UNITED STATES

NUCLEAR REGULATORY COMMISSION 

WASHINGTON, D.C. 20555-0001 

October 2, 2015 

Mr. Dean Curtland 

Site Vice President 

Seabrook Station NextEra Energy 

626 Lafayette Road 

Seabrook, NH 03874 

SUBJECT: REQUEST FOR ADDITIONAL INFORMATION RELATED TO THE REVIEW OF 

THE SEABROOK STATION LICENSE RENEWAL APPLICATION – SET 25 

(TAC NO. ME4028) 

Dear Mr. Curtland: 

By letter dated May 25, 2010, NextEra Energy Seabrook, LLC submitted an application 

pursuant to Title 10 of the Code of Federal Regulations Part 54, to renew the Operating License 

NPF-86 for Seabrook Station, Unit 1, respectively. The staff of the U.S. Nuclear Regulatory 

Commission (NRC or the staff) is reviewing the information contained in the license renewal 

application and has identified, in the enclosure, areas where additional information is needed to 

complete the review. 

The request for additional information was discussed with Mr. Edward Carley, and a mutually 

agreeable date for the response is November 30, 2015. If you have any questions, please 

contact me at 301-415-1427 or by e-mail at Richard.Plasse@nrc.gov. 

Sincerely, 

/RA/ 

Richard Plasse, Project Manager 

Projects Branch 1 

Division of License Renewal 

Office of Nuclear Reactor Regulation 

Docket No. 50-443 

Enclosure: 

Requests for Additional Information 

cc: Listserv 
October 2, 2015 

Mr. Dean Curtland 

Site Vice President 

Seabrook Station NextEra Energy 

626 Lafayette Road 

Seabrook, NH 03874 

SUBJECT: REQUEST FOR ADDITIONAL INFORMATION RELATED TO THE REVIEW OF 

THE SEABROOK STATION LICENSE RENEWAL APPLICATION – SET 25 

(TAC NO. ME4028) 

Dear Mr. Curtland: 

By letter dated May 25, 2010, NextEra Energy Seabrook, LLC submitted an application 

pursuant to Title 10 of the Code of Federal Regulations Part 54, to renew the Operating License 

NPF-86 for Seabrook Station, Unit 1, respectively. The staff of the U.S. Nuclear Regulatory 

Commission (NRC or the staff) is reviewing the information contained in the license renewal 

application and has identified, in the enclosure, areas where additional information is needed to 

complete the review. 

The request for additional information was discussed with Mr. Edward Carley, and a mutually 

agreeable date for the response is November 30, 2015. If you have any questions, please 

contact me at 301-415-1427 or by e-mail at Richard.Plasse@nrc.gov. 

Sincerely, 

/RA/ 

Richard Plasse, Project Manager 

Projects Branch 1 

Division of License Renewal 

Office of Nuclear Reactor Regulation 

Docket No. 50-443 

Enclosure: 

Requests for Additional Information 

cc: Listserv 

DISTRIBUTION: 

See next page 

ADAMS Accession No.:ML15251A333 *Concurred via e-mail 

OFFICE LA:RPB1:DLR* PM: RPB1:DLR BC:RPB1:DLR PM: RPB1:DLR 

NAME YEdmonds RPlasse YDiaz-Sanabria RPlasse 

DATE 9/ 21 /15 10/ 01 /15 10/ 2 /15 10/ 2 /15 

OFFICIAL RECORD COPY
 ENCLOSURE 

SEABROOK STATION, UNIT 1

LICENSE RENEWAL APPLICATION

REQUEST FOR ADDITIONAL INFORMATION SET 25

B.2.1.31A-8: Addressing Recent Operating Experience 

Background: 

The regulation in 10 CFR 54.21(a)(3) requires applicants to demonstrate that the effects of 

aging will be adequately managed so that intended functions will be maintained consistent with 

the current licensing basis during the period of extended operation. 

LR-ISG-2011-05 “Ongoing Review of Operating Experience” recommends that Aging 

Management Programs (AMPs) be informed and enhanced when necessary through the 

systematic and ongoing review of both plant-specific and industry operating experience (OE), as 

discussed therein. The mark-up in LR-ISG-2011-05 for Section A.1.2.3.10 “Operating 

Experience” of SRP-LR Appendix A.1 “Aging Management Review – Generic (Branch Technical 

Position RLSB-1)” states, in part: 

Consideration of future plant-specific and industry operating experience relating 

to AMPS should be discussed. The ongoing review of operating experience may 

identify areas where AMPs should be enhanced or new AMPs developed. As 

such, an applicant should ensure that it has adequate processes to monitor and 

evaluate plant-specific and industry operating experience related to aging 

management to ensure that the AMPs are effective in managing aging effects for 

which they are credited. The AMPs are informed by this review of operating 

experience on an ongoing basis, regardless of the AMP’s implementation 

schedule. The ongoing review of operating experience information should 

provide objective evidence to support the conclusion that the effects of aging are 

managed adequately so that the structure- and component-intended function(s) 

will be maintained during the period of extended operation. 

