ML18137A132
| ML18137A132 | |
| Person / Time | |
|---|---|
| Issue date: | 05/17/2018 |
| From: | George Thomas NRC/NRR/DE/ESEB |
| To: | |
| Brady B, NRR-DMLR 415-2981 | |
| Shared Package | |
| ML18137A131 | List: |
| References | |
| Download: ML18137A132 (9) | |
Text
NRC Staffs Licensing Perspectives on Alkali-Silica Reaction (ASR)
Effects on Concrete for SLR George Thomas Office of Nuclear Reactor Regulation, USNRC May 17, 2018
Overview
- Background
- NRC Guidance for SLR
- Key Expectations 2
Background on ASR 3
Definition slow chemical reaction that could occur in hardened concrete when moisture is present, in which alkalis predominantly from the cement combine with certain reactive forms of silica that may be present in some aggregates; the reaction produces a gel that can absorb water and expand to cause cracking and deformation
- ASR is a more common form of Alkali-Aggregate Reaction
- slow chemical reaction that could occur in hardened concrete when moisture is present, in which alkalis predominantly from the cement combine with certain reactive forms of silica that may be present in aggregates
- The reaction produces a gel that can absorb water and expand to cause cracking and deformation that has potential to affect structural performance
NRC Guidance for SLR
- Standard Review Plan for Subsequent License Renewal (SRP-SLR) and Generic Aging Lessons Learned Report for Subsequent License Renewal (GALL-SLR) include modified aging management review (AMR) line items and further evaluation (FE) guidance for the aging effect of Cracking due to Expansion from Reaction with Aggregates (e.g., ASR)
- The modified guidance incorporated industry operating experience on ASR (NRC IN 2011-20, Concrete Degradation by Alkali Silica Reaction), from which it is evident that the aging effect should not be determined to be not applicable based on aggregates passing ASTM screening tests at the time of construction 4
NRC Guidance for SLR
- SRP-SLR Table 3.5-1, Items 12, 19 address concrete ASR for Containment (inaccessible, accessible areas)
- Further Evaluation: SRP Sections 3.5.2.2.1.8 and 3.5.3.2.1.8 5
NRC Guidance for SLR
- SRP-SLR: Table 3.5-1, Items 43, 54 & 50, 96 address ASR for Groups 1-5, 7-9; and Group 6 structures, respectively
- Further Evaluation: SRP-SLR Sections 3.5.2.2.2.1.2 and 3.5.2.2.2.3.2 6
NRC Guidance for SLR Further evaluation is recommended A plant-specific AMP is necessary if (1) reactivity tests or petrographic examinations of concrete samples identify reaction with aggregates, or (2) accessible concrete exhibits visual indications of aggregate reactions, such as map or patterned cracking, alkali-silica gel exudations, surface staining, expansion causing structural deformation, relative movement or displacement, or misalignment/distortion of attached components.
7 Plant-Specific AMP(s) Needed if there is Plant-Specific Operating Experience of ASR From SRP-SLR Section 3.5.3.2.1.8:
Expectation:
Key Expectations for SLR (with respect to SRP/GALL-SLR guidance) 8 No plant-specific OE (including visual symptoms) of ASR identified at site No Plant-Specific AMP is needed; however, monitor accessible areas for common visual indications of ASR by visual inspection in applicable GALL AMP If plant-specific OE exists (e.g. visual, reactivity tests or petrography)
Submit plant-specific AMP meeting acceptance criteria in Appendix A.1 of SRP-SLR such that the aging effect will be adequately managed
QUESTIONS?