UNITED STATES

NUCLEAR REGULATORY COMMISSION

REGION I

2IOO RENAISSANCE BOULEVARD, SUITE IOO

KING OF PRUSSIA PENNSYLVANIA 19406-27 13

December 3, 2012

Mr. Kevin Walsh

Site Vice President

Seabrook Nuclear Power Plant

NextEra Energy Seabrook, LLC

c/o Mr. Michael O'Keefe

P.O. Box 300

Seabrook, NH 03874

SUBJECT: SEABROOK STATION, UNIT NO. 1 - CONFIRMATORY ACTION LETTER

FOLLOW-UP INSPECTION - NRC INSPECTION REPORT O5OOO443/2012009

Dear Mr. Walsh:

On November 2,2012, the U. S. Nuclear Regulatory Commission (NRC) completed a team

inspection at Seabrook Station, Unit No. 1. The enclosed inspection report documents the

inspection results, which were discussed on November 2,2012, with you and other members of

your staff.

The team inspection examined activities conducted under your license as they relate to safety

and compliance with the Commission's rules and regulations and with the conditions of your

license. Specifically, the team reviewed selected procedures and records, observed activities,

and interviewed station personnel regarding the adequacy of NextEra's actions to address the

impact of Alkali-Silica Reaction (ASR) on reinforced concrete structures. The team reviewed

selected Confirmatory Action Letter (CAL) 1-2012-002 commitments for adequacy and closure.

Based upon the inspection team (team) on site and in-office reviews, five CAL items were

reviewed and closed, as documented in the enclosed report. The remaining six CAL items will

be reviewed during our second planned follow-up inspection scheduled for early 2013.

The NRC determined that NextEra's methods for assessing operability of ASR-affected

reinforced concrete structures were reasonable and generally comprehensive. NextEra

conducted a margins analysis, using bounding ASR-affected concrete properties derived from

research data, to demonstrate that Seabrook structures remained operable. The team

concluded this margins assessment provided a reasonable operability basis and noted that

further testing and engineering analyses are planned by NextEra to address this reinforced

concrete structures non-conforming condition. The testing and additional analyses are

expected to be completed by mid-2014. The NRC will review NextEra's proposed testing to

address the uncertainties in evaluating the current level and progression of ASR on Seabrook

Station reinforced concrete structures during the team's follow-up inspection.
K. Walsh 2

It should be noted that the inspection team results are based solely on Title 10 of the Code of

Federal Regulations (10 CFR) Part 50 requirements. The NRC is currently in the process of

conducting a separate review of the ASR issue as part of the license renewal process in

accordance with 10 CFR Part 54. As such, certain aspects of the ASR issue discussed may

also have applicability to the license renewal review and involve additional consideration and

require additional information beyond that discussed in this report.

In accordance with 10 CFR 2.390 of the NRCs "Rules of Practice," a copy of this letter, its

enclosure, and your response (if any) will be available electronically for public inspection in the

NRC Public Document Room or from the Publicly Available Records (PARS) component of the

NRC's document system (ADAMS). ADAMS is accessible from the NRC website at

http://www.nrc.sov/readinq-rm/adams.html (the Public Electronic Reading Room).

Docket No. 50-443

License No: NPF-86

Enclosures:

1. lnspection Report No. 0500044312012009

w/ Attachment: Supplemental Information

2. Confirmatory Action Letter 1-2012-002

cc w/encl: Distribution via ListServ

Division of Reactor Safety
K. Walsh

ft should be noted that the inspection team results are based solely on Title 10 of the Code of

Federal Regulations (10 CFR) Part 50 requirements. The NRC is currently in the process of

conducting a separate review of the ASR issue as part of the license renewal process in

accordance with 10 CFR Part 54. As such, certain aspects of the ASR issue discussed may

also have applicability to the license renewal review and involve additional consideration and

require additional information beyond that discussed in this report.

In accordance with 10 CFR 2.390 of the NRCs"Rules of Practicei'a copy of this letter, its

enclosure, and your response (if any) will be available electronically for public inspection in the

NRC Public Document Room or from the Publicly Available Records (PARS) component of the

NRCs document system (ADAMS). ADAMS is accessible from the NRC website at

http://www.nrc.oovireadinq-rm/adams.html (the Public Electronic Reading Room).

Sincerely,

/RN

Christopher G. Miller, Director

Division of Reactor Safety

Docket No. 50-443

License No: NPF-86

Enclosures:

1. lnspection Report No. 0500044312012009

w/ Attachment: Supplemental lnformation

2. Confirmatory Action Letter 1-2012-002

cc w/encl: Distribution via ListServ

Distribution w/encl:

W. Dean, RA

D. Lew, DRA

D. Roberts, DRP

J. Clifford, DRP

C. Miller, DRS

P. Wilson, DRS

A. Burritt, DRP

L. Cline. DRP

A. Turilin. DRP

W. Raymond, DRP, SRI

K. Dunham, Acting Rl

M. Jennerich, DRP, Rl

A. Cass, DRP, Resident AA

RidsNrrPMSeabrook Resource

C. Santos, Rl, OEDO

RidsN rrDorl Lpll -2 Resource

ROPreports Resource

DOCUMENT NAME: G:\DRS\Seabrook Concrete\Oper-funct - TlAs\CALFU 92702 Report 1\lR 2012-009 12-03-12.docx

ADAMS Accession No.: M112338A283

V SUNSI Review

g Non-sensitive

tr Sensitive

g

n

Publicly Available

Non-Publicly Available

OFFICE mml RIiDRS RI/DRP RI/DRS RI/DRS RI/DRS

NAME WCook ABurritt RConte JTrapp CMiller

DATE 11128112 11t29t12 11t28t12 11t30t12 12t3t12

OFFICIAL RECORD COPY
Docket No.:

License No.:

Report No.:

Licensee:

Facility:

Location:

Dates:

Inspectors:

Accompanied by:

Approved by:

U.S. NUCLEAR REGULATORY COMMISSION

REGION I

50-443

NPF-86

05000443/2012009

NextEra Energy Seabrook, LLC

Seabrook Station, Unit No. 1

Seabrook, New Hampshire 03874

June 18,2012 to November 2, 2012

W. Cook, Team Leader, Division of Reactor Safety (DRS)

S. Chaudhary, Reactor lnspector, DRS

W. Raymond, Senior Resident Inspector

A. Buford, Structural Engineer, Division of License Renewal,

Office of Nuclear Reactor Regulation (NRR)

G. Thomas, Structural Engineer, Division of Engineering, NRR

Dr. Kent Harries, Associate Professor of Structural Engineering and

Mechanics, University of Pittsburgh

Richard Conte, ASR Project Manager

Division of Reactor Safety

Enclosure
SUMMARY OF FINDINGS

f R 0500044312012009; 0611812012 - 1110212012; Seabrook Station, Unit No. 1; Confirmatory

Action Letter (CAL) Follow-up Inspection Report.

This report covered three weeks of onsite inspection and four months of in-office review by

region based inspectors and headquarters reviewers to assess the adequacy of actions taken

by NextEra to address the occurrence of Alkali-Silica Reaction (ASR) in reinforced concrete

structures at Seabrook Station. The NRC's program for overseeing the safe operation of

commercial nuclear power reactors is described in NUREG-1649, "Reactor Oversight Process,"

Revision 4. dated December 2006.

Cornerstone: Mitigating Systems

During this inspection the team examined six of the eleven commitments identified in

CAL No. 1-2012-002, dated May 16, 2012. These commitments involve actions taken and

planned by NextEra to address the degradation of reinforced concrete structures at Seabrook

Station due to ASR. Based upon the team's onsite inspection activities and detailed in-office

reviews, the team closed CAL ltems #1,#3,#5,#6, and #10. The team reviewed CAL ltem #2,

but did not close this item based upon additional actions needed by NextEra to appropriately

address and document this issue. The details of the team's review of each CAL item and the

observations pertaining to the adequacy of NextEra's actions to address commitments to the

NRC are documented in the enclosed report.

The team determined during this inspection that NextEra does not plan to finalize its structural

evaluations and operability assessments until: 1) the degree of ASR degradation on station

reinforced concrete structures is appropriately reconciled with the station design and licensing

basis; and 2) the progression of ASR is appropriately monitored to ensure structural integrity

and operability is maintained for the duration of the current operating license. Further, the team

determined that NextEra's current position is that no reinforced concrete structure at Seabrook

Station will be precluded from monitoring for the effects of ASR until a satisfactory petrographic

examination has been completed on that structure to confirm the absence of ASR.

