Institute for Radiation Protection and Nuclear Safety (IRSN)
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Late Breaking Abstract - Association between Volatile Organic Compounds (VOCs) concentrations in daycares and child wheeze in the French CRESPI cohort
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OECD-NEA Expert Group on Reactor Systems Multi-Physics: Development of Verification and Validation Guidelines for Multi-Physics Simulations
No full textInternational audienceOver the past decades, national and multi-national efforts have been established to develop high-fidelity, multi-physics, and multi-scale modeling and simulation (M&S) tools for design and safety challenges for existing and advanced reactors. These tools are being developed and utilized to provide predictive capabilities that enhance safety, improve designs, and accelerate innovation. An expert group on reactor systems multi-physics (EGMUP) was established in 2014 by the OECD Nuclear Energy Agency (NEA) to address specific challenges with validation of such M&S tools with the intent to provide member countries of the NEA with consensus guidance and recommendations and to demonstrate the application of the validation principles. The EGMUP supervises several multi-physics benchmark exercises to develop and demonstrate best practices for validation. This paper will describe the overall mission of the group, provide a description of several of the validation exercises relevant to existing reactor technologies, and summarize key recommendations for validation approaches
Numerical simulation of corium flow through rod bundle and/or debris bed geometries with a model based on Lattice Boltzmann method
No full textInternational audienceA new model is proposed to investigate the relocation and the distribution of hot corium flows in different configurations (rod bundle, porous debris bed) representative of a severe accident in a Light Water Reactor (LWR). Our model relies on the coupling between a modified Lattice Boltzmann Method (LBM), called Free-Surface LBM, that solves hydrodynamics of unsaturated corium and a Finite Volume Method (FVM) that solves heat transfers. Corium solidification and melting are addressed by implementing a correlation between the temperature and the viscosity. Several simulations on representative elementary volumes were performed, varying configurations (debris bed, rod bundle with and without grid). From the results, it is possible to capture important details of the flow at a scale lower than the pore scale and, at the same time, it is possible to take into account the average effects at the scale of several pores. Presented as a proof of concept these preliminary studies show the interest of this kind of CFD approach to identify which parameters at microstructure scale can potentially govern the corium relocation kinetics at macroscopic scale. It will provide useful information that might improve core degradation models in severe accident codes, such as ASTEC
Bayesian spatial mixture of experts for a flexible dose-response assessment after brain radiotherapy
No full textInternational audienceRadiotherapy (RT) is one of the most important treatments for brain tumors. However, its potential toxicity on the central nervous system is a highly relevant clinical issue as cognitive dysfunction, mainly related to radiation-induced leukoencephalopathy, may alter the quality of life of patients. As part of the RADIO-AIDE research project, the aim of this work is to model and learn about the potential relationship between the dose of ionizing radiation absorbed in a voxel of the brain after RT (from CT-scan images) and the presence/absence of brain lesions in these voxels (from segmented brain MRI data). We propose to extend the class of mixture of experts’ models, including the well-known Gaussian Locally Linear Mapping model (GLliM), to a binary outcome and a spatially structured predictor. We thus propose and compare several mixtures of experts’ models based on a piecewise logistic regression and different spatial components (hidden Potts model, conditionally auto-regressive model) to account for dependency between neighboring voxels. Various Bayesian statistical learning methods (variational Bayes, MCMC, SMC) are implemented and compared from simulated data as well as real data from the EpiBrainRad prospective cohort, which includes patients treated with radiochemotherapy for glioblastoma. Many modelling perspectives and Bayesian computational challenges will also be discussed
Les capacités reproductrices, mais pas la consommation alimentaire, sont réduites par une exposition continue au stresseur génotoxique typique, le rayonnement gamma, de l'espèce sentinelle Gammarus fossarum
No full textInternational audienceThe long-term impacts of radiocontaminants (and the associated risks) for ecosystems are still subject to vast societal and scientific debate while wildlife is chronically exposed to various sources and levels of either environmental or anthropogenic ionizing radiation from the use of nuclear energy. The present study aimed to assess induced phenotypical responses in both male and female gammarids after short-term continuous γ-irradiation, acting as a typical well-characterized genotoxic stressor that can interact directly with living matter. In particular, we started characterizing the effects using standardized measurements for biological effects on few biological functions for this species, especially feeding inhibition tests, molting, and reproductive ability, which have already been proven for chemical substances and are likely to be disturbed by ionizing radiation. The results show no significant differences in terms of the survival of organisms (males and females), of their short-term food consumption which is linked to the general health status (males and females), and of the molting cycle (females). In contrast, exposure significantly affected fecundity (number of embryos produced) at the highest dose rates for irradiated females (51 mGy h–1) and males (5 and 51 mGy h–1). These results showed that, in gammarids, reproduction, which is a critical endpoint for population dynamics, is the most radiosensitive phenotypic endpoint, with significant effects recorded on male reproductive capacity, which is more sensitive than in females
