidence level was too low tobe useful), it did provide an engineering indication that the cyclic durability of thecouplers will far exceed 100 cycles.

Residual Strength Tests

Another test was also performed on randomly selected couplers to provide additionalinformation regarding cyclic durability and residual strength. The selected couplers,each having been subjected to 100 loading cycles, were subsequently loaded to failuremonotonically. This is the standard "tensile strength test" described in the previoussection. The concept here was to determine if the prescribed cyclic loadingsubstantially damaged the integrity of the splice assembly. The eight specimens testedachieved the same nominal strength as the corresponding specimens receiving nocyclic loading. Table 6 of the Bechtel/INEEL Test Report included in Appendix Bsummarizes these test results. These observations suggest that cyclic loading in thestress range from 3 to 54 ksi did very little, if anything, to reduce the strength capacityof 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 ProgramConclusions

The Bar-Lock coupler qualification testing program was carried out on tworepresentative sizes - the Model 6L and Model 8L couplers. A total of 160 couplerassemblies 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 testspecimens.


The tensile strength on 80 samples exceeded the two ASME requirements by a largemargin. Statistical analyses of the test results determined several importantperformance indicators. The overall probability of a coupler assembly (Models 6L and8L) failing to meet the minimum qualification criterion is less than 3 in 100,000.

In performing the Bechtel/INEEL laboratory testing documented in Topical Report24370-TR-C-001-A, there was some variation in strength between the two heats ofrebar used in the strength tests. Comparing and correlating these results showed thatBar-Lock L-Series (Models 6L and 8L) coupler splices can be expected to achieve atensile strength greater than 96% of the actual bar strength. While there were notenough different combinations of bar material and coupler size data, the combined testresults 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 couplersshowed a solid mechanical connection between the coupler and the rebar. There wasno tendency for the rebar to move within the coupler prior to developing full splicestrength. This was expected since the conical-tipped lock bolts physically embed intothe 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 passedthe 100-cycle test, with no obvious physical degradation of the spliced joint. To providean additional degree of assurance of adequate cyclic durability, selected specimensreceived 1000 cycles of loading, again with no noticeable physical degradation. Someof the specimens that passed the 100 cycle test were subsequently tested bymonotonic loading to failure. The resultant measured strengths were essentially thesame as the virgin strength specimens (no cyclic loading applied). These resultssuggested that the design of the Bar-Lock coupler is essentially insensitive to cyclicloading to levels below 90% of the minimum bar yield strength.

The results of these tests, compared to the ASME splice system qualificationrequirements, indicated that the Bar-Lock coupler design for rebar splicing was entirelyadequate from a strength point of view for use in nuclear safety-related construction.The additional quantity of couplers tested provided higher confidence that the couplersdo 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 newrebar to the existing rebar to prepare the temporary access openings in the SequoyahUnit 2 Shield Building dome for concrete placement. The 6L and 8L couplers will beinstalled in accordance with the manufacturer's instructions presented in Section 5.0 ofthis Technical Report. Installation will be implemented through standard TVA workcontrolling processes.


8.1 Splicing Crew Qualification

At least one member of each splicing crew will be trained to install the Model 6L andModel 8L couplers. Splicing crew qualification will be demonstrated by preparing twoqualification (test) splices using the largest bar size to be used. On successfulinspection and testing of the qualification splices, the crew will be considered to bequalified to perform production splices. Each qualified splicing crew shall be assignedan identification mark to be placed on each completed splice. Splicing crewqualification records shall be retained as permanent records.

8.2 Inspection Criteria

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

8.3 Production I Sister Splice Testing

During the original construction, both rebar production splices and sister splices wereused as samples for tensile testing. Sampling of production splices during therestoration of the temporary steam generator access openings in the Unit 2 ShieldBuilding during the SGR would increase the amount of concrete chipback and thepotential for reinforcing bar damage. In addition to increased concrete chipback, therewould be geometric constraints associated with replacing production splices taken fortensile testing.