The team acknowledged NextEra's plans to conduct structural performance testing of large

scale test specimens (both control and ASR-affected) and then apply the test data to evaluate

the current impact of ASR on Seabrook Station concrete structures and to develop appropriate

actions for the continued monitoring of the ASR-affected structures. The adequacy of NextEra's

proposed test program will be evaluated as part of the review of CAL ltem #8 during the second

CAL follow-up inspection. The adequacy of NextEra's current Structures Monitoring Program

will be evaluated coincident with the team's review of CAL ltem #9.

As discussed in Section 9.0 of the enclosed report, the team identified additional issues for

follow-up during the second inspection. These issues and the remaining CAL items will be

examined and assessed for adequacy prior to the closeout of CAL 1-2012-002.

Enclosure
REPORT DETAILS

1.0 Background

Alkali-Silica Reaction (ASR) is a chemical reaction occurring in hardened concrete that can

change the physical properties of the concrete and potentially affect structural performance. In

June 2009, NextEra identified potential degradation in below-grade concrete structures at

Seabrook. In August 2010, NextEra completed petrographic evaluation of concrete core

samples, which confirmed ASR as the degradation mechanism. The degraded condition in

Seabrook Category | structures was evaluated in the Corrective Action Program via a prompt

operability determination (POD) in September 2010, and revised in April 2011, September 201 1

and May 2012. The initial PODs (Revisions 0 and 1) addressed the B electric tunnel

(AR 581434) where ASR was first discovered. Five other buildings were identified as part of the

extent-of-condition (EOC) review and the evaluation of core samples taken from these

structures (AR 1664399). The PODs were updated as new information became available and

revised analytical techniques were incorporated.

NextEra initially used the results of mechanical testing of concrete cores to assess the degree of

structural degradation due to ASR. This is the traditional method described in American

Concrete Institute ( Cl) 228.1R for assessing existing concrete structures. NextEra tested the

cores for compressive strength and elastic modulus. NextEra used the methods defined in

construction and design code ACI 318-1971 to evaluate the structuralcapacity (operability) of

the ASR-affected buildings. However, the mathematical relationships in ACI-318 are based on

empirical data from testing of non-degraded concrete, and these relationships may not hold true

for all stages of ASR-affected concrete.

After further review of industry experience and literature pertaining to ASR, NextEra engineering

concluded that the core test data was not indicative of structural performance of ASR-affected

reinforced concrete structures. NextEra's engineering evaluation stated that once the cores are

removed from the structure, concrete core samples are no longer subject to the strains imposed

by the ASR-related expansion or restraints imposed by the steel reinforcing cage. The

engineering evaluation also stated that confinement provided by steel reinforcing bars (rebar)

and other restraints limit ASR expansion of the concrete within the structure and thereby limit

the adverse impact on structural performance. Therefore NextEra engineering concluded that

the reduction of mechanical properties observed in mechanical testing of cores was not

representative of in-situ concrete performance. NextEra's current position is that the testing of

core is only useful as a diagnostic tool to confirm the presence of ASR. Based on this

engineering judgment, NextEra stopped taking core samples to evaluate the concrete

mechanical properties of structures impacted by ASR and revised the operability assessment

approach. NextEra's current approach for assessing structural integrity and operability is to

compare available design margins to an assumed reduction in structural capacity due to ASR.

The extent of ASR at Seabrook was documented in an extent-of-condition walkdown review of

station structures. The review identified the visual signs of ASR through the presence of crack

patterns, ASR gel in wet and powder forms, and/or discoloration and dark staining. NextEra's

walkdown objectives were to: identify and assess apparent ASR degradation including

estimated expansion; identify the condition of concrete in the vicinity of supports that show ASR

Enclosure
2

distress; and identify the current or past areas of water intrusion. The walkdown results were

entered into the corrective action program (AR 1757861), in conjunction with six-month crack

indexing measurements on selected structures, to trend the progression of ASR and possibly

establish a rate of expansion.

NextEra's operability evaluations were based upon an examination of available design margins

and a presumed ASR-caused reduction in structural design capacity for critical limit states. The

details of this methodology and related assumptions were developed in NextEra's Interim

Assessment (FP 100716). The assessment assumed lower bound values of structural capacity

forASR-affected concrete for limit states based on research test data, primarily from test

specimens. The assessment focused on the structural limit states that are the most sensitive to

ASR effects (i.e., out-of-plane shear capacity, lap splice development length, and anchorage

capacity). The assessment determined the structures were suitable for continued service. A

final operability assessment will be conducted by NextEra following evaluation of structural

performance based on a proposed large scale testing program of beam specimens

representative of Seabrook reinforced concrete structures. The test program has been initiated

at the Ferguson Structural Engineering Laboratory at the University of Texas at Austin (UT-A),

with testing targeted to be completed in 2013 and the results reported in2014.

2.0 Confirmatory Action Letter 1-2012-002

Confirmatory Action Letter (CAL) 1-2012-002. dated May 16, 2012, was written to confirm

commitments by NextEra (established during a meeting with NRC management and staff on

April 23, 2012) with regard to planned actions to evaluate ASR-affected reinforced concrete

structures at Seabrook Station. In response to the CAL, NextEra committed to provide

information to the NRC staff to assess the adequacy of NextEra's corrective actions to address

this significant condition adverse to quality. CAL 1-2012-002 is provided as an Enclosure to this

report. The NRC staff also formed a working group to provide appropriate oversight of

NextEra's activities to address ASR and to coordinate NRC inspection and review activities.

The ASR Working Group Charter (ML121250588) outlines the regulatory framework and

general acceptance criterion for NRC oversight and review of this issue.

Based on the results of this inspection, CAL ltems #1 , #3, #5, #6, and #10 are closed; CAL ltem

#2 is updated; and CAL ltems H, #7, #8, #9, and #1 1 remain open pending NRC review in the

second CAL follow-up inspection (Report No. 0500044312012010).

3.0 Review of Operability Determinations and the Interim Assessment

(CAL ltems #1,#3, and #5)

3.1 Inspection Scope

CAL No. 1-2012-002 documented NextEra's commitment to submit the revised PODs for the B

electrical tunnel (CAL ltem #1) and the additional buildings identified as having indications of

ASR, based upon NextEra's corrective action to identify other affected structures (CAL ltem #5).

The team reviewed the PODs for the B Electric Tunnel of the Control Building (POD 581434)

and buildings identified in NextEra's extent-of-condition review (PODs 1664399 and 1757861).

As discussed in Section 1.0 above, these PODs were revised to reflect a change in the

Enclosure
3

approach taken by NextEra to evaluate the structural integrity of the station reinforced concrete

buildings. Revision 2 of the PODs provides the current quantitative and qualitative analyses of

the ASR-induced changes in structural performance, as further detailed in the licensee's Interim

Assessment. The team reviewed the supporting documentation for each significant structural

design attribute and conducted multiple interviews and discussions with the responsible NextEra

engineering staff and consultants. The team used 10 CFR Part 50, Appendix A (General

Design Criteria 1, 2, and 4), and 10 CFR Part 50, Appendix B, Criterion XVl, "Corrective Action,"

and Criterion Xl, "Test Control," and UFSAR, Section 3.8 as the regulatory basis to assess the

adequacy of NextEra's actions to address ASR effects on safety-related Category | reinforced

concrete structures that were considered in-scope for the Maintenance Rule. The team used

NRC Inspection Manual, "Part 9900 - Operability Determination and Functionality Assessments

for Resolution of Degraded or Nonconforming Conditions Adverse to Quality or Safety," to

evaluate the licensee's approach to assessing this significant condition adverse to quality.

The extent-of-condition POD (Revisions 0 and 1) initially addressed five structures

(AR 1664399). These five structures included the containment enclosure building (CEB), the

access tunnelto the radiologically controlled areas (RCAW), the emergency feedwater (EFW)

pump house, the residual heat removal (RHR) equipment vault (EV), and the diesel generator

building (DGB). During implementation of ASR Structures Walkdown (FP 100705), NextEra

identified additional structures with localized areas of patterned cracking, including: the

condensate storage tank enclosure, the control building air east intake, the service water

cooling tower, the A electricaltunnel, the fuel storage building, the east pipe chase, the west

pipe chase, the pre-action valve room, the primary auxiliary building, the service water pump

house, the mechanical penetration area (which includes portions of the outer containment wall,

AR 1804477), and the waste processing building (AR 1757861).

