ML19205A352

NRC008 - MPR-4273, Revision 0, Seabrook Station - Implications of Large-Scale Test Program Results on Reinforced Concrete Affected by Alkali-Silica Reaction, (July 2016)

ML19205A352
Person / Time
Site:	Seabrook
Issue date:	07/24/2019
From:	NRC/OGC
To:	Atomic Safety and Licensing Board Panel
SECY RAS
References
50-443-LA-2, ASLBP 17-953-02-LA-BD01, RAS 55104
Download: ML19205A352 (80)

Text

UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION ATOMIC SAFETY AND LICENSING BOARD In the Matter of NEXTERA ENERGY SEABROOK, LLC

(Seabrook Station, Unit 1)

Docket No. 50-443-LA-2 ASLBP No. 17-953-02-LA-BD01

Hearing Exhibit

Exhibit Number:

Exhibit Title:

SBK-L-16071 ENCLOSURE 3 MPR-4273, Revision 0, "Seabrook Station -Implications of Large-Scale Test Program Results on Reinforced Concrete Affected by Alkali-Silica Reaction." July 2016. (Non-Proprietary)

--Non-Proprietary Version--MPR-4273 R ev ision 0 (Seabrook FP# 101050) July2016 --Proprietary to NextEra Energy Seabrook and MPR Associates

--Seabrook Station -Implications of Large-Scale Test Program Results on Reinforced Concrete Affected by Alkali-Silica Reaction QUALITY ASSURANCE DOCUMENT This document has been prepared , reviewed , and approved in accordance with the Quality Assurance requirements of 1 OCFR50 Appendix Band/or ASME NQA-1, as specified in the MPR Nuclear Quality Assurance Program. Prepared for NextEra Energy Seabrook P. 0. Box 300; Lafayette Rd. Seabrook , NH 03874

--Non-Proprietary Version--m MPR Seabrook Station -Implications of Large-Scale Test Program Results on Reinforced Concrete Affected by Alkali-Silica Reaction MPR-4273 (Sea b roo k F P# 101 05 0) R ev i s ion 0 Jul y 2 016 QUALITY ASSURANCE DOCUMENT This document has been prepared , reviewed , and approved in accordance with the Quality Assurance requirements of 1 OCFR50 Appendix Band/or ASME NQA-1 , as specified in the MPR Nuclea r Quality Assurance Program. Prepared by: C /JJ ¥Y C. W. Bagley Reviewed J hn W. Simons Approved by: J es E. Mo ney Additiona l Contr i butors R. V ay d a A. Car d Pr e pared for NextEra E n ergy Seabrook P. 0. B ox 3 00; Lafayette Rd. Sea bro o k, N H 0 3 87 4 320 KING S T R EE T A LE X ANDRIA , VA 22314-3230 703-519-0200 F A X: 70 3-519-0224 www.mpr.com Revision 0 MPR-4273 R e v i s ion 0 Affected Pages All --Non-Proprietary Version--RECORD OF REVISIONS Description Initial I ss ue iii

--Non-Proprietary Version--Acknowledgements This report documents large-scale test programs conducted to support evaluation of the impact of alkali-silica reaction on reinforced concrete structures at Seabrook Station. The test programs were a collaborative effort between MPR Associates and the Ferguson Structural Engineering Laboratory (FSEL) (which is part of The University of Texas at Austin). These programs required a lar ge team of engineers and researchers , and count l ess man-hours over a four-year period. Successful completion of such an ambitious project is a testament to the dedication , commitment, and technical contrib uti ons of the ent ir e MPR/FSEL team, and active engagement and support by NextEra Energy. The individual team member s from each organization are acknowledged below: NextEra Energy Brian Brown Michael Col lin s Richard Noble Theodore Vassallo MPR Associates Christopher Bagle y Amanda Card Scott Eisele Benjamin Frazier Tom King James Moroney Kathleen Mulvaney Monique Neaves John Simons Robert Vayda MPR-4273 R e vi s ion 0 University of Texas at Austin Gloriana Arrieta-Martinez Morgan Allford John Bacon Oguzhan Bayrak Katelyn Beiter Michael Brown Nicholas Dassow Anthony Defurio Dean Deschenes Anthony Dandrea Daniel E li zondo Dennis Fillip Joe Klein Richard Klingner Cody Lambert A li ssa Neuhausen Joshua Ramirez Daniel Sun David Wald Sara Watts Heather Wilson Hosse in Y ousefpour E li zabeth Zetzman IV

--Non-P r op ri eta ry Ver s i o n--Executive Summary On behalf of NextEra , MPR directed several large-scale test programs to investigate the structural impact of alkali-silica reaction (AS! on reinforced concrete specimens.

The test programs involved fabrication and testing of large-scale test specimens that were designed to represent reinforced concrete structures at Sea rook Station and testing of two ASR-affected bridge girders. anchor capacity tests .shear load te ts l flexural load tests and evaluation o.instnunent configurations (total o fll instnunent ) for monitoring through-thickness expansion. This report integrates the conclusions of those studies to present the implications for structural assessments and monitoring of reinforced concrete structures at the plant , as follows:

• ASR cau es expansion of affected concrete that initially proceeds in all directions regardless of reinforcement configuration. Tue two-dimensional reinforcement mats in the test specimens confined expansion in the plane of the reinforcement mats (i.e. the in-plane directions) after-% expansion. Subsequent expansion was primarily in the through-thickness direction. Tue reinforcement configuration of the te t specimens reflects Seabrook Station structures.

Accordingly in-plane expansion measurements at Seabrook are sufficient for monitoring ASR progression until expansion reaches II%, after which through-thickness expansion measurements are necessru.y.

• Tue Combined Cracking Index (CCI) methodology (and the Seabrook Station procedure in particular) provides a reasonable approximation of true engineering strain and is an acceptable methodology for in-plane expansion monitoring.

• Snap ring borehole extensometers (SRBEs) provide an accurate and reliable methodology for monitoring through-thickness expan ion from the time the SRBE is installed.

• To determine total through-thickness expansion NextEra will also need to identify the through-thickness expansion before the SRBE is installed. The test programs identified that elastic modulus i sensitive to ASR degradation and provides a repeatable conelation with through-thickne s expansion. Through-thickness expansion determined from the empirical conelation may be added to the SRBE-dete1mined expansion to calculate the total through-thickness expansion. (See MPR-4153 for details.)

• Results from the Anchor Test Program indicate that there is no reduction in anchor i acity in ASR-affected concrete with in-plane expansion levels of less th a_rL mm/m %). Because in-plane expansion of fabricated test specimens plateaued a tm% expansion, anchor testing was pe1fonned on two ASR-affected bridge girders to investigate anchor pe1fo1mance at higher expansion levels. Anchor capacity is insensitive to through-thickness expansion and time of installation relative to ASR expansion (i.e. installed before or after the onset of expansion).

• Results from the Shear Test Program indicate that there is no reduction of shear capacity in ASR-affected concrete with through-thickness expansion levels up to.% which was the MPR-4273 v

--Non-Proprietary Version--maximum ASR expansion l eve l exh ibit ed by shear test specimens. (Test results show that th e shear capac i ty actual l y in creases due to pre-stressing from ASR expansion , but MPR recommends that this " benefit" shou ld not be cred i ted.)

• Results from the Reinforcement Anchorage Test Program indicate that there is no reduction in the performance ofre in forcement lap sp li ces in ASR-affected concrete with through-thickness expans i on levels up to.%, which was the maximum ASR expansion level e x hibited by reinforcement anchorage test specimens.

• The progression of ASR in the reinforcement anchorage test specimens resulted in a n otable change in st i ffness , character i zed by a decrease in deflection at y i e ld. The in crease in stiffness i s due to pre-stressing from ASR expansion.

A companion report (MPR-4 288, " Seabrook Station: Imp act of Alkali-Silica Reaction on the Structura l Design Basis") describes the effect of ASR on the structura l design basis of affected struct ur es at Seabrook Station and provides gu id ance for eva lu ations of those structures.

Content from this report provides evaluat i on criteria for selected limit states (s h ear , reinforcement anchorage , anchor capacity).

Execution of a multi-year l arge-scale test program to support eva lu at i on of A SR-affected reinforced concrete struct ur es i s unique in the nu c l ea r indu stry in purp ose , sca l e, and methodology. App lic ation of the results of the FSEL test programs r eq uir es that th e test spec im ens be representative of reinforced concrete at Seabrook Stat i on , and that expansion behavior of concrete at the plant be s imil ar to that observed in the test specimens. Test specimen design addressed representativeness of the test specimens , and promoted expansion behavior consistent with the plant (e.g., use of two-dim ensiona l reinforcement mats). To confirm that expans i on behavior at Seabrook Station i s simi l ar to the FSEL test spec im ens , this report recommends that NextEra perform the checks id entified in the table below. MPR-4 2 7 3 R ev i s i o n 0 V I

--Non-Proprietary Version--Recommendations for Confirming Expa n sion Behavior at Seabrook Sta ti on is S imil a r to Test Programs Objective Ongoing Monitoring Expansion within limits from test programs La ck of mid-plane crack Periodic Confirmation of E xpa nsion B ehavior Lack of mid-plane crack Expansion initially similar in all directions but becomes preferential in z-d irection E xpan sions within range observed in test programs Corroborate modulus-expansion correlation with plant data MPR-4 273 R ev i s i o n 0 Recommended Approach Compare measured in-plane expansion (8xy) and through-thickness expansion

(£M t the plant to limit , om test p r ograms (£,y s % and £zS %) I nspect cores removed from ASR-affected structures (and boreh oles) for evidence of mid-plane cracks Re view of r ecords for cor es rem oved to date or since last assessment Compare 8 x y to £z using a plot of £z versus Com b ined Cracking I ndex (CCI) Compare measured 8xy and £z li he plant to l it s from test programs (£,y s % and £z s %) t o check margin for future e x pansion Compare measured volumetric e.n sion to r ange from beam test programs %) and check marg in for future e xp ansion F or 3 e xtensome i ocati. with pre.tru.nt

£z i;j e range of % to % (e.g., %, % and %): . Remove cores for modulus testing at extensomete r locations wi th more s ignificant changes in e xte nsometer readings. . Compare !J.£z determined from the modulus-expansion correlation with !J.£z determ ined from the e xten someter When I ntervals as specified in Structures Monitoring Pr ogram (SM P) or Aging Management Pr ogram (AMP) When cores are remo ved to install extensometers or fo r other reasons. P eriodic assessments . At least 5 years prior to the Period of E xtend ed Operations (P EO) . E very 1 O years thereafter At least 2 years prior to PEO V il

--Non-Proprietary Version--Contents 1 Introduction

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1-1 1 . 1 Purpose .........................................................................................

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1-1 1.2 Background

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1-1 1.3 Commercial Grade Dedication

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1-4 1.4 Report Scope ...............................

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1-4 2 Selection of Approach for Test Programs ...............................

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........... 2-1 2.1 Summary of Literature Review ................................................................................

2-1 2.2 Importance of Confinement

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2-2 2.3 Available Structural Test Data ..............................................................

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..... 2-4 2.4 Test Program Considerations

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................... 2-5 3 Test Specimen Configuration

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3-1 3.1 Fabricated Test Specimens

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3-1 3.2 Girder Test Specimens

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3-3 4 Characterizing ASR Development

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.. 4-1 4.1 Methods for Determining ASR Development

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4-1 4.2 Ex pansion Monitoring

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4-2 4.3 Material Properties

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4-8 4.4 Petrography

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............... 4-10 4.5 Conclusions

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.... 4-12 5 Test Results ............................................

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5-1 5.1 Anchor Testing

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......... 5-1 5.2 Shear Testing ..................

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.... 5-5 5 .3 Reinforcement Anchorage Testing ...............................................

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........... 5-10 5.4 Instrumentation Testing ...........................................................................

............... 5-15 6 Implications for Seabrook Station ....................................

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6-1 6.1 6.2 MPR-4273 R ev i s ion 0 Expansion

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....... 6-1 Structural Performance

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6-3 V III

--Non-Proprietary Version--Contents (cont'd.)

7 References

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7-1 A Test Specimens

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A-1 B Guidelines for Periodic Expansion Behavior Check ...............

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B-1 MPR-4273 R e vi s ion 0 i x

--Non-Proprietary Version--Tables Tab le 1-1. Summary of Support Documentation

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................... 1-5 Table 2-1. Comparison of Test Specimen Approaches

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.............................. 2-6 Table 3-1. Comparison of Fabricated Test Specimens

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...... 3-2 Table 5-1. Proof-of-Concept Testing for Shear Retrofit...

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.................. 5-8 Table 5-2. Proof-of-Concept Testing for Reinforcement Anchorage Retrofit ..............

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5-15 MPR-4273 R ev i s ion 0 x

--Non-Proprietary Version--Figures Figure 1-1. ASR Expansion Mechanism

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1-1 Figure 1-2. Activities for Eva luating Structural Capacity of ASR-Affected Structures

.............. 1-2 Figure 2-1. Effect of Confinement on ASR-affected Concrete ..............

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..... 2-3 Figure 2-2. Representativeness oflnformation Sources for Evaluating Structural Performance

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...... 2-7 Figure 4-1. A SR-r elated Expansion in Specimen ..........................

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4-2 Figure 4-2. Large Crack from Surface Between Reinforcement Mats .......................................

4-4 Figure 4-3. Ex pansion Profile of Specimen. (as Measured with the Z-Frame) .....................

4-5 Figure 4-4. Expansion Behavior of Test Specimens

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4-6 F i gure 4-5. Normalized Compressive Strength of Test Specimens

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4-9 Figure 4-6. Normalized Elastic Modulus of Test Specimens

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....... 4-9 Figure 4-7. DRI (Traditional and Modified) vs. Through Thickness Expansion

..................... 4-11 Figure 4-8. VAR vs. Through Thickness Expansion

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... 4-11 Figure 5-1. Kwik Bolt 3 Anchor Test Results ..........................

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5-3 Figure 5-2. Shallow Drillco Maxi-Bolt Anchor Test Results ................................

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5-4 Figure 5-3. Full-Depth Drillco Maxi-Bolt Anchor Test Results ................

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5-4 Figure 5-4. Test Setup forl-in ch Shear Test Specimens (Elevation View) .....................

........ 5-6 Figure 5-5. Norma li zed Shear Stress-Deflection Plots forl-inch Shear Test Specimens

........ 5-7 F i gure 5-6. Test Setup for Reinforcement Anchorage Test Specimens (Elevation View) ....... 5-10 Figure 5-7. Load-deflection Plots for Se l ected Reinforced Anchorage Test Specimens

......... 5-1 1 Figure 5-8. Initial Part of Load Deflection Plot for Reinforcement Anchorage Control Specimen ...................................................................................

.............................. 5-12 Figure 5-9. Effect of ASR-Related Expansion on Initial Flexural Stiffness

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5-13 MPR-4273 R ev i sio n 0 XI

--Non-Proprietary Version--Figures (cont'd.)

Figure 5-10. Effect of ASR-R elated Expansion on Service Level F l exural Stiffness

.............. 5-14 F i gure 5-11. Comparison of SRBE In strument Measurements with Depth Gauge Meas ur eme n ts ..................................................

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................................... 5-17 Figure 5-12. lllu strat i on of SRBE during Installation

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5-18 Figure A-1. Photo of Girder Series Anc h or Test Specimen ..............................

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........... A-2 Figure A-2. Photo of Block Series Anc h or Test Spec im en with Anchors In sta ll ed ................... A-2 Figure A-3. Diagram of Block Series Anchor Test Specimen Showing Reinforcement...

......... A-3 Figure A-4. Diagram of 24-lnch Shear Test Specimen Show in g Reinforcem e nt .................

..... A-4 Figure A-5. Diagram of Reinforcement A n c h orage Test Specime n Showi n g Reinforcement...

A-5 Figure A-6. Diagram oflnstrumentation Test Specimen Show in g Reinforcement (E l evation V i ew) ....................................................................

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................ A-6 F i gure A-7. Diagram of In strumentation Test Specimen Show in g Reinforcement (P l an View) ............................................

.................................................................. A-6 Figure B-1. Volumetric Expans i on Check Criterion

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............................................ 8-3 F i gure B-2. Expansion Direction Tre nd C h art ........................................

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... 8-4 MPR-4273 Revision 0 X II

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*-------------------------------Non-Proprietary Version--1 Introduction 1.1 PURPOSE On b e h alf of NextEra , MPR directed several l arge-scale test programs to invest i gate the stmctura l impact of Alkali S i lica Reaction (ASR) on reinforced concrete specimens. 1bis repo 1 1 integrates the conclusions of those studies to present the implications for struc tu ra l assessments an d monitoring of reinforced concr e t e structures at the plant

1.2 BACKGROUND

1.2.1 Alkali-Silica Reaction ASR occurs in concrete when reactive silica in the aggregate react with hydroxyl i ons (Off) and alkali io n s (Na+ Kl in t h e pore solution.

