Periodic Reporting for period 3 - ACES (TOWARDS IMPROVED ASSESSMENT OF SAFETY PERFORMANCE FOR LONG-TERM OPERATION OF NUCLEAR CIVIL ENGINEERING STRUCTURES)
Reporting period: 2023-03-01 to 2025-05-31
This project is helping make NPPs safer and more reliable. NPPs concrete structures age over time. If these structures weaken, it could affect safety. ACES fills important knowledge gaps about how concrete ages under extreme conditions, such as heat, radiation, and chemical reactions, so that operators can make better decisions about maintenance and saftey.
The project has delivered tools and insights that improve how NPPs check the condition of these structures. For example, a robotic system was created that can inspect corrosion inside steel-concrete pipes, saving time and reducing risk. We also developed advanced models to predict how concrete behaves under stress and temperature changes, which helps prevent unexpected failures. By understanding issues like internal swelling and radiation damage, we can extend the life of existing NPPs safely and guide the design of future ones.
Main Objectives: Critical review of ageing management practices for EU NPPs, focusing on ageing in concrete and criteria for LTO decision-making; Improve methods for assessing components under LTO, considering operational demands; Develop innov. quantitative methodologies to transfer laboratory properties to large-scale structural integrity assessments; Advance simulation tools to reflect joined effects of loading/chemical/electrochemical reactions on performance; Enhance understanding of internal swelling reactions and temperature/moisture effects on delayed strains in containment buildings; Improve assessment of prolonged irradiation effects on concrete biological shields combining operating conditions, material degradation, and structural significance; Deepen understanding of corrosion of embedded liners, predict corrosion, and develop innov. inspection tool for early detection.
Main scientific/technical outcomes
WP1 – Completed a SOTA on ageing management approaches for NPP concrete structures. Integrated new knowledge from ACES on liner corrosion, ISR, creep/shrinkage in concrete containment, and irradiated concrete performance.
WP2 – Demonstrated a robotic platform for NDT corrosion inspection of steel cylinder concrete pipes (SCCP). Provided novel insights into crevice corrosion mechanisms of steel liners through extensive experimental and numerical work. Completed two Ageing Management Programs (AMPs) addressing corrosion risks in key NPP structures.
WP3 – Validated coupled TCHM models for ISR in NPP concrete. Advanced understanding of creep and combined pathologies through extensive lower-scale experimental work.
Developed recommendations for EUG on evaluating ISR degradation impact on structural capacity.
WP4 – Completed a comprehensive guidance report on CCB ageing calculations. Assimilated experimental results on concrete creep under LOCA conditions, including destructive post-thermal damage characterization.
Proposed improvements to Fib Model Code 2010 formulas for high-temperature and biaxial loading conditions, offering enhanced accuracy across loading scenarios.
WP5 – Characterized concrete under combined irradiation and temperature effects for European aggregate types, validating numerical models. Benchmarked models for irradiated concrete and its constituents.
Developed a critical tool to support reactor lifespan extension and inform next-generation designs. Assessed structural significance of radiation effects from both shielding and load-bearing perspectives. Provided EUG with a methodology to evaluate LTO of concrete structures exposed to prolonged ionising radiation. Successfully involved university and high school students in research activities.
The project has delivered tools and insights that improve how NPPs check the condition of these structures. For example, a robotic system was created that can inspect corrosion inside steel-concrete pipes, saving time and reducing risk. We also developed advanced models to predict how concrete behaves under stress and temperature changes, which helps prevent unexpected failures. By understanding issues like internal swelling and radiation damage, we can extend the life of existing NPPs safely and guide the design of future ones.
