Yann Le Pape

Oak Ridge National Laboratory | ORNL · Nuclear Energy and Fuel Cycle Division

Nuclear power plants are aging around the world, and a precise assessment of irradiation damage in their components is needed. One key component, concrete, and specifically the silicates in its aggregates, can undergo significant expansion upon neutron radiation, which can lead to cracking and, ultimately, structural failure. However, assessing and...

The main goal of this research is to develop a carbonated cementitious material (CCMs) mix design and demonstrate its rapid stiffening for manufacturing 3D printed or precast elements for building construction (i.e., concrete with enhanced durability and CO2 capture efficiency). The material development employs hydrated Ca(OH)2, and its distinct re...

The concrete biological shields used in light water reactors are exposed to high neutron and gamma irradiation doses over the long term. Irradiation deteriorates the physical and mechanical properties of concrete. Such effects must be investigated to predict the concrete's performance in the event of a lifetime extension of a nuclear power plant. T...

Concrete structures in light water reactors (LWRs) are exposed to varied in-service environmental conditions (e.g., irradiation, moisture ingress, temperature). In conjunction with the specific chemical composition of the concrete constituents, several degradation modes can be triggered, including radiation-induced volumetric expansion, alkali-sili...

While several decades of materials degradation research enabled the current US fleet of Light Water Reactors (LWR) to plan to produce electrical power through extended operations up to 80 years of plant life, it now seems appropriate to evaluate what issues, methods, and timelines need to be considered to meet the expected electric power demands fo...

The concrete biological shield of light water reactors is exposed to neutron and gamma irradiation throughout its lifetime, which results in the long-term degradation of the concrete’s mechanical properties. Under neutron irradiation, the concrete’s aggregates are subjected to radiation-induced volumetric expansion (RIVE), which strongly depends on...

is report documents the extensive set of characterization of the susceptibility of irradiation-induced damage in concrete is governed by the exposure level (fast neutron fluence > 1019 n.cm-2 at E > 0.1 MeV) and the mineralogy of the aggregates (high quartz content and chemical heterogeneity of the assemblage). Both conditions are met for the SONGS...

The concrete biological shield in a nuclear power plant receives ~100–200 MGy gamma dosage during an 80-year design life. However, precise changes in the mechanical properties and atomic environments of C-S-H at ultrahigh irradiation dosages have not been systematically documented. Here, we report that irradiation decreases C-S-H basal spacing (~ 0...

This paper describes the development of a micromechanical-based constitutive model accounting for the effect of internal expansion on the residual elasticity of a Hashin composite material. This material is made of spherical inclusions that are subjected to gradual swelling within a quasi-brittle matrix. The main focus of this work is to describe a...

Ten years after the Fukushima Daiichi Nuclear Power Plant accident, the nuclear industry is facing a pivotal moment. As we face growing public concerns in Japan and a highly competitive environment driven by the low cost of fossil energies in the United States, a gradual reduction of the nuclear power fleetʼs capacity may seem inevitable. Overcomin...

The disordering of the atomic network of minerals typically results in swelling of the structure. However, the origin of such expansion and the extent thereof remain unclear. Here, we conduct a series of molecular dynamics simulations of vitrification- and irradiation-induced disordering to reveal the nature of disorder-induced expansion in silicat...

A correction to this paper has been published: https://doi.org/10.1617/s11527-021-01655-4

As the nuclear fleet in the United States ages and subsequent license renewal applications grow, the prediction of concrete durability at extended operation becomes more important. To address this issue, a Fast-Fourier Transform (FFT) method is utilized to simulate aging-related degradation of concrete within the Microstructure Oriented Scientific...

The paper aims to identify potential correlations between mineralogical and chemical compositions of AAR reactive dolomitic limestone aggregates from Tennessee and their expansion on ASTM C1293 for quick evaluation of reactivity. The chemical compositions of 26 limestones, namely the silica content (SiO2), showed a strong correlation with the expan...

Mechanical properties of calcium silicate hydrates (C-S-H) with C/S ratios of 0.75, 1, and 1.33 were examined with nanoindentation after gamma-adsorbed doses of 0.145, 0.280, 0.500, and 0.784 MGy, and were compared with control samples. Young' s modulus and stress relaxation tests showed no apparent trend with irradiation dose. Qualitatively, most...

