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 Docket No. 50-443-LA-2 NEXTERA ENERGY SEABROOK, LLC ASLBP No. 17-953-02-LA-BD01 (Seabrook Station, Unit 1)
Hearing Exhibit Exhibit Number: NER048 Exhibit
Title:
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 W 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 Z
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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.
Current RC design procedure and practice do not account for effects of ASR 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.
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Technical Approach Accelerate ASR in experiments through mixture proportioning and curing Mobile batch plant ASR Gel Quantify Degree of Reaction over time (image analysis to measure volume percent ASR Gel of cracking and dissolution in paste and
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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 Research Plan: Five Tasks Task 1: Assessing In-Situ Mechanical Properties Task 2: Assessing Development and Lap-Splice Lengths of Reinforcing Bars Task 3: Evaluating Seismic Performance of Structural Members Task 4: Estimating the Degree of ASR and the Corresponding Expansion Task 5: Predicting Future and Ultimate ASR Expansion 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)
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Task 3 - Seismic Performance of Walls Wall Specimen Cross Section Boundary Elements Specimen No. Stirrup ASR (t) s (%)
Spacing 1 0% 2% 4 in 2 50 % 0% -
3 100 % 2% 4 in 4 100 % 0% -
Wall Specimen Geometry Wall Specimen Variables Task 3 - Seismic Performance of Walls (contd) t^ZŽ Seismic Lateral Load Test of Wall Task 4 and Task 5 - Lab Prisms Measurements
- 1. Selected measurement parameters through ~320 days under ambient conditions
D Ž D hŽ WsŽ D
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hWs
D D D
D
D
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d d d
- 2. Microstructure of ASR 1 (a, b) and Control Mix (c) at 180 days Paste Reactive Fine ASR Aggregate Gel Reactive Fine Paste Aggregate (a) (b) (c)
ASR 1 (0.15 % target), ASR 1 (0.15 % target), 180 ASR 4 (Control), 157 180 days, 36x mag days, 1050x mag days, 36x mag
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