ML25183A348
| ML25183A348 | |
| Person / Time | |
|---|---|
| Issue date: | 06/30/2025 |
| From: | Jeffrey Poehler NRC/RES/DE |
| To: | |
| JEFF POEHLER 3014158353 | |
| Shared Package | |
| ML25183A340 | List: |
| References | |
| Download: ML25183A348 (1) | |
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Z AA AB AC AD AE AF AG AH AI AJ AK AL AM AN AO AP AQ AR AS AT Panelist 1 Panelist 2 Panelist 3 Average ImportanceUncertaintyKnowledge ImportanceUncertaintyKnowledge ImportanceUncertaintyKnowledge Recommendation ID title of recommendation Scope, objectives, and/or topic modifications Score Score Score Rationale Score Score Score Rationale Score Score Score Rationale Importanc e (avg)
Uncertaint y (avg)
Knowled ge (avg) error bars Import Uncert. Know error More research could be used to gain knowledge on a topic expected to be important to safety More research could reduce uncertainty and clarify topic importance More research could improve knowledge but topic not expected to be safety significant Topic expected to have safety significance but likely could be addressed without additional research Topic may have safety significance but sufficient knowledge exists to manage Topic not expected to have safety significance and sufficient knowledge exists H/M/L H/M/L K/PK/UK H/M/L H/M/L K/PK/UK H/M/L H/M/L K/PK/UK RAD-1 Harvest and analyze service irradiated concrete to verify accelerated laboratory data (e.g., flux, specimen size), and reduce uncertainties. Investigate the formation of new phases in concrete as concrete ages.
H H
UK Verify irradiated concrete data is critical to reduce uncertainties in the long-term effects of irradiation, as large uncertainties remain in correlating accelerated test data with the behavior of in-service structures, and validation against harvested in-service materials is largely missing, with scaling effects adding significant additional uncertainty.
H H
UK Although the size effect in concrete is understood, little is known of how small fabricated concrete test specimens irradiated in test reactors provide insights to the behavior of structural concrete to radiation, but harvested test specimens from actual reactors will yield true structural behavior.
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UK Harvesting of irradiated concrete and components from plants with sufficient accumulated irradiation and susceptible aggregate/material has not been happened yet. Reduce uncertainty, verify flux effect, size effect, RIVE under structural confinement, radiation transport, attenuation profile, degradation depth, validate numerical approaches.
3.0 3.0 3.0 0.5
- 3.0000 2.9850 0.5 1
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RAD-2 Compare radiation-induced free expansion data from accelerated experiment to effects under structural confinement. Explore damage depth.
H H
UK Understanding radiation-induced expansion under confinement is critical for structural integrity, but there is high uncertainty due to limited data. While some studies address free expansion and explore confinement effects, a full understanding of in-service H
H UK expansion is counterbalanced by paste shinkage (total expansion or shrinkage) need to be evaluated.
What are the effects of radiation on triaxiality with respect to concrete depth needs to be quantified. In addition, new knowledge from Hamaoka H
H UK Damage under confinement is due to intrinsic strain + mechanical strain, hence damage is deeper than the expansion zone. Verify by harvesting from plant with appropiate pedigree (fluence, dose, material, structural layout and details).
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- 3.0000 2.9000 0.388889 2
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RAD-3 Refine radiation transport models using realistic irradiation histories, especially as more plants exceed radiation threshold during LTO.
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PK Refining radiation transport models using realistic irradiation histories is crucial for accurately predicting radiation-induced degradation in reactor structures, especially as more nuclear power plants are expected to exceed irradiation thresholds during Long-Term Operation (LTO).
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PK For modeling and simualtions a better definition of transport effects is needed for time dependant loading and material degradation to include thermal effects.
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UK Accumulation of neutron, gamma will increase with time. Verified and validated radiation transport method is needed to predict the level of accumulated radiation (neutron, gamma, heating) which can be used for assessment of potential degradation. Radiation transport is as function of multiple parameters which needs to be verified with the realistic conditions and materials.
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- 3.0000 2.3333 0.388889 3
RAD-4 Verify attenuation of radiation through thickness of the structure and study its impact on material degradation.
H M
PK Radiation attenuation is well understood, but verifying modeling date with in-serice irradiated structures to reduce uncertainty and knowledge gap is important to access degradation due to radiation H
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Numerous recent publications on the subject lead to moderate scoring.
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UK Verify the numerical models with service irradiated concrete cores, reduce uncertainty, assess strctural implications.
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- 2.0000 2.0000 0.388889 4
RAD-5 Study interactions of irradiation with ASR gel stability, creep in cement paste, and corrosion of rebar due to gamma.
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UK Interaction is important but considered a secondary effect comparing with overall implication; however, there is certain uncertainty in these coupled effects, and data and understanding remain very limited.
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UK To what extent can radiation precondition BSW concrete to ASR is relatively unknown. Little is known whether radiation with liner trapped moisture in concrete can initiate ASR.
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UK Very little or no data available on this topic. For CBS with liner and for thick concrete, presence of moisture (radiation induced ASR) is highly likely. Creep of cement paste can accommodate some RIVE but creep under radiation, and corrosion of steel under gamma are not well studied 2.7 3.0 3.0 0.5
- 3.0000 2.8000 0.388889 5
RAD-6 Collaborate globally to address long-term operation (LTO) beyond 80 years.
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UK Global collaboration on LTO beyond 80 years can improve data sharing, testing standards, and research on radiation effects, while advancing aging management strageties, harmonizing regulations, and supporting future reactor designs H
H PK Could be possible for developing bounding and gross results.
Otherwise difficult task to accomplish and obtain meaningful results due to variation of materials, methods of construction, and accessibility H
H UK Important to develop concensus knowledge, leverage experimental data, numerical simulation, predictive model developments, harvesting and testing, sharing of cost and efforts, and making more time efficient.
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- 2.6667 2.6817 0.222222 6
RAD-7 Standardize testing methods, improve predictive models and structural integrity assessment.
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PK Reliable testing and accurate models are essential for safely running nuclear plants beyond 80 years. Standardized testing and improved predictive models help reduce uncertainty, building shared understanding, support sound safety and regulatory decisions M
M PK Standardize coring techniques.
These could affect concrete strength and modulus values.
Correlate past small test specimens to standard concrete test specimens.
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PK Testing methods and multiscale modeling approaches have been developed, knowledge has improved based on accelerated experiments. After verifying the methods and models with real life service irradiated data, develop user friendly guidance and applied methods.
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- 2.3333 1.9000 0.277778 7
RAD-1 RAD-2 RAD-3 RAD-4 RAD-5 RAD-6 RAD-7 Importance Knowledge High Low Known Unknow RAD-1 RAD-2 RAD-3 RAD-4 RAD-5 RAD-6 RAD-7 1
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2 Importance Knowledge Session 8 - Civil Structures, Concrete and Components - Radiation High Low Known Unknown