ANSI N45.2.5-74 takes exception to taking production splice samples when the splicingsleeve is a leak tight barrier (embedded structural steel sections or liner plate) andinstead requires a representative sister splice sample to be taken. For the SequoyahUnit 2 SGR Project reinforcing bar splice testing program a similar approach will beused. Production splices will not be removed for tensile testing, and sister splices willbe used exclusively. With the exception of substituting a sister splice for a productionsplices on a one-to-one basis, the splice tensile testing using this sampling scheme isconsistent with the sampling in ANSI N45.2.5-74 when testing both sister andproduction splices. The proposed testing scheme also substitutes a sister splice for aproduction 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 editionof ASME Section III, Division 2, which requires tensile testing only one splice (sister orproduction) for every 100 production splices for ferrous filler metal splices.


8.4 Acceptance Criteria

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

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

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

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

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

If a sample splice used for testing fails to meet the above tensile test requirementsand the failure occurs in the splice, two additional sister splices made under thesame conditions and in the same position shall be produced. If either of theseretests fails to achieve 90,000 psi, splicing shall be halted until the cause of thefailures 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 15consecutive samples, splicing shall be halted until the cause of the failures has beenevaluated and resolved.

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

5) Material, installation, inspection and testing of Bar-Lock splices, includingqualification of installers, are classified as safety-related. Safety-related work willcomply with Steam Generating Team's Quality Assurance Program, whichdemonstrates compliance of quality controlled activities to TVA's Quality AssuranceProgram and ANSI N45.2. Qualification of inspection personnel will be inaccordance with ANSI N45.2.6.

8.5 Quality Assurance / Quality Control

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


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 systemqualification requirements, the Bar-Lock coupler design for rebar splicing is more thansufficient from a strength point of view for use in nuclear safety-related construction. Asdiscussed in Section 7 of this Technical Report, no failures occurred in any of thespecimens tested. The additional couplers tested provide higher confidence that thecouplers 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-LockModel 6L and Model 8L couplers that will be procured for the Sequoyah Unit 2 SGRProject. Therefore, use of the Model 6L and Model 8L Bar-Lock couplers for nuclearsafety-related applications at Sequoyah Unit 2 to support the SGR for that unit isconsidered acceptable. These Model 6L and Model 8L Bar-Lock couplers will beprocured as commercially dedicated equipment for use in the Sequoyah Unit 2 SGR inaccordance with the quality requirements described in Section 6 for installation andinstallation 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 GeneratorReplacement Alternate Rebar Splice - Bar-Lock Mechanical Splices TopicalReport, Revision 0

2. NRC Letter to Mr. J. A. Scalice, CNO and Executive V.P. of TVA, dated March13, 2003. Subject: Sequoyah Nuclear Plant, Unit 1, Safety Evaluation of TopicalReport No. 24370-TR-C-001, "Alternate Rebar Splice - Bar-Lock MechanicalSplices" (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 inTopical 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 LockMechanical Couplers for Splicing Reinforcing Bars in the Shield BuildingRestoration - 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 MechanicalCouplers for Splicing Reinforcing Bars in the Shield Building Restoration - TestResults 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 CouplerSystem, 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, andFoundations for Nuclear Power Plants, 2008

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

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

11. ACI 318-63, Building Code Requirements for Reinforced Concrete


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 TestingProgram 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 forReinforced Concrete

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

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

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

21. ASTM E 8, Standard Test Methods for Tension Testing of Metallic Materials


Appendix B

Test Reports for Sequoyah Unit I and Watts Bar Unit I Bar-Lock Rebar CouplerPrequalification 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


INEEUEXT-02-01387.