The reaction produces an alkali-silicate gel that expands as it absorbs moisture, e xerting tensile stress on t h e surrounding concr e te and res u lt i ng in cracking.

Typica l cracking caused by ASR is described as 'pattern" or " ma p" cracking a n d i s usually a c companied by dark staining adjacent to the cracks. Figure 1-1 provides an illustra ti on of t his pro ce ss. a l kal i ceme nt+ r eact i ve aggregate expans i ve ge l Figure 1-1. ASR E x pans i on M e ch a ni sm e r a cki ng o f th e agg r egate and paste The c racking may degrade t he material properties of the concrete necessitating an assess m e nt of the ade qu acy of t he affected stmctures and supports anchored to t he st:mc t ures. 1.2.2 ASR at Seabrook Station NextEra has identified ASR in multiple safety-related reinforced concrete structures at Seabrook Station (R e ference 1.1 ). After an extent of condit i on determination that ident i fied p otentia ll y MPR-4 2 73 Rcvi s ionO 1-1

--Non-Proprietary Version--affected stmctures at the site , MPR performed an interim stmctural assessment (Reference 2 .1) of selected ASR-affected structures to evaluate their adequacy given the presence of ASR. Based on the low level of observed cracking and the apparent slow rate of change , MPR concluded that these structures are suitable for continued service for at least an interim period (i.e. at least several years). The interim structural assessment (Reference 2.1) utilized a conse1vative treatment of data from existing literature , supplemented by limited testing of anc.hor bolts , to produce conclusions suitable for a sho11-te1m structural assessment.

NextEra will perform follow-up eva l uations to assess the long-tenn adequacy of the concrete structures and attachments at Seabrook Station. In support of these evaluations MPR conducted large-scale test programs of specimens that were designed and fabricated to represent reinforced concrete at Seabrook Station to the maximum extent practical Results from the large-scale test programs provide input to determine the potential effects of ASR on adequacy of structures at Seabrook Station. Because the design codes for Seabrook Station do not include provisions for ASR , NextEra is submitting a License Amendment Request (LAR) to incorporate a methodology for evaluating ASR-affected strnctures into the plant's licensing basis. This report provides the technical basis for portions of the LAR that were developed from the results of the large-scale test programs. Figure 1-2 provides a high-level summary of the key activities of the ASR project at Seabrook Station related to evaluation of structural capacity of ASR-affected structures 1 . * * ..

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• _. : ... I > . . . . . . . ... .. ' .. F i g ure 1-2. Activities for Evaluating Structur a l Capacity of AS R-Aff e ct e d Structures 1.2.3 Test Programs at FSEL MPR directed four test programs at the Ferguson Structural Engineering Laboratory (FSEL) at The University of Texas at Austin (UT-Austin) to suppo1t NextEra 's effo1ts to resolve the ASR issue identified at Seabrook Station. Three of the test programs focused on the stn1ctural perfo1mance data necessa1y to complete the follow-up structural evaluations of ASR-affected strnctures. The fomth test program evaluated instruments for monitoring expansion at Seabrook Station. In each stmctural test program, ASR developed in the fabricated test specimens and was routinely monitored so that testing could be perf01med at pa1ticular levels of ASR distress.

This approach enabled systematic development of trends for structural pe1fo1mance with the 1 Tue LAR will include the methodology for the final stmctural assessment

• the actual assessment may be completed after submittal of the LAR. MPR-42 7 3 Re.vision 0 1-2

--Non-Proprietary Version--progression of ASR. The resulting data sets were a significant improvement upon the collection of published literature sources , because test data across the range of ASR distress levels were obtained using a common methodology and identical test specimens.

A brief overview of each test program is provided below.

• Anchor Test Program -This test program evaluated the impact of ASR on performance of anchors and undercut anchors installed in concrete.

Test specimens included -large-scale blocks that were designed and fabricated to represent the reinforced concrete structures at Seabrook Station and two sections of a reinforced concrete bridge girder that was available at FSEL. The test program consisted of a tota l of. anchor tests. (Reference 4.1)

• Shear Test Program -This test program evaluated the impact of ASR on shear capacity of reinforced concrete specimens.

Three-point load tests were performed on large-scale beams that were designed and fabricated to represent the reinforced concrete structures at Seabrook Station. FSEL fabricated

.shear test specimens and conducted a total of .t ests (two tests performed on most specimens). (Reference 4.2)

• Reinforcement Anchorage Test Program -This program evaluated the impact of ASR on reinforcement anchorage ofrebar lap sp li ces embedded in concrete and also provided insights on flexural strength and st i ffness. Four-point l oad tests were performed on large-scale beams that were designed and fabricated to represent the reinforced concrete structures at Seabrook Station. FSEL fabricated I reinforcement anchorage test specimens and conducted a total of l tests (one test per specimen). (Reference 4.2)

• Instrumentation Test Program -This program evaluated instruments for the measurement of through-thickness expansion.

Insights gained from this program were used to select which instrument to use at Seabrook Station and to refine installation procedures.

The test specimen was a large-s cale reinforced concrete beam that was designed and fabricated to reinforced concrete structures at Seabrook Station. Testing included a total of -instruments over. different configurations. FSEL periodically monitored expansion using these instruments for one year. (Reference 4.3) 1.2.4Additional Testing The Anchor , Shear , Reinforcement Anchorage , and Instrumentation Test Programs were designed to produce data that would ultimately be used as inpu ts for safety-related evaluations at Seabrook Station. Additional testing was performed to inform decisions on directing these test programs and provide insights that help in terpret test program results.

Expansion Behavior As part of each test program , expansion of the test specimens was monitored in a variety of ways to character i ze ASR progression.

An additional study was performed outside the scope of the te s t program s that focused on monitoring the total axial and volumetric e x pan s ion of concrete cubes with varyin g reinforcement layouts , reinforcement density , and con c r e te mi x de s ign s. MPR-427 3 R evis i on 0 1-3

--Non-Proprietary Version--This additional study provides insights on the factors for expansion behavior and their relative importance. (Reference 6.1) Retrofit Testing For the Shear and Reinforcement Anchorage Test Programs , the original intent was to develop ASR and perform tests until a threshold for ASR distress was identified where structural performance declined.

FSEL would then install retrofits to specimens at higher ASR levels (e.g., by installing grouted rods to function like shear reinforcement) and perform load testing to qualify a repair methodology.

Proof-of-concept testing of candidate retrofits was performed using specimens that were not affected b y ASR 2. (References 6.2 & 6.3) Uniform Load Testing The load test setup for the Shear Test Program used a hydraulic ram and two beam supports to apply three-point loading. Use of point loads i s convenient, but a uniform distribution would be more repre se ntative of the loads applied to some actual structures (e.g., h y drostatic loading on the exterior surface of a below-grade wal I). FSEL performed uniform load shear testing on specimens with a design comparable to the specimens for the Shear Test Program to assess the difference in shear capacity for the different loading conditions.

The load test setup for the uniform load tests applied force usin g an air bladder to exert uniform pressure to th e underside of each specimen. (References 6.4 & 6.5) 1.3 COMMERCIAL GRADE DEDICATION The test programs were performed b y FSEL with technical direction and quality assurance oversight from MPR. The testing was governed by MPR test specifications (References 3.1 & 3.2) and was conducted under FSEL's project-specific quality system manual using test procedures approved by MPR. MPR commercially dedicated the testing services performed by FSEL and prepared Commercial Grade Dedication (CGD) Reports for the Anchor, Shear, Reinforcement Anchorage, and Instrumentation Test Pro grams (References 5.1 , 5.2 , 5.3 , & 5.4). The additional studies on expansion behavior of concrete cubes, retrofit testing on non-ASR affected specimens, and uniform load distribution were not commercially dedicated.

Conclusions from these efforts inform the overall project , but were not used to develop quantitative inputs for evaluation of structures at Seabrook Station. 1.4 REPORT SCOPE This report combines the key conclusions from the four te st program s, results from the additional testing studies, and information gathered as part of MPR's overall inve st igation of ASR at Seabrook Station to provide integrated conclusions that support NextEra's follow-up structural evaluations and monitoring of ASR-affected reinforced concrete.

Detailed informati o n on th e specimen de s igns , test method s, and test results are provided in the test program reports (References

4. I , 4.2 , & 4.3), which provide complete documentation of the test programs. 2 Ultimately, the retrofits were not tested on A SR-affected specimens, because structural testing of ASR-affected specimens without retrofits did not identify a decrease in str u ctural performance for the ASR lev e l s that were ach ie vab le within the duration of the test pro grams. MPR-4273 R evision 0 1-4

--Non-Proprietary Version--F urth er in formation on the additional testing st udi es is provided in UT-Austin documents (Refere nc es 6.1 , 6.2 , 6.3 , 6.4, & 6.5). Tab l e 1-1 summar i zes the primary source documentation for test results from the MPR/FSEL test programs.

Table 1-1. Summary of Support Documentation Test Program Test Reports CGD Reports MPR-3726 MPR-3722 MPR-4247 Anchor (Reference 4.1) MPR-4286 (References 5.1, 5.2, & 5.4) Shear MPR-4262 MPR-4259 Reinforcement (Reference 4.2) MPR-4286 Ancho r age (References 5.3 & 5.4) Instrumentation MPR-4231 (Reference 4.3) UT-Austin Information Only Documentation NIA (References 6.1, 6.2 , 6.3, 6.4 , & 6.5) A companion report (MPR-4288 , "Seabrook Station: Impact of Alkali-Silica Reaction on the Structura l Design Basis") describes the effect of ASR on th e structura l design basis of affected struct ur es at Seabrook Station and provides guidance for evaluations of those structures. MPR-427 3 R ev i s i o n 0 1-5

--Non-Proprietary Version--2 Selection of Approach for Test Programs This section highlights the reasons for pursuing large-scale test program s and summarizes the rationale for key decisions that shaped and focused the approach for testing. These key decision points were as follows:

• Focus on structural testing to capture the interplay between ASR expansion and the restraint provided by the reinforcement (i.e., confinement).

• Address I imit states of interest for structures at Seabrook Station where there were limitations or gaps in the available literature , especially where available margins are low or the apparent effect of ASR is high.

• Use laboratory-prepared test specimens to facilitate separate effects s tudies to determine the impact of ASR on structural performance as a function of the severity of ASR.

• Ensure results are applicable to structures at Seabrook Station by de s igning specimens to be representative and using test approaches consistent with those used to calibrate the code equations.

The decisions that defined the test program were informed by a comprehensive review of literature on ASR degradation and its impacts on structural performance.

The literature review and the key decision points are discussed below. 2.1

SUMMARY

OF LITERATURE REVIEW As part of developing the approach for addressing ASR-affected concrete at Seabrook Station, MPR conducted a comprehensive review of published research on the structural implications of ASR and industry guidance for evaluating ASR-affected structures.

Most research on ASR ha s focused on the science and kinetics of ASR, rather than engineering research on structural implications. Structural testing of ASR-affected test specimens has been performed , but application of the conclusions to a specific structure can be challenged by lack of representativeness.

Industry guidelines from the Institution of Structural Engineers (Reference l.2) and the Federal Highway Administration (Reference l.3) provide a summary of potential implications of ASR and high level information that MPR used to identify focus areas for addressing ASR at Seabrook Station. MPR's literature review included over a hundred detailed references to explore approaches for evaluating ASR-affected structures.

These efforts led to the initial series of actions at Seabrook Station including petrographic examinations to confirm the presence of ASR, extent of condition walkdowns that utilized crack width summation to quantitatively MPR-4273 R e vi s ion 0 2-1 I L --Non-Proprietary Version--characterize the effect of ASR , and development of a protocol for monitoring further development of ASR during the ongoing project. The literature also established the expectation for a reduction in material properties of cores from ASR-aff ected concrete , and identified that such a reduction does not necessarily reflect a corresponding decrease in structura l capacity.

The presence of two-dimensional reinforcement mats at Seabrook Station provides confinement that differentiates structural performance from un-reinforced concrete structures (e.g., dams) that are more appropriately represented by cores. ASR-indu ced expansion in reinforced concrete has a " prestressing" effect that mitigates loss of structural capacity.

A focused review of published research on the structura l implications of ASR (Reference 2.2) identified dozens of technical references on testing of A SR-affected concrete.

The most relevant references were used to support the interim structural assessment for Seabrook Station by providing a conservatively bounding capacity reduction factor for structura l limit states (e.g., shear) to account for the presence of ASR. For these technical papers, Reference 2.2 discussed the extent to which the experimental design and test specimens were representative of structures with two-dimensional reinforcement (like structures at Seabrook Station).

For completeness , Reference 2.2 also identified testing of ASR-affected concrete that was poorly representative of Seabrook Station and why it should not be used for a structural evaluation.

2.2 IMPORTANCE OF CONFINEMENT The presence of confinement is a central factor for the effect of ASR on structural performance.

Reinforcing stee l , l oads on the concrete structure (e.g., deadweight), and the configuration of the structure (i.e., restraint offered by the structural layout) provide confinement that restrains in-situ expansion of the ASR ge l and limits the resulting cracking in concrete.

Structura l testing of full-scale specimens simulates the in-situ confinement and therefore provides much more representative results than simp l er approaches that do not account for confinement (e.g., material property testing).

Confinement limit s ASR expans ion of the in-situ structure, which reduces the extent of deleterious crack ing and the resultant decrease in structura l performance.

Publicly available test data for structural performance of ASR-affected structures indicate a significant difference in results when adequate confinement is present. As an example, test data show that the one-way shear capacity of a specimen containing three-dimensional reinforcement was not significantly affected by ASR , but specimens without such reinforcement exh ibit ed loss of capac ity by up to 25% (References 1.4 & 1.5). The difference in structura l performance observed in published test data w ith vary in g degrees of confinement results from a "prestressing" effect. When reinforcement is present to restrain the tensile force exerted by ASR expansion , an equivalent compress iv e force develops in the concrete. lf l oads applied on the structure result in tensile stresses (direct, diagonal, or otherwise), the compressive stresses in the concrete must be completely overcome before additional tensile load is reacted by the reinforcement.

Cracking in confined concrete would not occur until the tensile stress in the concrete exceeds the compressive stres s in the concrete from the prestressing effect. The prestressing effect does not reduce the ultimate tensile capacity of MPR-4273 R ev i s ion 0 2-2

--Non-Proprietary Version--the reinforcement.

Tn some cases, literature indicates that the prestressing effect of ASR creates a stiffer structural component with a higher ultimate strength than an unaffected member 3. Test data show that this prestressing effect applies even when ASR expansion has yielded the reinforcing bars. (Reference 1.5) Given the interplay between ASR-induced cracking and structural restraint , it is imperative that evaluation of the structural impacts due to ASR focus on structural testing rather than material property testing of cores removed from the structure.

The concrete pre stress ing effect is only present when the expansion is confined.

If the concrete is removed from the stress field , the concrete prestressing effect is lost. A core sample from an ASR-affected, reinforced concrete structure will not be confined by the stresses imparted by the reinforcement and surrounding concrete after it is removed from the structure.

Therefore, such a core is not representative of the concrete within its structural context. Measured mechanical properties from a core taken from a confined ASR-affected structure have limited applicability to in-situ performance

such results only represent the performance of an unconfined or unreinforced structure.

Figure 2-1 illustrates the effect of confinement with photographs of two surfaces of the same ASR-affected, reinforced concrete beam 4. Confined Face of A SR-affected Beam (left); U nconfined face of Same A SR-affected Beam (ri g ht) Figure 2-1. Effect of Confinement on ASR-affected Concrete Based on the importance of the prestressing effect on structural performance , the typical approach ofre-evaluating structural calculations using updated material properties from cores 3 The planned approach for structura l eva luati ons at Seabrook Station (MPR-4 288) does not credit the possibility that ASR cou ld increase the ultimate strength of the member in question.

4 The beams shown in Figure 2-1 are not from the MPR/FSEL lar ge-scale test program s. MPR-4273 Revi s ion 0 2-3

--Non-Proprietary Version--would not be representative of structures at Seabrook Station. Instead , evaluations need to rely on structural test data of ASR-affected reinforced concrete. 2.3 AVAILABLE STRUCTURAL TEST DATA The interim structura l assessment considered the various limit states for reinforced concrete (e.g., shear , reinforcement anchorage) and applied capacity reduction factors based on data in publicly available literature.

However , determination of appropriate reduction factors was limited by the poor representativeness of available data for ASR-affected concrete with reinforcement comparable to structures at Seabrook Stat i o n (i.e., two-dimensional reinforcement mats). 2.3.1 Shear Capacity The interim structura l assessment (Reference 2.1) assumed a strength reduction of 25% for out-of-pl ane shear (References 1.4 & 1.6), but this was a co n servat i ve treatment that is not necessarily representative of the expected performance of the wa ll s at Seabrook Station.

• The available data on out-of-plane shear show a range of impa c ts from a reduction of 25% to a gain of 1 2% (Reference 1.4). Use of the 25% reduction for a structural assessment is on the conservative edge of the range.

