ML16168A412

Slides for Public Meeting with NextEra Energy Regarding Seabrook Station ASR License Amendment

ML16168A412
Person / Time
Site:	Seabrook
Issue date:	06/15/2016
From:	Justin Poole Plant Licensing Branch 1
To:	Mccartney E NextEra Energy Seabrook
Poole J, NRR-DORL
References
Download: ML16168A412 (30)

Text

License Amendment Request:

Methodology for the Analysis of Concrete Seismic Category I Structures with Concrete Affected by Alkali Silica Reaction Seabrook Station June 15, 2016

NextEra Energy (NYSE: NEE) is comprised of two strong businesses supported by a common platform

• $17B Consolidated Revenues (1)

• 44,900 MW in operation (1, 2)

• 13,800 employees

• One of the largest U.S. electric utilities

• U.S. leader in renewable generation

• 4.8 MM customer accounts

• Assets primarily in 25 states and Canada

• 25,100 MW in operation

• 19,800 MW in operation (1, 2)

Worlds largest generator of renewable energy from the wind and sun Among Fortunes 2015 list of Worlds Most Admired Companies and among top 10 companies in the world in both the categories of innovativeness and community responsibility Named to 2015 Worlds Most Ethical Company list (Ethisphere Institute)

(1) As of Dec. 31, 2014 from 10-k (2) Includes NEEs ownership share of NextEra Energy Partners portfolio 2

The foundation for everything we do are the Values and Core Principles of our Nuclear Excellence Model 3

Seabrook Attendees

• Ken Browne NEE Seabrook ASR Project Manager

• Mike Ossing NEE Seabrook Licensing Manager

• Brian Brown NEE Seabrook Principal Engineer

• Larry Nicholson NEE Fleet Licensing Director

• John Simons MPR Gen Manager Power Projects

• Dr. Said Bolourchi SG&H Senior Principal Engineer

• Jim Moroney MPR ASR Test Program PM

• Phil Rush MPR Engineering Associate 4

Presentation Outline

• Alkali-Silica Reaction

• Overview of License Amendment Request (LAR)

• Structural Capacity Testing of ASR-Affected Specimens

• Evaluation of Structural Deformation

• Monitoring of ASR Expansion and Structure Deformation

• Summary of LAR changes

• Closing Remarks

-Presentation describes Next Era current intent regarding License Amendment Application 5

Alkali-Silica Reaction 6

Alkali-Silica Reaction

• ASR (alkali-silica reaction) is a chemical reaction between silica from the aggregate (gravel and/or sand) and alkali constituents in the cement

• Reaction produces a gel that expands as it absorbs moisture and exerts a tensile stress from within the concrete K+ gel OH-SiO2 SiO2 forms + H2O SiO2 OH-Na+ gel alkali cement + expansive gel cracking of the reactive aggregate aggregate and paste 7

Overview of License Amendment Request 8

Overview of License Amendment Request

• Next Era proposes a change in the UFSAR methodology to address ASR concrete degradation at Seabrook Station

• ACI 318-71 and the ASME Code do not include provisions for addressing ASR and its effects

- Incorporate loads imposed by ASR into the design basis

• Evaluate structures affected by ASR to demonstrate that they satisfy the acceptance criteria of the original construction code

- ACI 318-71 for all seismic Category I structures other than containment

- ASME Boiler & Pressure Vessel Code,Section III for containment 9

Overview of License Amendment Request

- Applies to Seismic Cat 1 Structures and Containment Structure

- Establish ASR expansion limits from testing:

Shear capacity Flexural capacity and reinforcement development length Anchor bolts embedded in concrete with ASR

- 3 Stage Analysis process for Building Deformation Assessment:

Specify how ASR loads are combined with other design basis loads for analyzing structures including defining load factors Include the effects of concrete creep, shrinkage and swelling in structure deformation analyses Identify ANSYS as the computer code used for ASR building deformation analyses Permit use of the 100-40-40 procedure from Regulatory Guide 1.92, Revision 3 for detailed evaluations (Stage Three) analyses of ASR-affected structures.