LR-ISG-2011-05 also states that “Currently available operating experience applicable to new 

programs should also be discussed. ... Thus, when developing the elements for new 

programs, an applicant should consider the impact of relevant operating experience from 

implementation of its existing AMPs and from generic industry operating experience.” 

As documented in Seabrook Station, Unit No. 1 – Integrated Inspection Report 

05000443/2015002 (Agencywide Documents Access and Management System (ADAMS) 

Accession No. ML15217A256), Seabrook Station has recently discovered operating experience 

in structures affected by alkali-silica reaction (ASR), as described below, that may be potentially 

attributable to aging effects causing global bulk expansion of concrete. The report indicates that 

the applicant’s evaluation of the degraded conditions confirmed that the identified deformation is 

due to bulk expansion from long-term cumulative effects of ASR and strain associated with 

creep.
 - 2 - 

 

During walkdown of plant structures, and from NRC Inspection Reports 05000443/2015002, 

05000443/2014005 (ADAMS Accession No. ML15037A172), 05000443/2014003 (ADAMS 

Accession No. ML14212A458), and 05000443/2014009 (ADAMS Accession No. 

ML14349A751), the NRC staff noted the following: 

• Relative deformation (differential movement) of the Containment Enclosure Building (CEB) 

indicated by changes in the 3-inch seismic gaps or annulus gap between adjacent 

structures, damaged fire seals, misalignment of conduits/piping at penetrations or between 

adjacent structures, deformed flexible conduit couplings, bent small pipes/conduits and 

supports, etc. 

• Discrete wide horizontal cracking, spalling, doorway misalignments etc., in the Residual 

Heat Removal (RHR) and Containment Spray (CS) Vault. 

• Cracking, displacements or other indications of structural conditions adverse to quality 

associated with the Fuel Storage Building (FSB). 

The applicant’s response to RAI B.2.1.31A-5(a), by letter dated June 30, 2015, includes 

changes to the “parameters monitored or inspected,” “monitoring and trending,” and 

“acceptance criteria” program elements of the ASR Monitoring Program in License Renewal 

Application (LRA) Section B.2.1.31A, with qualitative descriptions for “monitoring building 

deformation” and a related new Commitment No. 91 which states: “In building geometry 

locations where the potential for deformation is likely, enhance the program to monitor for 

building displacement using laser targets and by taking gap measurements.” The 

implementation schedule for Commitment No. 91 is described as “within 10 years prior to the 

period of extended operation.” 

Issue: 

Regarding aging management of structure and component as they relate to the ASR Monitoring 

Program or the Structure Monitoring Program or both, the wording in the applicant’s response to 

RAI B.2.1.31A-5(a) appear to be unclear, relative to (a) monitoring building deformation, (b) the 

corresponding Commitment No. 91, and (c) implementation schedule (the descriptions in the 

response and new Commitment No. 91 appear to address the recently discovered operating 

experience related to the CEB). The staff identified the following concerns: 

• The applicant’s response does not include an update to the “Operating Experience” program 

element of the ASR Monitoring Program describing the review and evaluation of the cause 

and impact of any of the relevant recent operating experience, described in the 

“Background” section and other operating experience (if any), to determine how the AMP 

will be affected or new AMPs developed to ensure adequate aging management. The 

“Operating Experience” program element of the revised AMP appears to be incomplete in 

addressing the recent potentially ASR-related operating experience. 
 - 3 - 

 

• The AMP does not appear to provide information that “commits” ongoing and future review 

of all relevant plant-specific and industry operating experience related to ASR as is 

recommended in LR-ISG-2011-05 for Section A.1.2.3.10 “Operating Experience” of SRP-LR 

Appendix A.1 “Aging Management Review – Generic (Branch Technical Position RLSB-1). 

• It is not clear whether global aging effects of ASR such as potentially irreversible 

deformation, relative movement, displacements, or wide discrete cracking that manifests in 

the global direction of least restraint at the structural system level (as opposed to the 

structural component level) are addressed in the large-scale testing program that is being 

used to form the basis for structural functionality through the period of extended operation. 