• The shear capacity reduction due to ASR of 25% i s based on smal l-scale testing using 5-inch x 3-in ch beams (Reference 1.6). lt is well known that shear test results do not scale we ll. In fact , the study that generated the results suggest in g a 25% reduction specifically noted that the small test specimens likely exaggerated the deleterious effect of ASR , because the depth of ASR cracks i s relatively greater in sma ll er specimens. The li terature review (Reference 2.2) included published research on large-scale testing , such as the research that h ad been performed at the Delft University of Technology on test specimens that h ad been recovered from an ex i st in g bridge deck that exhibited ASR (Reference 1.8). MPR concluded that these tests were l ess repre se nt ative than the s maller sca l e l aboratory tests discussed above. In the examp l e of the Delft University study , test specimens in c lud ed significant differences in configuration relative to structures at Seabrook Station. Specifically , the bridge deck had plain reinforcement (i.e., no deformation) with a l ow yield strength (approx im ately 30 ksi) and the specimens required extensive l aboratory retrofit to generate a shear failure. In add iti on , the process of h arvesting a spec im en from an exist in g structure inherently results in damage that affects the results (see Section 2.4.1 for additional discussion).

2.3.2 Reinforcement Anchorage The int erim struct u ral assessment (Reference 2.1) assumed a strength reduction of 40% for reinforcement l ap sp li ces in ASR-affected concrete (Reference 1.9), but this was a conservat i ve treatment that i s not necessarily representative of the expected performance at Seabrook Station.

• While the stud y producing an average s trength reduction of 40% w a s the most relevant for the reinforcement anchorage limit state w i thout transverse reinforcement , this study was MPR-42 7 3 R ev i s i on 0 2-4

--Non-Proprietary Version--based on a rebar pullout test method that is outdated and known to be unrealistic.

In a rebar pullout test , the rebar i s placed in tension and the concrete i s placed in compression.

Th i s stress state is much different than the service condition for most reinforced concrete members , in w hi ch both the rebar and the surround in g concrete are in te n sion. According l y, a report from the ACJ Technica l Comm itt ee 408 stated that the rebar pullout method is " inappropriate and not recommended." (Reference 1.10)

• Testing performed for the study showing a 40% strength reduction used reinforcing steel sign ific ant l y smaller (#5 bars) than the reinforcement in structures at Seabrook Station (typ i ca ll y #8 bars or l arger for safety-r elated structures).

2.3.3 Anchor Capacity Review of publicly avai l ab l e li terature did not identify test data on capacity of anchors or shallow embedments in ASR-affected concrete (Reference 2.2). For the int erim structural assessment , MPR conducted testing on an ASR-affected bridge girder to provide a basis for the potential degradation.

2.3.4 Conclusion While th e lit erat ur e review and g ird e r testing provided in format ion to support the int er im structura l assessme nt , it a l so highlighted that the state of know l edge on ASR did not in clude test data that were c l ose l y representative of reinforced concrete structures at Seabrook Stat i on. Therefore , NextEra commissioned MPR to conduct testing to provide more representative data that would support fo ll ow-up structural eva lu ations. 2.4 TEST PROGRAM CONSIDERATIONS 2.4.1 Test Specimen Approach Large-sca l e structura l testing of ASR-affected concrete typica ll y inv o lv es specimens that are either harvested from exist in g ASR-affected structures or fabricated u sing constituents that accelerate ASR development.

Tab l e 2-1 summar i zes the differences between these approaches.

MPR-42 7 3 R evi s io n 0 2-5

--Non-Proprietary Version--Table 2-1. Comparison of Test Specimen Approaches Harvested Specimens Fabricated Specimens Advantages Advantages

• ASR developed along a timescale that

• Allows precise control of test variables, which represents an actual structure permits separate effects testing where there is

• Does not require capability to fabricate only one variable (e.g., ASR level) specimens and store specimens while ASR is

• Enables aging beyond currently-exhibited ASR developing levels

• Common basis for ACI Code provisions Disadvantages Disadvantages

• The harvesting process may damage the test

• ASR development is much faster than for specimens and affect results actual structures

• Range of testing is limited by currently-exhibited ASR levels Specimens for the MPR/FSEL test programs were fabricated b y FSEL so that the impact of ASR could be determined as a function of its severity , including levels of ASR expansion beyond those currently seen at Seabrook Station. The fabricated test specimens were designed with a reinforcement configuration and concrete mixture that represented structures at Seabrook Station to the ma x imum extent practical.

Using fabricated test specimens avoids the process of cutting out a section of reinforced concrete and transporting it to the laboratory, which results in damage that affects the test results. Specifically, the newly cut concrete surfaces would be subject to rapid expansion due to stress relaxation in the absence of the structural context. Additionally, cutting of rebar precludes its full development under loadin , which also reduces re resentativenes

s. Desi n features of fabricated te st specimens ) can restore a portion of the continuity that represents the original structure , thereby making the test results more representative of true structural performance. For these reasons , published research using harvested test specimens (e.g., the Delft University study, Reference 1.8) was avoided, and struc tural tests relied primarily on fabricated specimens.

NextEra and MPR considered harvesting samples from the canceled Unit 2 at Seabrook Station, but ultimately decided against this approach.

In addition to the damage incurred during the harvesting process, samples from Unit 2 would only be able to represent ASR-affected concrete to currently-observed expansion levels at Unit 2. Accelerated aging was an essential element of the MPR/FSEL test programs , because the results needed to address ASR-induced expansion that could occur in the future. 2.4.2 Representativeness Objectives of Test Programs MPR designed test programs for NextEra to eva luate s he ar capacity , r e infor cement anc h orage , and anchor capacity with the following key features:

MPR-4273 R evis i o n 0 2-6

--No n-Proprietary Version--* Large size to represent the scale of structures at Seabrook Station

• Experimental design that is consistent with the design basis of Seabrook Station and accepted in the concrete indust:Iy Test methods and experimental setups for shear and reinforcement anchorage testing are consistent with those used for tests that calibrate ACI Code equations Test methods for anchor capacity testing are consistent with those performed in response to NRC IE Bulletin 79-02 (Reference 2.3)

• Specimen design that use a reinforcement configuration and concrete mixture design that reflects reinforced concrete structures at Seabrook Station

• Presence of ASR to an extent that is consistent with levels currently obse1ved at Seabrook Station and at le vels that could be observed in the future Additional details on the e features are provided in the subsequent sections of this repo11. Figure 2-2 presents various sources of information and indicates their relative representativeness for evaluating stmctural performance of ASR-affected reinforced concrete stmctures at Seabrook Station. The data set obtained as pad of the MPR/FSEL test programs is a marked advancement from the collection of published literature sources and forms the definitive technical basis for evaluation of reinforced concrete strnctures at Seabrook Station for the applicable limit states. LEAST REPRESENTATIVE ( Material Property Data from eores -Ignores confinement

-Ignores structural context Literature load -Range of representativeness reflecting similarity to key factors for Seabrook -Level of ASR d i stress often not documented MPR/FSEL load Testing -Large scale -Experimental methods consistent with those used to ca li brate code equations

-Re i nforcement configuration reflects Seabrook -Concrete mixture reflects Seabrook *ASR d i stress greater than current levels at Seabrook MOST REPRESENTATIVE ) load Testing Actual Structures at Seabrook *Not practical

• Does not bound current ASR levels at Seabrook F igure 2-2. Representat iv eness of Information Sources for E valuating Structural Performance MPR-4 27 3 0 2-7

--Non-Proprietary Version--3 Test Specimen Configuration Development of ASR in concrete and symptoms of ASR that can be used to monitor the condition of the concrete are strongly influenced by the design of the affected member. The large-scale test programs used specimens that represented reinforced concrete stmctures at Seabrook Station to the greatest extent practical.

Fabricated test specimens were designed to incorporate specific features to maximize representativeness, whi l e the bridge girder was selected for anchor testing because it contained high levels of ASR distress. Content in this section is drawn from References 3.3 4.1 , 4.2, and 4.3. 3.1 FABRICATED TEST SPECIMENS 3.1.1 General Desc ri ption Te s t specimens designed and fabricated for the test programs incorporated several key characteristics that provide strong representativeness to Seabrook Station , as follows:

• Reinforcement configuration of two-dimensional rebar mat s with comparable reinforcement ratios to the plant in each in-plane direction

• Clear cover above reinforcement mats consistent with the plant. For the SheaI , Reinforcement Anchorage and Instnunentation Test Programs , the specimen design specified cover of 2 inches on the side representing the inte1ior surface and 3 inches on the side representing the exte1ior surface. For the Anchor Program the specimen design specified clear cover of 2 inches on both sides , which enabled installation and testing of anchors on both sides of the test specimen. Anchors of interest at Seabrook Station am installed on interior surfaces so the presence of 3 inches of cover on the opposite wall face to simulate the exterior surface was not necessary . * * *

• Large overall size (see Table 3-1 for dimensional summary) for the fabricated test specimens included highly reactive fine aggregate , which accelerated development of ASR. The s hear , reinforcement anchorage , and instnunentation specimens also included reactive coarse aggregate and cement with high alkali content. In this manner , the test specimens could reach MPR-4273 R cvis ionO 3-1

--Non-Prop r ietary Version--levels of ASR beyond that observed at Seabrook Station after only a short time of conditioning (i.e., maximum of 2.5 years for these test programs). To the extent practical concrete constituents were obtained from sources that were consistent with concrete at Seabrook Station. 3.1.2 Differences Between Specimens The different purpose s of the test programs necessitated dimen ional differences between the fabricated test specimens. Tab le 3-1 below summarizes selected parameters of interest and the a s ociated differences. Appendix A contains photographs diagrams and drawings of the test specllllens.

Table 3-1. Co mpari s on of Fa bricat ed T es t S p ec im ens Anchor Block Re i nforcement 24-i nch Shea r Ins t rument Parameter Spec i mens Anchorage Specimens Specimen Spec i mens H e i g ht *

• Wi dt h

• Le n g th .. .. P r esence o f No Y es N o N o L a p Sp li ce V ertica l Reba r S i ze ----& Spac in g H or i zonta l Reba r S i ze ----& S p a ci ng S tirrups S i ze * ---& S p ac ing -*T wo h a lf-length pccime os w ere fabricated in a s ingle pl a cemen t The most significant difference in the specimen configuration relates t o the reinforcement ratio in the horizonta l direction for the shear specimens. Thi s difference wa s needed for two reasons: (1) for consistency with the shear test specimens used to derive the concrete contribution to shear strength for the d esign code and (2) to p rec.lude failure of the test specimen v i a flexme at l oads less than the expected shea1* capacity.

The differences in reinforcement enabled a review of the potential impact of reinforcement ratio on ASR distre s s level and expansion behavior.

MPR-4 27 3 R cv i s ionO 3-2

--Non-Proprietary Version--The anchor , shear , and reinforcement anchorage test specimens included transverse reinforcement (i.e., stirrups) outside of the test region to ensure that the test specimen failed in the test region by the desired failure mode. These stirrups also supported constructability. The differences in stirrup configuration enabled a review of the potential impact of confinement at the edges of the specimen on ASR distress and expansion behavior.

3.2 GIRDER TEST SPECIMENS In addition to the fabricated test specimens , the Anchor Test Program also in cluded testing on A SR-affected bridge girders. These specimens exhibited high levels of in-plane expansion, beyond what was achieved in the fabricated spec im ens. A bridge girder was used in the initi al phase of the Anchor Test Program because it was available for immediate testing , which was necessary to support the interim structural assessment.

A second phase of anchor testing u sed another bridge girder to obtain more test data at higher levels of expansion.

The girder contains vertical #4 reinforcing bars spaced at 18 inches with a I-inch minimum cover. Horizontal prestressing strands are also present at the bottom of the beam. M PR-4273 R e v i s io n 0 3-3

--Non-Proprietary Version--4 Characterizing ASR Development The object i ve of each structural test program was to develop a trend for structura l capac i ty as a function of ASR distress l evel. According l y , i t was essential to accurately characterize the extent of ASR development in the test specimens.

Routine monitoring of ASR development a ll owed load tests to be performed at pre-defined levels across the range of ASR distress ach i eved over the duration of the test programs.

Over the course of rout in e monitoring , observations on ASR development a nd expansion behavior informed decision making on the test program and ultimately influ e n ced recommended monitoring practices at Seabrook Station. Th i s section discusses the efforts from the test programs to characterize ASR development , in sights ga in ed from these efforts that affected the course of the test programs , and the implications of key conc lu sions for structura l eva lu ations and long-term monitoring at Seabrook Station. Content in this sect i on i s drawn primarily from References 4.1, 4.2, and 4.3. 4.1 METHODS FOR DETERMINING ASR DEVELOPMENT Severa l different methods were used to characterize ASR development in the fabricated test specimens:

• Expa n sion Monitoring

-ASR-r e lat ed expans i on is a vo lum etr i c effect that r esu lt s in dimensional c h anges in a ll three directions.

FSEL mon it ored expansion on the surfaces adjacent t o the reinforcement mats (i.e., the in-pl ane direction) and in the direction normal to the reinforcement mats (i.e., the through-thi ckness direction) u s in g severa l different methods, including crack width summat i on, measurement of through-specimen embedded rods, and profiling of the spec im en thickness in several l ocat i ons over the spec im en h eight.

• Material Properties

-Technica l lit erature id e ntifi es that ASR de grades the material properties of the concrete.

FSEL tested concrete cy lind ers fabricated at the same time as the t est specime n s and cores obtained from the test spec im ens for compressive strength , e l astic modulus , and tensi l e strength to quantify this degradation.

• Petrography

-ASR distress m ay a l so be character i zed b y qu ant i fying observed degradation symptoms in concrete samp l es. A petrographic exam in ation was performed on a polished samp l e from a core taken from each test specimen at the time of l oad testing. The petrographer examined the sample under a microscope to confirm the presence of ASR and to quantify the extent of degradation using the Damage Rating lndex (DRI) and Visual Assessment Rating (VAR) methodologies.

MPR-4273 R evis i o n 0 4-1

--Non-Proprietary Version--For the girder specimens used in the Anchor Test Program , FSEL performed in-plane expansion measurements prior to te s ting and provided a core to a petrographer to confirm the presence of ASR by petrographic examination . 4.2 EXPANSION MONITORING 4.2.1 Expansion Direction All test specimens exhibited significantly more pronounced expansion in the through-thicknes s direction than the in-plane direction.

Expansion in the in-plane direction plateaued at l ow levels , while expansion in the through-thickness direction continued to increa se. Figure 4-1 is a plot of expansion for Spe c imen. and illu s trates thi s behavior. Expansion behavior in thi s te s t specimen i s typical of other fabricated te s t specimens 6. The blue line represent s expansion in the throu g h-thi c kne ss direction.

FSEL obtained most of these mea s urement s from pin s that were embedded in the test s pecimen durin g fabrication (open data points). In May 2015, FSEL implemented a more comprehensive approach whereby thickness measurements along the height profile of the specimen were averaged (solid data point s). The red and g reen lin es represent expansion in the in-plane direction s (horizontal and vertical) obtained using embedded pins. The orange line represents expansion in the in-plane directions from crack width measurement (i.e., cracking index). Figure 4-1. ASR-related Expansion in Specimen.

5 DRI a nd VA R were n ot utiliz e d on th e girder cores. 6 Expans i on of th e girder specimens from the Anchor Program was measured at the time of testing , but was not monitored wit h time. T h e instrumentation specimen ex hib ited comparab l e in-plane expansion , but through-thickness expa n sion was strong l y influ e n ced by the l ack of stir rup s on th e b ea m e nd s (see Section 4.2.5). MPR-4 2 73 R e vi s ion 0 4-2

--Non-Proprietary Version--At low expansion levels C-11% to.%), expansion occurred in all three directions. At higher ASR levels , expansion occurred preferentially in the through-thickness direction.

The difference between in-plane expansion and through-thickness expansion is due to reinforcement detailing and the resulting difference in confinement between the in-plane and through-thickness directions. The reinforcement mats confine expansion in the in-pl ane directions, whereas the lack of reinforcement in the through-thickness direction allows free expansion. Therefore, expansion occurs preferentially in the through-thickness direction. 4.2.2 Assessment of Combined Cracking Index Methodology NextEra has been monitoring expansion of ASR-affected concrete at Seabrook Station using crack width measurement (i.e., comb in ed crack in g ind ex (CCI)) s in ce 201 1. Measurement of concrete expansion can be approximated by crack width summation because concrete has minimal capacity for expansion before crack in g. While true engineering strain is represented by the sum of material elongation and crack widths, the crack width term rapidly dominates the overall expansion.

As shown in Figure 4-1 , in-plane CCI values agreed closely with the observed expansion from embedded pins in terms of both the trend and magnitude.