Use of cracked section properties and redistribution of self-limiting loads for ASR-affected structures

- Attachments:

UFSAR Markup and Clean Pages MPR 4288, Rev 0 Seabrook Station: Impact of ASR on Structural Design Structural Design Evaluations MPR 4273, Rev 0 Seabrook Station: Implications of Large Scale Test Program Results on Reinforced Concrete Affected by ASR SGH (#TBD) Computation of Load Factors for ASR Demands 10

Structural Capacity Testing of ASR-Affected Specimens 11

Structural Capacity Testing of ASR-Affected Specimens

• MPR conducted large-scale test programs to investigate structural impact of ASR on reinforced concrete

- Improve current understanding of ASR and its effects on reinforced concrete structures

- Evaluate instruments for monitoring (measuring) the through-thickness (out-of-plane) expansion of concrete from ASR 12

Structural Capacity Testing of ASR-Affected Specimens Reinforcement Instrument Anchor Test Shear Test Anchorage Evaluation Program Program Test Program Program Beam Test Programs 13

Structural Capacity Testing of ASR-Affected Specimens Test Program Results Key Conclusion Anchor Test

• Anchor performance No impact on anchors at Program

• insensitive to through-thickness expansion Seabrook based on expansion

• reduces at high levels of in-plane cracking levels expected

• No difference between performance of anchors installed before and after ASR expansion Beam Test

• Control specimens showed consistency with Original design strength and code Programs ACI 318 equations for shear capacity, flexural equations can be used for ASR-capacity and lap splice length affected reinforced concrete structures

• ASR-affected specimens showed:

• Shear capacity

• No adverse impact of ASR on shear capacity,

• Flexural capacity flexural capacity, reinforcement anchorage and lap

• Reinforcement development length splice performance

• Behavior indicative of pre-stressing due to ASR expansion Instrumentation Snap ring borehole extensometers were accurate Snap ring borehole Evaluation and reliable throughout duration of program extensometers selected for use at Program Seabrook Station 14

Structural Capacity Testing of ASR-Affected Specimens

• Licensing Implications

- Impact on UFSAR Large-scale testing or reinforced-concrete beams showed

- No adverse impact of ASR on shear capacity, flexural capacity or reinforcement development length

- Use of Code equations and design compressive strength to determine capacity is conservative No change to the UFSAR-described methodology is necessary for determining capacity provided ASR expansion is within limits from testing

- ASR expansion limits Expansion limits established based on range of expansion covered in testing Limits to be controlled within Structural Monitoring Program 15

Evaluation of Structural Deformation 16

Evaluation of Structural Deformation

• Inspections of Seabrook structures have identified deformation due to ASR expansion effects

- ASR-related expansion may impose an additional, internal load on reinforced concrete adjacent to ASR-affected areas

- ASR-related expansion of concrete backfill can impose an external load on adjacent structures

- Seismic gap widths and close clearances between structures and plant components may be reduced 17

Methodology for Analysis of Structural Deformation

• LAR describes progressive approach for evaluating structures with deformation

- Stage One - Screening Evaluation

- Stage Two - Analytical Evaluation

- Stage Three - Detailed Evaluation

• Structures require an analysis of all load combinations with ASR loads included 18

Evaluation of Structural Deformation Stage 1: Evaluate Field Screening Observations Responses due to Evaluation ASR loads (Sa)

Original Design Adequate No Stage 2:

Demands & Margin with Analytical Capacities Sa Evaluation Yes Sa = Load associated with ASR Define Threshold for Monitoring 19

Evaluation of Structural Deformation Stage 2: Analytical Evaluation Sa Inputs Based on Finite Correlate with Field Field Measurements and Element Observations other self straining loads Modeling Calculate Sa Stage 3:

Original Design Adequate No Margin with Detailed Demands & Capacities Evaluation Sa Yes Define Threshold for Monitoring 20

Evaluation of Stage 3 Structural Deformation Stage 3: Detailed Evaluation Original Finite Refined Sa Inputs Design Loads Element Based on Additional Inputs Modeling Field Measurements Evaluate Using Total Factored Design Demands Including Sa

• Cracked section

• Redistribution of Self-limiting load

• 100-40-40 Combination of seismic components Define Threshold for Monitoring 21

Evaluation of Structural Deformation

• Including ASR loads with other design basis loads requires definition of load factors for each loading combination

