ML13221A172
| ML13221A172 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 08/09/2013 |
| From: | Ray Lorson Division of Reactor Safety I |
| To: | Walsh K NextEra Energy Seabrook |
| Trapp J | |
| References | |
| IR-12-010 | |
| Download: ML13221A172 (34) | |
See also: IR 05000443/2012010
Text
UNITED STATES
NUCLEAR REGULATORY COMMISSION
REGION I
2IOO RENAISSANCE BOULEVARD, SUITE IOO
KING OF PRUSSIA. PENNSYLVANIA 19406-27 13
August 9,2013
Mr. Kevin Walsh
Site Vice President
Seabrook Nuclear Power Plant
NextEra Energy Seabrook, LLC
c/o Mr. Michael Ossing
P.O. Box 300
Seabrook, NH 03874
SUBJECT: SEABROOK STATION, UNIT NO. 1 - CONFIRMATORY ACTION LETTER
FOLLOW-UP INSPECTION - NRC INSPECTION REPORT O5OOO443/2012010
Dear Mr. Walsh:
On June 27,2013, 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 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.
The NRC determined that the eleven actions committed to in the CAL have been satisfactorily
completed. The team independently verified that NextEra had appropriately assessed and
determined that allASR-affected structures remain operable. The team also confirmed that
your root cause evaluation was thorough and identified appropriate corrective actions.
Many important corrective actions necessary to resolve this issue are currently in progress and
related commitments are documented in your ASR Project Corrective Action Program. These
actions include your planned two-year test program of ASR-affected large scale concrete
specimens at the University of Texas, Ferguson Structural Engineering Laboratory (FSEL).
Therefore, while our review of the CAL items was completed during this inspection, the NRC will
continue to provide oversight of both NextEra's testing program at the FSEL and onsite ASR-
related activities. The NRC is in the process of evaluating the technical inspection results
discussed in this report to inform our future regulatory decision regarding the status of the CAL.
The results of our evaluation will be provided to NextEra in a future correspondence.
K. Walsh 2
lt 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 require additional consideration and
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.qov/readinq-rm/adams.html (the Public Electronic Reading Room).
l, t'^-
Division of Reactor Safety
Docket No. 50-443
License No: NPF-86
Enclosures:
1. lnspection Report No. 0500044312012010
w/ Attachment: Supplemental Information
2. Confirmatory Action Letter 1-2012-002
3. Revision to Confirmatory Action Letter 1-2012-002
cc w/encl: Distribution via ListServ
Enclosure
ML13221A'172
g Nonensitive g Publicly Available
g SUNSlReview tr
tr Sensitive Non-Publicly Available
OFFICE RUDRS RYDRP RI/DRS RI/DRS
NAME WCook GDentel JTrappl RLorson/
DATE 08/09/1 3 08107113 08/09/13 08/09/2013
U.S. NUCLEAR REGULATORY COMMISSION
REGION I
Docket No.: 50-443
License No.: NPF-86
Report No.: 05000443/2012010
Licensee: NextEra Energy Seabrook, LLC
Facility: Seabrook Station, Unit No. 1
Location: Seabrook, New Hampshire 03874
Dates: November 3,2012 to June 27 ,2013
Inspectors: W. Cook, Team Leader, Division of Reactor Safety (DRS)
S. Chaudhary, Reactor Inspector, DRS
W. Raymond, Senior Resident lnspector
A. Buford, Structural Engineer, Division of License Renewal (DLR),
Office of Nuclear Reactor Regulation (NRR)
G. Thomas, Structural Engineer, Division of Engineering, NRR
A. Sheikh, Senior Structural Engineer, DLR, NRR
N. Floyd, Reactor Inspector, DRS
Approved by: James Trapp, Chief, Engineering Branch 1
Division of Reactor Safety
Enclosure
SUMMARY OF FINDINGS
1R 0500044312012010i 1110312012 - 0612712013; Seabrook Station, Unit No. 1; Confirmatory
Action Letter (CAL) Follow-up lnspection Report.
This report covered several weeks of onsite inspection at Seabrook Station, two weeks of
inspection at the Ferguson Structural Engineering Laboratory (FSEL) University of Texas -
Austin, and periodic in-office reviews, over the past eight months, by region-based inspectors
and headquarters reviewers to assess the adequacy of NextEra's actions to address the impact
of Alkali-Silica Reaction (ASR) on 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 second CAL follow-up inspection, the team examined the remaining six
commitments documented in CAL No. 1-2012-002, dated May 16, 2012. The CAL items
reviewed and closed during this inspection were 2, 4,7,8, 9 and 1 1. In addition, a number of
observations documented in the first CAL follow-up inspection (NRC Inspection Report 05000443/2012009, Section 9.0) were reviewed and closed in this report. Closure of CAL
Item 7 was administrative, in that, NextEra had withdrawn this commitment by letter dated
December 13,2012 (ML12362A323). NextEra's revision to this commitment was approved by
the NRC as documented in the CAL revision letter, dated January 14,2013 (ML13014A555).
The review and closure of each CAL item signifies the NRC's satisfactory assessment of
NextEra's commitments and planned corrective actions to address the ASR non-conforming
condition at Seabrook Station. However, the completion of the CAL follow-up inspections does
not represent the completion of NRC review and oversight of NextEra's actions to address the
ASR issue. As discussed in the team's review of CAL ltem 4 and the revised ASR Project
Corrective Action Plan (CAP), NextEra has planned a number of ongoing activities, in addition
to the FSEL testing program, to address ASR-affected structures.
NextEra's root cause evaluation (CAL ltem 2) appropriately identified the significant causal and
contributing factors resulting in ASR impacting reinforced concrete structures at Seabrook
Station. NextEra's ASR Project CAP (CAL ltem 4), provided in a letter to the NRC
(ML131514328), sufficiently captures the corrective actions taken and planned to address the
ASR non-conforming condition and will remain in place to track the resolution of ASR at
Seabrook Station.
The Mortar Bar Testing (CAL ltem 6, reference NRC Inspection Report 05000443/2012009) was
successfully completed, and the results indicated sufficient reactive silica and alkali in the
Seabrook structures to allow the progression of ASR for the foreseeable future. Consequently,
NextEra withdrew its commitment for Prism Testing (CAL ltem 7), and the NRC staff
administratively closed this commitment. The team reviewed NextEra's large specimen testing
program technical specifications (CAL ltem 8) and anchor testing program description (CAL
Item 11) and concluded that these programs were sufficiently developed and described to
support an understanding of the testing plans and objectives.
Enclosure
NextEra implemented a number of enhancements to the Structures Monitoring Program (CAL
Item 9) to adequately monitor the progression of ASR. The team concluded these monitoring
actions were consistent with currently available industry practices.
Lastly, the team completed a follow-up and review of a number of observations discussed in the
first CAL Follow-up Inspection Report, including: pending structural evaluations; containment
prompt operability determination (POD) observations; core sample material property testing;
quantification of pre-stressing effects of ASR expansion; additional rebar examinations; crack
indexing use in the SMP; and the Phase 3 walkdown plans and schedule.
iii 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 concrete and 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 numerous Seabrook
Category l structures was evaluated in the Corrective Action Program, and prompt operability
determinations (PODs) were performed. NextEra revised the PODs as new information became
available and improved analytical techniques were incorporated.
NextEra initially used the results of mechanical testing of concrete core samples to assess the
degree of structural degradation due to ASR. This is a traditional method described in American
Concrete Institute (ACl) 228.1R, "ln-Place Methods to Estimate Concrete Strength," 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, "Building Code Requirements for Reinforced Concrete," to evaluate the structural
capacity (operability) of the ASR-affected structures. However, the mathematical relationships
in ACI-318 are based on empirical data from testing of non-degraded concrete, and these
relationships may not be valid for 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. Based on this conclusion, NextEra suspended
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.
NextEra's operability evaluations were based upon an examination of available design margins
and a presumed ASR-caused reduction in structural design capacities. 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 for
ASR-affected concrete for limit states based on research test data, primarily from small-scale
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 that even after applying lower-bound values
to structural limit states to assume ASR effects, the structures were suitable for continued
service. A final operability assessment will be conducted by NextEra following evaluation of
Enclosure
2
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 sometesting (anchors) commenced in 2013 and large beam testing scheduled to be
completed by 2A15. Based upon the slow progression of the ASR expansion, the cunent
operability evaluations, coupled with the Structures Monitoring Program six-month combined
crack indexing, provide reasonable assurance of continued structural operability.