The expans i on values measured using embedded pins are a better measure of true engineering strain because these measurements reflect b oth material elongation and crack width. However, because of the close agreement with CCI, results from the large-scale test programs for expansion monitoring support use of CCI as an approximation for in-plane expansion. The procedure used by FSEL personnel to determine CCI was controlled under the FSEL Quality Assurance program and was identical to the procedure used to determine CCI at Seabrook Station. To assess the repeatability of CCI measurements obtained by FSEL personnel , the individual performing CCI at Seabrook Station traveled to FSEL to perform measurements on the test specimens (Reference 2.4). In general , results from this effort were consistent with results obtained by FSEL personnel with an average difference of.mm/m. For most l ocat ion s, the results were very close. The most s ignific a nt difference in the measurements was related to the minimum recording threshold for a crack width. The Seabrook methodology on l y includes cracks with a width of 0.05 mm/m or greater. Evaluation of the CCI comparison results indi cated that different operator judgment of the width of very small cracks resulted in the different CCI values. Where ASR is more significant, cracks are l arger and repeatability improves. The threshold for structural evaluat i ons at Seabrook Station is 1.0 mm/m, so measurement variab ili ty in the range observed by the CCI comparison study i s acceptab l e. An important advantage of the CCI methodology for Seabrook Station is that results can be used to approximate total expansion in the in-plane directions s in ce the time of or i gina l construction.

Other methodologies (e.g., installing reference pins and monitoring change in relative position) on l y determine expans i on s in ce the time of the first measurement, which estab li shes the baseline.

MPR-427 3 R ev i s ion 0 4-3

--Non-Proprietary Version--4.2.3 Large Crack on Specimen Edge As ASR developed in the test specimens, a large crack was noted in the center of the surfaces of the beam that were between the reinforcement mats. Figure 4-2 is a photograph showing the large crack in one of the beam specimens.

Figure 4-2. Large Crack from Surface Between Reinforcement Mats This large crack i s not representative of expansion behavior of structures at Seabrook Station, which have a network of members that are either cast together or integrally cast with special joint reinforcing details. In an actual structure, a vertical wall with two-dim ensional reinforcement wi ll be confined in the through-thickne ss direction at its intersection with neighboring member s (i.e., at the top and bottom with floor and ceiling slabs, at the sides with perpendicular walls, and uniformly a l ong the wall face by the subgrade for below grade external walls). The confinement provided by the network of members in a structure is likely sufficient to preclude l arge cracks like those see n in the FSEL test specimens.

Sectioning of Test Specimens To confirm that this l arge crack was an edge effect that did not compromise the representativeness of the test region , FSEL sec tioned the beam cross section (i.e., cut with a saw) to assess the depth of the crack for one anchor test specimen and two shear test specimens (after testing was completed).

In all cases, FSEL observed that the large crack penetrated only a few inches into the specimen height. Although the large crack was an edge effect, it was not clear whether it had affected the ab ili ty to measure expansion in the through-thickness direction u s ing the embedded pins (which are shown in Figure 4-2). The large crack concentrated the expansion between the embedded pin s , rather than distributing the expansion across the entire specimen widt h , as would be expected in actual structures at Seabrook Station. Damage incurred to the specimens by the sect ionin g process and MPR-4273 R e vi s ion 0 4-4

--Non-Proprietary Vers ion--the i mmediate expansion after sawing resulting from rela x at i on of confinement prevented quantitative eva l uation of the sect i oned specimen.

Expansion Measurements over Specimen Height Profile FSEL developed a new methodology for measuring expansion in the test specimens that obtained measurements a l ong t h e entire height of the shear and reinforcement anchorage test spec im ens using a laboratory-fabricated frame (i.e., the z-frame). The frame fit around a test spec im en and enab l ed repeatable mea s urements of through-thickness (i.e., z-direction) e x pansion at nine points along the .h t of the beam. Figure 4-3 provides a plot showing the expansion profile for Specimen u sing the nin e measurement l ocat i ons. The blue dots and solid line s h ow the nin e specific points a nd the dashed lin e gives the average va lu e. This pl ot i s typ i ca l of the ot h er test specimens. Figure 4-3. Expansion Profile of Specimen .(as Measured with the Z-Frame) The z-frame expansion measurements demonstrated that the expans i on measured near the edge of the beam (i.e., w h ere the l arge crack ex i sts) is consistent with the expansion m eas ur e d over the entire beam height. Based on the re l ative l y low variation about the mean , the results of the z-frame expans i on st ud y confirmed that u se of a n average value to describe through-thickness expansion of the entire spec im en is appropriate. Crack Development Profile T he z-frame data and the observat i ons from section i ng indi cate that whi l e total expans i on in the through-thickness direction is consistent across the profile of the test specimen , the cracking behavior is different.

The s e ob s ervation s su g ge s t that al o n g th e specimen ed g es , expan s ion i s c o ncentrated into a large crack; whereas away from the ed g e s, e x pansion i s distributed into finer cracks along the spec im en cross-section. Figure 4-4 illustrates this expansion behavior.

MPR-4273 R ev i sio n 0 4-5

--Non-P r op r ieta r y Version--Figure 4-4. E xp a n s ion Be h a vi o r of T es t Spe cim e n s 4.2.4 Effect of Reinforcement Ratio on Expansion Tes t s p ec im e n s fro m a ll t est p rog ram s ex hibit e d co mp ara bl e ex p a n s i on b e h av i o r in th e re in fo r ce d (i.e., in-pl a n e) dir ec ti o n s. T h e m ag nitud e of AS R-r e l a t e d ex p a n s i o n in eac h case p l a te a u e d a t -m t o.%. Th ese o b se rv a ti o n s indic a t e th a t th e d i ff e r e n ces in r e infor ce ment ra ti o b e t wee n the s h ear t es t s p ec im e n s 1%), th e r e in fo r ce m e nt a n c h o rage a nd in s trum e nt at i on t est spec im e n s.%), a nd t he a n c h or tes t s p ec im e n s.%), did n ot h ave a n ot i cea bl e effec t o n t h e ex p a n s i on b e h a vi o r of th e t es t s p ec im e n s. Th e nature a nd m ag nitud e of AS R-r e lat e d ex pan s i o n i s m o r e aff ect ed b y th e dir ec ti o n o f th e r e in fo r ce m e nt th a n th e r e i n fo r ce m e n t rat i o. T h e t est s p ec im e n s we r e r e in fo r ce d in the s am e d i r ect i o n, a nd as a r es ult , ex p e ri e n ce d s imil a r d i rec ti o n a li ty i n AS R-r e l a t e d ex p a n s i o n. 4.2.5 Effect of Stirrups at Ends of Specimen on Expansion Ex p a n s i on m o ni tor in g fro m th e va ri o u s t es t s p ec im e n s id e n t i fie d th a t t h e pr ese n ce of a n y l eve l of co nfin e m e nt a t the s p ec im e n e nds w as a n imp o rt a nt p ara m e t e r fo r ex p a n s i on b e h av i o r. Fa bri cate d s p ec im e n s fo r th e S h ea r , R e in fo r ce m e nt A n c h orage, a nd A n c h or Test P rog ram s i nc lud e d s tirru ps (ra n g in g from. to.s tirrup s) o n eac h e n d of th e b eam. D eve l o i ent of AS R in th e th ro u g h-thi c kn ess dir ec ti o n was co mp ara b l e fo r th ese s p eci m e ns (up to % m ax i m um over yea r s; a ll va l u es o b ta in e d away fro m the s tirru p reg i o n). M PR-4273 R ev i s i o n 0 4-6 -,

--Non-Proprietary Version--The Instrumentation specimen did not include st irru ps on the end of the specimen and the resulting expans i on caused a w id e crack in the concrete between the reinforcement mats. Measured through-thickness expans i on at the ends of the beam exceeded 1% after one year. The wide crack in the instrumentation specimen was an exaggerated version of the mid-plane crack described in Section 4.2.3; however , this crack progressed from the end of the spec im en toward the center , where expansion was l ess tharlo/o after one year. The ends of concrete members at Seabrook Station have some confinement in the through-thickness direction (e.g., connect i on w ith a wa ll). Accord in g l y , the expansion behav i or of the shear , reinforcement anchorage , and anchor test specimens is more representative of the plant. 4.2.6 Environmental Conditioning Effects ASR proceeds m ore rapidly in h ot and m oist condit i ons. Test spec im e n s were stored in an Env i ro nm enta l Conditioning Faci li ty (ECF) w ith a lt ernat in g wet and dry cyc l es to promote ASR deve l opment. To simu l ate the potential presence of groundwater on one s id e of the reinforced concrete at Seabrook Station, FSEL wetted absorbent fabric that was placed on the top s id e of each specimen.

M i sters in the ECF maintained a humid environment during wet cycles. Compar i so n of expansion data from both sides of the test spec im ens did not identify a discernib l e bias in ASR development resu ltin g from the wet fabric. The interna l humidity of the co ncr ete an d the at m osp h eric con diti ons in the ECF were s u ffic i ent to drive progression of ASR uniformly throu g h o ut the test speci m e n s. 4.2. 7 Additional Testing -Confined Cubes FSEL is currently performing a study to monitor expansion of a set of 19-inch cubes with vary in g r einforcement configurations and concrete mix designs. A total of 33 cubes are in volved in the study. This testing is not part of the MPR/FSEL test programs for NextEra , but does provide va lu ab l e insights on expa n sion behavior.

Preliminary r esu lt s indi cate that the most significant factor for expansion behavior is the presence of reinforcement or l ack thereof (Reference

6. 1 ). Spec ifi c observat i ons in c lud e the fol l owing:

• Cubes with one-dimens i ona l reinforcement exhibited s i gnificant l y l ess expansion in the reinforced direction than the unreinforced directions.

Variation of the reinforcement ratio in the reinforced direction did not affect the relative degree of expans i on in any direction.

The same relative distribution of expansion was observed for cubes with two-dimensional reinforcement.

Th i s expans i on behavior i s consistent with the results from the MPR/FSEL t est programs, w h ere expans i on occ urr ed pred om in a ntl y in the unr e in force d dir ect i on.

• Cubes w i th unequal two-d im ens i ona l and three-dimensional reinforcement exh ibit ed s li g htl y l ess expansion in the d irect i ons w ith hi g h er reinforcement ratios. Specifically , a reinforcement ratio difference of 1.1 % vs. 0.5% resulted in a maximum expansion differential of about 0. 1 % between the different directions.

These results are consistent with the conclusion from the MPR/FSEL test programs that differences in reinforcement MPR-4 27 3 R ev i s i o n 0 4-7

--Non-Proprietary Version--ratio between the various types of test specimens did not have a noticeable effect on the aging mechanism.

• Cubes with identical reinforcement configurations , but s li ghtly different concrete mix designs (i.e., substitution of coarse aggregate that is not reactive) resulted in comparable expans i on behavior in terms of the re l ative distribution of expansion in the different directions.

While the specimens for each MPR/FSEL program used a common concrete mix design , all specimens came from different batches with minor variations.

The repeatable results among the MPR/FSEL program test specimens are consistent with the observat i on from the new FSEL expansion study , that the presence (or l ack) of reinforcement i s more impactfu l than minor differences in the concrete mixture (as would be expected with different concrete placements during original construct i on of Seabrook Stat i on). 4.2.8 Comparison to Literature The expansion behavior of the test specimens agrees with li terature data from many sources , as summar i zed in References 1.2 , 1.3 , and 2.2. Of particular interest is Reference 1.11, which reports on ASR expansion of concrete blocks with varying reinforcement.

This study concluded that the presence of reinforcement decreased the expansion parallel to the reinforced direction , wit hout reducing (and in some cases in creasing) expans i on in ot her directions.

Literature so urce s state that dominant cracks form parallel to the direction of r e in forcement, w hi c h is cons i stent with the observation from the MPR/FSEL test programs that the majority of the expans i on occurred in the through-thickness (i.e., the unreinforced) direction.

Additiona ll y , the lit erature sources are consistent with the observation of the l arge crack between the reinforcement mats observed in the test specimens for the MPR/FSEL test programs.

Data co ll ated from multiple studies in Reference 1.2 yielded a conclusion that even a comparat i ve l y sma ll amount of reinforcement significant l y restra in s expansion.

Th i s conclusion supports the observat i on on the effect of st i rrups , which s ignificantly reduced expansion i n the regions of the beams where they were present. 4.3 MATERIAL PROPERTIES In addit i on to expansion monitoring , concrete material properties of the test spec im ens were used as an independent means for monitoring progression of ASR. To determine the baseline , FSEL tested cy lind ers that were fabr i cated at the sa m e time as the t est spec im ens. To d eter min e the ASR-affected material property , FSEL obtained and tested cores from eac h spec im en at the time of testing. For the In strumentation spec im en , FSEL tested cores that were removed as part of in strument in sta ll ation. Test Results For the shear , reinforcement anchorage, and in strumentation test spec im ens , FSEL performed material property testing for compressive strength and elast i c modulus. Results were normalized by calculating the ratio of the material property at the time the core was obtained to the material property result from the corresponding 28-day cylinder.

Figures 4-5 and 4-6 present the material properties as a function of through-thi ckness expansion for the reinforcement anchorage test MPR-4 2 73 R e vi s i o n 0 4-8 _J

--Non-Proprietary Version--specimens (A-Series; blue diamonds), shear test spec im ens (S-Series , green triangles), and instrumentation specimen (TB-Ser i es; purple c ir cles). Figure 4-5. Normalized Compressive Strength of Test Specimens Figure 4-6. Normalized Elastic Modulus of Test Specimens Figure 4-5 indicates a relatively sha ll ow decrease in compressive strength as a function of ASR development , which is consistent w i th l iterature data. As compared to compressive strength , modulus of elasticity (Figure 4-6) exhibited a greater sensitivity to ASR-related degradation and le s s data scatter. The observation that elastic modulus is a stronger function of expansion i s consistent with literature. MPR-4 273 R ev i s i on 0 4-9

--Non-Proprietary Version--Although FSEL performed compressive strength testing on cylinders and cores representing anchor test specimens, these data are not included in Figure 4-5. The methodology for determining through-thickness expansion of the block anchor test specimens was less sophisticated , so direct comparison of the results with those from the shear , reinforcement anchorage, and instrument specimens is somewhat misleading.

The material property test data from the anchor test specimens show average normalized compressive strengths of approximately.

an-at through-thickness expansions of about I% and.%, respectively. These data agree with the overall conclusion of a relatively shallow decrease as a function of ASR development.

Through-thickness measurements from the girder series anchor tests were not possible, so compressive strength data cannot be directly compared with the other results. Elastic modulus results were not obtained as part of the Anchor Test Program , so anchor test specimen data could not be included in Figure 4-6. As part of the Shear, Reinforcement Anchorage , and Instrumentation Test Programs, FSEL also performed testing on cylinders and cores for splitting tensile strength , although this practice was instituted late in the MPR/FSEL test programs , so only limited data are available.

These data showed a weak sensitivity to ASR development.

Comparison of Material Property Data for Different Test Programs As identified in published literature (e.g., Reference 1.2); changes in material properties are characteristic of the ASR aging mechanism.

The results observed in the MPR/FSEL test programs identify no discernible difference between the test specimens over the course of aging , despite the differences in dimensions , reinforcement ratios , and presence of stirrups between the various specimens.

The consistent relationship between aging and expansion for the various beam designs suggests that the aging mechanism is insensitive to the specific boundary conditions of a particular specimen design. 4.4 PETROGRAPHY 4.4.1 Presence of ASR Cores were obtained from most test specimens for petrographic examinations , which were performed by Wiss , Janney, Elstner Associates (WJE) to assess the general properties of the concrete and to confirm the presence of ASR. The results of the petrographic investigations confirmed the presence of ASR in the test specimens and determined that results of ASR were observed throughout the entire test specimen , not just at the surface. For cores from the control specimens , petrographic examinations noted the presence of ASR gel in pores and voids , but there were no indications of concrete distress. Therefore , the control specimens provided an appropriate baseline for the test programs.

4.4.2 Investigation of Petrography as a Correlating Parameter For shear and reinforcement anchorag e specimens , WJE also determined the degree of ASR using Damage Rating Index (DRI) and Visual Assessment Rating (VAR). Both methods rel y on tabulating visual observations to quantify the extent of ASR distress.

The DRI and VAR MPR-427 3 R ev i s io n 0 4-10

--Non-Proprietary Version--methods h ave been used in evaluatio n of cores from Seabrook Station. Petrographic st udie s we re included in the te s t programs to determine i f Traditiona l DRJ , Modified DRJ (which in corporates sy mptom s of ASR in fine aggregate), or VAR cou ld b e u se d to est im ate expansion to-date at Seabrook Station. F i gures 4-7 and 4-8 compare the petrographic examinat i o n results against the corresponding through-thickness expans i on for each test specimen.