It is also not clear if the applicant plans to address the global behavior of the structure by 

nonlinear analyses that simulate the kinetics of ASR. 

• Though the applicant stated that it will monitor building deformation aging effect by 

monitoring critical building geometry locations “for displacement via laser targets and gap 

measurements,” it is not clear (i) whether the observed indications are irreversible 

deformations (ii) what acceptance criteria the applicant has determined to be appropriate in 

terms of gap measurements to detect damage prior to a loss of intended function, (iii) how a 

structural evaluation would be performed, and (iv) how the results of the evaluation will 

affect the program. 

• It is not clear that the applicant has fully characterized the phenomena observed in the 

recent operating experience and its implications to the current design basis in terms of 

impact to original calculations, etc. Although the applicant performed a temporary “prompt 

operability determination” (POD) that structures have been determined operable under the 

current operating license, the staff has not received any information to support a basis for 

long term functionality of affected structures and structural systems. Information is needed 

with regard to the current and long-term effects of this recent OE, for the staff’s review. 

• The revised program appears only to address differential lateral movement between 

structures observed in areas such as the containment enclosure ventilation area slab-to-wall 

interface. It does not appear to address other recently identified operating experience of 

large horizontal cracks in the RHR vault and indications in the FSB. It is not clear whether 

these issues have been evaluated to be related, if there has been an evaluation to 

determine the mechanism and structural implications of large macro cracking in these areas, 

as well as any impact on aging management of those structures. It is also not clear whether 

there has been an evaluation to determine if rebar has yielded in these areas, how during or 

prior to the period of extended operation rebar yielding would be considered and/or 

evaluated, and the implications for service through the period of extended operation. 
 - 4 - 

 

• It is not clear if all potential aging effects of the ASR mechanism have been identified for 

monitoring in the AMP, including, but not limited to, those that involve irreversible 

deformation, relative movement, displacement, and discrete cracking. 

• The applicant’s response to RAI B.2.1.31A-5(a) asserts that the observed building 

deformation is not a structural capacity concern but does not provide any supporting basis. 

Commitment No. 91 does not appear to consider the basis for service through the period of 

extended operation for the CEB structures, and does not provide information for staff to 

evaluate the adequacy of this statement. Further, the intent of the wording of the 

implementation schedule for the commitment is unclear and, as written, conveys that it will 

be implemented during the 10-year period prior to the period of extended operation. It is not 

clear how the timeliness of this commitment would ensure adequate management of aging 

effects of ASR at the global structure (structural system) level for the period of extended 

operation. 

The staff does not have sufficient information to determine whether aging effects of ASR from 

the recent operating experience have been adequately evaluated and incorporated into the 

AMP to provide adequate aging management during the period of extended operation. 

Request: 

The staff requests information for resolution of the issues in the issue section. 

1) Describe, including technical basis, how the appropriate program elements of the ASR 

Monitoring Program, the Structures Monitoring Program, or other applicable AMP will 

adequately account for all relevant recent plant-specific operating experience described in 

the “Background” section, to address the concerns described in the “Issues” section. The 

information should provide objective evidence to support the conclusion that the aging 

effects of ASR will be managed adequately such that structure- and component-intended 

functions will be maintained during the period of extended operation. The information 

should also include an update to the “operating experience” program element to describe 

the recent operating experience in sufficient technical detail. 

2) If the applicant determines that no modifications or enhancements to the ASR Monitoring 

Program, the Structures Monitoring Program, or other applicable AMP are necessary based 

on the operating experience described as Issue items 1 and 2, explain, with sufficient 

technical detail, the basis for that determination. 

3) Update the LRA program elements and Updated Final Safety Analysis Report (UFSAR) 

supplement, as applicable, based on the response. To facilitate efficient staff review, 

provide the updated ASR Monitoring Program and associated UFSAR supplement, in its 

entirety. 
 - 5 - 

 

B.2.1.31A-5(a1): Justify Representativeness of Large-scale Test Data to Actual Structure 

Background: 

SRP-LR, Section A.1.2.3.3, states that the “parameters monitored or inspected” program 

element should provide a link between the parameters that will be monitored and how 

monitoring these parameters will ensure adequate aging management. 