The team conducted a detailed review of Foreign Print (FP) 100716, "Seabrook Station: lmpact

of Alkali-Silica Reaction on Concrete Structures and Attachments," Revision 1. FP 100716 is

the initial evaluation of concrete structures at Seabrook Station and provides the basis for

continued operability of ASR-affected structures. This document was submitted to the NRC for

review per CAL ltem #3. As documented in FP 100716 (also referred to by NextEra as the

Interim Assessment), this evaluation will be followed by a second evaluation that "will assess

the longterm adequacy of the concrete structures considering the results of the large scale

structuraltesting program, other in-progress test programs, and results from periodic monitoring

of the structures."

3.2 Findings and Observations

The team identified no findings in this area, and CAL ltems #1, #3 and #5 are closed. Based on

a detailed review of the PODs, referenced white papers and associated engineering analyses,

including an independent verification by the team of a number of supporting calculations, the

team determined NextEra's operability bases were appropriate. Given the current known extent

of ASR, there is reasonable expectation that the affected reinforced concrete structures at

Seabrook Station will remain capable of performing their intended functions while NextEra

continues to monitor the condition and complete detailed testing and further engineering

analyses (expected to be completed by mid-2014) per the Corrective Action Program (CAP).

Enclosure
4

The team noted that the areas identified by NextEra to be affected by ASR are generally

localized (i.e., part of a wall, not the entire wall or structural member exhibits evidence of ASR).

Even though the identified ASR areas are localized, NextEra's engineering evaluations

conservatively assume the entire structure or structural member (wall) is adversely affected.

Assuming an entire structural member is affected allows for a direct comparison to the original

design calculations of record. Noteworthy observations pertaining to the team's review of the

PODs and lnterim Assessment follow.

3.2.1 Operable, but Degraded and Non-Conforming

Based upon a detailed review of the quantitative and qualitative analyses documented in the

PODs and Interim Assessment, the team determined NextEra had appropriately demonstrated

that the ASR-impacted structures were operable, but degraded and non-conforming. NextEra

adequately demonstrated that the structures would maintain structural integrity for design basis

loads and load combinations for normal. accident and environmental extreme conditions

(including seismic). The degraded and non-conforming ASR-affected structures are being

addressed through NextEra's CAP and the planned UT-A testing program.

The team observed that 26 locations (including containment) had been identified via NextEra's

ASR Structures Walkdown as having patterned cracking with a combined crack index (CCl) of

greater than 1.0 mm/m. CCI is an ASR expansion monitoring method that sums the crack

widths measured along a fixed rectangular grid line. The sum of the crack widths is then divided

by the length (perimeter) of the grid to obtain the index value. Per the Structures Monitoring

Program (EDS 36180, Revision 2), Attachment 3, revised in July 2012, a CCI of >1.0 mm/m

requires a structural evaluation. NextEra's lnterim Assessment, Section 2.1.2 documents an

engineering judgment that biased the performance of detailed structural evaluations to the 11

locations with a CCI > 1.5 mm/m. Although not explicitly stated in Section 2.1.2, the team

learned from discussions with NextEra engineers that the locations with a CCI of between 1.0

and 1.5 mm/m (13 locations) were considered bounded by the 1 1 areas subjected to a detailed

evaluation. The lack of a documented structural evaluation for the 13 locations with a CCI of

between 1.0 and 1.5 mm/m was considered a minor performance deficiency. NextEra

acknowledged this procedural implementation error and entered the issue into their Corrective

Action Program (AR 1804477 and AR 1819080). A structural evaluation was completed for

containment and reviewed by the NRC prior to the completion of the inspection period (see

Section 3.2.8). However, the evaluations for the remaining locations were not completed by

NextEra before the end of the inspection. The team will examine these evaluations in the

second CAL follow-up inspection.

Near the conclusion of this inspection, NextEra completed a POD for containment

(AR 1804477). Preliminary review by the team identified areas for follow-up during the second

CAL follow-up inspection. Specifically, the team plans to assess NextEra's evaluation of the

potential for ASR-induced pre-stressing of rebar (reference Section 3.2.8) and to review

NextEra's future plans for monitoring the localized areas (three) of presumed ASR (not verified

by a petrographic exam) on the containment outer wall. NextEra's current monitoring plans for

the containment wall areas are documented in FP 100647, "Crack Index Determination." (See

Section 6.0 of this report for additional information and team observations concerning Crack

Indexing.)

Enclosure
5

3.2.2 Concrete Material Properties - Compressive Strength and Elasticity Modulus

As discussed in Section 1.0, NextEra stopped taking core samples to evaluate ASR-affected

structures. Notwithstanding, Revision 2 of POD 581434 for the B electrical tunnel, concluded

that there is no loss of concrete compressive strength due to ASR. This conclusion was based

on testing of 15 cores (12 ASR-affected concrete and 3 control locations). NextEra concluded

that ASR had increased the stiffness of the electric tunnel walls because the compressive

strength in the ASR impacted concrete was higher than in the control core samples. [The team

notes that this conclusion is different than the 22 percent measured compressive strength

reduction (compared to the 1979 cylinder test results) that had been previously identified by

NextEra from initial core sample results and reported in NRC Inspection Report

05000443/2011007.1 Team review of the available supporting concrete core data during this

inspection did not validate NextEra's current conclusion, as discussed below.

As-built concrete compressive strength can vary due to variations in the mixture (aggregate,

sand, cement, and water) and the curing process. Consequently, design and construction

specifications were developed to ensure, in spite of this variability, that concrete specified and

used in reinforced concrete structures meets acceptable standards of performance. In addition,

concrete strength is expected to increase with age and curing. The team also noted that

additional inaccuracies are introduced via the core sampling process and associated testing

methods. Accordingly, team examination of the 2011 core sample compressive strength values

and measured cylinder strength values from 1979 (two percent lower), led the team to conclude

there is neither a significant loss or increase in compressive strength in the ASR-affected B

electrical tunnel concrete material properties. Team review of core sample-measured modulus

of elasticity values identified that although individual cores showed a modulus that was reduced

(compared to design), the average modulus value in the RCA walkway, RHR equipment vault,

EFW pump house, and DGB was within 20 percent of the design modulus value (+20 percent is

acceptable by ACI 318). Based upon available core sample results, the team considered the

ASR effect on elasticity modulus inconclusive, also.

Overall, the team concluded that the core sampling and associated mechanical testing

completed, to date, has not conclusively established the current impact of ASR on concrete

material properties. While the team acknowledges that the core sample results may not

represent in-situ concrete structural performance, as NextEra has concluded, the core samples

and test results (mechanical and petrography) may still provide valuable information and

insights relative to the impact (relative degree and progression) of ASR on reinforced concrete

structures. Consequently, the team plans to examine core sampling in the second CAL

follow-up inspection, with respect to core sample test results being used to understand ASR

effects on ACI Code relationships and the overall adequacy of the Structures Monitoring

Program.

3.2.3 FlexuralCapacity and Dynamic Response

NextEra completed a comparative study of the Containment Enclosure Building (CEB)

(FP 100714 and FP 100715), which evaluated the effects of reduced elastic modulus on seismic

response. The CEB parametric study included: an evaluation of the building in a static,

three-dimensionalfinite element analysis (FEA) to determine the response (forces and

Enclosure
6

moments) to operating basis earthquake and safe shutdown earthquake seismic loads without

and with current ASR damage; a calculation of the wall section capacities; a calculation of

demand-to-capacity ratios (DCR); and, a comparison of the DCRs of ASR-affected walls to

unaffected walls. Based upon assumed boundary conditions and the assumed current state of

ASR degradation used in the FEA model, the analyses showed that the seismic acceleration

profiles, in-structure response spectrum, and distribution of forces and moments were not

significantly impacted. The effect of the lower modulus values on the response of other belowgrade, ASR-impacted structures was evaluated in Calculation C-S-1-10163. For these below

grade structures, NextEra determined that the dynamic structural response remained in the rigid

range with no appreciable amplification of the ground response spectra.

Based upon the above, NextEra concluded that the seismic response of the CEB, along with the

attached equipment (cable trays and supports) and anchor loads, remained practically

unchanged due to the assumed ASR effects. The team concluded that NextEra's assessment

of this ASR-affected structural design attribute was appropriate to demonstrate operability.