Figure 4-7. DRI (Traditional and Modified) vs. Through Thickness Expansion Figure 4-8. VAR vs. Through Thickness Expansion W h en compared to measured through-thickness expansion , Tradit i onal DRJ , Modified ORI , a nd VAR a ll in creased as ASR degradation in creased. However , the scatter in the data increa se d at higher l eve l s of ASR-r e l ated expans i on. In addition, in terpretat i on of petrographic examination results depend s on petrographer judgment , wh i ch i s l ess repeatable than purely quantitative measurement

s. Therefore , i t ma y be mi s leading to apply a corre l at i on of DRJ o r VAR to through-thi c knes s expansion ba se d on me as urements made b y another petrographer , such as those of concrete cores from Seabrook Station. According l y, MPR doe s not r eco mm end using DRJ or VAR to corre l ate expans i on l eve l s in the test program s with those at Sea b rook Stat i on. MPR-4273 Revision 0 4-11

--Non-Proprietary Version--

4.5 CONCLUSION

S As part of the large-scale test programs , MPR evaluated test data for ASR development across the various specimen types. Key conclusions from an evaluation of all data include the following:

• * * * *

• Observed expansion in the test specimens was much greater in the through-thickness direction than in the in-plane directions.

The test specimen design in cluded two-dim ensional reinforcement mats that confined expansion in the in-plane directions , wh i ch is representative of Seabrook Station. These observations are cons i stent with published literature , which indicates that expansion ofreinforced concrete will occur predominately in the unreinforced direction(s).

The rate of expansion was :oximately the same in all three directions until expansion reached.%-*% (i.e.,. mm/m). In-plane monitoring by crack width summation (i.e., CCI) sufficiently characterizes ASR development until this l eve l , after which through-thickness monitoring is required to track further ASR expansion.

Total expansion in the through-thickness direction is consistent across the profile of the test specimen.

However , the cracking behavior is different.

At the test specimen edges , expansion is concentrated in a l arge crack that runs the l ength of the s ur face; whereas away from the edges , expansion is distributed into finer cracks across the test specimen cross-section.

The single large crack is an edge effect and is not representative of structures at Seabrook Station. CCI va lu es agree closely with the observed in-plane expansion from embedded pins, which is more representative of true strain. Based on this close agreement , CCI data obtained by Seabrook Station is confirmed to be a reasonable approximation for in-plane expansion. Additiona ll y , a study of CCI measurements performed by FSEL personnel and the individual performing CCI for NextEra at Seabrook Station confirmed that repeatability is suitable for monitoring expansion at Seabrook.

The procedure used by FSEL is the same as the procedure used at Seabrook.

The internal humidity of the concrete and the atmospheric conditions in the ECF were suffic i ent to drive progression of ASR uniformly throughout the test specimens.

Wet fabric placed on the top s id e of the test specimens to s imulat e groundwater at Seabrook Station did not result in a discernible bias in ASR development.

Material properties decreased with increasing ASR-r elated expansion.

Elastic modulus was the property that was most sens iti ve to ASR degradation.

The trend between elastic modulus and ASR expansion was also the most repeatable among the material properties investigated.

Therefore , e la stic modulus is preferred over compressive strength or splitting tensile strength as a parameter for determining ASR development in the absence of monitorin g instrumentation. MPR-4273 R evision 0 4-12

--Non-Proprietary Version--* The consistent relationship between material properties and expansion for the variou s beam designs suggests that the specific boundary conditions of a particular specimen design do not affect the ASR aging mechanism.

• Petrographic investigation of cores obtained at the time of testing confirmed the presence of ASR. Cores from control specimens showed ASR gel , but only in voids , and without accompanying concrete distress , which establ i shed that the control specimens were free of ASR degradation.

Quantitative petrographic results using DRI and VAR trended with observed through-thickness expansion measurements.

However, the data scatter increased significant l y at higher l evels of ASR distress.

In addit i on , the DRI and VAR methodologies rely on subjective petrographer judgment and may not be as repeatable as more purely quantitative methods. Accordingly , neither technique is recommended for corre l ating expansion l evels in the test programs w ith those at Seabrook Station. MPR-427 3 R e vi s ion 0 4-13

--Non-Proprietary Version--5 Test Results Testing performed at FSEL included four test programs completed during a period of about four years. The test reports for the test programs provide detailed results (References 4.1 , 4.2, & 4.3). This section summarizes the results from each test program. 5.1 ANCHOR TESTING The purpose of the Anchor Test Program was to quantify the relative impact of ASR on anchor performance by comparing anchor tests at various levels of ASR expansion to tests performed prior to the development of ASR. 5. 1.1 Test Description The approach for anchor testing was consistent with testing performed by the anchor vendor (Hi I ti) for orig inal construction of Seabrook Stat ion. The vendor testing was u sed as an input to the plant eva lu at i on demonstrating compliance with NRC IE Bulletin 79-02 , which represents the plant design basis for anchor bolts. FSEL performed testing on two ASR-affected girders , and.fabr i cated test specimens that were designed to reflect reinforced concrete at Seabrook Statio n to the extent practicai7.

Two different types of anchors were used to represent post-installed anchors and cast-in-pl ace embedments at Seabrook Station: the Hilti Kwik Bolt 3 expansion anchor , and the Drillco Maxi-Bolt undercut anchor.

• The Hilti Kwik Bolt 3 is the preferred torque-controlled expans i on anchor for Seabrook Station. It is a more modern version of the Hilti Kw i k Bolt I and Kwik Bolt 2 anchors that were used when Seabrook Station was constructed and installed over time at the beginning of plant life. The Kwik Bolt 3 is representative of its predecessors , as the basic design of the anchor fam il y has not s i g nific antly changed.

• The Drillco Maxi-Bolt is an undercut anchor used at Seabrook Station. Undercut anchors are similar to cast-in-pl ace anchors as the y both utilize a positive bearing surface to transfer load to the concrete. Thus , undercut anchors are suitab l e representatives of cast-in-place anchors. A range of anchor s iz es and embedment depths were used for the series oftests. FSEL installed some anchors shortly after fabrication (i.e., prior to ASR development) and some anchors just 7 FSEL fabricated but one specimen was not tested. MPR-4273 R ev i s ion 0 5-1

--Non-Proprietary Version--before testing (i.e., after ASR development).

Anchors installed shortly after fabrication were set prior to ASR development , so expansion occurred around the anc h or shank. Anchors installed just before testing were set after ASR development , so expansion was independent of the presence of an anchor. These cond iti ons simulated the potential bounding conditions at Seabrook (i.e., anchor in sta ll e d at original construct i on; anchor in sta ll ed into ASR-affected concrete as part of a recent modification).

Anchor performance was eva lu ated using an unconfined tension test. This test method applies a tensile load to the anchor , and uses a reaction frame to distribute the l oad to a concrete surface a sufficient radius away from the anchor to avoid any confin in g stress (which cou ld preclude concrete breakout).

Load i s in creased until anc h or failure , whic h occurred by one of the fo ll ow in g modes:

• Concrete Breakout -Fracture of th e concrete around the anchor in a cone-lik e shape emanating from the anchor h ead.

• A n c h or Failure -Fracture of the anchor shank.

• Anchor Pull-out/Pull-through

-Loss of l oad resistance due to local concrete failure and/or deformation of the anc h or head. (Th i s mode only applies to expans i on anchors; i.e., the Hilti Kwik Bolt 3 for this test program.)

The l eve l of ASR degradation was c h aracterized by in-plane expansion , as measured using crack width s umm ation (i.e., Combined Cracking Index). in-pl ane expans i on due to ASR creates microcracks parallel to the axis of an anchor , wh i ch are most pronounced in the concrete cover. These microcracks that open perpendicular to the concrete surface have the potential to provide a preferential fai lur e path w ithin a potential breakout cone , l eading to degraded anchor performance.

5.1.2 Test Results Expansion Anchors F i gure 5-1 presents the results of unconfined t e n sion testing ofHi lti Kwik Bolt 3 expansion anchors in the girders and the blocks. Test results have been normalized relative to the measured 28-day compressive strength of the specimen , as fai lur es were related to anchor pull-out/pull-through or concrete breakout (not anchor fa ilur e). Figure 5-1 includes results from the range of tested anchor sizes and embedment depths. For reference, the dashed lin es show the theoretical concrete fa ilur e l oad for each anchor type , normalized by the measured 28-day compress i ve strengt h of the contro l test specimen , which was not affected by ASR. MPR-42 73 R ev i si on 0 5-2

--Non-Proprietary Version--Figure 5-1. Kwik Bolt 3 Anchor Test Results The results presented in Figure 5-1 indicate that there is no performance reduction for expansion anchors when in-plane expansion is less than lmm/m , which is the maximum ASR level exhibited by the test specimens used for expansion anchor testing. The majority of the test results were for in-plane expansion atlmm/m or less , because in-plane expansion of the block specimens did not exceed this level. The girder series tests extended the range of expansion covered by the test program. The low level of in-plane expansion in the fabricated specimens is consistent with the test specimens fabricated for the other test programs , which were also designed with two-dimensional reinforcement mats that provide confinement in the in-plane direction and closely represent the reinforced concrete at Seabrook Station. Undercut Anchors Figures 5-2 and 5-3 present the results of unconfined testing of Drillco Maxi-Bolt undercut anchors in the girders and the blocks. Results from the range of tested anchor sizes and embedment depths are provided.

The dashed lines show the normalized theoretical concrete failure load for each anchor type. Some of the Drill co Maxi-Bolt tests were installed at a depth less than the manufacturer's recommendation to ensure that tensile performance was limited by concrete failure, and would therefore investigate the effect of ASR in the concrete.

Figure 5-2 provides the results of shallow depth testing. Test results in Figure 5-2 were normalized relative to measured 28-day compressive strength of the specimen, becau se anchor failure was related to concrete breakout.

Figure 5-3 provides the results offull depth testing. Test result s in Figure 5-3 were not normalized for compressive strength of concrete, becau se failure of full depth undercut anchors is governed by steel failure of the anchor (i.e., concrete strength is not limiting). MPR-427 3 R ev i s ion 0 5-3

--Non-Proprietary Version--Figure 5-2. Shallow Drillco Maxi-Bolt Anchor Test Results Figure 5-3. Full-Depth Drillco Maxi-Bol t Anchor Test Resul t s The resu l ts presented in F i gures 5-2 and 5-3 indicate that no decrease in anchor performance was observed un ti 1 in-p l ane expansio n exceeded l mm/m. T h e reduct i on i n performa n ce observed in MPR-427 3 R ev i s i o n 0 5-4

--Non-Proprietary Version--the test program was only for anchors installed at a significantly reduced embedment depth such that concrete failure limits anchor performance.

Anchors with full embedment depth in ASR-affected concrete may perform satisfactorily at an expansion level of lmm/m or higher. Anchor Installation Timing Figures 5-1, 5-2 , and 5-3 includ e results from testing of anchors installed shortly after specimen fabrication (i.e., before development of ASR) and anchors installed just prior to testing (i.e., after development of ASR). Test results indicate that there is no significant difference in anchor performance related to when the anchor was installed.

Through-Thickness Expansion For the block s i cimens , through-thickness expansion was estimated at l o/o for.of the test specimens and % for.specimens.

The results indi cate that anchor performance is not sensit ive to through-thickness expansion.

Thro u gh-thickness expansion has the potential to create microcracks perpendicular to the axis of an anchor. These potential microcracks that open parallel to the concrete surface do not provide a preferential failure path to result in degraded anchor performance.

An anchor l oaded in tension would compress the through-thickness expansion and close any potential microcracks within the area of influ ence of that anchor. Without a " short-circuit" of the breakout cone , throug h-thi ckness expans i on does not affect anchor performance.

This observation w ith through-thickness expansion is in contrast to in-plane expans i on where the potential for a " short-c i rcuited" breakout cone ex i sts. 5.1.3 Additional Testing -Confined Anchor Tests During the first phase of the girder series in 20 1 2 , FSEL performed confined anchor testing that focused on the pullout behavior of expansion anchors in ASR-affected concrete. The testing rig for the confined tests placed the reaction l oad in the area immediately around the anchor, which prevents the breakout failure mode. The testing demonstrated that there is no significant l oss of pullout/pull-through anchor capacity in ASR-affected concrete until higher l eve l s of ASR expans ion. Minor lo sses were observed beginning at an in-plane expansion oflmm/m. The confined anchor test data were not included in the test results described in Section 5.1.2 , because the stress state in the concrete around the anchor was not consistent with actua l cond iti ons for anchors in-service.

5.2 SHEAR TESTING The purpose of the Shear Test Program was to determine the effect of ASR on out-of-pl ane shear capac i ty of reinforced concrete e l ements without shear reinforcement.

5.2.1 Test Description The effects of ASR were evaluated using three-point bending tests on large reinforced concrete beams .* I-inch wide shear test specimens were fabricated for this te s t program .* of these specimens were controls that were 30 days following fabrication (i.e., prior to the development of ASR). The other-t est specimens were allowed to develop ASR MPR-4273 R ev i s ion 0 5-5

--Non-Proprietary Version--and were e v aluated relati v e to the performance of the contro l tests 8. Figure 5-4 show s the te s t setup for the I-inch shear te s t specimens. E L EVAT I ON! I I I ... S up po rt ° F ixt u r e Load I I I T" 1lt '"-T-"' Suppo r t F ix tu re Figure 5-4. Tes t Se t up for.-i nc h S h ear Tes t Spec i mens (E l e v a ti on Vi e w) The te s t s pan , or te s t re g ion , i s defined a s the region bet w een t h e point where the load i s applied and the n eare s t support p oint. Thi s loading configuration made it p oss i ble to conduct one shear test on each end of t h e shear t es t specimen s thereby providing f\;vo sets of test re s ults for eac.h specunen. ACI 318 defines shear capac i ty based on the onse t of diago n al c racking. D uring the load test FSEL identified this point visually.

In addition the test equipment m onitoring l oad as a function of deflection wou l d indicate a s light reduction in load followed by a r eduction in the s lope of the overall re s pon s e. Load te s ting continued until failure of the spec im en, a s identified b y a rapid loss in load canying capacity.

5.2.2 T e st R e sults F i gure 5-5 provides the stress-displacement plot s for the.s h ear test specimens.

For cl arity only one of the f\ o tests from each specimen is presented.

Th e p air of r e u lt s from each te s t s pecimen were nearly identical, so Figure 5-5 i s repre s entative of all-s hear te s t re s ults. The stre s s wa s normalized by the measured 28-day compre s sive concrete for consi s tency with the a p proach u s ed in ACI code calculations. 8 Re s ul t from one of t h es e te t s pecimens .) i s for informa t io n onl y due to a te s t s pecimen nonconfonnance. MPR-4 27 3 lk v i s ionO 5-6

--Non-Proprietary Version--

Figure 5-5. Normalized Shear Stress-Deflection Plots for.-inch Shear Test Specimens The dashed circle indicates the region where diagonal cracking appeared, which is the shear capacity defined by ACI 318. The. plots in Fig ur e 5-5 (representing twenty shear tests) indicate a clear and trend of higher levels of ASR expansion corre l ating with higher shear capacity.

All-of the shear test results exceed the theoretical shear capacity calculated per ACI 318-7 1 , which is a normalized shear capacity of 2.0. The apparent in crease in shear capacity resulting from ASR is explained by the prestressing effect discussed in Sect i on 2.2. The l arge number of tests and the repeatability of the data provide strong confidence in the conc lu sion that there was no adverse effect on shear capacity at the expansion l eve l s tested. 5.2.3 Comparison to Literature Published literature on structural testing of ASR-affected reinforced concrete in c lud es a range of results that generally reflects the degree of reinforcement.

Literature notes that triaxially reinforced concrete w ill on l y be slightly affected even by fairly severe ASR expansions (Reference 1.1). As discussed in Section 2.3.1 of this report , published lit erature of ASR-affected test specimens without shear reinforcement indicate shear capacity results ranging from a slig ht in crease to a l oss of 25%. Based on the results from the S h ear Test Program s h ow in g no l oss in shear capac i ty, the test specimens actua ll y behaved more lik e triaxially reinforced concrete.

Because the MPR/FSEL test program specimens were much more representative of Seabrook Stat i on than published lit erature (e.g., I" x I" spec im en cross-section , as compared to 5" x 3") and the MPR/FSEL test results were highly repeatable , st ructural evaluations for Seabrook Station can use the MPR/FSEL conclusion (i.e., no lo ss of capacity) in lieu of the resu l ts from publi s hed literature. MPR-4273 R evision 0 5-7

--N on-Prop r ietary Version--5.2.4Additional Testing tnch Specimen , Retronts, and Uniform L o ading --inch test specimen was tested prior to the development of ASR to evaluate the effect of specimen depth on shear capacity. The specimen was des i gned and fabricated with reinforcement detailing typica l of structures at Seabrook Station and a concrete mix design identical to the other shear test specimens. A l though the allowable shear sfress in the ACI code is independent of beam depth there are test data that show the shear stress at initiation of diagonal cracking decreases at greater beam depths (Reference

1. 7). The Shear Test Program included evaluation of the effect of specimen depth to ensure that i t cou l d be taken into account if tests of ASR-affected specimens h ad shown a decrease in shear capacity.

