ML19205A518
| ML19205A518 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 07/24/2019 |
| From: | Morgan, Morgan, Lewis & Bockius, LLP, NextEra Energy Seabrook |
| To: | Atomic Safety and Licensing Board Panel |
| SECY RAS | |
| References | |
| 50-443-LA-2, ASLBP 17-953-02-LA-BD01, RAS 55113 | |
| Download: ML19205A518 (6) | |
Text
UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION ATOMIC SAFETY AND LICENSING BOARD In the Matter of NEXTERA ENERGY SEABROOK, LLC (Seabrook Station, Unit 1)
Docket No. 50-443-LA-2 ASLBP No. 17-953-02-LA-BD01 Hearing Exhibit Exhibit Number:
Exhibit
Title:
NER048 L. Phan, Structural Performance of NPP Concrete Structures Affected by Alkali-Silica Reaction (ASR), Slides for NRC Regulatory Information Conference Session TH27 (2018)
Session TH27 Concrete Degradation Part 1 Structural Performance of NPP Concrete Structures Affected by Alkali-Silica Reaction (ASR)
Long Phan, Ph.D., P.E.
Long.phan@NIST.GOV Engineering Laboratory National Institute of Standards and Technology Alkali-Silica Reaction (ASR)
Chemical reactions between the alkali hydroxides in pore solution of concrete and metastable forms of silica in reactive aggregate that forms alkali-silica gel.
Chemical reactions between the alkali hydroxides in pore solution of concrete and metastable forms of silica in reactive aggregate that forms alkali-silica gel.
Alkali-silica gel is hygroscopic and will absorb water and expand, resulting in expansive pressure and both micro-and macro-cracking over time.
Results in reduction of mechanical properties, stiffness, bond strength of concrete, and overall service life in dams, bridges, pavements, power plants, etc.
Results in reduction of mechanical properties, stiffness, bond strength of concrete, and overall service life in dams, bridges, pavements, power plants, etc.
Current RC design procedure and practice do not account for effects of ASR
Current RC design procedure and practice do not account for effects of ASR
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NIST Study Objectives and Outcome
Develop technical basis for regulatory guidance to evaluate ASR-affected NPP through service life.
Assess significance and quantify effects of ASR on structural performance and capability under design basis static and dynamic loads.
Identify and describe characteristics of an aging management program to adequately monitor and manage aging effects of ASR.
Methodology for determining, for an existing ASR-affected structure, in-situ and future structural capacity.
Technical Approach
Accelerate ASR in experiments through mixture proportioning and curing
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ASR Gel
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Quantify Degree of Reaction over time (image analysis to measure volume percent of cracking and dissolution in paste and aggregate that is attributable to ASR).
Correlate changes in microstructural features (microcracking, onset and evolution of ASR gel characteristics) with ASR-induced expansion, surface cracking, degradation of mechanical properties and structural capacities through experiments and modeling
Evaluate applicability of existing RC design standards and methods
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Mobile batch plant Task 4: Estimating the Degree of ASR and the Corresponding Expansion Task 5: Predicting Future and Ultimate ASR Expansion Research Plan: Five Tasks Task 2: Assessing Development and Lap-Splice Lengths of Reinforcing Bars Task 3: Evaluating Seismic Performance of Structural Members Task 1: Assessing In-Situ Mechanical Properties Research Progress: Task 1 - Block Specimens (10 ft x 6 ft x 4 ft)
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Research Progress: Task 1 - Block Specimens (contd)
Mechanical properties versus ages Strain development versus ages Research Progress: Task 2 - Beams
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Task 2 - Beams (contd)
Wall Specimen Geometry Task 3 - Seismic Performance of Walls Specimen No.
Boundary Elements ASR (t) s (%)
Stirrup Spacing 1
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Wall Specimen Cross Section Wall Specimen Variables Seismic Lateral Load Test of Wall Task 3 - Seismic Performance of Walls (contd) t^ZŽ Task 4 and Task 5 - Lab Prisms Measurements
- 1. Selected measurement parameters through ~320 days under ambient conditions
- 2. Microstructure of ASR 1 (a, b) and Control Mix (c) at 180 days ASR 1 (0.15 % target), 180 days, 1050x mag ASR 4 (Control), 157 days, 36x mag ASR 1 (0.15 % target),
180 days, 36x mag Paste Reactive Fine Aggregate Reactive Fine Aggregate Paste ASR Gel (a)
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Session TH27 Concrete Degradation Part 1 Structural Performance of NPP Concrete Structures Affected by Alkali-Silica Reaction (ASR)
Thank you! Questions?
Long Phan, Ph.D., P.E.
Long.Phan@NIST.GOV Engineering Laboratory National Institute of Standards and Technology