3.2.4 Shear Gapacity

NextEra analyzed the impact of ASR on the B electric tunnel using an FEA in calculation

FP 100730 to determine refined structural demand and to compare the shear capacity versus

demand for seismic and hydrodynamic loads. NextEra assumed a 25 percent reduction in

out-of-plane concrete shear capacity due to the effects of ASR on walls without shear

reinforcement. The team noted that NextEra's design calculation (CD-20, dated 3/28183) used

the average 28-day compressive strength value (5459 psi) to establish that the design shear

capacity exceeded the design load/demand. However, the FEA-based calculation used the

specified design concrete strength of 3000 psi to compare the available design capacity to

design load. The use of the 3000 psi vice 5458 psi value in the FEA provided results that

indicated adequate margin was available using the as-built specified concrete compressive

strength. The team noted that the FEA is a more precise computational design method than the

manual methods used in the 1983 design calculation. The team notes that NextEra identified,

but did not credit, additional conservatism in their margins analysis based upon the B electrical

tunnel average measured core sample compressive strength value of 5140 psi. NextEra's FEAbased evaluation concluded that adequate margin was available to account for the lower bound

ASR effect on out-of-plane concrete shear capacity. The inspection team acknowledged that:

1) some additional margin may be credited due to the compressive strength of core samples

exceeding the design minimum value of 3000 psi; and 2) the use of a 25 percent reduction in

shear capacity, as a lower bound ASR effect, was appropriate for the assessment of this limit

state. The team found the use of an FEA to assess shear capacity and the lower bound ASR

effects as appropriate to demonstrate operability.

3.2.5 Review of Finite Element Analysis Modeling

As discussed in Sections 3.2.3 and 3.2.4 above, NextEra used a linear elastic FEA to evaluate

the effects of ASR on certain structures and design attributes. The team noted that the input

data for the compressive strength and modulus of elasticity for the CEB model were determined

based on a visual examination of CEB walls and only a few directly obtained core sample

material properties. The observed crack patterns and dimensions on the CEB were correlated

Enclosure
7

by NextEra to a damage rating index (DRl) and associated concrete material properties from

test data obtained from core samples taken from several different structures. The input data for

Poisson's ratio was derived exclusively from research data. NextEra acknowledged the

limitations of this input data, but in FP 100696 deemed the approach justified because the

analysis was a parametric study of the CEB seismic response, comparing design values to

ASR-affected values. The team concluded NextEra's application of the FEA to a parametric

analysis was useful for providing a reasonable expectation of operability, but not conclusive with

respect to identifying a current or projected state of ASR impact. For example, the team noted

that the boundary conditions used at and below elevation zero-foot of the CEB FEA model may

need to be re-evaluated and better justified, considering the seismic isolation of the walls

(separated from the concrete backfill by the waterproofing membrane).

3.2.6 Anchorage

NextEra evaluated the impact of ASR-affected concrete on the performance of anchorage,

including both expansion and undercut post-installed anchors. The potential impact of

micro-cracking caused by ASR can negatively impact the structural capacity of anchorages and

embedments supporting safety-related components. NextEra's operability evaluation was

supported by anchor performance testing conducted on ASR degraded UT-A test specimens

(FP 100718). The tests showed satisfactory performance of the anchors in ASR-affected

concrete. NextEra's evaluation illustrated that the assumed reduction in capacity due to ASR

was offset by established anchor manufacturer's design margins (FP 100716). However, based

upon the limitations of the testing performed, to date, (on ASR-affected test specimens of

different composition and compressive strength than Seabrook structures) NextEra plans to

conduct further testing. Planned testing involves anchors installed in ASR-affected test

specimens that more closely reflect the reinforced concrete structures and anchor

configurations at Seabrook. The team concluded that NextEra's anchorage operability

assessment was satisfactory.

3.2.7 Lap Splice Strength

Section 6.3 of NextEra's Interim Assessment addressed reinforcement lap splice degradation as

another design attribute impacted by ASR. In accordance with the licensee's lower bound value

of a 40 percent reduction in lap splice strength, NextEra's review of design calculations

identified several structures with insufficient margin to accommodate this assumed ASR effect.

NextEra was able to "recove/' margin by adjusting the ACI 318 prescribed design load factors

for well predicted dead load and/or hydrostatic load. NextEra's term "recover'' represents

examining the design loads and load distributions and determining the accuracy and potential

variability of the predicted loads. lf the predicted load is well defined, accurately quantified, and

subject to minimum variability (such as dead load and hydrostatic load), then it is appropriate to

remove the load factor (LF) from the associated load/demand calculation. By ACI 318 ultimate

strength design, the LFs account for the uncertainty in accurately predicting the structural loads

and provide increased design margins for service load conditions/combinations. The team

examined this method and found it satisfactory for the operability assessment, but concluded it

would not be acceptable for a final operability determination under the current licensing basis.

The final operability assessment requires full conformance with the ACI design methodology or

revision to the licensing basis.

Enclosure
8

3.2.8 Goncrete Gonfinement and Rebar Pre-Stressing

The team's review of FP 100716, Sections 2.1 .2 and 4.1.3, identified that the Interim

Assessment stated, "Since ASR has a negligible impact on structural demand, the impact of

ASR on structures and structural attachments can be assessed solely on the basis of changes

in capacities." The team observed that restraint to ASR expansion, from concrete confinement

by reinforcement (in two or three dimensions) and other external constraints, may cause internal

pre-stress in the structural member. The consequence is to increase compressive stresses in

the concrete and increase tensile stresses in the rebar, as long as the restraint is sustained. The

team observed that NextEra has only addressed this ASR-induced pre-stress qualitatively in

FP 100716 and in the containment structural evaluation (AR 1804477). The team determined

that a quantitative evaluation of this pre-stress is needed to resolve this aspect of the nonconforming condition. Further, it should be recognized that the ASR-induced pre-stress varies

with time, depending on the degree of restraint and may not be sustained throughout the service

life of an affected structure. Accordingly, any potential beneficial effect should not be relied

upon or credited in design.

The team acknowledges NextEra's conclusion that ASR-induced pre-stress may result in some

beneficial effects in terms of structural stiffness. However. the team determined that this

structural demand should be quantified (if practicable) and accounted for in the design

calculations as a known load. Quantifying, or otherwise approximating the ASR-induced

pre-stress, is similar to accounting for the pre-stress load in pre-stressed concrete design. This

issue will be reviewed by the team in the second CAL follow-up inspection.

3.2.9 Gondition of Rebar

The team examined information gathered and assessed by NextEra with regards to the

condition of rebar and any potential erosion or corrosion due to ASR and water in leakage

through below grade reinforced concrete structures. The team observed that NextEra had

removed an area of surface concrete in the B electrical tunnel to examine the condition of the

rebar. The engineering staff identified no degradation of the rebar (no oxidation or signs of

distress). The team also learned that in the course of removing core samples, in two instances

the sample included minor amounts of rebar. Examination of the rebar sections removed

determined the steel to be in excellent condition (unaffected by ASR or moisture).

Preliminarily, NextEra has concluded that the condition of rebar in ASR-degraded concrete

should be unaffected unless the cracking becomes deleterious and exposes the rebar to

oxidation mechanisms. Otherwise, the alkaline condition within the concrete should prevent any

corrosion mechanisms. The NRC continues to evaluate the need for any additional rebar

intrusive monitoring or testing, and will evaluate this issue in the second CAL follow-up

inspection.

Enclosure
4.0

4.1

9

Review of Alkali-Silica Reaction Root Cause Evaluation (GAL ltem #2)

Inspection Scope

The team reviewed NextEras response to CAL ltem #2,'Submit the root cause for the

organizational causes associated with the occurrence of ASR at Seabrook Station and related

corrective actions by May 25,2012: The licensee submitted their root cause evaluation (RCE)

via letter dated May 24,2012. The purpose of the team's review was to assess the adequacy of

the licensees evaluation of the root cause for the ASR issue at Seabrook and the significant

contributing causes. The team also examined the methodology and thoroughness of the

licensees evaluation and associated corrective actions as outlined in 10 CFR Part 50,

Appendix B, Criterion XVl,"Corrective Actionl' The team made observations regarding the level

of detail and clarity of NextEras root cause evaluation.