In its response to RAI B.2.1.31A-5(a), dated June 30, 2015, the applicant included as 

Enclosure 4 the report MPR-4153, Revision 1, “Seabrook Station – Approach for Determining 

Through-Thickness Expansion from Alkali-Silica Reaction (Proprietary)” as the technical basis 

for the proposed methodology to quantitatively relate the observed ASR effects in existing plant 

structures at Seabrook Station to the results of the large-scale test program at the Ferguson 

Structural Engineering Laboratory (FSEL). Chapter 2 of this document discusses expansion 

behavior in the test specimens, including formation of a large discrete crack on each specimen 

face between the reinforcement mats. The propagation of this crack dominates the 

through-thickness expansion measurements on the surface, whether measured between the 

deep pins or across the width, and causes bending of the deep pins. Section 2.2.1 of the report 

states that “Once the large crack forms, expansion measured using the embedded rods is 

governed by the increase in crack width. Expansion in the regions outside the embedded rods 

remains relatively unchanged. Therefore, expansion must be calculated based on the total 

width of the beam, rather than the distance between the rods, to appropriately characterize the 

expansion.” Section 5.2 of calculation 0326-0062-CLC-03 appended to the report includes an 

expansion measurement correction equation (from Reference 21 of the report). This equation is 

based on average measured through-thickness expansions across the total width using 9 sets 

of measurements across the breadth, intended to correct and appropriately characterize the 

expansion measured between the pins. 

With regard to correlation between strain measurements in large-scale test beams versus 

Seabrook structures, the boundary conditions of the large scale test beams are such that they 

are free to expand at the top, bottom and all edges, causing a large crack to form in the center 

of the beam thickness around the perimeter. Currently it appears that the applicant is using 

deep pin measurements taken at the free edge of the concrete (with a correction) to determine 

total expansion (and using this total expansion as a surrogate for strain). 

The applicant indicated in its revised ASR Monitoring Program “Monitoring and Trending” 

program element that ASR expansion-to-date on Seabrook structures will be determined by 

directly comparing the reduction in elastic modulus (normalized modulus) on the structure to a 

correlating relationship between through-thickness expansion and reduction in elastic modulus 

and through-thickness expansion developed based on measured data on the large-scale 

specimens. 
 - 6 - 

 

Issue: 

It is not clear if the expansion measured on the test specimens is representative of ASR 

expansion and its potential effects on Seabrook structures to which the test results will be 

applied for reasons below: 

1) Expansion measured on test beams may be overestimated: ASR expansion at Seabrook is 

occurring in walls that are restrained at the four boundary edges, whereas the large-scale 

specimens with free edges have large cracking at the top and bottom that do not extend 

through the depth of the concrete. As indicated in Reference 21 to MPR-4153, this large 

cracking along the middle of the width is an edge effect unique to the design of the test 

specimen that may not be representative of Z-direction expansion of the entire specimen, 

and this effect is not likely to occur in actual structures with different restraints at the 

boundary. Even though the applicant stated that there is correction accounting for the crack 

by normalizing the expansion along the entire thickness of the beam as opposed to just 

between the deep pins, it appears that the measured top and bottom “expansions” across 

the width are predominantly a measure of the surface deformation from propagation of the 

wide discrete surface crack developed in the top and bottom faces of the test specimen, and 

the measurements at these two surfaces are possibly outliers, and thus not representative 

of ASR expansion on the specimen. It appears that this methodology would likely result in 

significantly larger measurements in the top and bottom (which the applicant has indicated 

are the areas currently being measured) that could cause the expansion to be inflated 

versus the true through-thickness measurements. Therefore, it is not clear that the throughwall expansion measured from the freely expanding deep pins in the large-scale specimens 

is a true representation of expansion in the through-wall direction for these specimens. The 

expansion measurements used for correlation and comparison to Seabrook appear not to 

have an appropriate correction for this phenomenon, nor is there information to indicate that 

measurements are being taken at the center of the specimen. Thus, it is not clear whether 

the ASR strain measurements in the large-scale specimens are accurate for direct 

comparison. 

Further, it appears that cores taken from the test specimens for measurement of elastic 

modulus at the time of expansion measurement do not traverse the large surface crack; 

therefore, its effect is not captured in the measured elastic modulus used for developing the 

correlation with measured expansion. Therefore, it is not clear whether outlier “expansion” 

measurements (i.e., on the surface with pins) in the large scale specimens can be directly 

associated with elastic modulus reduction of cores taken from the center where the large 

crack and free expansion is not occurring. 