2.0 Confirmatory Action Letter 1-2012-002
Confirmatory Action Letter 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. ln 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 and the revision to the CAL are
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. As
documented in NRC Inspection Report No. 0500044312012009, dated December 3,2012
(ML12338A283), CAL ltems 1, 3, 5, 6, and 10 were closed. Based on the results of this
inspection, the remaining six CAL ltems 2,4,7,8, 9, and 11 are closed.
3.0 Review of Alkali-Silica Reaction Root Cause Evaluation (CAL ltem 2)
Inspection Scope
As documented in lnspection Report No. 0500044312012009, the team reviewed NextEra's
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 its root cause evaluation (RCE) in a letter to the NRC dated May 24,
2012 (ML12151A396). Based upon the team's initial review, the inspectors concluded that the
second root cause identified was not sufficiently characterized in NextEra's May 24,2012,
submittal. Specifically, NextEra did not clearly describe the performance and organizational
factors that contributed to inadequacies in the Structures Monitoring Program (SMP) and the
failure of the Seabrook staff to have identified ASR degradation of reinforced concrete
structures sooner. The team discussed this observation with the responsible Seabrook staff.
NextEra determined that a revision to the RCE was warranted and revised the RCE to more
appropriately develop and characterize this second root cause and the associated corrective
actions.
3
NextEra submitted a revised RCE summary for NRC review in a letter dated May 1, 2013
(ML13151A328, Enclosure 1). The team reviewed the revised RCE summary for clarity and
appropriateness of associated corrective actions, consistent with guidance outlined in 10CFR50,
Appendix B, Criterion XVl, "Corrective Action," and NextEra's Corrective Action Program.
Findinqs and Observations
The team identified no findings. Based upon the team's review, CAL ltem 2 is closed.
As documented in Enclosure 1 to the May 1 ,2013letter, NextEra summarized the two root
causes as follows: RC1 - the ASR developed because the concrete mix design unknowingly
utilized a coarse aggregate that would, in the longterm, contribute to ASR. Although the testing
was conducted in accordance with American Society for Testing and Materials (ASTM)
standards, those testing standards were subsequently identified as limited in their ability to
predict slow reacting aggregate that produced ASR in the long-term; and RC2 - based on the
long-standing organizational belief that ASR was not a credible failure mode due to the concrete
mix design, dispositions for condition reports involving groundwater intrusion or concrete
degradation, along with the structures health monitoring program, did not consider the possibility
of ASR development. ln addition, NextEra identified a contributing cause that its organization
did not prioritize groundwater elimination or mitigation, resulting in more concrete area exposed
to moisture.
The team verified that NextEra had appropriately identified the root cause(s). The ASTM
concrete aggregate testing standards in effect at the time of plant construction were properly
implemented, but later determined to be ineffective in identifying slow-reacting, ASR-susceptible
aggregates. Those standards were subsequently revised by the industry and adopted by
NextEra to prevent recurrence. NextEra's RCE concluded that the Structures Monitoring
Program did not remain current with concrete industry operating experience and associated
failure modes, such as ASR. Contributing to the shortcomings of the SMP in not identifying this
concrete degradation mechanism earlier was the "organizational mindset" that the groundwater
in-leakage was an operational nuisance and nothing more. Consequently, station and
engineering staffs were insensitive to the potential detrimental effects of the groundwater
infiltration and did not assess the long{erm impact on station structures. NextEra's
implementation of a broad periodic review process to ensure all systems and component
monitoring programs remain current and effective was determined by the team to be an
appropriate corrective action for this causal factor.
4.0 Integrated Corrective Action Plan (CAL ltem 4)
Inspection Scope
CAL No. 1-2012-002 documented NextEra's commitment to submit, by June 8,2012, a
corrective action plan for the continued assessment of ASR in concrete structures at Seabrook
Station, including development of remedial actions to mitigate the effects of ASR where
Enclosure
4
warranted. By letter dated June 8, 2012 (ML12171A227), NextEra submitted its integrated
corrective action plan (CAP) for NRC review. The CAP outlined the major elements of
diagnosis, evaluation, prognosis and mitigation of ASR-affected structures as understood at the
time. Since June 8,2012, NextEra has made considerable progress in refining the elements of
this plan, implementing the initial phases, and more clearly defining and focusing future actions.
NextEra provided an updated ASR Project CAP in a letter dated May 1 , 2013 (M113151A328,
Enclosure 2) to document these plan changes.
During this inspection period, the team conducted numerous discussions, meetings, and
conference calls with NextEra, as well as onsite inspections at both Seabrook Station and UT-
Austin to review NextEra's actions to address the ASR-affected reinforced concrete structures.
From these interactions, the CAP has developed greater clarity of the necessary steps
(corrective actions) to address this non-conforming condition impacting safety-related reinforced
concrete structures. As previously documented in Inspection Report 05000443/2012009 and
detailed in other sections of this report, the team assessed the adequacy of completed and
ongoing ASR-related activities identified in the integrated CAP, consistent with guidance
outlined in 10CFR50, Appendix B, Criterion XVl, "Corrective Action," and NextEra's Quality
Assurance Program.
Findinqs and Observations
The team identified no findings. Based upon the team's review, CAL ltem 4 is closed.
NextEra's ASR project staff stated that they plan to maintain the ASR Project CAP as a "living
document" and will update it periodically to capture completion of activities and add new actions,
as appropriate.
5.0 Prism Testing Commitment Withdrawn (CAL ltem 7)
Inspection Scope
CAL ltem 7 committed NextEra to "Complete longterm aggregate expansion testing (ASTM
C 1293, Concrete Prism Test) by June 30, 2013." The purpose of this CAL item was to
determine, in conjunction with the Mortar Bar Testing (CAL ltem 6), if the coarse aggregate
contributing to ASR in Seabrook reinforced concrete still contained sufficient reactive silica for
the alkali-silica reaction to continue long-term under the existihg environmental conditions.
Alternatively, these tests could demonstrate that the progression of ASR at Seabrook could be
self-limiting due to the depletion of reactive silica in the concrete. The Prism Test (as defined by
ASTM C1293) involves monitoring the expansion (by measurement of specimen elongation due
to ASR) of the test specimen (a molded concrete brick approximately 3 by 5 by 12 inches in
length) over a one-year period. Expansion in excess of 0.04o/o is considered potentially
deleterious and a positive test for slow-reactive aggregate. The Prism Test is similar to the
Mortar Bar Test (reference ASTM C1260), but has a duration of 14 days and an expansion limit
of 0.1o/o.
Enclosure
5
Based upon the results of the completed Mortar Bar Expansion Testing (reference NRC
lnspection Report No. 0500044312012009, Section 5.0), NextEra concluded that the available
quantities of silica in the concrete would not be depleted in the near term and that additional
confirmatory testing via the Prism Test method was not warranted. NextEra ran the Mortar Bar
Test several weeks beyond the 14-day test (terminated after 103 days) and observed that the
alkali-silica reaction was still progressing at the conclusion of the test, indicating the presence of
sufficiently reactive aggregate to maintain ASR for a longer period of time. The team noted that
the Mortar Bar Test involved the reuse of aggregates from Seabrook test cores (concrete that
had already experienced appreciable ASR) and similar aggregate from concrete not affected by
ASR. The side-by-side comparison of the test specimens showed no appreciable difference in
ASR progression or observed expansion rates. Accordingly, NextEra concluded the Prism Test
would add no significant knowledge to the condition assessment of Seabrook concrete.
NextEra concluded that all Seabrook reinforced structures are or may be affected by ASR,
unless specifically ruled out by further analysis, such as petrographic examination. By letter
dated December 13,2Q12, NextEra requested that CAL ltem 7 be deleted. As documented in
NRC letter dated January 14,2013 (ML13014A555), the NRC accepted NextEra's technical
basis for deleting CAL ltem 7.
Findinqs and Observations
No findings were identified. CAL ltem 7 is administratively closed.