Dec 2001

Qualification of the Bar-Lock Rebar CouplerFor Use in Nuclear Safety-Related Applications

Mechanical Testing Programand Performance Analysis

W. R. Lloyd


INEEL/EXT-02-01387

Qualification of the Bar-Lock Rebar CouplerFor Use in Nuclear Safety-Related Applications

Mechanical Testing Programand Performance Analysis

W. R. Lloyd

Published Dec 2001

Idaho National Engineering and Environmental LaboratoryMaterials Department

Idaho Falls, Idaho 83415-2218


Summary

Bechtel Corporation and INEEL developed and performed an independent mechanical testing andanalysis program to assess the mechanical performance characteristics of the Bar-Lock L-Series rebarcoupler system. A test plan that exceeded the assessment requirements given in ASME Section CC -4333was developed. To achieve high statistical confidence in measured sample parameters, e.g. ultimatestrength, the number of specimens tested was increased to forty (40) from the ASME Code-requiredquantity of six (6). Bechtel QA/QC personnel monitored the testing program to ensure that it wasperformed 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 exceededthe ASME-specified minimum strength levels by large margins. Statistical analysis of the results showeda 99.998% probability that the average strength of a group of coupler assemblies would exceed the ASMEstatic strength requirement of 90% of the joined rebar tensile strength. Assessing the performance ofindividual coupler assemblies against the ASME-specified minimum strength (75 ksi for the Grade 60rebar used in the tests) for individual assemblies showed that the average strength of an individualassembly was more than 8 standard deviations above the specified minimum. This corresponds to theprobability 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 determinetheir cyclic loading durability. The test procedure cycled each assembly between 5 and 90% of specifiedminimum bar yield strength (60 ksi) 100 times. None of the specimens failed in any manner, e.g. barbreak, or bar slip within the coupler.

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

Further, some coupler assemblies randomly selected from those already receiving 100 loading cycleswere subsequently loaded to failure monotonically (static strength test). This test determined if theprescribed 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 cyclicloading.

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

iii


CONTENTS

Summary ................................................... .............. ........ . ............................... Iv

I. O verview ............................... 4................................................................ ...... ................... 4

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


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


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

Mechanical Testing Programand Performance Analysis.

1. OVERVIEW

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

The Bechtel/INEEL test program tested and demonstrated that the mechanical properties of the L -SeriesBar-Lock mechanical splices meet the existing Codes and NRC requirements and are an acceptablemethod 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 nuclearsafety-related applications. While the strength specifications are moderately high, the quantity of testspecimens required is relatively low. To achieve high statistical confidence in measured sampleparameters, e.g. ultimate strength, a larger sample size (n) is required. To achieve the desired level ofconfidence that any installation of these couplers will have the requisite performance characteristics, thequantity 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 wasincreased to n = 40 for each size tested. For the cyclic durability test, the ASME Code requires threespecimens to survive the 100-cycle test. This was increased to n = 40 for each size. Increasing thestatistical 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 cyclicdurability requirements specified in the Code.

The Bar-Lock testing was monitored by Bechtel QA/QC personnel to ensure that it was performed inaccordance 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 withproject test procedures, incorporating relevant American Society for Testing and Materials (ASTM) teststandards and procedures (ASTM Designation A 370-96, Standard Test Methods and Definitions fotMechanical Testing of Steel Products; and ASTM Designation E 8-99, Standard Test Methods forTension Testing of Metallic Materials). All mechanical properties tests were performed on the sameuniversal test machine, using the same measurement transducers. The same test machine, load cell, andextensometer were used in all of the coupler assembly tests as well. Bechtel Quality AssuranceDepartment retains all calibration certification and records for this equipment and these devices.

Technical Report No. SQN2-SGR-TR3Page 36 of 56

The reinforcing bar used in the Bar -Lock coupler testing program was ASTM A615 Grade 60 material in#6 (C/ in. nominal diameter) and #8 (1 in. nominal diameter) sizes. Consolidated Power Supply, thevendor of the rebar, provided ce-tified material test reports (CMTRs). The values reported in the CMTRsare based on the results of a single tensile test. The CMTR value, while confirming the nominal materialperformance, is inadequate to determine "actual" material properties. The ASTM test standardrecommends a minimum of three specimens be tested and the results averaged. Additional verificationtesting was performed as part of this test program to determine the '"ctual"or m easured mechanicalproperties of the different heats of rebar employed in specimen assembly. Figures I and 2 showrepresentative 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 beused 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 ofmaterial. Table I summarizes the test results. Material properties obtained from Consolidated PowerSupply CMTR are provided for comparison.