The methodology proposed by the applicant is such that this measured expansion value is 

applied directly to elastic modulus reduction factors (i.e., normalized modulus) which will be 

direct surrogates for expansion to-date in Seabrook structures; it is not clear whether this
 - 7 - 

 

method of measuring expansion will accurately represent Seabrook expansion to date. 

The through-thickness expansions measured on the width of test specimen (even with the 

correction) appears to potentially overestimate the ASR expansion. This measured 

expansion on the specimen may not be conservative in developing the relationship between 

expansion and normalized modulus used to correlate the large scale test data to the actual 

structure and may need to be further corrected. 

2) Boundary conditions of Seabrook structures and components: For the large-scale beam 

test specimens, there is no external restraint and the progression of ASR is likely to be 

relatively more uniform in the specimen because of the significantly aggressive reactive 

material in the concrete mix uniformly distributed through the volume to facilitate accelerated 

expansion. The boundary conditions (constraints at the boundary edges) of the test 

specimens are generally free on all the edges. The test specimens do not appear to 

represent the boundary conditions of the structural components (e.g., walls) and other 

external restraints on Seabrook structures. In addition to internal confinement provided by 

the reinforcement, the boundary conditions of the monolithically constructed structural 

system and components and other external features, such as concrete structural fill in 

below-grade areas, may also provide significant external restraint that influences the overall 

expansion and distribution of aging effects (e.g., cracking) from ASR in the Seabrook 

structures. Further, in the actual structures, ASR results in differential volumetric expansion 

that is initiated and propagated randomly in a non-uniform manner. As a result of these 

boundary conditions, the volumetric expansion (i.e., swelling of the gel) will re-orient in the 

direction(s) of least restraint, which at the component level may be the out-of-plane 

direction, but likely more focused in the more unrestrained surface layers near the 

reinforcement mat; or at the structural system level in the global direction of least restraint 

(e.g., could be vertical or some other dimension). It is not clear whether through-wall 

measurements are fully representative of volumetric expansion. Since the boundary 

conditions are different between the large-scale specimens and the Seabrook walls, 

resulting in potentially different through-wall expansion behavior, the staff needs additional 

information to determine whether through wall measurements as the single monitoring 

parameter are sufficient and a basis for direct comparison of large-scale test specimens to 

Seabrook structures and structural components that are also subject to external restraint. 

3) The descriptions in LRA Sections A.2.1.31A and B.2.1.31A, as revised by applicant’s 

response to RAI B.2.1.31A-5(a), do not appear to include reference to the technical basis 

document(s) (e.g., Report MPR-4153) used by the revised AMP to correlate the large-scale 

test program results to Seabrook structures. 
 - 8 - 

 

Request: 

1) Considering the issues above, provide information, with supporting objective evidence, to 

demonstrate that ASR expansions observed and measured (even after proposed correction) 

on the large-scale test specimens at FSEL are representative of ASR effects on actual 

Seabrook structures, and appropriate for correlation of results between test specimens and 

actual Seabrook structures. 

2) Since ASR results in volumetric expansion that can reorient in direction(s) of least restraint, 

explain why out-of-plane expansion (and not volumetric strain) is considered the appropriate 

parameter to correlate test results to Seabrook structures. 

3) Update the ASR Monitoring Program elements and UFSAR supplement, as applicable, 

based on the response, and also to incorporate by reference the document(s) (e.g., Report 

MPR-4153) used as the technical basis for methodologies used by the AMP to correlate the 

large-scale test program results to Seabrook structures. 

B.2.1.31A-5(a2): Uncertainties and Variations Associated with Estimate of Normalized 

Modulus 

Background: 

In its response to RAI B.2.1.31A-5(a), dated June 30, 2015, the applicant included as 

Enclosure 4 the report MPR-4153, Revision 1, “Seabrook Station – Approach for Determining 

Through-Thickness Expansion from Alkali-Silica Reaction (Proprietary)” as the technical basis 

for the proposed methodology to quantitatively relate the extent alkali-silica reaction (ASR) in 

existing plant structures at Seabrook Station to the results of the large-scale test program at the 

FSEL. Figure 3-3 and Equation 1 of the report show the development of the correlation 

between normalized concrete modulus and expansion data from the test specimens. Based on 

Sections 3.1.1 and 3.2.1 of report MPR-4153, the normalized modulus value used in Figure 3-3 

and Equation 1 of the report for developing the relationship between normalized modulus and 

through-thickness expansion, is the ratio (Et/ E0) of the elastic modulus by testing cores 

extracted from the specimen at the time of expansion measurement (Et) to the 28-day elastic 

modulus (E0) obtained by testing cylinders (8 inches in height and 4 inches in diameter), that 

were molded at the time of specimen fabrication, at age 28 days. 