6.0 Review of Technical Details of Large Specimen Testing Program (CAL ltem 8)
lnspection Scope
CAL ltem 8 committed NextEra to "Submit the technical details of the testing planned at the
contracted research and development facility by June 30,2012." By letter dated June 21 ,2012
(ML12179A281), NextEra submitted the Shear and Lap Splice Testing overview prepared by the
Ferguson Structural Engineering Laboratory (FSEL) at the University of Texas at Austin, dated
March 15, 2012. The purpose of the test program, as described in the FSEL document, is to
provide sufficient data and insights to establish the current and future implications of ASR on
Seabrook reinforced concrete structures. Since there is limited available literature or test data
relative to the impact of ASR on walls without transverse shear reinforcements (i.e., the majority
of Seabrook ASR-affected structures), destructive testing of ASR-affected test specimens is
being conducted to evaluate the impact of ASR on out-of-plane shear strength and lap splice
development. The test specimens being prepared at FSEL will be of representative scale and
design such that the test results may be correlated to Seabrook structures.
The team reviewed the June 21,2012, submittal and conducted a conference call on
December 18,2012, with the NextEra and UT-Austin FSEL staff to discuss the merits of the
proposed test program. Based upon the complexity of the information discussed and follow-up
inspection activities, NextEra prepared a test program overview document and a detailed test
Enclosure
6
specification to supplement the June 21 , 2012, CAL response letter. By letter dated May 1,
2013 (ML13151A328 redacted and M113151A291 un-redacted), NextEra provided the NRC
with the "seabrook Station - Specification for Shear and Reinforcement Anchorage Testing of
ASR-Affected Reinforced Concrete," (Enclosures 3 & 4) and "Approach for Shear and
Reinforcement Testing of Concrete Affected by Alkali Silica Reaction," (Enclosure 5 & 6). Each
of these documents has a proprietary and non-proprietary version.
The team reviewed the revised testing specification and the associated overview document to
verify that the overall test program approach and application of test results would reasonably
address the Seabrook ASR-affected concrete non-conforming condition. The team discussed
the test program with the FSEL, MPR and responsible NextEra engineering staffs.
Findinqs and Observations
No findings were identified. Based upon team review of the submitted testing program
documents and related inspection activities, the team concluded that NextEra has provided an
appropriate level of detail of the proposed large-scale specimen testing program, and CAL ltem
8 is closed.
As documented in NextEra's ASR Project CAP (ML 13151A328, Enclosure 2), and assuming
satisfactory outcomes, the acceptance of the testing results to resolve ASR concerns
associated with design basis structural calculations may follow the regulatory process for
approval and would include evaluations pursuant to 10CFR50.59 and 10CFR50.90. The
submitted test plans satisfy NextEra's commitment to explain the scope and depth of the large-
scale specimen testing program,
7.0 Review of Structures Monitoring Program (CAL ltem 9)
Inspection Scope
CAL ltem 9 committed NextEra to implement an update to the Maintenance Rule (10CFR50.65)
Structures Monitoring Program (SMP) to include monitoring requirements for selected locations
in areas that exhibit ASR by July 15, 2012. NextEra issued Revision 2 to Structural Engineering
Standard 36180, "Structural Monitoring Program," effective July 12,2012. The primary changes
incorporated in Revision 2 to the SMP were: 1) performing periodic (every six months) crack
indexing measurements at 26 locations to collect quantitative information on the progression of
ASR expansion/degradation; 2) establishing crack width (1.0 mm or greater) and Combined
Crack lndex (1.0 mm/m or greater) thresholds for conducting structural evaluations (reference
Foreign Print 100716, Seabrook Station: lmpact of ASR on Concrete Structures and
Attachments); and 3) the addition of Federal Highway Administration (FHWA) document FHWA-
HIF-09-004, "Report on the Diagnosis, Prognosis, and Mitigation of Alkali-Silica Reaction in
Transportation Structures," dated January 2010, as a reference.
Enclosure
7
The team reviewed the adequacy of these changes to the SMP to monitor ASR in Seabrook
reinforced concrete structures. While not endorsed by the NRC or committed to by NextEra in
Seabrook's licensing basis, the team used the American Concrete lnstitute (ACl) Committee
Report 349.3R-96, "Evaluation of Existing Nuclear Safety-Related Concrete Structures," as a
reference to assess the adequacy of the revisions made to the SMP for monitoring the
progression of ASR.
Based in part on NRC observations, NextEra issued Revision 3 to the SMP on April 30, 2013.
The SMP enhancements are: 1) the addition of periodic (every 30 months) combined crack
indexing (CCl) measurements at 72 discrete locations identified as Tier ll (Acceptable with
Deficiency) areas (CCl values between 0.5 mm/m and 1.0 mm/m, or crack widths greater than
0,2 mm, but less than 1.0 mm) to collect quantitative information on the progression of ASR
expansion/degradation (this monitoring was being performed, but not documented in the SMP);
and, 2) inclusion of the periodic groundwater sampling program for monitoring of chemical
attributes detrimental to concrete structures. During a follow-up discussion with the NextEra
staff, the team noted that NextEra is considering additional SMP revisions, dependent upon the
results of the large specimen test program and further engineering evaluation. One of the
revisions involves the installation of deep pins for monitoring of expansion in the out-of-plane
direction (reference NextEra's May 1 ,2013, Response to Confirmatory Action Letter
(M113151A328) Enclosure 2, ASR Project Corrective Action Plan).
Findinos and Observations
The team identified no findings in this area. CAL ltem 9 is closed.
The team noted that changes made to the SMP to address ASR were generally consistent with
the evaluation and monitoring methods outlined in ACI 349.3R-96. The team confirmed that
NextEra had incorporated a three-tiered visual inspection criteria, as outlined in Sections 5.1
through 5.3 of ACI 349.3R-96. NextEra has also augmented this visual inspection criteria with
periodic (six-month and 3O-month interval) CCI measurements and associated structural
evaluation thresholds based upon direct measurement (CCl) results. The CCI monitoring,
performed at 98 selected locations (including containment), was implemented by NextEra based
upon this method being a readily measurable indicator of ASR-related progression and based,
in part, upon endorsement by FHWA as outlined in FHWA-HIF-09-004.
The crack growth monitoring provides a visual indication of the progression of ASR within a
reinforced concrete structure, The relative width and number of visible cracks may be
correlated to the overall progression of ASR and may be used to evaluate ASR impact on
structural performance. However, ASR cracking and crack propagation is closely associated
with the specific reinforcement design and structural loading. Accordingly, the adequacy of CCI
measurement as a long-term structures monitoring methodology for Seabrook structures is
being further evaluated by NextEra as part of the UT-Austin FSEL testing program. The results
of the UT-Austin testing program are intended to be used to validate this methodology for
application at Seabrook.
Enclosure
8
With respect to the evaluation of infiltration water chemistry and groundwater monitoring, ACI
349.3R-96 discusses environmental monitoring and related effects of aggressive water
chemistry, including the potentialfor leaching. Accordingly, NextEra has integrated the periodic
monitoring of groundwater chemistry into the SMP (reference Revision 3, dated 413012013,
Attachment 4). NextEra plans to investigate the expansion of the water chemistry monitoring
program (reference AR No. 1758920-40) to include periodic analysis of infiltrated water (i.e.,
water that has migrated through below-grade reinforced concrete walls). The establishment of
an initial baseline analysis and continued periodic monitoring could provide some relative trend
data for further evaluation and follow-up actions, as appropriate.
The team concluded that the implemented and planned SMP enhancements provide NextEra
with an improved program to assess the extent and degree of ASR progression and to more
thoroughly monitor the environmentalfactors contributing to ASR. NextEra's initial SMP
revision (Revision 2) was adequate; however, the SMP Revision 3 enhancements include
multiple activities that are more closely aligned with ACI 349.3R guidance.
8.0 Review of Anchor Testing Program (CAL ltem 11)
lnspection Scope
The micro-cracking caused by ASR may adversely impact the structural capacity of anchors that
support safety-related piping, cable trays and other components. NextEra's initial operability
determinations were supported by anchor performance testing conducted on available ASR-
degraded specimens previously fabricated at or obtained by FSEL, UT-Austin (reference FP
100718). As documented in lnspection Report 05000443/2012009, the initialtesting
demonstrated satisfactory performance of the anchors in ASR-affected concrete during the
earlier stages of ASR progression. NextEra's evaluation also stated that the eventual reduction
in capacity due to ASR was sufficiently offset by established anchor manufacturer's design
margins (FP 100716). However, based upon the limitations of the testing performed (on ASR-
affected test specimens of different composition and compressive strength than Seabrook
reinforced concrete structures), NextEra planned to conduct additionaltesting. The planned
testing involves anchors installed (both during specimen fabrication and post-fabrication) in
ASR-affected test specimens that more closely replicate the reinforced concrete structures and
anchor configurations at Seabrook.