It is apparent that the differences in yield strength as determined by three different definitions areminimal. For this type of steel, the yield point is the appropriate measurement and provides the mostconsistent value (smallest standard deviation). Where "measured" or 'actual" yield strength is required inthe analyses, 67.7 ksi is used for the #6L coupler tests. Where "measured"or "actual"ultimate tensilestrength (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)(ksi) Yield (ksi) Yield (ksi) (0/)

#6 Average 99M67.9 68.2 67.9 13.2 27.8

#6 Std Dev 1.03 1.19 1.14 1.12 1.26 0.89

#6CMTR - -- 67.6 107.4 15 --

#8 Average U 72.4 72.5 ___I- 11.5 29.2

#8 Std Dev 0.45 0.57 0.47 0.74 0.98 0.46

#8 CMTR -- - 73.1 112.0 14 -

#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 testassemblies used in the tensile strength tests. Per ASME requirements, the same 14.5 inch extensometer

2


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 lotof material. Table I summarizes the results of those tests. Material properties obtained fromConsolidated Power SupplyCMTR are also provided for comparison. Again, the yield point strength isselected for the material yield strength value. Where "measured"or "actual"yicld strength is required inthe analyses, 72.6 ksi is used for the #8 tests. Where "measured'or "a ctual"ultimate strength (UyTS) isrequired 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 couplerassemblies. There are no measured strength parameters (only specified minimums) associated with thecyclic test procedures, so no verification testing of this material was performed. The CMTR-reportedvalues 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 arehigher 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 NominalDesignation 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 serratedrails. Figure 3 (4-1) shows a schematic diagram of the coupler design. The seamless, hot-rolled steeltube conforms to ASTM A-519, with a minimum tensile strength in excess of 100 ksi. The lockshear boltmaterial 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 eachsize, forty test specimen assemblies were made up for tensile strength tests, and forty assemblies weremade up for the cyclic durability tests. The test specimen assemblies were made up by stel constructionworkers using Bar-Lockk assembly instructions in a normal field environment. Assembly of the testspecimens 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 setaverages 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 accordingto relevant sections of ASTM A 370 and E 8, and ASME CC-4333.2.3(a). A representative stress-straincurve for a coupler strength test is provided in Figure 4. No practical differences were observed in thegeneral character of the stress-strain curve of any of the 80 specimens tested. All test data collectedincluded stress, strain, crosshead displacement, applied force, and elapsed time. The actual individual testspecimen results obtained through standard analysis methods provided in ASTM E 8 are tabulated inTables 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 Bf EIV (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 11•• SA 11.5 29.2

4


In addition, several specimens of each size were randomly selected to receive an initial slip test prior tothe normal strength test. A statistically -legitimate random selection process, using a random numbergeneration algorithm on a computer, was applied to make the selections. Virgin test specimens wereinstalled in the test machine, and instrumented as for a normal strength test. The applied stress wasincreased from 0, through 3 ksi, up to 30 ksi, and then reduced to 3 ksi. The change in displacementacross the coupler between the two 3 ksi stress levels was measured with an extensometer. Figure 5shows the traces of applied stress and resultant displacement for the six specimens. In all cases, nomeasurable slip was detected.' The observation of no bar slip within the coupler on initial loading meansthe 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 strengthof the reinforcing bar being tested, nor less than 100% of the specified minimum tensile strength."

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

The coupler assembly performance for both sizes evaluated exceeded both of these criteria. Table 5tabulates the results of the individual strength tests. Discussion of the comparisons of test results toASME 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#8 group, the specified minimum average strength value is 99.1 ksi.