Section 3.3 of report MPR-4153 describes two approaches for obtaining elastic modulus at 28 

days in Seabrook structures for the purpose of normalization and determining the expansion to 

date. “Approach 1” uses 28-day elastic modulus calculated using the American Concrete 

Institute (ACI) 318 equation based on original concrete cylinder strength (f’c) measured at 28 

days. For “Approach 2,” MPR-4153 states that it plans to test the elastic modulus of the cores 

obtained during installation of extensometers at “control locations where ASR has not affected 

the structure.” MPR-4153 states that the applicant “should evaluate selection of a 

representative reference core on a case-by-case basis. 
 - 9 - 

 

In both approaches, there are variations introduced in the estimate 28-day elastic modulus from 

the use of the ACI 318 equation based on 28-day cylinder strength (“Approach 1”) or measured 

elastic modulus from cores because of change (i.e., increase) in concrete strength with age 

(“Approach 2”). In both cases, the normalized modulus at the time of installation of 

extensometers is determined as the ratio of the measured modulus on cores extracted at the 

installation location to the 28-day modulus estimate from Approach 1, or Approach 2, or both. 

Section 3.3.1 of MPR-4153, states: 

NextEra has retrieved records for concrete fabrication from original construction for 

selected buildings...For structural assessment of particular concrete members; 

application of values from [MPR Calculation 0326-0062-CLC-02] will need to be 

evaluated on a case-by-case basis to determine whether the available data are 

sufficiently representative of the concrete being evaluated. NextEra may need to 

retrieve additional original construction records to implement this approach. 

Section 4.2 of MPR-4153 discusses an uncertainty value related to the approach for 

determining original elastic modulus but does not give any information regarding the 

methodology for determining this uncertainty value. 

Issue: 

• Report MPR-4153 does not provide the size, orientation, and locations of cores extracted 

from test specimens to be used in conducting tests for concrete material properties at the 

time of expansion measurement and load test. 

• It is not clear if using the concrete material properties (i.e., modulus); from cylinder test, data 

at 28-days and core test data from the large scale beam specimens at the time of expansion 

measurement is appropriate for normalization of elastic modulus to determine ASR 

degradation. It is not clear whether the error associated with variations such as type of 

specimen (cylinder vs core) and size (diameter, d; height, h; and h/d ratio) of test specimens 

used may influence the values obtained for the normalized modulus were considered in the 

calculation of uncertainty or in the development of the correlating factors between expansion 

and normalized modulus. 

• It is not clear what value of f’c (mean, median, or probability of exceedance consistent with 

the statistical basis in the ACI 318 code) will be used in the ACI 318 equation for arriving at 

the 28-day elastic modulus based on 28-day test data of cylinder strength. 

• With regard to the statement from Section 3.3.1 of MPR-4153 referenced in the 

“Background” section above, it is not clear how the applicant will assess the data and the 

criteria to be used to determine whether the available data are “sufficiently representative.” 

It is not clear whether original data is available and if not, how the inputs to the modulus 

calculation will be determined.
 - 10 - 

 

• Uncertainties and variations associated with the recommended correlating approach based 

on estimate of normalized elastic modulus on the test specimens and on Seabrook 

structures are not addressed and it is not clear whether they need to be addressed 

statistically in a bounding manner. 

Request: 

The staff requests information for resolution of the issues in the issue section. 

1) Provide additional information regarding the methodology used to determine the uncertainty 

value associated with developing the empirical relationship between concrete material 

property and measured expansion. Include the basis for determination of the uncertainty 

value used for the normalized correlation between expansion and reduction in elastic 

modulus. 

2) Discuss whether and how the methodology considered factors such as size variation, 

orientation and locations of cores from the test specimens used in measuring concrete 

material properties, including elastic modulus. In addition, discuss whether and how the 

methodology considered uncertainty or errors associated with comparison between concrete 

cylinders 28-day test data and extracted cores. If these factors were not considered, 

provide technical justification that such consideration is not needed. 

3) Clarify, with the basis, what value of f’c (mean, median, or probability of exceedance 

consistent with the statistical basis in the ACI 318 code) will be used in the ACI 318 equation 

in “Approach 1” for arriving at the 28-day elastic modulus based on 28-day test data of 

cylinder strength of Seabrook structures. 