By licensee letter dated December 13, 2012 (ML123624323), NextEra requested a revision to
CAL ltem 11 to address a schedule challenge to the targeted anchor testing program
completion date. NextEra also proposed redefining CAL ltem 11 to be consistent with the
wording of CAL ltem 8, regarding large-scale specimen testing. Specifically, NextEra revised its
commitment to read, "Submit technical details of the anchor test program planned at the
contracted research and development facility by February 28,2413." The original commitment
read, "Complete anchor test program by December 31 ,2012. Results will be available for NRC
review approximately 30 days after testing is complete." Based upon unexpected specimen
fabrication delays and the slow progression of accelerated ASR aging, NextEra identified that it
would not be possible to complete the anchor testing per the original commitment date.
Enclosure
9
The NRC accepted NextEra's revised commitment, as documented in NRC letter dated
January 1 4, 2013 (ML1 301 4A555).
The team reviewed the details and adequacy of NextEra's anchor testing program as outlined in
the proprietary "Anchor Testing Program Overview," dated February 26,2013. The anchor
testing program overview and associated testing specifications were docketed for NRC review
via NextEra letter dated February 28,2013 (ML13088A218 redacted and ML13088A229 un-
redacted, dated March 15,2013). The technical overview document and accompanying
specifications outline the major elements of the proposed anchor testing program, including the
key attributes of the fabrication of the test specimens, monitoring of the specimens as
accelerated ASR aging progresses, and the details of the testing of individual anchor bolt
configurations.
Findinqs and Observations
The team identified no findings. Based upon the team's review, CAL ltem 11 is closed.
During the team's visits to the UT-Austin FSEL, the team observed the conditions and controls
implemented for the aging of the test blocks and testing of concrete sample cylinders for
compressive strength and modulus of elasticity. The team witnessed appropriate
implementation of the testing procedures by FSEL staff and proper oversight of these activities
by the MPR staff.
At the conclusion of this inspection, the desired level of ASR progression in the test blocks had
not been achieved to conduct the first round of ASR-affected anchor testing. The team
reviewed the results of the control specimen anchor testing completed in November 2012. The
purpose of the control specimen testing was to establish a baseline to determine the potential
reduction in anchor bolt capacity due to ASR. Review of the test data (reference MPR
Memorandum DRN 0326-0058-163, dated June 18, 2013) identified that all anchor bolt test
results were in agreement with calculated capacities, and an appropriate baseline had been
established for comparison during future testing.
9.0 Review of Previously ldentified lssues of Interest
9.1 Structural Evaluations for 13 Locations
As documented in Inspection Report 05000443/2012009, NextEra identified 26 locations
(including containment) as having patterned cracking with a CCI of greater than 1.0 mm/m. In
accordance with the SMP, Revision 2, structures with a CCI of >1.0 mm/m require a structural
evaluation. NextEra's lnterim Assessment documented an engineering judgment that biased
the performance of detailed structural evaluations to the 1'l locations with a CCI > 1.5 mmlm.
The locations with a CCI of between 1.0 and 1 .5 mm/m (13 locations) were considered bounded
by the 11 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 a minor
Enclosure
10
performance deficiency which NextEra entered into its Corrective Action Program (AR 1804477
and AR 1819080). During this inspection, the team reviewed Calculation C-S-10168,
Revision 1, and FP 100716, "Seabrook Station: lmpact of Alkali-Silica Reaction on Concrete
Structures and Attachments," Revision 2, which incorporated the additional evaluations for the
13 locations.
The evaluation methodology included reviewing the original calculations that govern the design
of the structures to determine the design parameters associated with the general area of ASR
degradation. The structural member's load demand and capacity were then noted and the
margin calculated for comparison against the potential reductions in load capacities caused by
ASR. The assumed reductions in capacity were determined based on lower-bound values
established in industry literature. A summary of the evaluation results was provided in Table 3
of FP100716, Revision 2. For areas where design margins were insufficient to offset assumed
lower-bound reductions in capacity due to ASR, further review was performed to determine if
analysis could show that there was additional margin. For each of these areas, the analysis
either reduced load factors that were applied to the demand loads in the original design basis
calculations, or used the 28-day compressive strength (based on field testing performed at the
time of construction) to obtain a higher as-built structural capacity value. The analysis is
described in Calculation C-S-1-10168, Revision 1. The team found the approach of reducing
load factors to establish more representative demand loads in order to demonstrate additional
margin to assure structural integrity acceptable for the current state of ASR degradation.
NextEra plans to credit the load factors in the load demand calculation to establish full
qualification per the Final Safety Evaluation Report (FSAR) licensing basis in the final operability
determination, following completion of the testing program at UT-Austin.
The team concluded that NextEra's initial approach to perform a bounding analysis for areas
with CCI >1.5 mm/m was not conservative, because the design margins vary in each structural
member of each reinforced concrete structure. Once the impact of the ASR degradation on
structural capacities is determined from the UT-Austin FSEL test program, NextEra plans to
review the design calculations for each ASR impacted area to assure margins remain
acceptable. The team concluded that the revised assessment appropriately completed the
engineering evaluations for the 13 locations.
9.2 Review of Core Sample Material Property Testing
As documented in Inspection Report 05000443/2012009, Section 3.2.9, the NRC planned to
reexamine the need of additional core sampling of Seabrook structures for the purpose of
monitoring and assessing the condition of ASR-affected reinforced concrete. For the long-term,
NextEra has elected to evaluate structural performance (operability) of the Seabrook ASR-
affected reinforced concrete structures by developing a testing program involving large
specimens that are fabricated to closely replicate the Seabrook concrete and reinforcement
design. NextEra has pursued this method, instead of conducting detailed material properties
testing of core samples, based upon available laboratory testing and data that indicates that
measurable material properties of removed cores do not, under all circumstances, accurately
represent the "in situ" mechanical properties of the concrete. The reason for the difference is
that prior to removal of the core sample, that concrete specimen is subjected to the specific
structural compressive stresses (dead loads, live loads, and hydrostatic loads) and inherent
Enclosure
11
restraint due to reinforcement bars. When removed from the structural member, that concrete
specimen is unrestrained. In addition, as identified in the associated core sampling standard
(ASTM C42, "Standard Test Method for Obtaining and Testing Drilled Cores and Sawed Beams
of Concrete"), core sample test results may be "...affected by many factors such as the strength
level of the concrete, the in-place temperature and moisture histories, the degree of
consolidation, batch-to-batch variability, the strength-gain characteristics of the concrete, the
condition of the coring apparatus, and the care used in removing cores."
The team's review of this issue has identified two general approaches to gaining an informed
understanding of the impact of ASR on reinforced concrete structures. One approach is that
being taken by NextEra to assess the overall structural performance of an ASR-affected
structural member, much like (but not the same) as the performance of a load test prescribed by
ACI 318, "Building Code Requirements for Structural Concrete," Chapter 20, "Strength
Evaluation of Existing Structures." Whereas, the alternative approach involves analytical
evaluations using as an input the measureable steel and concrete material property values
derived from samples from the affected structure, also recognized by ACI 318, Chapter 20.
NextEra is challenged to appropriately correlate the FSEL test program results to the Seabrook
structures. Accordingly, NextEra plans to take additional core samples from both the test
specimens and the Seabrook structures to better correlate the large specimen test results using
petrography and mechanical testing. The team viewed additional core sampling as a positive
means to better correlate FSEL test data to the plant structures.
9.3 Containment Prompt Operability Determination (POD) and Pre-stressing Effects
of ASR
As discussed in Inspection Report 0500044312012009, the team noted that the confinement
provided by the steel reinforcement bar (rebar) cage restrains ASR expansion resulting in ASR-
induced or "chemical" pre-stressing of affected structural members. The team observed that
NextEra had provided a qualitative explanation of this condition in the Interim Assessment (FP
100716), and in the containment POD and structural evaluation (reference AR 1804477). The
team had concluded that a quantitative evaluation of this condition may be warranted to address
this aspect of the non-conforming ASR condition.