5.1.1.1 Couplerlbar size #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 analysismethods. The results show a near normal distribution, i.e. only slight departure fromnormality. Where necessary in the assignment of confidence limits, the assumption ofnormality is justified.

The size #6 group (sample set, n = 40) average tensile strength is 106.2 ksi (98.8% of theaverage #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 observedhysteresis error In the extensometer.2This is a single average value, calculated from the entire group (sample set) of replicate test specimens, i.e. from one heat ofmatenal, in one size.

3This is the strength value of each individual test speeimen (coupler assembly) consisting of one coupler unit and two attachedsections 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 standarddeviations below the sample average. This corresponds to a probability of less than 3 in 10million 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 lowerlimit strength value for any #6L coupler assembly. Based upon this data set 99% of allcouplers 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 achievethe required minimum strength. These results are confirmed in a letter report (seeAppendix F) from INEEL statistician JJ. Einerson. Mr. Einerson reviewed the statisticalanalyses of the mechanical test data.

&1.t1.2 Coupleribar size #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 theaverage #8 bar actual tensile strength), with a standard deviation of only 2.78 ksi. Therequired average strength value of 99.1 ksi is 3.6 standard deviations below the sampleaverage. This corresponds to a probability of less than 2 in 10,000 couplers Would have astrength less than the required 99.1 ksi minimum value. Further, the one -sided test for lowerbound (described above) based upon this data set indicates that, with 99% confidence, 99% ofall couplers of this type will have a tensile strength greater than 99.94 ksi (see letter reportincluded in the Appendix). This is a very strong indication that the size #8 coupler designwill achieve the required minimum strength.

To assess the general capabilities of the overall coupler design, the results from both sizestested can be normalized by their respective bar lot (mill heat) tensile strengths and combinedinto one sample set. In so doing, the conclusion is that the Bar -Lock coupler design producesa splice that will achieve an average strength that is 98.9% as strong as the rebar itself. It isobvious that this greatly exceeds the ASME Code-required 90% value. The cumulativestandard deviation is 2.2%A of the bar strength, making the required minimum strength 4.0standard deviations below the sample average. The equivalent likelihood is that only 3 in100,000 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 theoccasional sample tested that may have a relatively low strength value, as compared to thesample set average, at least has an absolute minimum necessary strength for structuralconsiderations. For the Grade 60 rebar used in this study, this required value is 75.0 ksi, andis 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 samplesize of 80, with no observed failures (strength below 75.0 ksi), the statement can be made thatwith 90% confidence, no more than 2.8% of couplers would fail this test. By the nature ofthis type of binomial probability distribution (pass/fail), it is difficult to state reliabilities with

6


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

5.1.2.2 Assessment Using Normalized Coupler Strength Distribution

This distribution of normalized strengths shows that the average coupler strength is 144% ofthe minimum required level for individual couplers, with a standard deviation of less than4%. So the required strength value is 11 standard deviations below the sample average. Theprobability tables do not show probabilities below 8 standard deviations from the mean, but atthat value, the probability is less than 2x10-15 that the strength of an individual assemblywould be lower than the requirement, i.e. practically impossible.

5.1.2.3 Assessment Using Alternative Strength Criterion

A comment by the US Nuclear Regulatory Commission (USNRC), during a presentation onthe Bar-Lock couplers on August 9, 2001, was that the minimum strength criterion forindividual test specimens should be based upon the actual, measured yield strength of the barmaterial, rather than the specified minimum value (as done above, per the ASMEqualification specification). This makes more sense from a practical view, and it removesone variable (the specified material yield strength) from the comparison. However, thisapproach does apply a more stringent test of the coupler capability, since the actual yieldstrength will always be higher than the minimum allowable. To apply this criterion, the size#6-and size #8 specimens must be treated separately since the measured yield strengths of thetwo bar sizes are significantly different.