4) With regard to the statement from Section 3.3.1 of report MPR-4153 referenced in the 

“Background” section above, clarify how the applicant will assess the data and the criteria to 

be used to determine whether the available data are “sufficiently representative.” Also 

clarify whether “original data” referenced in that statement are available and if not, how the 

inputs to the modulus calculation will be determined. 

B.2.1.31A-5(a3): Representative Sample for Monitoring Through-wall Expansion

Background: 

The applicant’s response to RAI B.2.1.31A-5(a), dated June 30, 2015, states that the ASR 

Monitoring Program will be enhanced (revised Commitment No. 83) to install borehole 

extensometers in at least 34 representative locations that the applicant has stated are 

representative of the ASR on site such that the program will monitor, trend, and assess ASR 

expansion in the out-of-plane (through-wall) direction.
 - 11 - 

 

Section A.1.2.3.4 “Detection of Aging Effects” of Appendix A.1 “Aging Management Review – 

Generic (Branch Technical Position RLSB-1) of SRP-LR states, in part: 

For a condition monitoring program, when sampling is used to represent a larger 

population of SCs, applicants should provide the basis for the inspection 

population and sample size. The inspection population should be based on such 

aspects of the SCs as a similarity of materials of construction, fabrication, 

procurement, design, installation, operating environment, or aging effects. The 

sample size should be based on such aspects of the SCs as the specific aging 

effect, location, existing technical information, system and structure design, 

materials of construction, service environment, or previous failure history. The 

samples should be biased toward locations most susceptible to the specific aging 

effect of concern in the period of extended operation. Provisions on expanding 

the sample size when degradation is detected in the initial sample should also be 

included. 

Section A.1.2.3.4 “Detection of Aging Effects” of the SRP-LR also states that this program 

element describes “when,” “where,” and “how” program data are collected (i.e., all aspects of 

activities to collect data as part of the program), including how frequently evaluated. The 

section further states that the discussion should provide information that links the parameters to 

be monitored or inspected to the aging effects being detected and managed prior to loss of 

function. 

Issue: 

1) The response to RAI B.2.1.31A-5(a), dated June 30, 2015, does not include an update to 

the “detection of aging effects” program element of the ASR Monitoring Program with the 

information recommended in Section A.1.2.3.4 of SRP-LR (as described in the Background 

section) with regard to the representative sample of locations and aspects of activities to 

collect and evaluate data in the program enhancement to monitor out-of-plane ASR 

expansion. 

2) In the breakdown of number of instruments to be installed provided in the applicant’s 

response to RAI B.2.1.31A-5(a), Issue No. 3, almost 50 percent of the extensometers are to 

be installed in “Tier 1” ASR locations and over 50 percent will be installed in “Ambient 

Weather Conditions.” The staff needs additional information to determine whether the 

chosen locations and sample will be sufficient to manage through-wall cracking. 

3) ASR damage is likely to progress more quickly in areas of high humidity and temperature. It 

is not clear, from the tables given in the RAI response, whether the most severe areas are 

well-represented. It is also not clear whether the areas that exhibit the highest combined 

crack index (CCI) are the most severely affected areas, and the criteria that will be used to 

determine if an increase in sample size is required. 
 - 12 - 

 

4) The response to RAI B.2.1.31A-5(a) does not appear to address the durability and long-term 

reliability of the borehole extensometer proposed to be used to monitor out-of-plane 

expansion, and how the measurements would continue if an extensometer became 

non-functional in service. The response also does not discuss the data acquisition system 

that will be used to gather and process data from the proposed extensometers to ensure 

adequate aging management. 

Request: 

The staff requests information for resolution of the issues in the Issue section with regard to the 

representative sample for monitoring through-wall expansion. Also, the staff requests the 

applicant to update the “detection of aging effects” program element to the ASR Monitoring 

Program and UFSAR supplement, as applicable and appropriate (based on the response). 

1) Provide an update to the “detection of aging effects” program element of the ASR Monitoring 

Program with information recommended in Section A.1.2.3.4 of SRP-LR (as stated in the 

background section) to describe the basis for (a) the inspection population and sample size 

and (b) all aspects of activities to collect data, including how frequently the data are sampled 

and evaluated, regarding representative sample of locations in the program enhancement to 

monitor out-of-plane ASR expansion. 

2) Provide additional information to demonstrate the adequacy of sampling locations for 

through-wall cracking management (i.e., determination of whether the chosen locations and 

sample will be sufficient to manage through-wall cracking). 