Occupational exposure: Results from the international collaborative studies (BECOME, INWORKS)
No full textInternational audienceEpidemiological studies often suffer from a lack of statistical power in their analyses. To overcome this problem, pooling two or more databases from studies using similar methodology is the key to furthering knowledge in ionizing radiation epidemiology. This is the case for workers in the medical and nuclear sectors included in the international BECOME and INWORKS studies, respectively
Étude ORICAMS: Occupational radiation-induced cancer in medical staff
No full textInternational audienceLe risque de cancer radio-induit reste discuté pour une exposition aux faibles doses de rayonnements ionisants (RI), notamment pour le personnel médical pour lequel aucune étude n’a été réalisée en France à ce jour. La cohorte ORICAMs a ainsi pour objectif d’étudier la mortalité par cancer radio-induit chez les professionnels de santé exposés aux RI en France
Fiber-coupled nuclearized raman probe for remote gas monitoring in nuclear containment: proof-of-concept for h2-risk management of design & beyond-design accidents
No full textInternational audienceDuring the course of a severe accident (SA) in a Light Water Reactor (LWR), large amounts of hydrogen (H2) gas are likely to be generated and released into the containment during core degradation, potentially raising a combustion hazard. Additional burnable gases (H2 and CO) may be released into the containment volume in case of Molten Corium/Concrete Interaction (MCCI). Within the extension period of the MITHYGENE Project, CEA LIST, IRSN and ARCYS have designed, assembled and tested a fiber-coupled nuclearized gas prototype probe, based on optical Raman technology, and complying with the specifications of a severe accident. This monitoring technique conveys many decisive advantages such as chemical-selective, distributed and local gas measurement (cm 3 ). It aims at providing in situ accurate information on gas mixture (H2, O2, N2, steam, CO, CO2) in quasi real-time and in several locations inside the containment and the annulus. Compared to the previous Raman probe developed within the first period of the MITHYGENE Project, this new Raman probe is more efficient and includes improved functionalities such as polarization-diversity Raman measurements and anti-fogging anti-aerosol device with the aim to prevent both water condensation and aerosol deposition. Two algorithms are evaluated to compensate for Cerenkov perturbations (background subtraction and polarization correction). We describe experimental qualifications performed in the NC2V gas cell (CNRS-ICARE) and in the IRMA irradiation cell (IRSN). The MITHYGENE Project ends up with a proof-of-concept of Raman probe dedicated to H2/MCCI-risk management. The Technological Readiness Level (TRL) of the prototype probe is between 5 and 6
Experimental verification to developing safety technology for liquefied hydrogen: Project "STACY": Global efforts are underway to decarbonize the energy sector. Liquefied (cryogenic) hydrogen (LH2) has high storage density, making it excellent for large-scale storage and transportation, and is expected to play a fundamental role in the hydrogen economy. However, liquid hydrogen has several properties that are potential safety risks.An international collaboration between Germany, France, and Japan is underway in the project "Towards the Safe Storage and Transport of Cryogenic Hydrogen" (acronym "STACY"). Project activities are allocated to five work packages to achieve specific goals. This paper reports on the development of hydrogen safety technology using a catalyst (WP3).This technology is called "Passive Autocatalytic Recombiner: PAR" because it works autonomously without external heating, blowing, or stirring. Liquid hydrogen has the characteristics of extremely low temperature and high energy density, and in the event of a leak, it will expand highly. To achieve the PAR required for these safety measures, the crystal structure of the catalyst was designed from the atomic level, and an actual catalyst was prototyped, and repeated tests were carried out in a large reaction vessel as well as laboratory evaluations. As a countermeasure against the unlikely event of a liquefied hydrogen leakage, progress is being made in the development of catalysts that can oxidize hydrogen even in extremely low temperatures, high expansion, and low-oxygen environments, are resistant to catalyst poisons, and can prevent spontaneous ignition due to heat generation. The catalyst technology uses not only general alumina supports, but also ceria and perovskite-type oxides to control the surface state of precious metals, suppressing hydrogen ignition through multi-stage configuration and showing resistance to contamination from oxygen and carbon monoxide. Furthermore, the mechanism of catalyst poison resistance was elucidated using synchrotron radiation.