Size #6 Couplers

Using the appropriately normalized test results from the #6 test specimens, the same analysisdescribed above was carried out. The size #6 coupler specimen tensile strengths averaged106.2 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 thanII standard deviations above the proposed minimum level, with the probability beingessentially 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 strengthsaveraged 109.0, 20.1% above the USNRC-proposed strength level of 90.8 ksi (125% *72.6 ksi) with a standard deviation of 2.81 ksi. The proposed minimum strength here is still6.5 standard deviations above the proposed minimum level. The resultant failure probabilityis 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, basedon this comprehensive test program of different size couplers. There were no failures to meet any of thespecified or proposed strength criteria in any case. As the various failure probability values indicate, thelikelihood of any individual Type 6L or 8L coupler assembly failingto achieve the ASME requiredstrength levels is very low.

7


Table 5. Re-Bar Splice Assemblies Strength Test Results

Specimen Failure Final UTS Specimen Failure Final UTSID (#6) Type' Strain (%) (ksi) ID (#8) Type Strain (%) (ksi)

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

S6-01 0

S6-02 P

S6-03 P

S6-04 P

S6-05 0

S6-06 0

S6-07 0

S6-08 P

S6-09 T

S6-10 0

S6-11 P

S6-12 0

S6-13 T

S6-14 P

S6-15 P

S6-16 0

S6-17 P

S6-18 P

S6-19 P

S6-20 P

56-21 P

S6-22 P

S6-23 T

S6-24 0

3.8 107.9 $8-01 0

15.2 108.0 S8-02 T

14.4 98.9 58-03 0

15.2 106.4 S8-04 0

4.9 107.3 S8-05 P

4.1 107.8 S8-06 T

4.2 107.6 S8-07 T

13.1 106.9 S8-08 T

2.7 103.2 S8-09 0

4.6 107.6 S8-10 T

13.0 107.3 $8-11 T

4.4 105.6 S8-12 *

2.7 103.4 S8-13 0

10.8 105.8 S8-14 T

12.3 104.0 S8-15 *

3.8 108.0 S8-16 T

9.8 103.7 S8-17 T

11.5 106.3 S8-18 T

19.1 106.1 S8-19 T

15.4 107.6 S8-20 0

11.0 106.0 S8-21 T

11.6 105.0 S8-22 T

2.7 103.1 S8-23 T

4.1 107.8 S8-24 T

3.7 109.6

1.4 96.8

4.9 109.8

3.7 110.1

10.4 108.4

4.9 109.7

4.4 1104A

3.6 109.4

3.6 110.5

1.8 102.1

2.1 106.0

3.8 108.0

3.4 110.5

3.2 110.1

3.7 106.7

4.0 111.0

2.1 104.5

4.5 109.3

4.0 109.4

4.6 110.1

3.5 109.7

4.3 109.4

3.8 109.8

3.3 108.5

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

Ile final stram is d ependent on several factors, including mode of failure An average value for all tests has no significance.For example, m a pull-out failure the final strain is detennined by the length of time the operator chooses to continue the testonce 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) (ksi) ID (#8) Type Strain (%) (ksi)-1 ý .' ": " "-' b "' "

Average -- NA5 '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). Fortyspecimens of each of the two types (6L and 8L) received 100 load cycles between 5 and 90% of specifiedminimum bar yield strength (60 ksi). None of the specimens failed in any manner, e.g. bar break, or barslip within the coupler.

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

Based on the binomial probability function (pass/fail testing), and no observed failures in 80 tests, it canbe stated with 90% confidence that less than 2.8% of all couplers would fail prior to the completion of100 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 eachsize were selected at random to receive additional cyclic loading. Each selected specimen was subjectedto an additional 1000 cycles. None of the specimens failed, and none of them showed signs ofdeterioration through excessive strain accumulation or physical deformation. While this does not providea verifiable improvement in the statistical probability of failure (the confidence level is too low to beuseful), it does provide an engineering indication that the cyclic durability of the couplers will far exceed100 cycles.