4.2 Findings and Observations

This CAL ltem will remain open pending NRC review of NextEras final RCE. NextEra identified

two root causes: 1) ASR developed because the concrete mix design unknowingly utilized an

aggregate that was susceptible; and 2) the monitoring program for plant systems and structures

does not contain a process for periodic reassessment of failure modes. A contributing cause

identified by NexEra was the failure to prioritize groundwater elimination or mitigation resulting

in more concrete areas exposed to moisture.

The first licensee-identified root cause involved the licensees use of susceptible aggregate in

the concrete mix design that was undetected by the testing specified by ASTM construction

standards, at the time (late 197Os). Since this time, the role of slow-reacting aggregate in ASR

has been identified in the construction industry and standard tests are now available to ensure

slow reactive aggregates would be properly identified prior to use in construction. The team

concluded that this causal factor was beyond the licensees control.

The team concluded that the second root cause was not adequately characterized in NextEra's

May 24,2012, submittal. Specifically, NextEra did not clearly state the personnel and

organizational factors that led to inadequacies in the Structures Monitoring Program (SMP).

The team discussed the absence of any human performance aspects in the description of this

causal factor, and NextEra initiated a revision to the RCE to more appropriately develop and

characterize this second root cause and the associated corrective actions. NextEra plans to

submit the revised RCE for NRC review. The team will review this revision in the next CAL

follow-up inspection report.

The team also noted that NextEra excluded a contributing cause, identified in the RCE, from the

evaluation executive summary and May 24, 2012,letter. As stated in the RCE, this contributing

cause involved the longstanding'brganizational mindset'that groundwater infiltration was more

of an'bperational nuisancd'than a structural integrity concern. This station and engineering staff

'tnindset'prevented a more timely and thorough investigation and examination of the effected

concrete reinforced structures on site. NextEra acknowledged this observation and agreed to

address it in the revision to the RCE.

Enclosure
10

5.0 Review of Mortar Bar Testing (GAL ltem #6)

5.1 Inspection Scope

CAL ltem #6 committed NextEra to submit the results of short term aggregate expansion testing

to the NRC. The team reviewed the results of NextEra's recently completed short term

expansion testing of mortar bar specimens per test procedures SGH-2001-12 and SGH-2002-

12. The results of the testing were evaluated per ASTM C1260, "Mortar Bar Expansion Test."

The licensee initiated the testing to establish and compare the reaction rates of ASR-affected

concrete to non-ASR affected concrete on site. The tests were performed by a consultant at an

offsite facility. The mortar bar specimens were made using the aggregate extracted from core

samples taken from ASR-affected structures and non-affected concrete from a slab removed

from the waste processing building. NextEra noted that the non-affected concrete slab used for

aggregate extraction had shown no visible indications of ASR and was not petrographically

examined. The details of the testing are documented in SGH Report 1201 10-RPY-01

(FP 100734). The team reviewed the SGH report and associated test documents to ascertain

the adequacy and technical validity of the testing.

5.2 Findings and Observations

No findings were identified and CAL ltem #6 is closed. The test results indicated that both

affected and non-affected concrete specimens contained ample reactive aggregate to sustain

ASR. The team notes that normaltest duration is 14 days and that a specimen expansion of

greater than 0.1 percent indicates reactive aggregate, per ASTM C1260. Test results identified

that the non-ASR-affected specimens exceeded the 0.1 percent threshold in 5 days and the

ASR-affected specimens exceeded the 0.1 percent threshold in 7 days. NextEra allowed the

test to extend to 103 days and both specimen types continued to demonstrate active expansion

due to ASR. Accordingly, NextEra concluded that there remains the potential for future

volumetric expansion due to ASR in concrete structures at Seabrook.

Based upon the Mortar Bar Testing results, NextEra plans to revise their commitment to conduct

Prism Testing. Prism Testing is similar to Mortar Bar Testing, but a longer term test of the

susceptibility to ASR of aggregate used in concrete. NextEra had hoped to establish, via the

Mortar Bar Test, a difference in the remaining versus available concrete constituents for ASR in

the specimens. The results demonstrated ample reactive materials in both specimen types and

NextEra concluded the Prism Test will not provide any additionalASR insights. The team had

no additional observations and will review the revised Prism Testing commitment when it is

submitted.

6.0 Review of Grack Indexing (CAL ltem #{0)

6.1 lnspection Scope

CAL ltem #10 involved NextEra's commitment to perform the initial six-month interval crack

measurements and crack indexing at 20 locations in areas that exhibit the highest crack indices

by July 15,2012, and provide the results for NRC review. The team conducted a review of FP

100647, "Crack lndex Determination," Revision 1, to understand the methodology for NextEra's

Enclosure
11

monitoring of ASR progression in selected reinforced concrete structures. The team used 10

CFR Part 50, Appendix B, Criterion V, "lnstructions, Procedures, and Drawings," to evaluate the

implementation and adequacy of the procedural guidance. The team's review was limited in

scope, in that, the adequacy of crack mapping, as the sole means of monitoring ASR

progression in Seabrook structures, is still under NRC review. The team will evaluate the

adequacy of the Structures Monitoring Program, which includes crack indexing as a component

of the overall program, during the review of CAL ltem #9, "Update the Maintenance Rule

Structures Monitoring Program to include monitoring requirements for selected locations in

areas that exhibit ASR,' during the second CAL follow-up inspection.

The team observed field measurements taken on June 20,2012, by the responsible contractor

and discussed the general methodology and procedural guidance with the individuals

performing the crack indexing measurements and the supervising NextEra staff. The team

noted that NextEra found ASR patterned cracking in many areas of Seismic Category |

structures and structures in-scope within the Maintenance Rule, but only a limited number of

these areas have sufficient ASR degradation to merit continued monitoring and detailed

evaluations. The ASR walkdowns identified 131 locations with some level of pattern cracking.

Of the 131 localized areas, 26 exceeded the initial screening criteria of a combined crack index

greater than 1.0 millimeter per meter (mm/m). The '1.0 mm/m threshold was contained in the

Structures Monitoring Program, Attachment 3, for conducting a structural evaluation. These 26

areas will continue to be monitored at six-month intervals, per FP 100647.

6.2 Findings and Observations

No findings were identified and the CAL ltem #10 commitment is closed. The team noted that

the periodic crack indexing currently provides the principle method selected by NextEra to

monitor the progression of ASR on reinforced concrete structures. The six-month interval

measurements are currently planned until a reliable trend of ASR progression can be

established, per Structural Engineering Standard Technical Procedure 36180, "Structures

Monitoring Program," Attachment 3, Revision 2. As stated above, additional NRC review of the

Structures Monitoring Program will be conducted in the second CAL follow-up inspection.

The team also reviewed the current methods and terminology used by NextEra to characterize

the degree of ASR pattern cracking, previously addressed in NRC lnspection

Report 05000443/2011007. When ASR was initially identified in the B electrical tunnel in

midto-late 2010, the licensee referred to the Federal Highway Administration (FHWA) guidance

document FHWA-HIF-09-004 for crack and damage characterization. Three major categories

were identified. mild, moderate, and severe, with ratings such as mild to moderate and

moderate to severe, also used. Per FHWA-H|F-09-004, these categories were used to define

the recommended remedial actions to be taken once ASR was identified. At that time. NextEra

labeled the observed cracking as "severe." Per the FHWA guidance, this category requires

"further investigation for selecting remedial actions." This characterization was repeated in the

above referenced inspection report. NextEra revised their crack characterization scheme prior

to the implementation of the structures extent-of-condition review. The revised crack rating

system was based upon "best practices" taken from the Building Research Establishment (BRE)

in the United Kingdom (UK). The revised numeric rating system range is from 0 (no cracking

detected) to 6 (heavily fractured ASR-related damage). FP 100636, "Petrographic Examination

Enclosure
12

PE Reports," Revision 0, lists the material property results of all core samples taken and

petrographically analyzed. FP 100636 also provides the BRE crack rating for each specimen

examined. The crack ratings for the specimens examined range from 0 to 4 (a rating of 4

represents severe cracking). The team determined NextEra's revised crack rating scheme is

more informative.