During this inspection, the team discussed the impact of ASR-induced pre-stressing on
reinforced concrete structures with NextEra and reevaluated NextEra's assessment in AR
1804477, The effect of "chemical" pre-stressing is to both increase the compressive stresses in
the concrete (within the rebar cage) and to increase the tensile stresses in the rebar, as long as
the rebar cage restraint is sustained (i.e., the concrete remains anchored to the rebar). Similar
to fabricated pre-stressed concrete structural members, the ultimate load carrying capacity of
the reinforced member is not significantly changed by the ASR-induced pre-stress. Some
studies have identified that the tensile stress in the reinforcing steel caused by the ASR
expansion results in a corresponding compressive stress on the concrete that balances the
added load and initially results in reduced deflections under load and a stiffer structural
behavior. However, without the ability to quantify the effect and account for the chemical pre-
stressing in engineering evaluations, the team concluded that even though the ASR-induced
Enclosure
12
pre-stressing may result in some beneficial effects in terms of structural stiffness, this cannot
and should not be credited for the purpose of structural evaluation. lt is possible that more
advanced ASR conditions could result in the steel reinforcement strain limits being exceeded
that could compromise the overall structural performance.
The team noted that although the combined crack index (CCl) had been measured at three
locations on the outside surface of containment, absent quantitative analyses, NextEra had not
shown that the containment reinforcements were below yield. Further, the team noted that the
current design code for containment does not allow containment reinforcement strains to be
above yield. The Seabrook containment was designed to ASME Section lll, 1975 edition and
used allowable stress design methodology. This methodology does not allow for stresses to
exceed the elastic limit. Specifically, "in order to keep the containment basically elastic under
service load conditions and below the range of general yield under factored primary loads, the
allowable stresses and strains in this subsection shall not be exceeded." This issue was
discussed with NextEra representatives who stated actions would be taken (reference AR
1804477) to determine the effects of ASR relative to the containment design code requirements.
As this issue has been documented in the Seabrook CAP with an open operability
determination, resolution of the issue will be monitored via the ROP baseline inspection
activities.
The team concluded there was no significant safety concern with containment reinforcement
strain at this time because: (1) the containment is heavily reinforced and ASR is highly localized
affecting a small percentage of containment area; (2) the concrete strain (crack index)
measured at the surface may not reflect the condition of the reinforcement; and, (3) the
integrated leak rate test in 2010 showed the containment returning to pre-existing conditions.
As documented in NextEra's containment POD, primary containment is fully operable and
capable of meeting all its design basis functions, with some reduced margin.
9.4 Assessment of the Need for Further Rebar Examinations
As documented in Inspection Report 05000443i2Q12009, Section 3.2.9, the NRC reviewed the
potential for ASR having an adverse impact on rebar. NextEra and its engineering consultants
had concluded that rebar is unaffected by ASR-degraded concrete unless the cover concrete is
severely damaged and the rebar is exposed. NextEra concluded that ample alkali remains in
the concrete to maintain rebar passivity and to preclude a corrosive environment.
The team determined that NextEra's position was acceptable. Based upon the examination of a
limited number of Seabrook rebar, and the review of available industry operating experience
associated with concrete degradation mechanisms, the team concluded that at the current level
of ASR there is no evidence to suggest that the reinforcing steel bars at Seabrook are
corroding. ln accordance with the Seabrook SMP and the referenced American Concrete
lnstitute 349.3R-96, "Evaluation of Existing Nuclear Safety Related Concrete Structures,"
periodic visual inspections (signs of leaching, staining, spalling and pop outs) coupled with soil
and groundwater testing for aggressive chemistry conditions (i.e., chlorides, sulfates and pH)
provide appropriate monitoring and industry recommended detection methodology. Inspections
conducted have not identified any iron oxide staining attributed to rebar corrosion on any ASR-
Enclosure
13
affected concrete structures at Seabrook. Consequently, the team has concluded that no
additional rebar examinations (i.e., removing the cover concrete to expose rebar for visual
inspection) are currently warranted.
9.5 Use of Combined Crack Indexing for Structures Monitoring Program
As previously documented in Inspection Report 05000443/2012009, Section 6.0, the team
planned to examine NextEra's basis for using Combined Crack Indexing (CCl) as the primary
SMP method to monitor the progression of ASR in Seabrook structures. The team noted that
the basis for NextEra's selection of CCI for monitoring, as endorsed by the FHWA, is that CCI
provides a direct visual and measurable method for the detection and monitoring of ASR
progression. Although the objective of NextEra's UT-Austin testing program is to establish and
correlate the degree of ASR progression to overall structural performance, the interim use of the
CCI method and the 6-month interval measurements taken, to date, provide reasonable
assurance that the level of degradation due to ASR remains essentially the same and that the
progression rate is low. As such, the bounding engineering calculations and associated prompt
operability determinations remain valid.
Best available information concerning the impact of ASR on a structural member indicates that
the formation of ASR gel within the concrete matrix, and subsequent absorption of water by that
gel, results in gel expansion that generates stresses within the concrete matrix. These
expansion stresses are transferred to the concrete and relieved by cracking that is present in
both the exterior cover concrete and inside the rebar cage. For structures that are not triaxially
reinforced (this includes the majority of the walls at Seabrook Station that have no through-wall
shear reinforcement), the potential exists for some undetected out-of-plane crack formation that
could result in an adverse impact on structural performance. As documented in Section 6.0, the
large-scale testing program is intended to provide additional insights to the overall performance
of non-triaxially reinforced wall structures.
In support of the use of CCl, which is a two-dimensional concrete surface measurement,
NextEra is developing plans to install deep pins in ASR-affected walls at Seabrook to better
monitor ASR progression. The large-scale test specimens fabricated at the UT-Austin facility
include three-dimensional through-wall pin placements which will provide a more
comprehensive measurement of the ASR expansion and associated impact on structural
performance. NextEra plans to install similar deep pins at the site in order to better correlate the
UT-Austin testing results and the two-dimensional CCI data to actual structural performance.
As stated above, within the confines of the reinforcement cage, the ASR expansion is restrained
and some of the expansion stresses are transferred to the reinforcing bars. The added stresses
are carried by the steel rebar. As a result, within a reinforced concrete structure, the visible
ASR patterned cracking will be smaller and finer since the rebar is carrying the load and
providing restraint to the concrete. The amount of restraint provided by the rebar is dependent
upon the type, size and design of the concrete section. More heavily reinforced structures
would more readily resist ASR expansion and may depict a different level of CCI compared to a
lightly or non-reinforced structure with a similar degree of ASR progression. The team
concluded that the use of periodic CCI measurements to monitor ASR progression appears
appropriate, pending the outcome of the UT-Austin testing.
Enclosure
14
9.6 Planned Regulatory Actions
As discussed in Section 6.0 of this report, and in NextEra's ASR Project CAP, the crediting of
the FSEL test results for demonstrating current and longer term operability of ASR-affected
reinforced concrete structures may be evaluated by NextEra pursuant to 10CFR50.59 (changes,
tests, and experiments) and 10CFR50.90 (license amendment requests). The team concluded
that this approach is appropriate and consistent with existing regulatory processes. The team
notes that CCI may become the principle method used by NextEra for monitoring the
progression of ASR in affected structures. Pending the results of the FSEL testing program,
NextEra may propose the use of this methodology for assessing current and future operability of
ASR-affected structures.
10.0 Review of Six-Month Combined Crack Indexing Data
Inspection Scope
The team reviewed the periodic concrete expansion measurements and observed field
measurements for ASR-impacted Seabrook structures. Specifically, the team examined the
supporting documentation for the ASR Crack lndex Report, dated March 18, 2013 (FP 10081 1 ),
and the ASR Expansion Measurements Report, dated March 18,2013 (FP100812). The team
also conducted interviews and discussions with the responsible NextEra engineering staff. The
team used 10CFR50, Appendix B, Criterion XVl, "Corrective Action," and Criterion Xl, "Test
Control," as the regulatory guidance to assess the adequacy of NextEra's actions to address
AS R-affected rei nforced concrete structu res.
Findinqs and Observations
No findings were identified. The combined crack index (CCl) data indicated that there was
some evidence of expansion caused by the ASR; however, the CCI data was inconsistent with
the pin-to-pin measurements that indicated no measurable expansion, at the same monitored
locations. There was no change in the CCI data for the containment, but the Electric Tunnel
and the Primary Auxiliary Building/Residual Heat Removal (PAB/RHR) vault both showed an
increasing trend in CCI value in the six months since June 2012. While this may be the result of
seasonal effects, ASR degradation appears to be ongoing in some Seabrook structures as
indicated by minor incremental crack groMh. Collectively, the CCI measurements indicate
essentially no structural changes, and therefore no challenges to the conclusions in the current
ASR-affected structures' prompt operability determinations. The team noted NextEra's plans to
continue the 6-month CCI measurements to establish a stable trend in observable ASR
expansion for each uniquely ASR-affected structure. Continued periodic measurements should
eliminate the potential influence of seasonal ambient temperature changes from the trend
results.