This paper presents a pixel-based modeling approach of concrete which combines an experimental characterization of concrete and the Fast-Fourier transform simulations. High-resolution phase maps created from experimental characterization by micro X-ray fluorescence, energy dispersive X-ray analysis, and X-ray diffraction contain 9 different phases,...

Alkali-silica reactivity (ASR) has been recognized as one of the most deleterious phenomena in concrete. In fact, ASR can cause significant loss of mechanical properties and cracking in concrete structures that could lead to structural failure. The challenge now exists in evaluating the degree of the ASR damage in existing structures so that inform...

A number ofBenchmark problems structures worldwide are known to (or will) suffer from chemically induced expansion of the concrete. This includes not only the traditional alkali aggregate reaction (also known as alkali silica reaction) but increasingly delayed ettringite formation (DEF)

The radiation-induced volumetric expansion (RIVE) of aggregate-forming minerals causes damage in concrete exposed to high levels of fast neutrons fluence (\(>\,\sim \,10^{19}\, \hbox {n}\,\hbox {cm}^{-2}\) at kinetics energy above 0.1 MeV). Historical post-irradiation RIVE and Young’s modulus data obtained in test reactors were revisited using a po...

Alkali-silica reaction (ASR), which was recently discovered in nuclear power plant structures commonly without shear reinforcement, has previously been shown to induce anisotropic expansion in confined concrete. The fracture properties (strength, stiffness, and specific fracture energy) of ASR-induced anisotropically-damaged concrete specimens were...

Alkali-silica reaction (ASR) is a major deterioration mechanism that affects the durability of concrete structures. As the slow rate of ASR development and the restrained expansion in field concrete might affect the development of ASR damage, an experimental program was performed to investigate the effects of the rate of ASR expansion and confineme...

When exposed to irradiation—e.g., in nuclear power plant environments—minerals may experience alterations in their atomic structure which, in turn, result in changes in their physical and chemical properties. Herein, we mimic via Ar⁺ implantation the effects of neutron irradiation on calcite (CaCO3) and dolomite (CaMg(CO3)2) – two carbonate mineral...

Alkali-silica reaction (ASR) causes cracks in civil concrete structures such as nuclear power plants and may endanger their serviceability and integrity. The damage caused by ASR in the nuclear structures initiates mainly inside the structure and appears later on the surface. Acoustic emission (AE) is a passive method to monitor structural health....

Alkali-silica reaction (ASR) was recently diagnosed as having affected reinforced concrete structures in the nuclear power industry. ASR is a deleterious degradation mechanism in concrete that induces expansion and eventually leads to cracking. Because the presence of ASR in a nuclear power facility was recently discovered, experimental testing of...

The chemical‐structural properties of synthetic calcium silicate hydrate (C‐S‐H) with C/S (Ca/Si) ratios of 0.75, 1 and 1.33 were studied after gamma irradiation‐absorbed doses ranging from 0.145 to 0.784 MGy and compared with those of control specimens. The results showed that the total water content given by thermogravimetric analysis and the dim...

When subjected to irradiation or vitrification, minerals become disordered at the atomic scale, which, in turn, affect their density and stiffness. However, the nature of the relationship between structural disorder, density, and stiffness remains poorly understood. Here, based on molecular dynamics simulations, we investigate the effect of irradia...

As the US Light Water Reactor (LWR) fleet ages, irradiation and environmental effects may degrade concrete structures within the reactor cavity of nuclear power plants (NPPs). Concrete components provide structural support and serve as a containment barrier and radiation shield. Among the most important constituents of concrete are the aggregates a...

Alkali-silica reaction has caused damage to concrete structures, endangering structural serviceability and integrity. This is of concern in sensitive structures such as nuclear power plants. In this study, acoustic emission (AE) was employed as a structural health monitoring strategy in large-scale, reinforced concrete specimens affected by alkali-...

Description Get the latest information on databases, benchmark studies, techniques, and standardization of radiation metrology and regulatory information related to reactor dosimetry. Learn more about modern technologies used in radiation imaging and the development of radiation instrumentation. Plus you’ll get over 50 peer-reviewed papers covering...