5.2.2 Residual Strength Tests

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

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#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 twoheats 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 ASMErequirements by a large margin. Statistical analyses of the test results determined several importantperformance indicators, all of which suggested that any given coupler assembly would far exceed the

10


ASME-specified strength requirements. The overall probability of any coupler assembly (in size #6 or#8)failing to meet the minimum qualification strength 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 toachieve a tensile strength greater than 96% of the actua l.strength of the bar material that is connectedusing the coupler device. While there are not enough different combinations of bar material and couplersize data to make this statement with high probabilistic certainty, the combined test results from thisprogram appear similar when normalized by the actual bar strength. Therefore, it is likely these testresults are representative of the performance of other sizes of Bar-Lock L-Series couplers. In otherwords, the mechanical design of the Bar-Lock L-Series coupler is such that spliced joints can be expectedto 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 betweenthe coupler and the rebar. There was no tendency for the rebar to move within the coupler prior todeveloping full splice strength. This was expected since the conical-tipped lock bolts physically embedinto 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, withno obvious physical degradation of the spliced joint. To provide an additional degree of assurance ofadequate cyclic durability, selected specimens received 1000 cycles of loading, again with no noticeablephysical degradation. Some of the specimens that passed the 100 cycle test were subsequently tested bymonotonic loading to failure. The resultant measured strengths were essentially the same as the virginstrength test specimens (no cyclic loading applied). These results suggest that the design of the Bar-Lockcoupler 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 theBar-Lock coupler design for rebar splicing is entirely adequate from a strength point of view for use innuclear safety-related construction. The large quantity of couplers tested provides higher confidence thatthe couplers do meet, and indeed far exceed, those ASME-specified requirement.


120

100#Ur6-18

Size #6 Rebarso IHeat #589 812 8 99

60

40

20

00 4 8

Engineering Strain (%)

Figure 1. Representative Stress-Strain Curve from #6 Rebar Material

12

12 16


120

100

so

60

40

20

08 12

Engimenng Strain (OA)16

Figure 2. Representalive Stress-Strain Curve from #8 Rebar Material

Figure 3. Bar-Lock Coupler Cutaway View Showing Internal Details

13


Crosshead Displacement (in.)

0 0.5 1 1.5 2120

100

Extensometer removed80 at 2% strain level

-10" G.L. Strain40 Crosshcad Position

I

0 I

0 12 3 4Strain (1.)

Figure 4. Representative Test Data from a Coupler Assembly Strength Test

14


40

30 .. / )

20

Found knife edges on extensometeto be loose following the test0 / • 1 , , I,, , , ,. , I I . ,

0000 0002 00o4 0006 0o0aDisplacement across Coupler (in)

Figure 5. Data Curves Showing Load-Unload Cycle to Assess Bar Slip in Couplers

15

0012


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

Figure 6. Cyclic Stress-Displacement History for a Typical Test

16


ENCLOSURE

WATTS BAR NUCLEAR PLANT (WEN) UNIT IEXCERPTS FROM THE

ENGINEERING TEST REPORT 24900-ETR-001, REVISION 1FOR

BAR-LOCK MECEANICAL COUPLER QUALIFICATION


24900-ETR-001. Rev. 1

ENGINEERING TEST REPORTFOR

BAR-LOCK QUALIFICATION

1.0 GENERAL

1.1 Watts Bar Nuclear Power Plant Is a two-unit power plant located approximately 50miles northeast of Chattanooga at the Watts Bar Site In Rhea County,Tennessee, which Is operated by Tennessee Valley Authority (TVA, hereafterreferred to as 'OWNER'). Bechtel (hereafter referred to as the CONTRACTOR)has the overall responsibility for execution of the Unit 1 Steam GeneratorReplacement (SGR) Project. The SGR project requires that openings be createdIn 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 Inthe repair of the opening in the Unit 1 Shield Building dome made during thesteam generator replacement project.

1.3 The purpose of these tests Is to provide the required documentation for thequalification of the Badlock couplers to the requirements of ASME Section IIIDivision 2 Article CC 4330, "Splicing of Reinforcing Bars" for use In the repair. ofthe construction opening In the concrete Shield Building Dome made during thesteam 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 notedbelow.