Main Objectives: Critical review of ageing management practices for EU NPPs, focusing on ageing in concrete and criteria for LTO decision-making; Improve methods for assessing components under LTO, considering operational demands; Develop innov. quantitative methodologies to transfer laboratory properties to large-scale structural integrity assessments; Advance simulation tools to reflect joined effects of loading/chemical/electrochemical reactions on performance; Enhance understanding of internal swelling reactions and temperature/moisture effects on delayed strains in containment buildings; Improve assessment of prolonged irradiation effects on concrete biological shields combining operating conditions, material degradation, and structural significance; Deepen understanding of corrosion of embedded liners, predict corrosion, and develop innov. inspection tool for early detection.
Main scientific/technical outcomes
WP1 – Completed a SOTA on ageing management approaches for NPP concrete structures. Integrated new knowledge from ACES on liner corrosion, ISR, creep/shrinkage in concrete containment, and irradiated concrete performance.
WP2 – Demonstrated a robotic platform for NDT corrosion inspection of steel cylinder concrete pipes (SCCP). Provided novel insights into crevice corrosion mechanisms of steel liners through extensive experimental and numerical work. Completed two Ageing Management Programs (AMPs) addressing corrosion risks in key NPP structures.
WP3 – Validated coupled TCHM models for ISR in NPP concrete. Advanced understanding of creep and combined pathologies through extensive lower-scale experimental work.
Developed recommendations for EUG on evaluating ISR degradation impact on structural capacity.
WP4 – Completed a comprehensive guidance report on CCB ageing calculations. Assimilated experimental results on concrete creep under LOCA conditions, including destructive post-thermal damage characterization.
Proposed improvements to Fib Model Code 2010 formulas for high-temperature and biaxial loading conditions, offering enhanced accuracy across loading scenarios.
WP5 – Characterized concrete under combined irradiation and temperature effects for European aggregate types, validating numerical models. Benchmarked models for irradiated concrete and its constituents.
Developed a critical tool to support reactor lifespan extension and inform next-generation designs. Assessed structural significance of radiation effects from both shielding and load-bearing perspectives. Provided EUG with a methodology to evaluate LTO of concrete structures exposed to prolonged ionising radiation. Successfully involved university and high school students in research activities.
ACES has disseminated the scientific and technological advances achieved –effectively being used by industry, regulators, policymakers, and the scientific community. The main results are briefly described below have been published online (ACES website), in technical reports and journal papers, in social media (LinkedIn), shared with the EUG and presented at various technical and scientific organizations (OECD NEA, IAEA IGALL, SNETP, FIB):
WP1: completed SOTA report of ageing management approaches for NPP concrete structures, updated with knowledge gained from ACES for studied ageing processes.
WP2: Robotic platform corrosion NDT for internal surfaces of SCCPs. Novel understanding of crevice corrosion mechanism of steel liners. Completion of two AMPs to address corrosion risks in key NPP structures.
WP3: Advancements validating models for internal swelling reactions . Significant advancement on the impact of creep and pathologies combined on the observed outcome. Developed EUG recommendations for evaluation of ISR degradation impact on the overall capacity of the critical concrete structures.
WP4: Significant Guidance report of CCB ageing calculations. Assimilation of experimental results on the creep behaviour of concrete in LOCA conditions. Proposal for improvement of Fib code model 2010 formulas for high temperature and biaxial loading conditions.
WP5: Characterisation of concrete for effects of irradiation and temperature on European aggregates used for validation of developed numerical models. Benchmarking of models for irradiated concrete and constituents. Critical new tool for extending reactor lifespans and for informing next-gen designers. Methodology for EUG to assess the LTO of concrete structures exposed to prolonged ionising radiation.
WP1: completed SOTA report of ageing management approaches for NPP concrete structures, updated with knowledge gained from ACES for studied ageing processes.
WP2: Robotic platform corrosion NDT for internal surfaces of SCCPs. Novel understanding of crevice corrosion mechanism of steel liners. Completion of two AMPs to address corrosion risks in key NPP structures.
WP3: Advancements validating models for internal swelling reactions . Significant advancement on the impact of creep and pathologies combined on the observed outcome. Developed EUG recommendations for evaluation of ISR degradation impact on the overall capacity of the critical concrete structures.