When exposed to high-energy radiations, the silicate aggregates used in concrete can exhibit some swelling. This, in turn, can result in some internal stress, which can lead to micro-cracks or de-bonding along the cement–aggregate interface. However, there is presently some uncertainty regarding the long-term effect of such high-energy irradiation...

Nanoscale resolved quantifications of almandine’s (Fe3Al2(SiO4)3) dissolution rates across a range of pH’s (1 ≤ pH ≤ 13) – established using vertical scanning interferometry (VSI) – reveal that its dissolution rate achieves a minimum around pH 5. This minimum coincides with almandine’s point of zero charge (PZC). These trends in almandine’s dissolu...

Neutron radiation-induced volumetric expansion (RIVE) of concrete aggregate is recognized as a major degradation mechanism causing extensive damage to concrete constituents (Hilsdorf et al. 1978; Seeberger and Hilsdorf 1982; Field et al. 2015). Nearly 400 RIVE data obtained in test-reactors on varied rock-forming minerals were collected by Denisov...

A large-scale testing program on alkali silica reaction (ASR)-affected concrete structural members without shear reinforcement representative of structural members found in nuclear power plants is presented. Three concrete specimens, designed to experience a free expansion rate of approximately 0.15% per year were fabricated and placed within a con...

Alkali-Silica Reaction (ASR) is a reaction that occurs over time in concrete between alkaline cement paste and reactive, non-crystalline silica in aggregates. An expansive gel is formed within the aggregates which results in micro-cracks in aggregates and adjacent cement paste. The reaction requires the presence of water and has been predominantly...

This paper presents a 12-year-long creep and shrinkage experimental campaign on cylindrical and prismatic concrete samples under uniaxial and biaxial stress, respectively. The motivation for the study is the need for predicting the delayed strains and the pre-stress loss of concrete containment buildings of nuclear power plants. Two subjects are ce...

Noncrystalline solids can be classified into glassy and amorphous, wherein glasses and amorphous solids relax toward the supercooled liquid and crystalline states upon heating, respectively. However, the structural origin of such distinction remains unknown. Herein, based on molecular-dynamics simulations of irradiation-induced disordering of α-qua...

Albite (NaAlSi3O8), a framework silicate of the plagioclase feldspar family and a common constituent of felsic rocks, is often present in the siliceous mineral aggregates that compose concrete. When exposed to radiation (e.g., in the form of neutrons) in nuclear power plants, the crystal structure of albite can undergo significant alterations. Thes...

Under irradiation, minerals tend to experience an accumulation of structural defects, ultimately leading to a disordered atomic network. Despite the critical importance of understanding and predicting irradiation-induced damage, the physical origin of the initiation and saturation of defects remains poorly understood. Here, based on molecular dynam...

2017 American Society of Civil Engineers. Among various degradation mechanisms possibly affecting the long-term operation of nuclear power plants, the effects of induced expansion and internal degradation occurring in concrete exposed to high-flux neutron radiation require additional research. Notably, using short-term test-reactor data to assess t...

Irradiation and vitrification can both result in the disordering of minerals. However, it remains unclear whether these effects are comparable or if the glassy state represents an upper limit for irradiation-induced disordering. By reactive molecular dynamics simulations, we compare the structure of irradiatedquartz to that of glassy silica. We sho...

By affecting the connectivity of atomic networks, composition, temperature, or pressure can induce topological transitions between the three atomic states of rigidity — flexible, isostatic, and stressed-rigid. However, no clear structural signature of such transitions has been elucidated thus far. Here, based on realistic molecular dynamics simulat...

Among various degradation mechanisms possibly affecting the long-term operation of nuclear power plants, the effects of induced expansion and internal degradation occurring in concrete exposed to high-flux neutron radiation require additional research. Notably, using short-term test-reactor data to assess the long-term structural significance of li...

Life extensions of nuclear power plants (NPPs) to 60 years of operation and the possibility of subsequent license renewal to 80 years have renewed interest in long-term material degradation in NPPs. Large irreplaceable sections of most nuclear generating stations are constructed from concrete, including safety-related structures such as biological...