Results from this testing indicate t h at the normalized shear capacity of the I-inch test specimen was l ess than that observed in the I-inch control specimens. The nonnahzed capacity was approximately l% of the t heoretical value specified by t h e ACI code. This resu l t is consistent with the data available in the ACI database for shear tests of larger width spec i mens (Reference 1.12). It is important to note that this test was conducted on a non-ASR-affected test specimen and does not i mpact the conclusions regarding t he effect of ASR-related expansion on shear pe1fo1mance.

Retrofit Concept Testing The original scope of the Shear Test P rogram included testing of retrofit concepts on specimens exhibiting ASR-induced expansion above which a deleterious effect was observed.

A reduction in shear was not observed at the highest expansion l evels exhibited by the test specimens so retrofit testing was n ot performed as part of the t est p rogram. FSEL pe1formed proof-of-concept testing on retrofit concepts installed in trial specimens (Reference 6.3). Shear performance of specimens with retrofits was c ompared t o shear pe1fo1mance of control sp e cimens. T wo retrofit methods we r e investigated in this testing: (1) undercut anchors installed in t l1 e through thickness direction and t ensioned 011 the smface with a n ut a11d plate to provide co11finement and (2) threaded rod grouted into a drilled hole in the concrete and te11sio11ed on the smface with a nut 311d p l ate. Four specimens were fab1icated for this testing and each specimen was tested on both ends. Tab le 5-1 summarizes the test specimens used for retrofit testi n g. MPR-4273 Rc"-i s ionO Specimen LD 1 LD 1 SR 1 SR 1 S R2 SR 2 Tab l e 5-1. P r oo f-of-Co n ce pt T es ti ng for S h ear Re t ro fi t E nd Shear Reinforcement Retrofit N ort h No None So u t h No N o n e North No Gro u ted Rods Sout h No Unde r cut A n c h o r s N o rth No U nde r c u t Anchors So u t h No None 5-8

--Non-Proprietary Version--Table 5-1. Proof-of-Concept Testing for Shear Retrofit Specimen End Shear Reinforcement Retrofit SR3 North Yes None SR3 South No Grouted Rods Test results indicated that both undercut anchors and grouted rods were effective at shear strengthening.

Shear strength and deformation capacity can be increased significantly by adding the retrofit anchors. The anchors behave simi l ar to cast-in-place transverse reinforcement.

Uniform Load Testing The test setup for the Shear Test Program used asymmetric three-point loading. Use of point loads is convenient and consistent with the test data used to calibrate the ACI code equations for shear. A uniform distribution would be more representative of the l oads applied to some structures (e.g., hydrostatic loading on the exterior surface of a below-grade wall). Information in technical literature on the effect of uniform loading is generally based on small-scale test specimens , and indicates a higher capacity with uniform l oad in g. FSEL performed uniform load shear testing on two sets of specimens with designs comparable to the specimens for the Shear Test Program. Force was applied using an air bladder to exert uniform pressure to the underside of each specimen. (References 6.4 & 6.5) The first set of tests (Reference 6.4) included six beam specimens , three with point loading comparable to the Shear Test Program , and three with uniform loading applied over the middle 2/3 of the test specimen.

For these tests , uniformly loaded specimens exhibited a slightly higher shear capacity than specimens subjected to point loads. Additiona l data on two 24-inch specimens were obtained as part of an in vestigation of uniform load testing of 48-inch specimens (Reference 6.5). For those tests , the uniformly loaded spec i men exhibited l ower shear capacity than the specimen subjected to point l oads. In the second set oftests (Reference 6.5), two 48-inch thick specimens and two 24-inch thick specimens were fabricated.

The design of these specimens was comparab l e to the Shear Test Program specimens , although the 48-inch specimens were considerably longer (i.e., 45 feet , 4 inches). One specimen of each thickness was tested with uniform load and one specimen of each thickness was tested with point loads. Load test results indicated that the shear capacity associated with uniform l oad distribution was slight l y less than the shear capacity for point loading of the 48-inch spec im en. The observation from Reference 6.4 and other literature that a uniform load distribution resu lt s in higher shear capacity may not apply for larger member depths. Reference 6.5 identified that uniform loading of 24-inch and 48-inch specimens was lower than corresponding tests performed with point l oading. Cons id ering these results , MPR concludes that uniform l oading cannot be used to recover shear margin for the typical wall thicknesses in structures at Seabrook Stat i on. MPR-42 73 R ev i s i o n 0 5-9

--Non-Proprietary Version--5.3 REINFORCEMENT ANCHORAGE TESTING The objectives of the Reinforcement Anchorage Test Program were to determine the effect of ASR on (1) the reinforcement anchorage performance (including lap splice), and (2) the fle x ural stiffness of reinforced concrete elements.

5.3.1 Test Description The effects of ASR were evaluated using four-point bending tests to apply flexural load on large reinforced concrete beams that contained reinforcement splices at the longitudinal center of each beam (i.e., the constant moment region). The length of the reinforcement overlap (i.e., the lap splice) is specified by provisions in the ACJ code , and was reflected in the test specimen design .

• test specimens were fabricated for this test program. One of these specimens was a control that was tested 30 days following fabrication (i.e., prior to the development of ASR). The other-test specimens were allowed to develop ASR and were evaluated relative to the performance of the control test. Figure 5-6 shows the test setup for the reinforcement anchorage test specimens.

ELEVATION

=----Tiil Support Fixtur Load 'SYMMCTRK:

Load Roller Support Fixture Figure 5-6. Test Setup for Reinforcement Anchorage Test Specimens (Elevation View) Ideally , a concrete element with spliced reinforcing bars should perform similarly to elements with continuous reinforcement.

Performance of the splice in the test specimens was considered satisfactory if the following criteria were met:

• Flexural yielding of the test specimens occurred at (or above) the theoretical

" yield moment" (M y), which is calculated by a moment-curvature analysis.

Reinforced concrete members are designed such that the reinforcement will yield prior to failure. lf the load applied to the test specimen results in a " yield moment" that is at least M y, then the reinforcement has been developed up to its yield strength and the splice is performing like a continuous segment of reinforcement bar.

• Failure of the specimen occurs at or above its nominal flexural capacity (M n), which is calculated using the provisions of ACI 318-71 , and represents the maximum capacity of a MPR-4 2 7 3 R ev i s i on 0 5-10

--Non-Proprietary Version--flexural e l ement. If the applied load to the test specimen demonstrates a flexural capacity of at le ast Mn, then the bond between the reinforcement bars and the co n crete has not been adverse l y affected. In s umm ary , i f both cr i teria are sat i sfied , then the presence of ASR h as not adverse l y affected reinforcement anchorage or flexural capacity of the test specimen. 5.3.2 Test Results Figure 5-7 provides load-displacement plots for the control test.) and a test spec im en that exh ibited the highest lev e l of expa n s i on .), w hich i s ty pi ca l of all ASR-affected spec imen s (tota l of-ASR-affected specimens).

Figure 5-7. Load-deflection Plots for Selected Reinforced Anchorage Test Specimens The test results shown in Figure 5-7 indi cate that ASR in the test specimens did not result in any adverse effect on the reinforcement anchorage capacity , although there is a change in the st iffne ss behavior , as shown by the l ower deflection at flexural yie ldin g and the absence of a notable s l ope c h ange at l ow l oads C--!lkip) when flexural cracking begins. Detailed evaluat i on identified that the criter i a for satisfactory reinforcement anc h orage performance were satisfied for each of the nine reinforcement anchorage tests. the app li ed load resulted in a " y i e l d moment" that exceeded the theoretical by-%, and the flexural capacity exceeded the nomina l flexural capacity (Mn) by-%. The l arge M P R-42 7 3 R e v i s i o n 0 5-11

--Non-Proprietary Version--number of tests and the repeatability of the data provide strong confidence in the conclusi o n that there was no adverse effect on reinforcement anchorage at the expansion levels tested. 5.3.3 Compar i son to Litera t ure The published stud y discussed in Section 2.3.2 (Reference 1.9) included test results for reinforcement anchora g e both with and without tran s verse reinforcement.

Testing on specimens with transverse reinforcement indicated no si g nificant loss of reinforcement anchorage strength , while testing on specimens without transver s e reinforcement exhibited 40% decrease.

Based on the results from the Reinforcement Anchorage Test Program , the test specimens actually behaved more like concrete with transverse reinforcement.

Because the MPR/FSEL test program used a more realistic test method (e.g., flexural test of a large-scale beam containing a rebar splice , as compared to a rebar pullout test of a small specimen), specimens were more representative of structures at Seabrook Station , and the test results were highly repeatable , s tructural evaluations for Seabrook Station can use the MPR/FSEL conclusion (i.e., no loss of reinforcement anchorage) i n lieu of the results from published l iterature. 5.3.4 Evaluation of Flexural Stiffness The fle x ural behavior of a reinforced concrete element is non-linear over the full range of loading for two reasons: (I) changes in the stress-strain relationship of concrete in the tension zone as cracks initiate and grow and, (2) a non-l inear (approximately parabolic) stress-strain re l ationship in the concrete compression zone. This behavior is illustrated in Figure 5-8 , which shows a portion of the load-deflection response for the control test specimen.

Figure 5-8. Initial Part of Load Deflection Plot for Reinforcement Anchorage Control Specimen MP R-4273 Revi s i on 0 5-12

--Non-Proprietary Version--Evaluation of the effect of ASR on flexural stiffness requires consideration of test specimen stiffness over the entire range of loading. Figure 5-8 id entifies the following loads of in terest:

• P crack (Po in t B) i s the l oad at which tensile stresses at the bottom of the test spec im en (tens i on s id e) reach the tensile strength of co n crete, resu l t in g in flexural crack in g.

• P serv i ce (Point D) is the l oad on the test specimen at t h e serv i ce-l evel cond iti on (defined by ACI as 60 percent of the flexural yielding load).

• P y (Po int E) is the l oad corresponding to the flexural y i eldi n g of the test spec im en. The flexural stiffness of each test spec im en over variou s regions can be ca l culated by find in g the slope of the l oad-d eflect i on plot between two se l ected po int s of reference.

Initial Flexural Stiffness T h e initi a l flexural st i ffness (pr i or to the onset of flexural cracking) is the s l ope from Point A to Point C (from F i gure 5-8). This va lu e provides a di rect compar i son to the ca l cu l a t e d flexural st i ffness , which i s typ i cally used in structura l eva lu ations, and is referred to as the un-cracked concrete stiffness. F i g u re 5-9 shows the initial flexural st i ffness for each test specimen r e l ative to the theoretical value determined from material properties of the 28-day cylinders.

Figure 5-9. Effect of ASR-Related Expansion on Init i al Flexural Stiffness While Fig u re 5-9 shows a decrease in i nit i a l normalized flexural stiffness in the ASR-affected test specimens with respect to the contro l test specimen , there is no clear trend of chang in g MPR-42 7 3 R ev i s i on 0 5-13

--Non-Proprietary Version--stiffness as a function of through-thickness expansion.

The decrease in ini tial st i ffness may be due to the presence of sma ll ASR-indu ced cracks at the onset of testing. Service Level Flexural Stiffness The serv i ce le ve l flexural stiffness i s the slope from Point A to Point D (from F i g u re 5-8), and represents the st i ffness of the test specimen linearized from initial l oading to the serv i ce l eve l load (defined as 60 percent of the flexural y i eld l oad in AC J 318-71 ). This va lu e is commonly used in reinforced concrete structura l eva lu atio n s and is referred to as the cracked concrete stiffness.

Modern design codes (ACI 318-11) allow the flexural st i ffness of cracked beams and walls du e to serv i ce l oads to be taken as 0.35 times the nominal st i ff n ess (EI). F i gure 5-10 plots the measured flexural stiffness (normalized to the calcu lat ed flexural st i ffness) as a function of through-thi ckness expansion. Figure 5-10. Effect of ASR-Related Expansion on Service Level Flexural Stiffness Figure 5-10 shows that the st i ffness in ASR-affected test specimens is clear l y greater than the control test specimen and that there i s an increasing trend with respect to through-thickness expansio n. Summary of Results on Flexural Stiffness T h e Reinforcement Anchorage Test Program provided data to assess changes in the flexural stiffness ofreinforced concrete caused by development of ASR. Test results indicated that the initial flexural stiffness (i.e., prior to onset of flexural crack in g) was generally lower than the theoretical va lu e when ASR was present. However, the serv i ce level flexural stiffness , which is commonly used in structural evaluations , is within the limits specified by modern design codes. MPR-4 273 R ev i s io n 0 5-14

--Non-Proprietary Version--5.3.5 Additional Testing -Retrofit for Reinforcement Anchorage T h e or i g i na l scope of th e R e in forcement A n c h orage Test Program i ncluded testi n g of r etrofit concepts o n spec i me n s exh ib iti n g ASR-ind u ce d ex p a n s i on a b ove w hi c h a de l ete r io u s effect was o b se r ve d. A r e du c ti o n in r e in force m e nt a n c h orage was n o t obse r ve d at th e ex p a n s i on l eve l s exhi bi ted b y th e t est s p ec im e n s, so r etrofit t est in g was n ot p e r fo rm e d as p art of th e test p rogra m. However , MP R a nd FSEL p erforme d proof-of-co n ce p t testing o n tr i a l spec im e n s (R eference 6.2). Spec i me n s were fa b ricate d wi th in a d e qu ate l a p s pli ce d eve l o pm e n t l e n gt h (r e l a ti ve to t h e AC I 3 1 8-71 r e quir e m e n t) to e n a bl e t est in g of a r e t rofit to a u g m e nt r e in fo r ce m e n t a n c h o r age. T h e t es t s p ec im e n s we r e co mp ara bl e to th ose u se d in t h e R e in force m e nt A n c h orage Test Program. T h e r etrofit co n sisted of post-in sta ll ed u nderc u t anc h ors pl aced in th e t h ro u g h-thi c k ness dir ec ti o n th at wo uld b e h ave li ke cas t-i n-pl ace t ra n sverse r ei n force m e n t , co nfining t h e l a p s pli ce r eg i o n. R e t rofits we re o nl y in sta ll e d fro m o ne s id e of th e t es t s p ec im e n to s imul ate a n act u a l st ru c ture w h ere o nly o ne s ur face was access ibl e (e.g., u n d ergro und s t r uctur es at Sea b rook S t a ti o n). P roof-of-co n ce p t test in g was perfor m ed o n fo u r test s p ec im e n s , as s u mma ri zed i n Ta ble 5-2. Table 5-2. Proof-of-Concept T esting for Reinforcement Anchorage Retrofit Specimen Lap Splice Retrofit Moment Capacity Development Length Relative to Design ARO Meets ACI 318-71 No 1.13 Requirement AR1 Half of ACI 318-71 No 0.83 Requirement AR2 HalfofACI 318-7 1 Yes 0.98 Requirement AR3 HalfofACI 318-71 Yes 1.02 Requirement T h e res ul ts i n d i cate d t h at th e retrofi t concep t ca n in c r ease the s tr e n gt h of a me mb er wi th a d e fi cie n t l a p sp li ce. H owever , speci m e ns w i t h t h e r etrofit d id n ot ex hi b it d uct ilit y th at was co mp ara bl e to th e co nt ro l s p ec im e n (A RO). 5.4 INSTRUMENTATION TESTING T h e pu r p ose of th e In strume n tat i o n Test Progra m was t o eva lu a t e th e performa n ce of severa l ca ndi da t e in stru m e n ts for m eas uring t h roug h-t h ick n ess ex p a n sion of r e i nforced co n c r ete struct ur es th at h ave b een affec t ed b y AS R. MPR-427 3 R ev i s io n 0 5-1 5

--Non-Proprietary Version--5.4.1 Test Description The Instrumentation Test Program evaluated three candidate instruments including one vibrating wire deformation meter (VWDM) and two extensometers.

All instruments are installed in the concrete after core drilling to create a core bore.

• The VWDM consists of a vibrating wire strain gauge in series with a spring, which extends the effective range of the strain gauge. Measurements from the VWDM are performed using a battery-powered readout device. The observed expansion is calculated by comparing the readout device output with a baseline value recorded at the time of instrument installation.

• The snap ring borehole extensometer (SRBE) uses a spring-l oaded , expanding snap ring to affix two anchors in a bore hole. A gauge rod of known length is connected to the base anchor (i.e., the deep anchor) and extends to the collar anchor (i.e., the shallow anchor). Expansion of the concrete is determined by using a calibrated depth micrometer to measure the distance between the reference surface on the collar anchor and the end of the gauge rod.