CCI Measurements
ln the ASR Crack Index Report (FP10081 1), NextEra measured CCI values lor 26locations in
the monitoring program and compared the results to the data taken in June 2Q12. The
December CCI data shows an apparent increase in most (19 of 26) of the monitored locations.
Enclosure
15
NextEra concluded the apparent increase in CCI values may be due to seasonal temperature
variations because the concrete (in December) was significantly colder, which may cause the
concrete to contract between the cracks, increasing the apparent crack widths,
As reported by NextEra, uneven cracking (total crack width in one direction is much larger than
in the other direction) and measured larger cracks were identified in the horizontal direction
compared to the vertical. The team observed that, over the long{erm, averaging the horizontal
and vertical CCI values may be an adequate representation of overall changes due to ASR of
the specific structural member. However, the practice of averaging the horizontal and vertical
CCI values is different than outlined by available industry guidance (FHWA-HlF-09-004) that
recognizes the influence of reinforcements on crack growth. Thus, reporting an averaged CCI
vice directional CCI values separately could mask the expansion in a preferred direction and
hamper the identification of a trend in the short term. NextEra acknowledged this team
observation and initiated a Condition Report (CR 1758920-41) to evaluate this issue.
The team also noted that NextEra revised the method of calculating CCI in the recent 6-month
measurement report (December 2012). The CCI measurement reporting method was changed
to account for the use of rectangular grids to determine crack index and thereby normalize index
to the total number of lines in the both directions. In so doing, NextEra recalculated the CCI
values for the December 2011 and June 2012 data to eliminate potential biasing errors. The
team concluded that NextEra's more consistent use of a calculation method would aid the
identification of apparent trends.
Structure Expansion Measurements
In the Expansion Measurement Report (FP100812), NextEra performed measurements
between pins embedded in the surface of plant buildings at the 26 established CCI monitoring
locations. The 26 monitored locations were selected from the 131 locations identified in the
ASR Walkdown Report (reference FP100705) which exhibited the highest visible ASR-
associated distress. NextEra noted a null result for expansion measurements between pins in
most of the 26 monitored locations. Specifically, data recorded in most (436) measurement
lines showed no significant changes compared to the baseline data. However, for 5 of the 436
measurement lines, NextEra noted length changes that were unexpected. NextEra plans to
evaluate these locations further.
The team noted that the crack index data shows an apparent increase when expansion data in
2-dimensions shows no change. lt appears that the CCI data better reflects expansion in the
structure compared to the expansion measurements in only two dimensions, which may not be
a complete indicator of changes in the structure. The team noted that NextEra plans to add
deep pins to ASR-impacted walls in the monitored locations that will allow expansion
measurements in the out-of-plane direction (reference CR 1758920-39).
Enclosure
16
11.0 Review of Adequacy of Revisions to the Phase 3 Walkdown Plans and Schedule
lnspection Scope
During the previous inspection, the team reviewed the overall thoroughness of NextEra's
completed and planned ASR walkdown activities conducted in accordance with FP 100642,
"ASR Walkdown Scope," Revision 1, and documented in FP 100705, "Seabrook Station:
Summary of Alkali Silica Reaction Walkdown Results," Revision 0. At the time of the inspection,
not all of the potentially affected structures had been examined and NextEra had drafted a
tentative schedule for the completion of the Phase 3 (areas not readily accessible) walkdowns.
During this inspection, the team assessed NextEra's final Phase 3 schedule for completeness
and to ensure a timely examination of the extent of condition of ASR-affected structures.
Findinqs and Observations
No findings were identified.
NextEra's ASR extent of condition structures 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 Fhase 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 at the
earliest opportunity (e.9., routine maintenance or outage activities). Team examination of the
Phase 3 walkdown areas identified a minor documentation issue (in addition to the previously
documented containment IWL inspection oversight) that the spent fuel pool (SFP) reinforced
concrete walls were not included in the planned Phase 3 walkdown list even though NextEra
was planning to do these inspections. The SFP walls pose a particular challenge to NextEra
due to the limited accessibility of the concrete surfaces. At the conclusion of this inspection,
NextEra was working to complete its evaluation of various methods to assess the SFP concrete
walls (reference ASR Project Corrective Action Plan, revised April 2013). NextEra had already
initiated plans to perform one shallow core bore in an area that was continuously wetted (SFP
telltale sump) from borated water. This core will be examined for concrete degradation and to
look for any degradation of rebar (reference ML 1227A023, Commitment No. 67).
The team assessed the Phase 3 walkdown schedule and concluded the target dates for
completion were reasonable. With respect to completing a comprehensive examination of the
containment structure, the team concluded that performing this inspection concurrent with the
scheduled 2015 refueling outage IWL examination was appropriate and commensurate with the
safety significance of the issue. The balance of the Phase 3 extent of condition walkdowns are
scheduled for completion in mid-to-late 2013 and during the April 2014 refueling outage. In
summary, the team concluded that NextEra's completed and planned extent of condition
reviews for identification of ASR-affected reinforced concrete structures was appropriate.
Enclosure
17
12.0 Aircraft lmpact Review
lnsoection Scope
The team reviewed NextEra's evaluation of the aircraft impact study performed in response to
the identification of ASR. The aircraft impact study for Seabrook containment is described in
UFSAR Section 3.8.1.3 and Appendix 2P. As noted in the Updated Final Safety Analysis
Report (UFSAR), the postulated aircraft impact load is not combined with any other containment
transient design loading. Further, the study assumes the impact area to be on the dome just
above the spring line.
Findinqs and Observations
No findings were identified.
The effects of an aircraft impact were found not to be controlling for overall containment design
considerations. Also, the analysis assumes that the enclosure building fails when struck by the
aircraft and deforms until the aircraft contacts the containment structure. The containment
enclosure building design and analysis is described in UFSAR Section 3,8.4. NextEra's
evaluation states that ASR has only been identified in below-grade elevations of the
containment and containment enclosure buildings, where sufficient moisture has contributed to
ASR progression. To date, no above-grade (or vicinity of the anticipated aircraft impact area)
evidence of ASR has been identified on containment. Accordingly, NextEra has concluded that
the Seabrook aircraft impact study remains valid and unaffected based upon engineering
evaluations of other ASR-affected reinforced concrete structures completed to date.
13.0 UT-Austin Ferguson Structural Engineering Laboratory Visits
Scope of Review
On two separate occasions, members of the team visited the UT-Austin testing facility to
observe ongoing activities and inspect general facility quality assurance and control measures.
The team noted that NextEra has contractual agreements with MPR Associates and the UT-
Austin Ferguson Structural Engineering Laboratory to oversee and conduct, respectively, the
ASR large-scale testing program. The team toured the facility, including: main fabrication and
testing areas with overhead crane lifting capabilities; outside exposed and protected (green
house) specimen curing areas with continuous or cyclic wetting and drying capability; aggregate
and sand storage yard; and office and laboratory spaces for storage and use of calibration and
test equipment, as well as, environmentally controlled storage units for a variety of mortar bar,
prism, and concrete cylinder test specimens. The team examined the large block anchor bolt
test specimens, including the control specimen block which had been tested. The team also
witnessed fabrication of the second large shear and lap splice test beam, and some testing of
cylinders for compressive strength and Modulus of Elasticity determination.
Enclosure
18
Findinqs and Observations
No findings were identified. The team observed appropriate oversight and quality control
practices being implemented. Direct oversight by both UT-Austin supervisory staff and MPR
engineers was evident and effective.
