Periodic Reporting for period 2 - ACES (TOWARDS IMPROVED ASSESSMENT OF SAFETY PERFORMANCE FOR LONG-TERM OPERATION OF NUCLEAR CIVIL ENGINEERING STRUCTURES)
Reporting period: 2021-09-01 to 2023-02-28
The purpose of this project is to advance the assessment of safety performance of civil engineering structures by addressing remaining scientific and technology gaps for the safe and long-term operation of nuclear power plants safety-critical concrete infrastructure. This collaborative project aims to clarify, enhance, and unify methods of structural integrity assessment in the long-term operation of safety critical concrete SSCs. The main objectives are:
• Critical review of ageing management practice across EU NPPs focusing on ageing mechanisms of reinforced concrete, related to structural integrity assessment and ageing management criteria required for effective decision-making regarding LTO.
• Improved engineering methods to assess components under LTO considering specific operational demands.
• Innovative quantitative methodologies to transfer laboratory material properties to assess the structural integrity of large concrete components.
• Advanced simulation tools reflecting the latest findings related to combined effect of various loading and chemical/electrochemical reactions on concrete performance.
• Improved understanding of internal swelling reactions and temperature/moisture effects on the delayed strains of containment buildings.
• Improved assessment of the effects of prolonged irradiation of the concrete biological shield using a holistic approach combining operating conditions, materials degradation, and structural significance.
• Improved understanding of corrosion phenomena focusing on embedded liners, predicting the occurrence of corrosion, and developing an innovative inspection tool for early detection of corrosion.
• Critical review of ageing management practice across EU NPPs focusing on ageing mechanisms of reinforced concrete, related to structural integrity assessment and ageing management criteria required for effective decision-making regarding LTO.
• Improved engineering methods to assess components under LTO considering specific operational demands.
• Innovative quantitative methodologies to transfer laboratory material properties to assess the structural integrity of large concrete components.
• Advanced simulation tools reflecting the latest findings related to combined effect of various loading and chemical/electrochemical reactions on concrete performance.
• Improved understanding of internal swelling reactions and temperature/moisture effects on the delayed strains of containment buildings.
• Improved assessment of the effects of prolonged irradiation of the concrete biological shield using a holistic approach combining operating conditions, materials degradation, and structural significance.
• Improved understanding of corrosion phenomena focusing on embedded liners, predicting the occurrence of corrosion, and developing an innovative inspection tool for early detection of corrosion.
WP2: Literature review on corrosion mechanisms and degradation models of SCCP. •Exp. study of crevice corrosion mechanisms on steel liner in concrete. •Exp. evaluation and selection of NDTs for corrosion detection. •Manual demonstration of selected NDTs inside real used SCCPs. •Prototype development of robotic platform and manipulator for selected NDTs. •Phenomenological modelling. •Probabilistic analysis of chlorides corrosion degradation. •Initial activities regarding probabilistic analysis of crevice corrosion of the steel liner in containment building. •Literature overview on documentation on existing maintenance and inspection strategy for NPPs.
WP3: Finished residual expansion tests, analysis and correlation work, microscopic characterisation campaign, and start of PhD. •Continuing developing of mesoscale models to incorporate reaction kinetics in function of alkalis, temperature and saturation. •Continuing developing of full field fracture model. •Identification of cohesive parameters and simulation of DEF at the mesoscale.
WP4: Benchmarking structural computation codes. •Effects of temperature on drying and delayed strains of concrete (Performing experimental tests to characterize the behaviour of VERCORS concrete at temperatures 20-100°C; Performing experimental tests to characterize the behaviour of VERCORS concrete in LOCA conditions (pressure 4 bars, temperature up to 150°C, high relative humidity around 80%); Performing destructive characterization post TH perturbation; and developing and validating a constitutive modelling of the behaviour of VERCORS concrete at elevated temperatures). •Prediction of creep and shrinkage from the mix at ambient temperature.
WP5: Obtaining irradiated specimens made of concrete, mortar and aggregates and their post-irradiation examination. •Development of models of physical and mechanical response of concrete and its constituents to irradiation. •Numerical description of the neutron and gamma fields in the VVER-type reactors. •Development of numerical code for prediction of response of concrete biological shield to long-term irradiation. •Identification and discussion of needs of EUGs and gathering operation data valid for European NPP fleet.
WP6: Prepared Initial exploitation plan CVR. •Prepare project material such as newsletter and poster template. •Organized and hosted Mid-term workshop. •Upkeep of the project website and LinkedIn account.
WP7: Overall management of the project, addressing needs for changes to the DoA. •Productive communication with the EC, within the Consortium and with external bodies. •Project event planning •Financial, legal and administrative management. •Data Management Plan. •Communication to and with external stakeholders.
WP3: Finished residual expansion tests, analysis and correlation work, microscopic characterisation campaign, and start of PhD. •Continuing developing of mesoscale models to incorporate reaction kinetics in function of alkalis, temperature and saturation. •Continuing developing of full field fracture model. •Identification of cohesive parameters and simulation of DEF at the mesoscale.