7.0 Alkali-Silica Reaction Structures Walkdown - Extent of Condition Assessment

7.1 Inspection Scope

The team examined NextEra's program documents FP 100642, "ASR Walkdown Scope,"

Revision 1, and FP 100705, "Seabrook Station: Summary of Alkali Silica Reaction Walkdown

Results," Revision 0, to assess the adequacy of the licensee's extent of condition assessment,

per the Seabrook Station Corrective Action Program (CAP). The team reviewed the walkdown

scope and examination criteria and the associated field data, photographic evidence, and

analysis of NextEra's observations, as documented in FP 100705. The walkdown scope

included Seismic Category | and some structures in scope within the Maintenance Rule.

NextEra's walkdown is being conducted in three phases. Phase 1 involved examination of

readily accessible areas of interest; Phase 2 included examination of coated surfaces identified

during Phase 1 inspections (coatings had to be removed to expose the concrete surfaces); and

Phase 3 examines normally inaccessible structures and areas (e.9. high radiation, manholes,

etc.) which have or will be inspected as the opportunity presents itself (e.9. routine maintenance

or outage activities).

The walkdowns assessed the extent of ASR throughout the plant with the primary objectives of:

identifying and assessing any apparent degradation from ASR (including measurement of ASR

expansion via CCI); assessing whether concrete in the vicinity of supports for safety-related

systems or components show any indications of ASR distress; and documenting and

characterizing water intrusion or evidence of previous water intrusion, based upon water being a

key contributor to concrete deterioration and distress caused by ASR. The visual criteria for

documenting potentialASR indications included: typical patterned surface cracks in concrete;

crack dimensions (width, length, orientation); evidence of water ingress and/or out-seepage;

visual evidence of salt deposit and/or ASR gel; and indications of surface deterioration (i.e.,

pop-outs and/or spalling). Also, any expansion anchors or structural embedments located

within 5 feet of the area of interest were examined and documented.

The team performed a number of independent walk-through inspections to verify and assess the

thoroughness of the licensee's efforts. The team independently evaluated the extent-ofcondition of ASR-affected structures that are readily accessible. The team used the expertise of

a consulting structural engineer to assist in the team's review of the current condition of

ASR-affected reinforced concrete structures at Seabrook Station.

7.2 Findings and Observations

The team identified no findings. On a sampling basis, the team's independent walkdown

observations were consistent with the licensee's observations and assessments. At Seabrook,

the presence of ASR has been conclusively established by petrography in certain buildings

Enclosure
13

(where core samples were obtained) and in other buildings by visual comparison, using visual

examination criteria. The team confirmed that NextEra's position is that all reinforced concrete

structures on site are susceptible to ASR, dependent upon the exposure to moisture.

Therefore, NextEra does not intend to exclude any structures from ASR monitoring without

confirmation via petrography that ASR is non-existent.

The complete list of structures and localized areas of ASR identified, to date, is documented in

FP 100705, Revision 1 . The team noted that the results of the walkdown inspection by NextEra

were appropriately documented with extensive observation narratives and well supported by

clear sketches and photographs. As NextEra completes Phase 3 examinations, the licensee

plans to capture the additional observations through revisions to FP 100705. The team noted

that the majority of localized areas of ASR are: 1) below grade walls subjected to either ground

water intrusion, or particularly high spatial humidity; or 2) structures exposed to precipitation and

high ambient humidity (some exterior above grade structures).

Based upon the team's review of the Phase 1 and 2 ASR walkdown results and via discussions

with responsible engineers overseeing the proposed Phase 3 walkdown areas and tentative

schedule, the team identified a minor oversight in the Phase 3 walkdown plan. Specifically, the

upper elevations of the containment outer wall were not adequately examined for ASR during

the Phase I review and not included in the proposed Phase 3 walkdown schedule. The team

identified from discussion with the NextEra engineering staff that the 2010 examination of

containment, per American Society of Mechanical Engineers (ASME) Boiler and Pressure

Vessel Code, Section 1 1, Subsection lWL, was being credited for part of the Phase 1 ASR

walkdown. The team's detailed review of the 2010 IWL inspection results and associated visual

examination attributes (reference implementing procedure, ES 1807.031, "lnservice Inspection

Procedure Primary Containment Section Xl lWL,') identified that the 2010 IWL exam did not

include sufficient examination criteria (i.e., active or pattern cracking) for identification of ASR.

As evidence of the absence of ASR identification criteria in the IWL examination, during the

subsequently performed Phase 1 ASR walkdown by consulting engineers, three locations of

ASR-related pattern cracking were identified on areas of the containment previously examined

by the IWL examiners. NextEra acknowledged this oversight in crediting the IWL examination

and initiated action (AR 1819069), per the CAP, to revise Phase 3.

During the second CAL follow-up inspection, the team plans to examine the adequacy of the

Phase 3 changes. The team also plans to discuss the Phase 3 implementation schedule for

com pletion of the AS R-affected structu res extent-of-cond ition review.

8.0 Follow-up of Open ltems

8.1 (Closed) Unresolved ltem 05000443/2011003-03 - Open Operability

Determ i nations for Safety-Related Structu res Affected by Al kal i-S i lica

Reaction

This item was open pending NRC review of NextEra actions to revise operability determinations

for the electric tunnel and other structures addressed in the extent of condition review for ASR.

The open aspects, as documented in Inspection Reports 2011-03 and 2011-10, were related to:

1) the effect of the reduced modulus of elasticity on natural frequency of the structures; 2) the

Enclosure
14

effect of the modulus of elasticity on structure flexural response as related to components

attached to the structures, such as piping and cable supports and their anchor bolts; 3) related

effects from increased flexure of building on the loading and seismic effects on safety-related

pipes and cable trays; and, 4) the effect of reduced parameters on the whole building (global)

response of the CEB structure to seismic loads including further information of the effect on

stress and strain in the concrete and rebar system. Following inspector review in Inspection

Report 2011-10, the unresolved item remained open pending NRC review of additional

information from NextEra on aspects number 3 and 4, above.

The team reviewed the revised operability determinations for the safety related structures listed

below and as described in POD 1664399, Revision 2.

. Control Building - "B" Electrical Tunnel,

. Containment Enclosure Building,

o Diesel Generator Building,

o Residual Heat Removal Equipment Vaults, and

o Emergency Feedwater Pump House

As part of the ASR extent of condition review, NextEra provided structural assessments for the

RCA tunnel and other ASR impacted buildings (reference Calculation C-S-1-10168).

The open aspects of numbers 3 and 4 were resolved after NextEra provided additional

information. Revision 2 of POD 581434 for the B electric tunnel (ET) provided additional

quantitative and qualitative analyses with consideration of ASR-induced changes in concrete

properties. As discussed in Sections 3.2.3 thru 3.2.6, the revised PODs addressed the impact

of changes in modulus on building frequency; flexure capacity and dynamic response; shear

capacity; and support anchors. The revised POD incorporated the results of the Interim

Assessment (FP 100716) relative to the performance of reinforcing steel anchorage to show

that postulated reductions in capacities were offset by conservatisms in ACI 318 Code and the

assumed loads. The revised PODs also incorporated the testing at the Ferguson Structural

Engineering Laboratory (FP 100718) of cast-in-place and drilled-in anchors to assess the impact

of anchor performance in ASR-affected concrete. The test results showed that the anchor

capacities remained above the theoretical capacity at crack indices (Cl) well above the

maximum Cl observed in Seabrook structures.

The team concluded that the initial failure of NextEra to adequately consider the ASR impacts

on structural performance, relative to support anchors and dynamic response, were examples of

minor performance deficiencies, in that, upon further evaluation these issues were determined

to be acceptable, as documented in NextEra's operability assessment. Additional inspector

review of this issue was documented in Finding FIN 0500044312011-10-02. This unresolved

item is closed.

8,2 (Closed) Unresolved ltem 2011-010-01 - Adequacy of Calculation Methods for ASR

NextEra initially pursued mechanical testing of concrete cores because that was the traditional

method as described in ACI 228.1R for determining properties of existing concrete structures.