14.0 Meetings, Including Exit
On June 27,2013, 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
M. Ossing, Licensing Manager
K. Walsh, Site Vice President
P. Willoughby, Licensing Engineer
LIST OF ITEMS OPENED, CLOSED, DISCUSSED, AND UPDATED
Updated
None
Opened
None
Closed
None
LIST OF DOCUMENTS REVIEWED
Procedures
Maintenance Rule Scoping Document, Revision 0
EDS 36180, Structures Monitoring Program, Revisions 1, 2, 3
Corrective Action Documents (AR)
1651969,1629504,574120,581434,1636419,1673102,1647722,1664399,1677340,
1687932, 1692374, 1 698739, 1755727, 1757861, 1 81 9080, 1804477, 1 81 9069
Drawinqs
Licensinq and Desion Basis Documents and Calculations
Seabrook Station UFSAR, Revision 14
ACt 318-71
Calculation CD-20; Calculation CD-18; and Calculation C-S-1-10168
Attachment
A-2
Miscellaneous Documents
FP 1 00348, 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 lnvestigation
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, lnterim Assessment: lmpact of ASR on Structures (MPR-3727)
FP 100717, ACI 318-Tl 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."
ASME lll, Division 2, 1975 Edition, Winter'77 Addenda
Documents Reviewed at FSEL
Purchase Order No. 0326 - 0058 -25, dated December 1, 2011 and change order Nos. 1, dated
March 21,2012; No. 2,dahed March 27,2012; No.3, dated July23,2Q12; and No.4, August2,
2012 betvreen MPR Associates lnc. and Ferguson Structural Engineering Laboratory as applied
to Anchor Testing Program
Contract No. 02293285, dated June 6, 2011, and Amendment Nos. 1, dated October 25,2011:
No.2, dated December 17,2011; No.003, dated January 3,2012: No.004, dated February27,
2012; Amendment 6, dated July 26, 2012, between NextEra and MPR Associates Inc.
MPR Letter to Ferguson Structural Engineering Laboratory, dated December 1, 2011, Notice of
Intent to Contract for Testing of Anchors in ASR-affected Concreter - authorizing FSEL to
develop project-specific quality system manual, implementing procedures for testing and
perform initial characterization of the ASR degradation on girders.
MPR Letter to Ferguson Structural Engineering Laboratory, dated December 1, 2011, Research
on Performance of Anchors in ASR-affected Concrete
MPR Letter to Ferguson Structural Engineering Laboratory, dated March 27,2012, Research on
Performance of Anchors in ASR-affected Concrete
Attachment
A-3
MPR Letter to Ferguson Structural Engineering Laboratory, dated July 23, 2012, Research on
Performance of Anchors in ASR-affected Concrete
MPR Letter to Ferguson Structural Engineering Laboratory, dated August 2,2012, Research on
Performance of Anchors in ASR-affected Concrete
MPR Letter to Ferguson Structural Engineering Laboratory, dated October 26,2012, Research
on Performance of Anchors in ASR-affected Concrete
Purchase Order No. 0326 - 0063 -01, dated June 4, 2012, between MPR Associates Inc. and
Ferguson Structural Engineering Laboratory as applied to Beam Testing Program
Contract No. 02207204, dated April27, 2012, NextEra and MPR Associates Inc., related to ASR
Concrete Beam Testing Program (for Shear and Lap-splice anchorage)
Project Plan 0326 - 0062 -01, Revision 0, dated May 1 , 2012, by MPR Associates Inc. as
applied to Beam Testing Program
Attachment
A-4
LIST OF ACRONYMS
ACI American Concrete Institute
ADAMS Agencywide Documents Access and Management System
AR Action Request
ASME American Society of Mechanical Engineers
ASR Alkali-Silica Reaction
ASTM American Society for Testing and Materials
CAL Confirmatory Action Letter
CAP Corrective Action Plan
CCI Combined Crack lndex
CFR Code of Federal Regulations
CR Condition Report
DLR Division of License Renewal
DRP Division of Reactor Projects
DRS Division of Reactor Safety
FHWA Federal Highway Administration
FP Foreign Print
FSAR Final Safety Analysis Report
FSEL Franklin Structural Engineering Laboratory
MPR MPR Associates, Inc.
NRC Nuclear Regulatory Commission
NRR Office of Nuclear Reactor Regulation
PAB Primary Auxiliary Building
PARS Publicly Available Records
POD Prompt Operability Determination
RCE Root Cause Evaluation
SFP Spent Fuel Pool
SMP Structures Monitoring Program
SRI Senior Resident Inspector
UFSAR Updated Final Safety Analysis Report
UT-A University of Texas at Austin
Attachment
ffi
UNITED STATES
NUCLEAR REGULATORY COilMlsSloN
REGIOI{ l
21 00 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 RELATED TO CONCRETE DEGMDATION ISSUES
Dear Mr.
(NextEra) in regard
This tetter confirms recent commitments by NextEra Energy Seabrook, LLC
due to an Alkali'silica
to pranneo actions forih; degr;dation of concrete in certain structures
which occurs over time in the
n"..tion (ASR). The ASR iJa chemical reaction in concrete, silica that is
pi"ren"" of water, between the alkaline cement paste and reactive non-crystalline
ASR forms a gel that
found in some common coarse aggregates. In tlie presence of water, the
properties of the
expands, causing micro-cracks that can change the physical structural
information is
concrete. NextEra's completion of these comiritments will ensure important a
piouiolJ to the NRC staff to determine if the ticensee is taking adequate corrective actions for
significant condition adverse to quality.
grade concrete
ln June 2OOg, NextEra initially identified concrete degradation of below
analyses for
structures at Seabrooi, In August 2010, NextEra completed core sample
petrogianic evaluation, comprissive strength, andrnodulus of elasticity. Theseanalyses
"B" electrical tunnel in the control
identified a change in materiat properties d-ue'to ASR for the
modulus of
briidi;g (CB), wi[h reouatons i"pdtt"o in the concrete compressive strength andto determine
elasticity from expected values. NextEra evaluated these
parametric reductions
n" irnpi"t on the design basis of the "8" electrical tunnel. By its process, the licensee
the "8"
performed both an imriediate and a prorfiopgrability determination and concluded that
observed
electricaltunnel*"r-op"r"ule. As aioitiohat information was obtained, including of the
later revisions
degradation of other siructures through an extent of condition review,
concludeo ttrat the'8" electricaltunneland other structures were
operable but degraded.
Encl osure
P. Freeman 2
performing
NRC expert review determined the ASR affected structures remained capable of
tnJii satbty-related functions. This determination was based in part.by the following:
1) conservative safety load factors in controlling load conditions and engineering
conservatisms
in Oesign provide reaionable expectation that iffected structures can
perform their safety
functioi, despite the current licensing and design bases design margln being reduced by the
cnange of mechanical properties; 2) field walk-downs confirmed no visible indication
of
or displacement of structures, or rebar coqqsion; 3) ASR
iigniic"nt deformationf Oirtortion,
id6ntified timited to localized areas in the concrete walls; 4) progression of ASR degradation
is
monitor the
occurring slowly based on existing operating experience and NextEra continues to
affected structures.
system
By fetters dated May 3 and May 10,2012 (Agencywile _Do^cuments and Management
(nonrvrs) Accession Numbers M]12125AOZZ anlML12131A479, respectively), you described
ine aAions that you will be taking to address the degraded conditions as well as to ensure that
it is
Seabrook meets its cunent ficeniing basis as a result of the ASR issue. More specifically,
determination for all
our understanding that you will be eltabtishing a bounding operability
is
ASR-affected buildingsLs well as interim monitoring actions to ensure the degradation
to be completed as
effectively managed. The commitments addressed below are expected
indicated:
'Reduced
1. Revise the prompt operability determination (POD) associated with AR581434,
Concrete Rioperiies'Aelow Grade in "8" Electrical Tunnel Exterior Wall,' by May 25,2012'
upon completion of
NextEra energy Seabrook will notify the site NRC Resident Inspector
this action.
2. Submit the root cause for the organizational causes associated with the occurrence of ASR
at Seabrook Station and relatedlorrective actions by May 25,2012.
3. Submit the evaluation, "lmpact of ASR on Concrete Structures and
Attachments," (Foreign
Print 100716) by MaY 25,2012.
ASR in concrete
4. Submit the corrective action plan for the continued assessment of actions
structures at Seabrook Station including development of remedial to mitigate the
affects of ASR, where warranted, by June 8,2012'
Revise the pOD associated with AR1664399, 'Reduced Concrete Modulus of
Elasticity
5. Pump
Below Grade in Containment Enclosure Building, RHR EquipmentVaults' E:.FW
expanded
House, and OesliGenerator Fuel Oil Storage Rooms,' by June 30, 2012'..The
the site
scope'buildings r"itt U" included in this POD. NextEra Energy Seabrook will notlfy
NRb Resident Inspector upon completion of this action'
6. Complete short term aggregate expansion testing -(ASTIV! C 1260 Mortar Bar Expansion
resti by -lune sd, ioii-Cjsuns,niill ue availablJfor NRC review approximately 30 days
after testing is comPlete.