- ACI 318-71 and 1975 Edition of ASME B&PV Section III Division 2 does not include load factors for ASR

- SGH developed load factors consistent with ACI 318-71 and ASME 1975 Edition load factor development

- Load factors for ASR will be used in the analysis of Seabrook structures and included in Tables 3.8-1 and 3.8-16 of the UFSAR

• Structures evaluated to demonstrate that additional ASR expansion is permissible

- Margin is included in the acceptance criteria for each stage to ensure that additional deformation does not challenge design limits

- A higher level of deformation is analyzed relative to current measurements to set the threshold for monitoring 22

Evaluation of Structural Deformation

• Stage 2 or Stage 3 evaluation will use an ANSYS finite element model

- Alternate computer codes were used in the original analyses of Seabrook structures

- ANSYS has been used for analyzing safety-related structures in other plant designs (e.g., AP1000, ESBWR)

- NRC has previously accepted the use of ANSYS for structural analysis at other facilities

• Effects of creep, shrinkage, and swelling of concrete must be accounted for in the structure deformation analyses

- Creep, shrinkage and swelling loads are discussed in the Seabrook UFSAR but they were considered negligible in the original design analyses

- ACI 318-71 includes load factors for loads caused by creep, shrinkage and swelling 23

Review of ASR Expansion and Structure Deformation Monitoring 24

Review of ASR Expansion and Structure Deformation Monitoring

• Continued monitoring of ASR and its effects is necessary

- Expansion caused by ASR must be measured and remain bounded by limits established from the large-scale test program

- Periodic measurements of structure deformation are necessary to ensure limits from deformation analyses are satisfied

• Separate monitoring requirements will be included in the Structural Monitoring Program (SMP) for ASR expansion and structure deformation

• SMP uses a three-tiered approach to classify the results of inspections

- ASR expansion levels and structure deformation measurements will be evaluated using classification levels

- Increased monitoring and analysis are necessary for progressively higher levels of ASR expansion and structure deformation 25

Review of ASR Expansion and Structure Deformation Monitoring Typical methods used to measure ASR expansion at Seabrook 26

Review of ASR Expansion and Structures Monitoring Tiers for classifying ASR cracking Recommendation for CRITERIA Structural Monitoring Tier Individual Concrete Combined Cracking Index Program Category Components (CCI)

Unacceptable (requires further 3 Structural Evaluation 1.0 mm/m or greater evaluation)

Quantitative Monitoring and 0.5 mm/m or greater Trending Any area with visual presence of ASR (as defined in FHWA-HIF-2 Acceptable with Deficiencies12-022) accompanied an Qualitative Monitoring estimated summation of crack widths not supporting a 0.5 mm/m CI in the vertical or horizontal direction.

Routine inspection as prescribed Area has no indications of pattern 1 Acceptable by the Structural Monitoring cracking or water ingress- No Program visual presence of ASR

• Limits established in the large-scale test program will be included in the Structural Monitoring Program 27

Review of ASR Expansion and Deformation Monitoring

• Inspection requirements for structures with ASR-induced deformation Stage Deformation Evaluation Stage Monitoring Interval 1D Screening 3 years 2D Analytical 18 months 3D Detailed 6 months

• Parameters that are measured are specific to each structure

- Parameters will be defined in the structure deformation evaluation

- Limits established from deformation evaluation 28

Summary of LAR Changes

• NextEra will submit the following changes to the Seabrook UFSAR:

- ASR expansion loads are taken into account for seismic Category I structures

- Load factors for ASR loads are included in the design load combinations

- Creep, shrinkage and swelling effects are evaluated in the process of analyzing structures with ASR-related deformation

- ANSYS is used for deformation evaluations

- Stage Three deformation evaluations may use 100-40-40 method from NRC Regulatory Guide 1.92, Revision 3, for combining seismic loads instead of the SRSS method in Revision 1 of this regulatory guide.

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Closing Remarks

• License Amendment Request Represents multiple years of research and learning about ASR

• Third Party Reviews in progress

• Submit to NRC by July 31st 30