2.2 American Society for Testing and Materials (ASTM)

A 370- 97a Standard Test Methods and Definitions for Mechanical Testing ofSteel Products

A 615- 96a Standard Specification for Deformed and Plain Billet-Steel Bars forConcrete 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 NuclearFacilities .

ANSI N45.2.2-72 Packaging, Shipping, Receiving, Storage, and Handling ofitems for Nuclear Power Plants

ANSI N45.2.5-74 Supplementary Quality Assurance Requirements forInstallation, Inspection, and Testing of Structural Concreteand Structural Steel During the Construction Phase ofNuclear Power Plants

N45.2.6-1978 Qualifications of Inspection, Examination, and TestingPersonnel for Nuclear Power Plants

Confldentlalc Bechtel Power Corporation 2005. All rights reserved. Page 3 of 6


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 newlymanufactured couplers) was per the requirements of Specification 24900-C0602,"Technical Specification for Qualification Testing of Bar-Lock Mechanical RebarSplices." The testing occurred during the week of August 29, 2005. The testingwas performed using Bechtel's SATEC machine located at Palo Verde NuclearStation 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 eachrebar size (spares were also prepared).

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

3.5 Static Tensile Test Acceptance Criteria

3.5.1 The average tensile strength of the splices shall not be less than 90% of theactual tensile strength of the unspliced rebar being tested, nor less than 100% ofthe specified minimum tensile strength of the rebar. For Grade 60 rebar, theminimum specified tensile strength is 90 ksl.

3.5.2 The tensile strength of an Individual splice shall not be less than 125% of thespecified minimum yield strength of the rebar. For Grade 60 rebar, the minimumspecified 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 from5% to 90% of the specified minimum yield strength of the rebar. For Grade 60rebar, 5% minimum specified yield strength Is 3 ksi, and 90% minimum specifiedyield 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 Corporation 2005. All rights reserved. Page 4 of 6


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, "TestChecklist.Summary'/) Therefore, Pass

4.4 New Bar-Lock Couplers #6

4.4.1 Average Ultimate Strength (FPuav(#ea~ ) of #6 Bar-Lock Coupler (New): 107,730psi


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, "TestChecldlst 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


A. Fuw(eafn tk) > .9 Fu,,vab.) and

B. Fu awo( Barwk) > Fu(ap.lkd minbum)

C. Fu(each apflu)> 1.25 Fy

4.6.3 Test Result


B. 102,306 psi > 90,000 psi Therefore, PassConfidentiala Bechtel Power Corporation 2005. All rights reserved. Page 5 of 6


24900-ETR-001. Rev. 1

C. All Individual couplers Fu >.1.25 (60 kpsi) =75 kpsl (See Appendix .C, "Test IChecklist 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): 99,951psi


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:


B. 99,951'psi > 90,000 psi Therefore, Pass

C. All Individual couplers Fu > 1.25 (60 kpsl) = 75 kpsi (See Appendix C, "Test IChecklist Summary") Therefore, Pass

4.8 Cyclic Tensile Tests

4.8.1 All #6 and #8 rebar assembles completed the required number of cycles withoutfailure.

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 domeof the Shield Building at Watts Bar Nuclear Plant This qualification applies to thenew couplers manufactured In 2005 as well as the remaining Sequoyah couplers.

Confidentlal@ Bechtel Power Corporation 2005. AI fights reserved. Page 6 of 6


w

Enclosure 2

Commitment Listing

Commitment Statement Committed DateAs part of the dedication process to be performed to qualify theModel 6L and Model 8L Bar-Lock couplers for use in restoring the U2C18 RefuelingSQN, Unit 2, Shield Building, TVA will confirm that there have beenno changes in the design and manufacturing parameters from thoseModel 6L and Model 8L Bar-Lock couplers used at SQN, Unit 1, andWBN, Unit 1.

E2-1