Upon further review of industry experience and literature for ASR-affected concrete, NextEra

Enclosure
15

determined that the core test data was not indicative of structural performance of the

ASR-affected structures. NextEra's position is that once removed from the structure, the

concrete in the cores is no longer subject to the strains imposed by the ASR-related expansion

or restraints imposed by the reinforcing cage. Confinement provided by reinforcing steel and

other restraints (e.9., deadweight of the structure) limits ASR expansion of the concrete within

the structure, which reduces the extent of deleterious cracking and associated reduction of

concrete material properties. NextEra has determined that the structural evaluations based on

mechanical properties derived from core samples may under-predict structural performance (FP

100697, Structural Assessment of ASR-State of the Art). Since the reduction of mechanical

properties derived from testing of cores may not necessarily be representative of the structural

performance, NextEra changed its approach. For the current operability assessment, NextEra

compared the structural design capacities to design loads and demands and an assumed lower

bound ASR effects. This operability assessment was based on available industry data from

small scale test specimens having ASR degradation worse than that observed at Seabrook. For

the final operability assessment, NextEra plans to monitor structures via Crack Indexing and

pursue large scale testing of concrete specimens that are representative of the Seabrook ASR

conditions to demonstrate overall structural performance and operability. This large scale

testing will be conducted at the Ferguson Structural Engineering Laboratory (FSEL) at the

University of Texas, Austin (UT-A).

NextEra responded to CAL ltem #8 by letter dated June 21 , 2012, and provided a broad

overview of the testing planned at FSEL, which will include a shear test program, a lap splice

test program, and an anchor test program. The test program will include control specimens that

are intended to provide a baseline by which to determine the reductions in capacity due to ASR

and to quantify the margins available as calculated using ACI-318. NextEra plans to use the

test program to reconcile the ASR condition with the licensing design basis, to inform the

Structures Monitoring Program, and to evaluate potential mitigation strategies. NextEra's

actions, approach and methods used to resolve the ASR issue, including the proposed test

program, will be evaluated by the team in the second CAL follow-up inspection. Based upon

team review of the issues associated with this unresolved item, no violation of regulatory

requirements or performance deficiency was identified. This unresolved item is closed.

9.0 Conclusions and Follow-Up lssues

The team concluded that NextEra provided sufficient bases to close CAL ltems #1,#3, #5, #6

and #10. CAL ltem #2was reviewed, but remains open, pending completion of revisions to the

root cause evaluation by NextEra. The team determined during this inspection that NextEra

does not plan to finalize their structural evaluations and operability assessments until: 1) the

degree of ASR degradation on station reinforced concrete structures is appropriately reconciled

with the station design and licensing bases; and2) the progression of ASR is appropriately

monitored to ensure structural integrity and operability is maintained for the duration of the

current operating license. Further, the team determined that NextEra's current position is that

no reinforced concrete structure at Seabrook Station will be precluded from monitoring for the

affects of ASR until a satisfactory petrographic examination has been completed on that

structure to confirm the absence of ASR. As discussed in the above sections, NextEra's

corrective actions to address the non-conforming ASR-affected reinforced concrete structures

include plans to complete performance testing of large scale test specimens and use the test

Enclosure
16

results to finalize the structural operability assessments and modify the Structures Monitoring

Program.

The team plans to conduct a second CAL follow-up inspection to review the remaining open

CAL items and the open issues documented in this report and listed below:

Review of pending structural evaluations, including follow-up of the containment POD

observations (Section 3.2.1);

Review of core sample material property testing and SMP (Section 3.2.2);

Review quantification of pre-stressing effects of ASR expansion (Section 3.2.8);

Assess the need for any further rebar examinations or testing (Section 3.2.9);

Review revised RCE submittal (Section 4.2);

Confirm revised commitment to CAL ltem #7 (Section 5.2);

o Review Crack Indexing and its physical significance for SMP application (Section 6.2);

and,

o Review adequacy of revisions to the Phase 3 walkdown plans and schedule

(Section 7.2).

10.0 Meetings, Including Exit

On November 2,2012, the team conducted an exit meeting to discuss the preliminary findings

and observations with Mr. Kevin Walsh, Site Vice President, and other members of Seabrook

Station staff. The inspectors verified that no proprietary information was retained by the

inspectors or documented in this report.

Enclosure
A-1

SUPPLEMENTAL INFORMATION

KEY POINTS OF CONTACT

Licensee Personnel

B. Brown, Design Engineering Manager

A. Chesno, Performance lmprovement Manager

K. Chew, License Renewal Engineer

R. Clich6, License Renewal Project Manager

M. Collins, Design Engineering Manager

J. Connolly, Site Engineering Director

R. Noble, Project Manager

M. O'Keefe, Licensing Manager

T. Vassallo, Principal Design Engineer

K. Walsh, Site Vice President

P. Willoughby, Licensing Engineer

LIST OF ITEMS OPENED, CLOSED, DISCUSSED, AND UPDATED

Updated

None

Opened

None

Closed

05000443/201 1-010-01

05000443/201 1-003-03

URI

URI

Adequacy of Calculation Methods for ASR

Open Operability Determinations for Safety-Related

Structu res Affected by Al kal i-S i I ica Reacti on

LIST OF DOCUMENTS REVIEWED

Procedures

Maintenance Rule Scoping Document, Revision 0

EDS 36180, Structures Monitoring Program, Revision 0, 1, 2

Corrective Action Documents (AR)

1 651 969, 1629504, 574120, 581434, 1 63641 9, 1673102, 1647722, 1 664399, 1677340,

1687932, 1692374, 1 698739, 1755727 , 1757861, 1 81 9080, 1804477 , 

1 81 9069

Attachment
A-2

Drawings

Licensing and Desiqn Basis Documents and Calculations

Seabrook Station UFSAR, Revision 14

ACt 318-71

Calculation CD-20

Calculation CD-18

Calculation C-S-1 -1 01 68

Miscellaneous Documents

FP 100348, Statistical Analysis-Concrete Compression Test Data (PTL)

FP 100642, Scope for Alkali-Silica Reaction Walkdowns

FP 100641, Procedure for ASR Walkdowns and Assessment Checklist

FP 100661, Compression Testing Concrete Cores (WJE)

FP 100696, Material Properties of ASR-Affected Concrete

FP 100700, Field Investigation

FP 100705, Structure ASR Walkdown Report (MPR 0326-0058-58)

FP 100714, Three Dimensional Dynamic Analysis of Containment Enclosure Building

FP 100715, ASR lmpact Study on Containment Enclosure Building

FP 100716, Interim Assessment: lmpact of ASR on Structures (MPR-3727)

FP 100717, ACI 318-71 Perspectives

FP 100718, AnchorTest Report (MPR-3722)

FP 100720, Crack lndex and Expansion Measurement

FP 100738, Measurements for ASR Crack lndexing on Concrete Structures

FP 100697, MPR 0326-0058-53, White Paper on Structural lmplications of ASR:

State of the Art, Revision 1

MPR 0326-0058-83, Shear Screening Criteria Used in MPR-3727

FHWA-HlF-09-004, Federal Highway Administration, "Report on the Diagnosis, Prognosis, and

Mitigation of Alkali-Silica Reaction in Transportation Structures."

Attachment
ACI

ADAMS

AMP

AR

ASME

ASR

BRE

CAL

ccl

CEB

CFR

CW

DCR

DGB

DRI

DRP

DRS

EDG

EFW

EPRI

EOC

ET

EV

FEA

FHWA

FP

FPL

FSEL

tMc

IP

LF

MPR

NRC

PARS

P&ID

PM

POD

PRA

psi

QA

RCA

RCE

RHR

SDP

SG&H

A-3

LIST OF ACRONYMS

American Concrete I nstitute

Agencywide Documents Access and Management System

Aging Management Program

Action Request

American Society of Mechanical Engineers

Alkali-Silica Reaction

Building Research Establishment

Confirmatory Action Letter

Combined Crack Index

Containment Enclosure Building

Code of Federal Regulations

Circulating Water

Demand to Capacity Ratios

Diesel Generator Building

Damage Rating lndex

Division of Reactor Projects

Division of Reactor Safety

Emergency Diesel Generator

Emergency Feedwater

Electric Power Research Institute

Extent-of-Condition

Electric Tunnel

Equipment Valve

Finite Element Analysis

Federal Highway Administration

Foreign Print

Florida Power and Light

Franklin Structural Engineering Laboratory

Inspection Manual Chapter

[NRC] Inspection Procedure

Load Factor

MPR Associates, Inc.