3) Provide additional information to demonstrate the bounding conditions of the aging 

management measures relative to (a) sampling most severe locations (correlation with CCI) 

and (b) triggering point for increasing sample size. 

4) Provide additional information to demonstrate the reliability of the aging management 

measures relative to durability of supporting instrumentation (e.g., borehole extensometer 

and data acquisition system). 

RAI B.2.1.31A-5(a4): CCI as a surrogate for ASR expansion in the in-plane direction

Background: 

The applicant’s response to RAI B.2.1.31A-5(a), dated June 30, 2015, for Issue 1 states that 

“CCI [Combined Crack Index] is used as a surrogate for accumulated strain from ASR 

expansion in the in-plane directions.” 
 - 13 - 

 

In the changes to LRA Section B.2.1.31A by letter dated September 13, 2013, under “Program 

Description,” the applicant provided the basis for use of the crack index methodology on page 8 

of 18 of Enclosure 1. The applicant states “The total strain in the concrete can be 

approximated as the sum of the strain at crack initiation plus the crack index (ε = εcr + CI)...” 

The applicant provided an illustration in Figure A-1 of the expansion in ASR-affected concrete 

and goes on to conclude that “the Cracking Index (CI) provides a reasonable approximation of 

the total strain applied to the concrete after crack initiation.” SRP-LR, Section A.1.2.3.3, states 

that the “parameters monitored or inspected” program element should provide a link between 

the parameters that will be monitored and how monitoring these parameters will ensure 

adequate aging management. 

Issue: 

While continued surface crack indexing may be a necessary component for a complete 

measure of ASR expansion, which is volumetric in nature, there is a lack of clarity in the ASR 

Monitoring Program with regard to the following. 

• It is not clear whether the applicant’s statement referenced in the “Background” section is 

indicating that the large-scale test program directly measures rebar strain and correlates to 

CCI. For its review, the staff needs additional information in support of the statement that 

CCI is a “surrogate for accumulated strain.” 

• In order to maintain strain compatibility between concrete and rebar in ASR-affected 

concrete, the strain in the rebar will be equal to the strain applied to the concrete. 

Therefore, a CCI of 1 mm/m (which is the acceptance criteria used in the program to 

distinguish between Tier 2 and Tier 3 criteria for initiation of a structural evaluation 

corresponds to 1 millistrain of expansion resulting in rebar stress of 29 ksi. The staff is 

concerned that this may represent a significant magnitude of rebar stress due to ASR 

expansion that has not been or will not be accounted for during the period of extended 

operation. The program does not address rebar strain limits as compared to ASR 

progression through the period of extended operation to ensure the concrete maintains its 

design functionality. 

• The current AMP uses the Tier 1-2-3 approach to determine monitoring frequency and it 

relies upon CCI in two directions. It is not clear if and how CCI will be used to characterize 

ASR progression during the period of extended operation. Also, there is lack of clarity with 

regard to the correlation of CCI with anchor bolt capacity. 

• It is not clear whether in-plane cracking measurements will be used, qualitatively or 

quantitatively, in conjunction with through-wall expansion measurement data, to characterize 

ASR severity or progression.
 - 14 - 

 

Request: 

The staff requests information for resolution of the issues in the Issue section. 

1) Clarify the physical significance of CCI as a surrogate for strain in rebar due to ASR as 

explained in the applicant’s revision to LRA Section B.2.1.31A by letter dated 

September 13, 2013, and whether and how the corresponding rebar stress is accounted for. 

2) Clarify whether the large-scale test program directly measures rebar strain and correlates to 

CCI. Provide the technical basis as to how CCI correlates to stress in the rebar and how 

rebar stress is quantified. 

3) Describe the role of CCI in the large scale test program with regard to correlating the test 

results to Seabrook structures and components, including evaluating impact on anchor 

capacity. 

4) Clarify, with supporting basis, if and how the program will account for information gained 

from the elastic modulus testing in terms of comparison of ASR severity for monitoring 

purposes. 

5) Clarify whether in-plane cracking measurements will be used, qualitatively or quantitatively, 

in conjunction with through-wall expansion measurement data, to characterize ASR severity 

or progression. 

6) Update program elements and UFSAR supplement, as applicable, based on the responses. 
Letter to D. Curtland from R. Plasse dated October 2, 2015 

SUBJECT: REQUEST FOR ADDITIONAL INFORMATION RELATED TO THE REVIEW OF 

THE SEABROOK STATION LICENSE RENEWAL APPLICATION – SET 25 

(TAC NO. ME4028) 

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