No full textInternational audienceGlobal efforts are underway to decarbonize the energy sector. Liquefied (cryogenic) hydrogen (LH2) has high storage density, making it excellent for large-scale storage and transportation, and is expected to play a fundamental role in the hydrogen economy. However, liquid hydrogen has several properties that are potential safety risks.An international collaboration between Germany, France, and Japan is underway in the project "Towards the Safe Storage and Transport of Cryogenic Hydrogen" (acronym "STACY"). Project activities are allocated to five work packages to achieve specific goals. This paper reports on the development of hydrogen safety technology using a catalyst (WP3). This technology is called "Passive Autocatalytic Recombiner: PAR" because it works autonomously without external heating, blowing, or stirring. Liquid hydrogen has the characteristics of extremely low temperature and high energy density, and in the event of a leak, it will expand highly. To achieve the PAR required for these safety measures, the crystal structure of the catalyst was designed from the atomic level, and an actual catalyst was prototyped, and repeated tests were carried out in a large reaction vessel as well as laboratory evaluations.As a countermeasure against the unlikely event of a liquefied hydrogen leakage, progress is being made in the development of catalysts that can oxidize hydrogen even in extremely low temperatures, high expansion, and lowoxygen environments, are resistant to catalyst poisons, and can prevent spontaneous ignition due to heat generation.The catalyst technology uses not only general alumina supports, but also ceria and perovskite-type oxides to control the surface state of precious metals, suppressing hydrogen ignition through multi-stage configuration and showing resistance to contamination from oxygen and carbon monoxide. Furthermore, the mechanism of catalyst poison resistance was elucidated using synchrotron radiation.</p
The European Fault-Source Model 2020 (EFSM20): geologic input data for the European Seismic Hazard Model 2020
No full textInternational audienceEarthquake hazard analyses rely on seismogenic source models. These are designed in various fashions, such as point sources or area sources, but the most effective is the three-dimensional representation of geological faults. We here refer to such models as fault sources. This study presents the European Fault-Source Model 2020 (EFSM20), which was one of the primary input datasets of the recently released European Seismic Hazard Model 2020. The EFSM20 compilation was entirely based on reusable data from existing active fault regional compilations that were first blended and harmonized and then augmented by a set of derived parameters. These additional parameters were devised to enable users to formulate earthquake rate forecasts based on a seismic-moment balancing approach. EFSM20 considers two main categories of seismogenic faults: crustal faults and subduction systems, which include the subduction interface and intraslab faults. The compiled dataset covers an area from the Mid-Atlantic Ridge to the Caucasus and from northern Africa to Iceland. It includes 1248 crustal faults spanning a total length of ∼95 100 km and four subduction systems, namely the Gibraltar, Calabrian, Hellenic, and Cyprus arcs, for a total length of ∼2120 km. The model focuses on an area encompassing a buffer of 300 km around all European countries (except for Overseas Countries and Territories) and a maximum of 300 km depth for the subducting slabs. All the parameters required to develop a seismic source model for earthquake hazard analysis were determined for crustal faults and subduction systems. A statistical distribution of relevant seismotectonic parameters, such as faulting mechanisms, slip rates, moment rates, and prospective maximum magnitudes, is presented and discussed to address unsettled points in view of future updates and improvements. The dataset, identified by the DOI https://doi.org/10.13127/efsm20 (Basili et al., 2022), is distributed as machine-readable files using open standards (Open Geospatial Consortium)