Nuclear Regulatory Commission

Publicly Available Records

Piping and Instrument Diagram

Preventative Maintenance

Prompt Operability Determination

Probabilistic Risk Assessment

pounds per square inch

Quality Assurance

Radiologically Controlled Areas

Root Cause Evaluation

Residual Heat Removal

Significance Determ ination Process

Simpson, Gumpertz & Heger

Attachment
SMP

SRI

UFSAR

UT-A

UK

WO

A-4

Structures Monitoring Program

Senior Resident Inspector

Updated Final Safety Analysis Report

University of Texas - Austin

United Kingdom

Work Orders

Attachment
UNITED STATES

NUCLEAR REGULATORY CO]UIi' ISSION

REGPil I

21(X) Renaissance Boulevard

KING OF PRUSSIA, PENNSYLVANIA 1940G1415

May 16,2012

CAL No. 1-2012-002

Mr. PaulFreeman

Site Vice President, North Region

Seabrook Nuclear Power Plant

NextEra Energy Seabrook, LLC

c/o Mr. MichaelO'Keefe

P.O. Box 300

Seabrook, NH 03874

SUBJECT: CONFIRMATORY ACTION LETTER, SEABROOK STATION, UNIT 1 .

INFORMATION REI.ATED TO CONCRETE DEGMDATION ISSUES

Dear Mr. Freeman:

This letter confirms recent commitments by NextEra Energy Seabrook, LLC (NextEra) in regard

to planned actions for the degradation of concrete in certain structures due to an Alkali-Silica

Reaction (ASR). The ASR iJa chemical reaction in concrete, which occurs over time in the

presence of water, between the alkaline cement paste and reactive non-crystalline silica that is

found in some common coarse aggregates. In the presence of water, the ASR forms a gel that

expands, causing micro-cracks tliat can change the physical structural properties of the

concrete. NextEia's completion of these commitments will ensure important information is

provided to the NRC stafito determine if the licensee is taking adequate corrective actions for a

significant condition adverse to quality.

In June 2009, NextEra initially identified concrete degradation of below grade concrete

structures at Seabrook. ln August 2010, NextEra completed core sample analyses for

petrograhic evaluation, compressive strength, and modulus oJ elasticity. These analyses

iOentiieO a change in material properties due to ASR for the "8" electrical tunnel in the control

building (CB), wiih reductions reported in the concrete compressive strength and modulus of

elasticily'from expected values. NextEra evaluated these parametric reductions to determine

the impict on the design basis of the "B' electrical tunnel. By its process, the licensee

performed both an immediate and a prompt operability determination and concluded that the'B"

electricaltunnelwas operable. As additional information was obtained, including observed

degradation of other structures through an extent of condition review, later revisions of the

operability determinations concluded that the'8" electrical tunnel and other structures were

operable but degraded.

Encl osure 2
1.

P. Freeman

NRC expert review determined the ASR affected structures remained capable of performing

their safety-related functions. This determination was based in part by the following:

1) conservative safety load factors in controlling load conditions and engineering conservatisms

in design provide reasonable expectation that affected structures can perform their safety

function, despite the cunent licensing and design bases design margin being reduced by the

change of mechanical properties; 2) field walk-downs confirmed no visible indication of

significant deformation, distortion, or displacement of structures, or rebar corrosion; 3) ASR

identified limited to localized areas in the concrete walls; 4) progression of ASR degradation is

occurring slowly based on existing operating experience and NextEra continues to monitor the

affected structures.

By letters dated May 3 and May 10,2012 (Agencywide Documents and Management System

(ADAMS) Accession Numbers M112125A022 and M112131A479, respectively), you described

the actions that you will be taking to address the degraded conditions as well as to ensure that

Seabrook meets its current licensing basis as a result of the ASR issue. More specifically, it is

our understanding that you will be establishing a bounding operability determination for all

ASR-affected buildings as well as interim monitoring actions to ensure the degradation is

effectively managed. The commitments addressed below are expected to be completed as

indicated:

Revise the prompt operability determination (POD) associated with AR581434, 'Reduced

Concrete Properties Below Grade in "8" Electrical Tunnel Exterior Wall,' by May 25,2012.

NextEra Energy Seabrook will notify the site NRC Resident lnspector upon completion of

this action.

Submit the root cause for the organizational causes associated with the occurrence of ASR

at Seabrook Station and related corrective actions by May 25,2012.

Submit the evatuation, "lmpact of ASR on Concrete Structures and Attachments," (Foreign

Print 100716) by May 25,2012.

Submit the corrective action plan for the continued assessment of ASR in concrete

structures at Seabrook Station including development of remedial actions to mitigate the

affects of ASR, where warranted, by June 8,2012.

Revise the POD associated with AR1664399, 'Reduced Concrete Modulus of Elasticity

Below Grade in Containment Enclosure Building, RHR Equipment Vaults, EFW Pump

House, and Diesel Generator Fuel Oil Storage Rooms,' by June 30,2012. The expanded

scope buildings will be included in this POD. NextEra Energy Seabrook will notify the site

NRC Resident Inspector upon completion of this action.

Complete short term aggregate expansion testing (ASTM C 1260 Mortar Bar Expansion

Test) by June 30, 2012. Results will be available for NRC review approximately 30 days

after testing is complete.

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P. Freeman

Complete long term aggregate expansion testing (ASTM C 1293 Concrete Prism Test) by

June 30, 2015. Results will be available for NRC review approximately 30 days after testing

is complete.

Submit the technical details of the testing planned at the contracted research and

development facility by June 30,2012.

Update the Maintenance Rule Structures Monitoring Program to include monitoring

requirements for selected locations in areas that exhibit ASR by July 15, 2012. NextEra

Energy Seabrook will notify the site NRC Resident Inspector upon completion of this action,

10. Perform the initial six-month interval crack measurements and crack indexing at 20locations

in areas that exhibit the highest crack indices by July 15,2012. Crack measurement will be

performed at six-month intervals until a reliable trend of ASR progression is established.

NextEra Energy Seabrook will notify the site NRC Resident Inspector upon completion of

these periodic measurements.

11. Complete anchor test program by December 31, 2012. Results will be available for NRC

review approximately 30 days afier testing is completePursuant to Section 182 of the Atomic Energy Acl, 42 U.S.C 2232 you are required to:

1) Notify me immediately if your understanding differs from that set forth

Notify me if for any reason you cannot complete any of the actions and commitments

within the specified schedule and advise me in writing of your modified schedule in

advance ofthe change; and,

Notify me in writing when you have completed allthe actions and commitments

addressed in this Confirmatory Action Letter (CAL).

lssuance of this CAL does not preclude issuance of an Order formalizing the above

commitments or requiring other actions on the part of NextEra, nor does it preclude the NRC

from taking enforcement action for violations of NRC requirements that may have prompted the

issuance of tnis letter. Failure to take the actions as described in this CAL may also result in an

Order if the NRC determines that failure to meet that action or action(s) would result in a loss of

reasonable assurance of the protection of public health and safety or the common defense and

security.

This CAL will remain in effect until the NRC has concluded that all actions listed above have

been satisfactorily completed. We note that, regarding the ASR issue, license renewal is a

separate ticensing action before the Commission and the NRC may require the submittal of

further information as part of the licensee renewal application review beyond that provided in

response to this CAL.

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P. Freeman 4

In accordance with 1O CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter, its

enclosure, and your Fesponse (if any), will be available electronically for public inspection in the

NRC Public Doiument Room or from the Publicly Available Records System (PARS)

component of NRC'g Agencywide Documents Access and Management System (ADAMS),

accessible from the run-C W6U site at http://www.nrc.gov/reading-rm/adams.html (the Public

Electronic Reading Room). To the extent possible, your response should not include any

personal privacy, proprietiry, or safeguards information so that it can be made available to the

public without ridaction. lf proprietary information is necessary to provide an acceptable

iesponse, then please provide a bracketed copy of your response that identifies the information

tnaisnouid be protected and a redacted copy of your response that deletes such information. lf

you request wiihhotOing of such material, you must specifically identify the portions of your

iesponie that you see[to have withheld and provide in detailthe bases for your claim of

withholding (e.g., explain why the disclosure of information will create an unwarranted invasion

of personal iriJacy or providl the information required by 10 CFR 2.390(b) to support a request

forwithholding confidential commercial or financial information). lf safeguards information is

necessary to irovide an acceptable response, please provide the level of protection described

in 10 CFR 73.21.

After reviewing your response, the NRC will determine whether further action is necessary to

ensure comptilnce with regulatory requirements. lf you have any questions, please contact

Richard J. conte at (610) 337-5183 or e-mail richard.conte@nrc.gov.

Sincerely, M

Regional Adm inistrator

Docket No. 50-443

License No. NPF-86

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