Encl osure
P. Freeman 3
Test) by
7. Gomplete tong term aggregate expansion testrlg (ASTM C 1293 Concrete Prism
30 days after testing
June'30, 201d. nesu[Jwiir be av'ailable for NRC ieview approximately
is complete.
g. Submit the technical details of the testing planned at the contracted research
and
development facility by June 30,2012.
g. 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 wiff notity the site NRC Resident lnspector upon completion of this action'
at 20 locations
10. perform the initial six-month interval crack measurements and crack indexing
measurement will be
in areas that exhibit the highest crack indices by July 15,2012. Crack
performed at six-month iniervals until a reliable treni of ASR progression is established'
of
NextEra Energy SeanrooX will notify the site NRC Resident Inspector upon completion
these periodic measurements.
available for NRC
11. Complete anchor test program by December 31 ,2012. Results will be
review approximately 30 days after testing is complete'
you are required to:
Pursuant to section 182 of the Atomic Energy Act, 42 U.S.C 2232
1) Notify me immediately if your understanding differs from that set forth above;
2) Notify me if for any reason you cannot complete any of the ac'tions and commitments
in
within the specifie'd schedule and advise me in writing of your modified schedule
advance ofthe change; and'
3)' Notify me in writing when you have completed allthe actions and commitments
addrissed in this Confirmatory Action Letter (CAL)'
above
lssuance of this CAL does not preclude issuance of an Order formalizing the
actions on the part of NextEra, nor does it preclude the NRC
commitments or requiiing othei prompted the
have
from taking enforcemeniaaion for violations oi ttRC requirements that may
may also result in an
issuance of this letter. Failure to take the actions as described in this CAL
result in a loss of
order if the NRC determines that failure to meet that action or action(s) would and
oi ne protection of public health and safety or the common defense
reasonable
security. "grr"n""
listed above have
This cAL will remain in effect untilthe NRC has concluded that all actions
been satisfactorily completed. we note that, regarding the 4SR issue,
license renewal is a
the submittal of
separate licensing action before the Commissio-n anOIhe NRG may require
that provided in
further information as part of the licensee renewal application review beyond
response to this CAL.
Encl osure
P. Freeman
In accordance with 10 cFR 2.390 0f the NRC's "Rules of Practice," a copy of this letter, its
public inspection in the
enclosure, and your r"rpont" tif any), will be available electronically for
(PARS)
NRC public Document Room or from the Publicly Available Records System
component of NRC's Agencywide Documents Aicess and Management Syltg1
(ADAMS)'
Public
accessibte from the rvn-c w6o site at http://www.nrc.gov/reading-rm/adams-html(the
any
Electronic Reading Room). To the extent possible, your response should not include
personal privacy, Fropri"tiw, or safeguard's informaiion so that it can be made available to the
pubtic witi.rout r6Oictibn. f proprietary information is necessary to provide an. acceptable
then please pruiJ"'a Orac-t<eteO copy of your response that identifies the information
that should be protected and a redacted copy oi your response that deletes such
',"rponr", information' lf
you request witnnoUing of such material, you must specifically identify th_e portions of your
r"tito have withheld and provide in.detail the bases for your claim of
iesponie that you
create an unwarranted invasion
withholding (e.g., explain why the disclosure of information will
request
of personal irivacy dr proviO6 the information required by 10 CFR 2.390(b) to support a
lf safegyards information is
forwithholding-provide commercial or financial information)-
provide level of protection described
necessary to "onn6ehtialan acceptable response, please the
in 10 CFR 73.21.
to
After reviewing your response, the NRC will determine whether further action is necessary
questions, please contact
ensure comptiance wiin'regutitory requirements. lf you hav_e any
Richard J. ionte at (010) 337-5183 or e-mail richard.conte@nrc.gov.
Docket No. 50-443
License No. NPF-86
M Sincerely,
Regional Administrator
cc: Distribution via ListServ
Encl osure
ttur,r,
-ol9^" -oa UNITED STATES
+t
5\
UL-^ -'l NUCLEAR REGULATORY COM]'lSSION
E -L\I O
REGION I
6 !l!nnF.r.. I
-9- 21 00 Renaissance Boulevald
\ {flS}!
^re KING OF PRUSSIA, PENNSYLVANIA 1940G1415
January 14, 2013
CAL No. 1-2012-002 (Revision 1)
Mr. Kevin Walsh
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
REVISION TO CONFIRMATORY ACTION LETTER, SEABROOK STATION,
UNIT 1 - INFORMATION RELATED TO CONCRETE DEGRADATION ISSUES
Dear Mr.
This letter confirms receipt of your letter of December 13,2012, related to the NRC
Confirmatory Action Letter (CAL) issued to NextEra Energy Seabrook, LLC (NextEra) on
May 16, 2012 (ADAMS Accession Number ML12125A172). The CAL confirmed actions
planned to be taken by NextEra in regard to the degradation of concrete in certain structures
due to an Alkali-Silica Reaction (ASR). In the December 13,2012,letter, you requested
changes to two of the commitments (CAL ltems Nos. 7 and 1'1). We accept your proposed
changes as discussed below:
CAL ltem No. 7 - You requested the deletion of this commitment, which required that NextEra
conduct a long term aggregate expansion test (ASTM C 1293 Concrete Prism Testing) by
June 30, 2013. Your letter states that the Mortar Bar Expansion testing conducted in
accordance with CAL ltem No. 6 identified that the coarse aggregates contain sufficient reactive
silica for the ASR reaction and expansion to continue long-term under existing environmental
conditions. Therefore, the results of the Mortar Bar Expansion Testing have obviated the need
to conduct additional aggregate expansion testing. Further information regarding this issue is
provided in NRC Inspection Report No. 0500044312012009, Section 5 (ADAMS Acc,ession
Number ML12338A283). Accordingly, the NRC has concluded that NextEra's commitment to
complete long term aggregate expansion testing by June 30, 2013, may be deleted.
CAL ltem No. 11 - You requested that the NRC change this commitment from completing the
anchor test program by December 31,2012, to "submit the technical details of the anchor test
program planned at the contracted research and development facility by February 28,2013."
You requested this change because the anchor testing program, while in progress, would not be
complete by December 31, 2012. NextEra's committed date for completing the anchor testing
was based on the best available projected test schedule in May 2012, and did not fully
anticipate allthe complexities involved in completing the test program. NextEra has completed
some limited testing of anchor performance of ASR-affected concrete as described in
Encl osure
K. Walsh 2
Section 2.3.6, of NRC Inspection Report No. 0500044312012009. These tests results
demonstrated satisfactory performance of the anchors and were used to support NextEra's
prompt operability evaluation. Based on our findings regarding anchor performance, the NRC
finds the requested commitment change acceptable.
The originalConfirmatory Action Letter 2O12-AO2 issued May 2012 remains in effect except as
modified for CAL ltems 7 and 11, above.
fn accordance with Title 10 of the Code of Federal Regulafions (10 CFR) 2.390 of the NRC's
"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 System (PARS) component of NRC's Agencywide Documents
Access and Management System (ADAMS), accessible from the NRC Web site at
http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room). To the extent
possible, your response, if you choose to provide one, should not include any personal privacy,
proprietary, or safeguards information so that it can be made available to the public without
redaction. lf proprietary information is necessary to provide an acceptable response, then
please provide a bracketed copy of your response that identifies the information that should be
protected and a redacted copy of your response that deletes such information. lf you request
withholding of such material, you must specifically identify the portions of your response that
you seek to have withheld and provide in detail the bases for your claim of withholding (e.9.,
explain why the disclosure of information will create an unwarranted invasion of personal
privacy or provide the information required by 10 CFR 2.390{b) to support a request for
withholding confidential commercial or financial information). lf safeguards information is
necessary to provide an acceptable response, please provide the level of protection described
in 10 CFR 73.21.
lf you have any questions, please contact Richard J. Conte at (610) 337-5183 or e-mail
richard. conte@nrc. gov.
Sincerely,
Regional Administrator
Docket No.: 50443
License No,: NPF-86
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Encl osure