WP4: Significant Guidance report of CCB ageing calculations. Assimilation of experimental results on the creep behaviour of concrete in LOCA conditions. Proposal for improvement of Fib code model 2010 formulas for high temperature and biaxial loading conditions.
WP5: Characterisation of concrete for effects of irradiation and temperature on European aggregates used for validation of developed numerical models. Benchmarking of models for irradiated concrete and constituents. Critical new tool for extending reactor lifespans and for informing next-gen designers. Methodology for EUG to assess the LTO of concrete structures exposed to prolonged ionising radiation.
WP1: Significant contribution to understanding of ageing mechanisms of concrete; Synergistic effects of ageing processes under single and multiple loading conditions.
WP2: Novel understanding of crevice corrosion of liner in concrete; New capability for inspection of steel cylinder concrete pipes with robotic platform that handles NDT for corrosion inspection; Completion of AMPs to address corrosion risks in key NPP structures - containment liners, integrating novel aspects.
WP3: Investigated interaction mechanisms between ISR and ageing phenomena (creep/shrinkage); Developed methodologies to extrapolate long-term concrete degradation, based on common civil engineering practices and in-situ monitoring; Develop advanced prediction tools for the simulation of the long-term behaviour of ISR-affected structure; Practical simulation provided technically sound recommendations enabling EUG to account for the ISR impacts in engineering calculations.
WP4: Validation of existing constitutive laws for structural design currently used regarding the simulation of containment behaviour during operational phases; Completion of the largest database on a single concrete mix regarding drying, creep and shrinkage behaviour; Proposition of a new empirical model for concrete behaviour up to 150°C; Proposition of evolution of the FIB Code Model to account for multiaxial effects on creep at moderate temperature (up to 40°C); Validation of existing models for the prediction of concrete delayed strains from the mix.
WP5: Critical data currently missing for the irradiation induced degradation of concrete for European rock types. Study of gamma-irradiated concrete/steel reinforcement interface to enhance knowledge related to steel corrosion and bond; Benchmark of a multiscale modelling approaches, to assess and validated irradiated concrete performance; New critical tool for extending reactor lifespans and for informing next-generation designers; Providing EUG with an methodology to assess LTO of concrete structures exposed to prolonged ionising radiation.
WP2: Novel understanding of crevice corrosion of liner in concrete; New capability for inspection of steel cylinder concrete pipes with robotic platform that handles NDT for corrosion inspection; Completion of AMPs to address corrosion risks in key NPP structures - containment liners, integrating novel aspects.
WP3: Investigated interaction mechanisms between ISR and ageing phenomena (creep/shrinkage); Developed methodologies to extrapolate long-term concrete degradation, based on common civil engineering practices and in-situ monitoring; Develop advanced prediction tools for the simulation of the long-term behaviour of ISR-affected structure; Practical simulation provided technically sound recommendations enabling EUG to account for the ISR impacts in engineering calculations.
WP4: Validation of existing constitutive laws for structural design currently used regarding the simulation of containment behaviour during operational phases; Completion of the largest database on a single concrete mix regarding drying, creep and shrinkage behaviour; Proposition of a new empirical model for concrete behaviour up to 150°C; Proposition of evolution of the FIB Code Model to account for multiaxial effects on creep at moderate temperature (up to 40°C); Validation of existing models for the prediction of concrete delayed strains from the mix.
WP5: Critical data currently missing for the irradiation induced degradation of concrete for European rock types. Study of gamma-irradiated concrete/steel reinforcement interface to enhance knowledge related to steel corrosion and bond; Benchmark of a multiscale modelling approaches, to assess and validated irradiated concrete performance; New critical tool for extending reactor lifespans and for informing next-generation designers; Providing EUG with an methodology to assess LTO of concrete structures exposed to prolonged ionising radiation.