• The hydraulic borehole extensometer (HBE) uses a copper bladder , which is expanded with hydraulic fluid that is injected with a hand pump , to affix two anchors in the bore hole. A check va l ve in the fluid injection line maintains pressure in the bladder. Similar to the SRBE , a gauge rod of known length is connected to the base anchor and extends to the collar anchor. Expansion of concrete is determined by using a calibrated depth micrometer to measure the distance between the reference surface on the collar anchor and the end of the gauge rod. The of extensometers were installed with .di fferent gauge l engths, resulting in a total of-di fferent configurations.

Reduced length extensometers were investigated because they wou ld not be installed as deep and would therefore reduce the risk of cutting rebar on the exterior reinforcement mat during installation.

To provide a point of reference to compare the expansion measured by each instrument , FSEL drilled companion hole s through the entire thickness of the instrumentation specimen , such that each instrument location had companion holes on the left and right. A milled flat plate was placed on the opposite face of the beam to serve as a contact point for measurements with a depth gauge. FSEL cast the instrumentation test specimen in July 2014 and in stal l ed instruments on se l ected dates from August 2014 through May 2015. The test program concluded in July 2015. Staggering instrument installation investigated the impact of installing in struments after the onset of ASR (as will be the case at Seabrook Station).

MPR-4273 R ev i s ion 0 5-16 _J

--Non-Proprietary Version--5.4.2 Results Base d on th e exper i ence d ur i ng t h e test program r egard in g qua li ty of data, ease of i n sta ll ation, an d re li a bili ty , the SRBE was iden t ified as t h e b est i nstr u ment for meas u r i ng t h ro u gh-t hi ckness ex p a n s i o n a t Sea b roo k Stat i o n. Data Quality Me a s ur e m e nts o bt a in e d fro m t h e sta nd ar d-l engt h S RB E s h owed t h e b est agree m e nt w ith th e i r efe r ence meas u reme n ts from t h e d ept h ga u ge. In s t rume nt d a t a ag r eed to w i t hin a b o ut.% wi th th e refere n ce m easure m e n ts at ex p a n s i o n va lu es b e l ow.%, w h ic h excee d s th e ran ge of es tim ate d ex p a n s i on l eve ls c urr e ntly o b served at Sea b roo k Stat i o n (l ess th a n.%, b ase d on : in formatio n ava il a bl e at the time t hi s repor t was publ ishe d). F i g u re 5-1 1 prese nt s th e da t a o b ta in e d fro m t h e.sta nd a r d-l e n gt h S RB Es in s t a ll e d in th e in s trum e nt a ti o n s p ec im e n. T h e p urpl e l i n e r e p rese nt s S RB E m eas ur e m e n ts an d th e blu e lin es a r e th e r efe r e n ce m eas ur e m e nt s (o n e d as h e d lin e for eac h co mp a ni on h o l e; t he so lid lin e i s t h e average).

Oth e r in s trum e n ts exh ibit e d irr eg ul ar d a ta t h a t did n o t agree as we ll w ith th e r efe r e n ce m eas ur e m e nt s (H B E , re duc ed l e n gt h S RB E) o r fa il e d a t hi g h er l eve l s of ex p a n s i o n (VWD M). Figure 5-1 1. Comparison of SRBE Instrument Measurements with Depth Gauge Measurem'ents MPR-427 3 R evisi on 0 5-17

--Non-Proprietary Version--Figure 5-1 1 shows a l arge increa s e at the end of the te st program for two of the four SRBEs. Those instruments were located nearer to the end of the beam whe r e the wide cracking (as discussed in Section 4.2.3 and 4.2.5) occuned due to the lack of stinups. Ease of Installation The SRBE and HBE were much easier to install than the VW D M, which requires refilling the volume around the instnunent with grout after installation. Figure 5-12 illustrates the configuration of an installed SRBE. Reference Surface C oll a r A n c h o r B ase A nchor_/ Alignment Aid Figure 5-12. Illu s tr at i o n o f SRBE dur i ng I n sta llation Long-Term Reliability None of the SRBEs exhibited during t he test period. -of the. VWDMs stopped functioning after-. Additionally the VWDM 1s the v endor but can.not be recalibrated following installation. FSEL observed s l ippage of the anchor s for the HBEs which resulted in enoneou s measurement

s. 5.4.3 Conclusion For the reasons li s ted above , MPR recommended nonnal-l ength SRBE as the i nstnunent for monitoring through-thickness expansion at Seabrook Station. MPR-4 273 R evisionO 5-18

--Non-Proprietary Version--6 Implications for Seabrook Station Results from the large-scale test programs will be used to support evaluations of ASR-affected reinforced concrete structures and future monitoring activities.

This section summarizes the key implications for Seabrook Station identified as part of the large-scale test programs and related activities.

6.1 EXPANSION

6. 1. 1 Expansion Behavior The reinforcement configuration of the test specimens in the large-scale test program included two-dimensional reinforcement mats in the in-plane directions to match most concrete structures at Seabrook Station. Expansion monitoring during the test programs identified that expan s ion will occur in all directions.

However , after expansion in the in-plane directions reached .% to.%, the confinement provided by the reinforcement mats caused in-plane expansion to plateau. Subsequent expansion occurred primarily in the unreinforced through-thickness direction.

Technical literature (References 1.2 , 1.3 , and 1.13) and the large-scale test programs identified that expansion below.% lmm/m) does not result in significant structural consequences.

Accordingly, expansion monitorin.i.:t Seabrook Station in only the in-plane directions is sufficient until expansion reaches.%, at which point through-thickness monitoring should begin. The Structures Monitoring Program for Seabrook Station requires periodic visual inspections of all concrete surfaces.

These inspections will identify new locations with ASR symptoms or existing locations with changing ASR symptoms. (Reference 2.5) 6. 1.2 ln-P/ane Expansion Measurements NextEra has been monitoring expansion of ASR-affected concrete at Seabrook Station using crack width measurement (i.e., combined cracking index (CCI)) since 2011. In the large-scale test programs , in-plane expansion monitoring of specimens included both CCI and measurement of the distance between pins embedded in the specimen during fabrication.

The expansion values measured using embedded pins are a better measure of true engineering strain because these measurements reflect both material elongation and crack width. However, the test data showed that CCI and embedded pin measurements were in close agreement both in trend and magnitude , as the crack width measurements rapidly dominate the overall e x pansion. Therefore , use of CCI at Seabrook Station i s a rea s onable approximation for in-plane e xpansion sinc e the beginning of plant life. MPR-42 7 3 R ev i s i on 0 6-1

--Non-Proprietary Version--CCI is a labor-intensive methodolog y that may be cumbersome to maintain.

As an alternative , NextEra could install embedded pins , which can be measured more rapidly with calipers , but will only provide expansion data from the time the pins are installed by taking the difference between the original distance between the pins and the measured distance.

Adding this difference to the CCI measured at the time the pins are installed will provide an approximation for total in-plane expansion since the beginning of plant life. 6.1.3 Through-Thickness Expansion Measurements The Instrumentation Test Program identified that the snap ring borehole extensometer (SRBE) is a reliable instrument that can provide accurate measurements of through-thickness expansion at Seabrook Station. The SRBE uses spring-loaded , expanding snap rings to affix two anchors in a bore hole. A gauge rod of known length is connected to the base anchor (i.e., the deep anchor) and extends to the collar anchor (i.e., the shallow anchor). Expansion of the concrete is determined by using a depth micrometer to measure the distance between the reference surface on the collar anchor and the end of the gauge rod. 6.1.4 Determining Total Through-Thickness Expansion Installation of extensometers provides a means for monitoring expansion from the time that the instrument is installed.

For structural evaluations at Seabrook Station , NextEra must be able to determine the total expansion from original construction. ln the large-scale test programs , material property testing of cylinders and cores representing the test specimens at various levels of ASR development identified that modulus of elasticity is a sensitive and repeatable indicator of through-thickness expansion.

MPR-4153 (Reference 2.6) provides a methodology for using this observation to enable Seabrook Station to determine total through-thickness expansion , as follows:

• Determine the current elastic modulus of the concrete by material property testing of cores removed from the s tructure at the extensometer location.

• Establish the original elastic modulus by either (1) using the ACI 318-71 correlation to calculate elastic modulus from the 28-day compressive strength records , or (2) obtaining cores from representative ASR-free locations and testing for elastic modulus.

• Calculate the reduction in elastic modulus by taking the ratio of the current elastic modulus of the ASR-affected area to the original elastic modulus.

• Determine through-thickness expansion from original construction to the time the extensometer is installed using an empirical correlation.

The correlation relates reduction in elastic modulu s with measured expansion from test specimens used during the large-scale ASR structural programs.

The recommended method in MPR-4153 applies a reduction factor of-to the elastic modulus ratio , which results in a conservatively high calculation of pre-in s trument expan s ion. MP R-4 273 R ev i sio n 0 6-2

--Non-Proprietary Version--* Calculate total expansion by adding the extensometer measurements to the expansion at the time of instrument installation.

6.1.5 Recommendations for Implementation Exec ution of a multi-year larg e-scale test program to support evaluation of A SR-affected reinforced concrete structures is unique in the nuclear industr y in purpose , scale, and methodology. Application of the results of the FSEL test programs requires that the test spec imens be representative of reinforced concrete at Seabrook Station, and that expansion behavior of concrete at the plant be similar to that observed in the test specimens.

Test specimen design addressed representativeness of the test specimens, and promoted expansion behavior consistent with the plant (e.g., u se of two-dimensional reinforcement mats). To confirm that expansion behavior at Seabrook Station is similar to the FSEL test specimens, MPR recommends that NextEra perform checks to ensure that expansion behavior at Seabrook Station is similar to expansion behavior of the FSEL test specimens, as follows:

• Inspect cores obtained for determining through-thickness expansion for mid-plane cracks. As discussed in Section 4.2.3 , the test specimens did not exhibit large cracking betwe e n the reinforcement mat s away from th e specimen edges.

• Perform routine inspections of through-thickness and in-plane expansion and compare results to the limits of the test program. Application of the test results be yo nd the limits of the test program would require further evaluation.

• Periodicall y compare expansion behavi or trends at Seabrook Station w ith observations t o FSEL test specimens.

Appendix B of this report provides guidelines for the approach and content of these periodic comparisons.

MPR recommends that an initial comparison be performed in the near term after extensometers are installed.

MPR re co mmends follow-up comparisons at least 5 years prior to the Period of Extended Operations (PEO) and every 10 years thereafter

9.

• Two years prior to PEO , remove cores from three locations near extensometers and perform modulu s testing to determine expansion using the methodolog y from MPR-4153.

Compare the re s ult s with the change in through-t hickness expansion observed with the extensometers to provide data corroborating applicability of the MPR-4153 correlation at Seabrook Station. This investigation should select locations wit h pre-instrument expansion in the range of.% to.% (e.g.,.%.%, and.%). 6.2 STRUCTURAL PERFORMANCE This section summarizes the conclusions of the test pro gra ms that can be u se d for structural evaluations.

A companion report (MPR-4288, "Sea brook Station: Impact of Alkali-Silica Reaction on the Structural De sig n Basi s") describes the effect of ASR on the structural design 9 As an example , the PEO wi ll begin in 2030. If the next assessment is performed 5 years prior to P E O in 2025. subsequent assessments wou ld be performed in 2035 and 2045. MPR-4273 R e vi s ion 0 6-3

--Non-Proprietary Vers i on--ba s is of affected s truct:ui-e s at Seabrook Station and pro v ide s guidance for e v aluations of th os e structm*e s_ 6.2.1 Anc h ors a nd Embed m e n ts Result s from the Anchor Te s t Program indicate that there i s no reduction of anchor capacity in ASR-affected concrete with in-plane expan s ion level of le ss than l mm!m. Tue cmTent maximum in-plane expan s i o n ob s erved at Seabrook Station i s considerabl y le s s than this expansion level. Becau s e the two-dimen s ional reinforcement mat s at Seabrook Station s h o uld cause in-plane e x pansion to plateau at relatively low le v els it is unlikely that ASR will cause expansion of l rmn!m. In-plane expansion due to ASR create s microcracks parallel to the axis of an anchor , which are most pronom1ced in the concrete co v er. The s e microcracks that open perpendicular to the concrete surface have the p o tential to provide a preferential failure path within a potential breakout cone leading to degraded anchor perfonnance. Con v ersel y , through-thickne ss expansion ha s the potential to create microcrack s perpendicular to the a x i s of an anchor. The s e potential microcracks that open parallel to the concrete smface do not provide a preferential failure path to re s ult in degr a ded anchor performance. Test re s ults confumed that anchor pe1fo11113nce w a s in s ensiti ve t o through-thickne ss expa ns ion of up to abou l%-Accordin g l y .MPR recommends in-plane expan s ion (e.g. via CCI) a s the monitored parameter fo r a s ses s ing anchor pe1formance. 6.2.2 S h ea r Performance Re s ults from the Shear Te s t Pr o gram indicate that the re i s no reduction of shear capacity in ASR-affected concrete with thr o ugh-thickne ss expans i on which i s the maximum expan s ion level exhibited by the te s t s pecimen s. Tue llllAS R-affected te s t specimens (total te s t s) were all capable of reaching their calculated shear strength per ACT 318-71. The te s t re s ult s indicated a repeatable trend that higher levels of ASR re s ulted in higher shear capacity due t o ASR-induced pre s tres s_ For con s ervatism MPR does not recommend taking credit for thi s prestressing as palt of s tructural eva l uation s. While ASR-rela t ed e x pan s ion i s a v olmnetric effect , the Shear Te s t Program u s ed through-thickne ss expansion a s the monitored parameter repre s enting ASR de g radation becau s e in-plane expan s ion plateaued at relatively low le v els (approximately JI%). 6.2.3 Re i nforcement Anchorage Re s ult s from the Reinforcement Anchorage Te s t Program indicate that there i s no reduction in the performance of reinforcement lap splice s in ASR-affected concrete with through-thicknes s expansion l e v el s up to*% which i s the ma x immn e x pan s ion le v el exhibited by the te s t s pecimen s_ Tue eight .As'R-affected te s t s pecimen s were all capable of reaching their calculated flexural s trength per ACI 318-71 , and the yield and bendin g moment s were relatively in s en s itive to the le v el of ASR-induced e x pan s ion. MPR-4 273 R evisio n 0 6-4

--Non-Proprietary Version--Consistent w ith the Shear Test Program , through-thickness expansion was used to monitor ASR degradation in the reinforcement anchorage test specimens because in-plane expansion pl atea ued at relatively low levels. 6.2.4 Flexural Stiffness While progression of ASR in the reinforcement anchorage test specimens did not imp act the yield or ultimate flexural capacity of the test specimens, there was a notable change in the stiffness, characterized by a decrease in deflection at yield. Key observations on the changes in flexural st i ffness included the fol lowin g:

• The service level flexural stiffness is the value commonly used in reinforced concrete structural evaluations and is referred to as the cracked concrete stiffness.

Modern design codes (ACI 318-11) al l ow the flexural stiffness of cracked beams and wa ll s due to service l oads to be taken as 0.35 times the nominal stiffness (EI). The test program results indicated that all ASR-affected test specimens exceeded this stiffness value.

• The flexural stiffness of the ASR-affected specimens was l ess than that of the control test specimen at l oads l ess than I% of the l oad at which the test specimen yielded. The reduction is attributed to the presence of numerous ASR-induced cracks in the test specimen prior to the application of the l oad during the structural tests.

• The fle x ural stiffness between the onset of flexural cracking and flexural yielding was observed to be greater in the ASR-affected test specimens compared with the control test specimen and showed a generally increasing trend with the increase in ASR-related expansion at the time of structura l test. The increased stiffness with the progression of ASR i s attributable to the ASR-induced prestressing in the test specimens. The impact on se ismic performance resulting from these differences in flexural stiffness wi ll be evaluated as part of the companion report (MPR-4288).

6.2.5 Use of Structural Test Program Results Applicability to Site Structures Results of the MPR/FSEL test program are genera ll y app li cable to all reinforced concrete structures at Seabrook Stat i on, which have similar reinforcement configurations and concrete mixture designs. This approach was corroborated by material property testing of the various test specimens for the MPR/FSEL test programs , which had minor differences in reinforcement ratio and number of st irrup s on specimen ends , and were fabricated from different concrete batches (a lthou gh the mix designs were comparab l e). Observed material properties exhibited a consistent relationship between aging and expans ion across the var i ous beam designs , which suggests that the aging mechanism is insensitive to the specific boundary conditions of a particular specimen design. This conclusion supports application of structura l performance results from the l arge-sca l e test programs to the range of structures at Seabrook Station. Interpretation of Threshold Values The large-scale test program results provide threshold values for which ASR has no effect on the respective limit state. These values reflect the extent of ASR development that was achieved as MPR-4273 R ev i s ion 0 6-5

--Non-Proprietary Version--part of the test program s; they do not repre se nt limits above which ASR has a deleterious effect. Expansion at Seabrook Station is currently well below these threshold values. If expansion approaches the threshold values, NextEra ma y perform additional research to justify structural adequacy beyond the ASR development levels evaluated in the MPR/FSEL large-scale test programs.