WP4: Benchmarking structural computation codes. •Effects of temperature on drying and delayed strains of concrete (Performing experimental tests to characterize the behaviour of VERCORS concrete at temperatures 20-100°C; Performing experimental tests to characterize the behaviour of VERCORS concrete in LOCA conditions (pressure 4 bars, temperature up to 150°C, high relative humidity around 80%); Performing destructive characterization post TH perturbation; and developing and validating a constitutive modelling of the behaviour of VERCORS concrete at elevated temperatures). •Prediction of creep and shrinkage from the mix at ambient temperature.
WP5: Obtaining irradiated specimens made of concrete, mortar and aggregates and their post-irradiation examination. •Development of models of physical and mechanical response of concrete and its constituents to irradiation. •Numerical description of the neutron and gamma fields in the VVER-type reactors. •Development of numerical code for prediction of response of concrete biological shield to long-term irradiation. •Identification and discussion of needs of EUGs and gathering operation data valid for European NPP fleet.
WP6: Prepared Initial exploitation plan CVR. •Prepare project material such as newsletter and poster template. •Organized and hosted Mid-term workshop. •Upkeep of the project website and LinkedIn account.
WP7: Overall management of the project, addressing needs for changes to the DoA. •Productive communication with the EC, within the Consortium and with external bodies. •Project event planning •Financial, legal and administrative management. •Data Management Plan. •Communication to and with external stakeholders.
WP1: Effect of long-term climate change on environmental loading with the potential impact on concrete performance. • Synergetic effects of ageing processes under single and multiple loading conditions
WP2: Concentrate on special conditions leading to chloride-induced corrosion of steel cylinder concrete pipes (SCC) and crevice corrosion of steel liner embedded in concrete of containment building. • Upgrade of a robotic platform with the ability to handle and applied suitable NDT for corrosion inspection on the internal side of SSC. • Development of a metamodel describing the link between the input variables and the corrosion rate. The originality of this concept will help the corrosion specialists in the process of building the physical model to judge the relevance of the input variables. In combination with probabilistic modelling, the stakeholders will be able to predict locations and possible rates of corrosion in the containment liner and concrete pipes.
WP3: Investigate the interaction mechanisms between ISR and other ageing phenomena such as creep and shrinkage. • Develop methodologies for extrapolating the long-term concrete degradation, for an existing ISR-affected structure, based on common civil engineering practices and in-situ monitoring. • Develop robust and advanced prediction tools allowing the simulation of the long-term behaviour of NPP affected by ISR based on a multi-scale approach. • A practical simulation to provide technically sound recommendations that would allow the End-Users to properly account for the ISR impacts in the engineering calculations of NPP structures.
WP4: Validation of existing constitutive laws and structural modelling approaches 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 at ambient and elevated (up to 150°C). • Proposition of a new empirical model for concrete behaviour up to 150°C. • Proposition of evolutions of the FIB Code Model to better 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 from the open literature will be created on the neutron-irradiation induced degradation of concrete aggregates relevant for European NPPs. This project will partly fill this gap through the characterization of uniquely gamma-irradiated concrete at doses encompassing nearly >~+80-equivalent years of prolonged exposure in NPPs. • Benchmark of a large variety of modelling approaches, the capabilities and limitations will be assessed and lead to thoroughly validated irradiated concrete models that are expected to serve as references for future uses.• The main advance of this research will be to establish a rigorous structural assessment based on operation data, materials consideration and validated materials and structural models.
WP2: Concentrate on special conditions leading to chloride-induced corrosion of steel cylinder concrete pipes (SCC) and crevice corrosion of steel liner embedded in concrete of containment building. • Upgrade of a robotic platform with the ability to handle and applied suitable NDT for corrosion inspection on the internal side of SSC. • Development of a metamodel describing the link between the input variables and the corrosion rate. The originality of this concept will help the corrosion specialists in the process of building the physical model to judge the relevance of the input variables. In combination with probabilistic modelling, the stakeholders will be able to predict locations and possible rates of corrosion in the containment liner and concrete pipes.
WP3: Investigate the interaction mechanisms between ISR and other ageing phenomena such as creep and shrinkage. • Develop methodologies for extrapolating the long-term concrete degradation, for an existing ISR-affected structure, based on common civil engineering practices and in-situ monitoring. • Develop robust and advanced prediction tools allowing the simulation of the long-term behaviour of NPP affected by ISR based on a multi-scale approach. • A practical simulation to provide technically sound recommendations that would allow the End-Users to properly account for the ISR impacts in the engineering calculations of NPP structures.
WP4: Validation of existing constitutive laws and structural modelling approaches 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 at ambient and elevated (up to 150°C). • Proposition of a new empirical model for concrete behaviour up to 150°C. • Proposition of evolutions of the FIB Code Model to better 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 from the open literature will be created on the neutron-irradiation induced degradation of concrete aggregates relevant for European NPPs. This project will partly fill this gap through the characterization of uniquely gamma-irradiated concrete at doses encompassing nearly >~+80-equivalent years of prolonged exposure in NPPs. • Benchmark of a large variety of modelling approaches, the capabilities and limitations will be assessed and lead to thoroughly validated irradiated concrete models that are expected to serve as references for future uses.• The main advance of this research will be to establish a rigorous structural assessment based on operation data, materials consideration and validated materials and structural models.