Water, under conditions of nanoscale confinement, exhibits anomalous dynamics, and enhanced thermal deformations, which may be further enhanced when nanoconfined water is in contact with hydrophilic interfaces. Such heightened thermal deformation of water could control the volume stability of hydrated materials with nano-confined structural water....

Long-term creep (i.e., deformation under sustained load) is a significant material response that needs to be accounted for in concrete structural design. However, the nature and origin of creep remains poorly understood, and controversial. Here, we propose that concrete creep at RH (relative humidity) > 50%, but fixed moisture-contents (i.e., basic...

A review of the current state of knowledge on the effects of radiation on concrete in nuclear power production applications is presented. Emphasis is placed on the effects of radiation damage, as reflected by changes in engineering properties of concrete, in the evaluation of the long-term operation and for plant life or aging management of nuclear...

Neutron irradiation exposure causes aggregate expansion, namely radiation-induced volumetric expansion (RIVE). The structural significance of RIVE on a portion of a prototypical pressurized water reactor (PWR) concrete biological shield (CBS) is investigated by using a meso- scale nonlinear concrete model with inputs from an irradiation transport c...

Aggregate radiation-induced volumetric expansion (RIVE) is a predominant mechanism in the formation of mechanical damage in the hardened cement paste (hcp) of irradiated concrete under fast-neutron flux (Giorla et al. 2015). Among the operating conditions difference between test reactors and light water reactors (LWRs), the difference of irradiatio...

Concrete, a mixture formed by mixing cement, water, and fine and coarse mineral aggregates is used in the construction of nuclear power plants (NPPs), e.g., to construct the reactor cavity concrete that encases the reactor pressure vessel, etc. In such environments, concrete may be exposed to radiation (e.g., neutrons) emanating from the reactor co...

A new nonlinear ultrasonic technique for nondestructive evaluation of concrete components is developed and implemented to characterize the effects of carbonation on concrete. The physical principle of this method is the second harmonic generation (SHG) in propagating Rayleigh surface waves which are detected by a non-contact air-coupled transducer....

A numerical model accounting for the effects of neutron irradiation on concrete at the mesoscale is detailed in this paper. Irradiation experiments in test reactor (Elleuch et al., 1972), i.e., in accelerated conditions, are simulated. Concrete is considered as a two-phase material made of elastic inclusions (aggregate) subjected to thermal and irr...

The isotherm sorption curve is a first-order parameter used in the Finite Element modelling of concrete moisture transport, shrinkage and creep behaviour. An original experimental campaign was developed by EDF R&D in order to characterise the first desorption isotherm at room temperature of a laboratory concrete. Long-term drying tests were carried...

The post-tensioned inner concrete containment building of nearly half of the French nuclear power plants has the role of barrier against potential radiological release , since these containments buildings have no metallic liner. Hence, the integrity of concrete and the stability of post-tensioning are of paramount importance. Since the variation of...

Long-term performance of aging concrete in nuclear power plants (NPPs) requires a careful examination of the physical phenomena taking place in the material. Concrete under high neutron irradiation is subjected to large irreversible deformations as well as mechanical damage, caused by a swelling of the aggregates. Mesoscale numerical simulations ar...

License renewal up to 60 years and the possibility of subsequent license renewal to 80 years has resulted in a renewed focus on long-term aging of materials at nuclear power plants (NPPs) including concrete. Large irreplaceable sections of most nuclear generating stations include concrete. The Expanded Materials Degradation Analysis, jointly perfor...

Corrosion assessment of embedded steel in concrete structures is generally performed by electrochemical methods that are not fully nondestructive because the device requires connection to the steel. For practical applications, the development of a truly nondestructive technique for the detection of corrosion is desirable. This paper presents an exp...

Dommages d’irradiation du béton des puits de cuve des réacteurs T.M. Rosseel1, J.J. Wall2, K.G. Field1, Y. Le Pape1*, D.J. Naus1, I. Remec1, J.T. Busby1, P. Bruck3 1 Oak Ridge National Laboratory 2 Electric Power Research Institute 3 LPI, Inc. Le prolongement de la durée de fonctionnement des réacteurs au-delà de 60 ans et l’amélioration de leur p...