6.2.6 Retrofit Testing Proof-of-concept testing for potential retrofits provided insights that would have supported subsequent qualification testing of retrofits on A SR-affected test specimens for shear and reinforcement anchorage.

However , because the test specimens did not exhib it any degradation in structural performance , the retrofits were not tested on ASR-affected specimens.

lf ASR-related expansion at Seabrook Station approaches the maximum expansion identified in the test programs and additional actions are necessary to justify structura l adequacy, NextEra may pursue follow-up testing of the retrofit s to demonstrate their efficacy in A SR-affected concrete.

MPR-4273 R e vi s ion 0 6-6 _J

--Non-Proprietary Version--7 References I. Publicly Available Literature 1.1. Un it ed States Nuclear Regulatory Commission , NRC Information Notice 2011-20 , " Concrete Degradation by Alkali-Silica Reaction ," November 18 , 2011. (ADAMS Accession No. ML112241029) 1.2. Institution of Structural Engineers , " Structural Effects of Alkali-Silica Reaction:

Technical Guidance on the Appraisa l of Existing Structures

," London , UK , 1992. 1.3. Fournier , B. et al , FHWA-H IF-09-004.

" Report on the Diagnosis , Prognosis , and Mitigation of Alkali-Silica Reaction in Transportation Structures

," January 2010. 1.4. Ahmed , T., Burley , E., and Ridgen , S., " The Static and Fatigue Strength of Reinforced Concrete Beams Affected by A lk ali-Si lica Reaction ," ACJ Materials Journal Vol. 95 No. 4 (1998): 356-368. I .5. Deschenes , D., Bayrak , 0., and Folliard , K., " ASR/DEF-Damaged Bent Caps: Shear Tests and Field Implications

," Technical Report No. 12-8XXlA006 , Center for Transportation Research , University of Texas at Austin , August 2009. 1.6. Chana , P., and Korobokis, G., " Structural Performance of Reinforced Concrete Affected by Alka li Silica Reaction:

Phase 1," Transport and Road Research Laboratory , Contractor Report 267, October 1990. 1.7. Collins, M. and Kuchma , D., " How Safe Are Our Large , Lightly Reinforced Concrete Beams , Slabs , and Footings?", ACI Structural Journal , July-August 1999 , pp. 482-491. 1.8. den Uijl, J., and Kaptijn , N., " Structural Consequences of ASR: An Example of Shear Capacity ," Heron Vol. 47 No. 2 (2002): 125-139. 1.9. Chana , P., " Bond Strength of Reinforcement in Concrete Affected by A l ka li-Silica Reaction ," Crowthorne:

Transport and Road Research Laboratory, Department of Transport , 198 9 , Contractor Report 141. 1.10. ACI Committee 408, " Bond and Development of Straight Reinforcing Bars in Tens i on ," (ACJ 408R-03), Farmington Hills: American Concrete Jnstitute , 2003. 1.11. Smaoui , N., Bissonnette , B., Berube , M., and Fournier , B., " Stresses Induced by Silica Reactivity in Prototypes of Reinforced Concrete Columns Incorporating Variou s Types of Reactive Aggregates

," Canadian Journal of Civil Engineering , Volume 34 , 2007. MPR-4 2 7 3 R e v i s io n 0 7-1

--Non-Proprietary Version--1.12. Reineck , K., Bentz , E., Fitik , B., Kuchma , D., and Bayrak 0., " The ACI-DAfstb Database of Shear Tests on Slender Reinforced Concrete Beams without Stirrups , ACI Structural Journal , Vol. 110 , No. 5 September

-October 2013 , pp. 867-875. 1.13. ORNL/NRC/LTR-95/14, " In-Service Inspection Guidelines for Concrete Structures in Nuclear Power Plants , December 1995. I .14. Chen , W., " Plasticity in Reinforced Concrete ," J. Ross Publishing, Fort Lauderdale , 2007. 2. Seabrook Station Documentation 2.1. MPR-3727, " Seabrook Station: Impact of Alkali-Silica Reaction on Concrete Structures and Attachments

, Revision 1. (Seabrook FP# 100716) 2.2. Bayrak , 0., " Structural Implications of ASR: State of the Art ," July 2014 (Seabrook FP# 100697). 2.3. Public Service Company ofNew Hampshire letter , dated Jan. 3, 1980 , to NRC Region I , Office oflnspection and Enforcement (response to NRC IE Bulletin 79-02 , " Pipe Support Base Plate Designs Using Concrete Expansion Anchor Bolts , Revision 2, November 8 , 1979). 2.4. MPR Document 0326-0058-165, " Approach to Measuring Cracks due to Alkali-Silica Reaction in Concrete Test Specimens ," Revision 0. 2.5. NextEra Energy letter SBK-L-15202 , dated December 3 , 2015, "Response to Request s for Additional Information for the Review of the Seabrook Station , License Renewal Application

-SET 25 (TAC NO. ME4028) Re l ating to the Alkali-Silica Reaction (ASR) Monitoring Program." (MLl 5343A470 in NRC ADAMS Database.) 2.6. MPR-4153 , " Seabrook Station -Approach for Determining Through-Thickness Expansion from Alkali-Silica Reaction ," Revision 2. (Seabrook FP# 100918) 3. Planning Documents for MPR/FSEL Test Programs 3.1. MPR Document 0326-0058-26 , " Specification for Strength Testing of Attachments in ASR-Affected Concrete," Revision 7. 3.2. MPR Document 0326-0062-05 , " Specification for Shear and Reinforcement Anchorage Testing of ASR-Affected Reinforced Concrete ," Revision 10. 3.3. MPR-3757 , " Shear and Reinforcement Anchorage Test Specimen Technical Evaluation

, Revision 4. (Seabrook FP# 100760) MP R-4273 R evis i o n 0 7-2

--Non-P r o prietary Version--4. Te s t Reports for MPR/FSEL Test Programs 4.1. MPR-3722 , " Strength Testing of Anchors in Concrete Affected by Alkali-Silica Reaction ," Revision 2. (Seabrook FP# 100718) 4.2. MPR-4262 , " Shear and Reinforcement Anchorage Testing of Concrete Affected by Alkali-Silica Reaction ," Volume I , Revision 1 & Volume II , Revision 0. (Seabrook FP# 100994) 4.3. MPR-4231, " Instrumentat i on for Measuring Expansion in Concrete Affected by Alkali-Silica Reaction ," Revis i on 0. (Seabrook FP# 100972) 5. Commercial Grade Dedication Report for MPR/FSEL Test Programs 5.1. MPR-3726, " Commercial Grade Dedication Report for Seabrook ASR Anchor Testing," Revision 0. (Seabrook FP# 100719) 5.2. MPR-4247 , " Commercial Grade Dedication Report for Seabrook ASR Anchor Testing (Block Series and Girder Series Phase 2)," Revision 0. (Seabrook FP# 100986) 5.3. MPR-4259, " Commercial Grade Dedication Report for Seabrook ASR Shear , Re i nforcement Anchorage, and Instrumentation Testing ," Revision 0. (Seabrook FP# 100995) 5.4. MPR-4286, " Supp l ementa l Commercial Grade Dedication Report for Seabrook ASR Test Programs ," Revision 0. (Seabrook FP# 10 I 003) 6. Documentation for Information Only Testing at FSEL 6.1. Letter from FSEL (Bayrak) to MPR (Simons), " Morgan Therese Allford's Research ," dated April 21 , 2016. 6.2. Be i ter , K., "Retrofit of Deficient Lap Sp li ce with Post-Insta ll ed Anchors ," University of Texas at Austin , December 2015. 6.3. Dandrea , A., " Undercut and Grouted Anchors as Post-Installed Shear Reinforcement

," University of Texas at Austin, August 2014. 6.4. Dassow , N., " Effect of Uniform Load on the Shear Strength of Slender Beams w i thout Shear Reinforcement

," University of Texas at Austin , August 2014. 6.5. K l ein , J., " Behavior of Slender Beams without Stirrups:

Effects of Load Distribution and Member Depth ," University of Texas at Austin , December 2015. MPR-4 273 Rev i s i on 0 7-3

--Non-Proprietary Version--A Test Specimens This appendix provide s photographs , diagrams, and drawings for the te st s pe c imen s u se d in the Anc h or, Shear , Reinforcement Anchorage , and Instrumentation Test Programs. (References 4.1 , 4.2 , & 4.3) MPR-4273 R ev i sion 0 A-1 MPR-4273 Re v i sio n 0 --Non-Pr oprietary Ve r sion--Figure A-1. Photo of G i rder Series Anchor Test Specimen Figure A-2. Photo of Block Series Anchor Test Specimen with Anchors Installed A-2 MP R-4273 R.n iYoaO --Non-Proprietary Version--Figure A-3. Diagram of Block Series Anchor Test Spec i men Sho win g Re i nforcement A-3 MPR-4273 Revision 0 --Non-Proprietary Version--Figure A-4. Diagram of 24-lnch Shear Test Specimen Showing Reinforcement A-4 MPR-4273 R ev i s i o n 0 --Non-Proprietary Version--Figure A-5. Diagram of Reinforcement Ancho r age Test Specimen Showing Reinforcement A-5 MPR-4 273 RcvisiooO

--Non-Proprietary Version--Figure A-6. Diagram of Instrumentation Test Spec i men Sho wi ng Re i nforcement (Elevation V i e w) Figure A-7. Diagram of Instrumentation Test Spec i men Sho w ing Reinforcement (Plan V i e w) A-6

--No n-Proprietary Version--B G ui delines for P e riodic Expans io n Behavior C he ck 1. P U RPOS E This appendix provides guidelines for performing periodic checks of observed expansion behavior at Seabrook Station to confirm that expansion behavior is consistent with FSEL test specimens.

2. BACKGROUND Application of the result s of the FSEL test programs requires that the test specimens be representative of reinforced concrete at Seabrook Station , and that expansion behavior of concrete at the plant be similar to that observed in the test specimens.

Test specimen design addressed representativeness of the test specimens, and promoted expansion behavior consistent with the plant (e.g., use of two-dimensional reinforcement mats). To confirm that expansion behavior at Seabrook Station is similar to the FSEL test specimens , MPR recommends (in Section 6.1.5) that NextEra perform periodic checks of expansion behavior at Seabrook Station and compare observations from the MPR/FSEL test programs.

MPR recommends that an initial check be performed in the near term after extensometers are installed , and follow-up checks were recommended at least 5 years prior to the Period of Extended Operations (PEO) and every 10 years thereafter

3. CHECK 1 -R E VIEW OF CORES FOR MID-PLANE CRACKING As recommended in Section 6.1.5, NextEra should inspect cores for mid-plane cracks upon removal of the core. As part of the periodic check of expansion behavior , NextEra should review documentation of all cores obtained more recent than the last periodic check for any trends in observation of mid-plane cracks. Such a trend would be unexpected and would prompt an evaluation to determine appropriate follow-up actions. 4. CHECK 2 -EXPANSION RELATIVE TO TEST PROGRAM LIMITS The FSEL test programs included structural testing of reinforced concrete specimens with a range of ASR development.

The conclusions of the test program are applicable to reinforced concrete at Seabrook Station that is within the range of ASR development tested at FSEL. Specifically , the limit s of ASR development eva luat ed by FSEL testin g in c lud e the following:

• Shear.% through-thickness expansion MPR-4273 R ev i s ion 0 B-1

--Non-Proprietary Version--* Reinforcement Anchorage

-*% through-thickness expansion

• Anchor Capacity -lmm/m .%) in-pl ane expansion Routine monitoring of ASR-affected locations will id entify if the observed expansion at Seabrook Station exceeds these limits , and would necessitate a locati on-spec ifi c structura l evaluation.

As part of the periodic check , MPR recommends that NextEra determine the potential for future expansion to exceed the te s t program limits. This review of margin to the test program limits may be performed by considering the " expansion rate" observed over a series of measurements and the projected time to reach the test program limit s. If such projections indi cate that the limit s may be exceeded prior to the next periodic check , NextEra should further investigate the location(s) in question or develop contingency plans for extend in g the expansion limit (e.g., supplemental testing).

5. CHECK 3 -VOLUMETRIC EXPANSION The limits provided in Check 2 foc u s on expansion in the direction of interest for each limit state (i.e., through-thickness for shear and reinforcement anchorage; in-plane for anchor capacity).

This approach is simple and easy to implement.

While test data show that restraint of ASR expansion in one direction does not sign ifi cantly increase expa n sion in unrestrained directions (Reference 6.1 ), potential volumetric effects sho uld be addressed conservatively.

As part of the periodic assessment of expansio n behavior , MPR recommends that NextEra determine the volumetric expansion of the monitored locations at Seabrook Station and compare the results to the FSEL test spec imen s. Volumetric strain is determined by adding the observed strain in each of the three directions (Reference 1.14), as fo ll ows: Where: Ev= volumetric stra in E 1 =principal strain (e.g., in the length direction)

E 2 =principal stra in (e.g., in the height direction)

E 3 =principal strain (e.g., in the depth direction)

For the parameters monitored at Seabrook Station , this equation can be re-written , as fol l ows: E v = 2 X (0.1 X CCI) + ETI Where: MPR-4 2 7 3 R ev i s ion 0 Ev= vo lum etric strain , % CCJ = combined cracking index , mm/m ETI = through-thickness expan s ion , % B-2

--Non-Proprietary Version--Using thi s expression for the FSEL test specimens, the ma x imum volumetric expansion of a shear test specimen was.% and the maximum volumetric expansion of a reinforcement anchorage test specimen was.%. MPR recommends a check criterion of.% for volumetric expansion to confirm that the FSEL test data bound s the observed expansion at Seabrook Station in terms of volumetric expansion. Figure B-1 is a chart illustrating this check criter i on. Fig u r e B-1. V o lumetric E xp a nsi on Check Cr i terion Note that th e anchor capacity criterion of l mm/m i s bounded by the check criterion in Figure B-1. If all of the.% volumetric expansion were in the in-plane direction , the CCI would only be.mm/m. MPR recommends that NextEra evaluate any locations exhibiting expansion that exceeds the .% volumetric expansion check criterion.

NextEra should also consider the potential for future vo lumetric expansion to exceed the check criterion illustrated in Figure B-1. Similar to the approach for Check 2, this review of margin to the criterion may be performed by considering the "expa nsion rate" determined over a series of mea s urement s and the projected time to reach the volumetric expansion criterion.

If such projection s indicate that the criterion may be exceeded prior to the ne x t periodic check, NextEra shou l d perform an engineering evaluation to determine appropriate follow-up action. MPR-4273 Revi s ion 0 B-3

--Non-Propriet a ry Version--6. CHECK 4 -EXPANSION DIRECTION For the FSEL test specimens , the rate of ex i nsion was the same in all three directions until expansion reached.% to % (i.e., I to 1 mm/m). Thereafter, the FSEL test specimens exhibited much greater expansion in the through-thickness direction than the i n-plane d i rections. These observations led to a conclusion that in-plane monitoring by crack width summation (i.e., CCI) sufficiently characterizes ASR development until at least.% expansion (i.e., l mm/m), after which through-thickness monitoring is required to track further ASR expansion.

NextEra has installed extensometers in selected locations where in-plane expansion is less than l mm/m. For locations where NextEra has installed an extensometer, MPR recommends that NextEra check the trend for expansion direction as a confirmation of consistency with the expansion behavior observed in the FSEL test program. NextEra has installed severa l extensometers in l ocations where in-p l ane expansion is l ess than 1 mm/m. This provides the opportunity to check consistency of expansion behavior over the entire range exhibited at Seabrook Station. Figure B-2 is a chart that may be used for analyzing the trend for observed expansion direction at Seabrook Stat i on. MPR-4273 R evisio n 0 Figure B-2. E x pa n s i on Di r ect i on T rend Chart B-4

--Non-Proprietary Version--MPR recommends that NextEra perform an engineering evaluation if the periodic expansion check identifies either of the fol l owing circumstances:

• Any location with CCI less than lmm/m exhibits through-thickness expansion approaching the test program limit (i.e., greater than.%). Such an observation would challenge the premise that an extensometer is not needed for l ocations with a CCI of l ess than lmm/m. The engineering evaluation would focus on the suitability of this criterion.

• The general trend of expans i on behavior at Seabrook Station s i gnificantly departs from the expansion behavior of the FSEL test specimens.

The expected trend at Seabrook Station is that in-plane and through-thickness expansion values wi ll be comparable at l ower expansion l eve l s and eventua ll y transition to predominately through-thickness expansion.

Plotting of expansion data at Seabrook Stat i on onto a chart like Figure B-2 is expected to result in a " cloud" of data that exhibits cons id erab l e variability.

For the FSEL test specimens , the point at which expansion reoriented primarily in the through-thickness direction varied between specimens, which were designed to be essentially identical.

Data from Seabrook Station may exhibit further variability from configuration (e.g., wall thickness) and the confinement associated with deadweight and configuration.

MPR-4273 R ev i s ion 0 B-5