The European Journal of Physics N (EPJ-N)
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Rheological investigation of bitumen, used for radioactive waste conditioning, with ultrasonic waves
No full textIn the context of bituminized radioactive waste storage and disposal, nucleation monitoring at room temperature and radiolysis bubbles migration at elevated temperature is crucial particularly in fire scenarios where bubble may impact thermal properties. Traditional methods are limited by the opacity of bitumen. To gain a deeper insight into bitumen rheology and ultrasonic wave propagation, we conducted a pilot study using ultrasonic testing cells spanning temperatures from 10°C to 60°C. Ultrasonic velocities and attenuations were measured at around 500 kHz in a 70/100 grade bitumen. Rheological information was deduced with the Time-Temperature Superposition principle and a behaviour model was proposed to describe bitumen across a wide frequency range. Notably, our study reveals a transition point around 50°C to 60°C, where bitumen’s liquid behaviour becomes dominant. The shear-thinning characteristics gradually give way to a more Newtonian response. Using the proposed model, ultrasonic attenuation and viscosity were estimated at 110°C. Acceptable ultrasonic frequencies for monitoring the nucleation and migration of radiolysis bubbles are discussed for future investigations. These findings have significant implications for safety measures and a deeper understanding of bitumen response within the realm of radioactive waste management
An overview of last decade’s developments in RayXpert
No full textThis article provides an overview of the developments made over the last 10 years within RayXpert®, a CAD-based geometry 3D Monte Carlo software developed by TRAD – Tests & Radiations. The main features of RayXpert® are its 3D Monte Carlo engine and its CAD-based geometry. It is also possible to import STEP file, automatically detect overlaps, and perform parallel Monte Carlo computations. During the last 10 years, numerous new features were added to the software: TTB approximation, dose and flux mapping, computation resumption, radioactive decay computation, script support, MPI computation, advanced convergence indicators, etc. New features such as advanced biasing or neutron-induced activation simulation are under development. This article presents the past and future functionalities of RayXpert®
A contribution for dismantling of nuclear facilities: a functional pattern for dismantling operations and indicators design and management
No full textOptimizing nuclear installation decommissioning and dismantling operations is an ongoing quest. Faced with the complexity of this activity, Model Based System Engineering promotes relevant principles and modeling techniques. It motivated the definition of a functional generic pattern model of the waste package production line and the decommissioning of the facility. It proposes a global and generic functional architecture of such a system aiming to reduce the level of the pollutant. This pattern is coupled with a process of logistics. Six functions are combined to define this functional pattern. The application of this pattern model to a case of waste recovery in a pit shows the relevance of the model-based system engineering approach, reducing the weight of the history in the development of scenarios by optimizing the control means for nuclear safety and product quality
MC21 v.10 – coupled-radiation Monte Carlo transport solver with support for multiphysics simulations
No full textOver the past decade, the development of the MC21 Monte Carlo radiation transport solver has focused on extending the functionality of the code beyond static calculations of reactivity and reaction rate distributions, as well as improving accuracy, performance, and scalability. Notable improvements include enhanced interaction physics models, efficient model representation and tracking algorithms, support for coupled physics calculations using both in-line and externally coupled feedback modules, and the development of native visualization and results post-processing tools. As a result of these improvements, MC21 v.10 provides a comprehensive analysis framework that allows complicated engineering problems to be solved with minimal reliance on external tools
Overview of the TRIPOLI-4 Monte Carlo code, version 12
No full textIn this paper we present an overview of the recent advances of the general-purpose Monte Carlo code TRIPOLI-4®, developed at CEA. The features described in this work, which refer to the current version 12 of the code, encompass applications to radiation shielding (variance-reduction methods: Consistent Adjoint-Driven Importance Sampling, Adaptive Multilevel Splitting, and Weight Windows), material activation calculations (Rigorous Two-Step Scheme), reactor physics (fission matrix, kinetics parameters, critical parameter search, kinetics with delayed neutron precursors), criticality-safety (perturbation and sensitivity methods: Standard and Generalized Perturbation Theory) and nuclear instrumentation (fission models, improvements in the electromagnetic shower models, and coupling with the code Geant4)
Main achievements and impact of EURAD, the European Joint Programme on Radioactive Waste Management (2019–2024)
No full textCo-funded by the European Commission, EURAD has operated for 5 years and has successfully achieved a step-change towards a more effective and efficient use of public funding in Europe by bringing the European waste management community together.
Its main achievements are rooted in its governance structure, fostering interaction and collaboration among Waste Management Organisations, Technical Safety Organisations and Research Entities. A key success factor was the development and update of the Strategic Research Agenda and Roadmap, which guided efforts, addressed emerging challenges and ensured alignment across Member States.
EURAD’s impact is highlighted by its comprehensive R&D framework, which covers the entire lifecycle of radioactive waste management. EURAD successfully advanced knowledge in various areas, including advanced waste treatment, geological disposal, and safety assessments. The programme also emphasised the importance of knowledge management, ensuring the transfer and preservation of expertise between waste management programmes and across generations through training, mobility, guidance and the publication of scientific resources, and making information more easily available.
EURAD not only strengthened collaboration among EU Member States but also fostered international partnerships, significantly contributing to the global advancement of radioactive waste management. As EURAD concludes, its legacy will continue with EURAD-2, set to begin in October 2024, further building on the foundations laid by its predecessor
Radiolysis of bituminized radioactive waste: a comprehensive review
No full textIn the realm of radioactive waste management, the impact of radiolysis on bitumen and bituminized radioactive waste also called bituminized waste product (BWP) is considered one of the most significant factors influencing structural changes and the generation of radiolysis gas bubbles. This review provides a comprehensive overview of several studies that have explored the intricate interaction between radiation and various types of bitumen, to gain a better understanding of how such waste ages when exposed to radiation. While these studies provide insights into the diverse effects of radiolysis on bitumen, they also highlight numerous unanswered questions. The absence of gas bubbles does not necessarily indicate an absence of gas production, leaving further research to be undertaken. The complexities of bitumen radiolysis offer multiple avenues for future investigation, aiming to enhance our understanding and provide comprehensive solutions for bituminous radioactive waste management. Among the studied types of bitumen, blown R85/40 bitumen and straight-run distilled bitumen with a penetration grade of 70/100 stands out due to their widespread use in immobilizing co-precipitated radioactive sludges. These bituminous matrices play an essential role in understanding the broader implications of radiolysis within the context of bituminous waste management. This review underscores the significance of further research into radiolysis and bitumen ageing, emphasizing the need for a more in-depth exploration of these complex phenomena and their implications for the long-term safety and efficacy of repositories and disposal facilities
Papillon Nuclear Data Library – a free and open-source C++/Python library for interacting with ACE files for continuous-energy neutron data
No full textIn this paper, a new C++ and Python library, called the Papillon Nuclear Data Library, is presented. This library gives users a simple interface to read and interact with continuous-energy neutron data in the form of ACE files. Using the library, one can easily evaluate or plot cross-sections for different nuclides and reactions, or sample scattering distributions. Currently, all continuous-energy neutron physics is implemented, and the library can read free-gas neutron and thermal scattering law ACE files. The Python interface makes using nuclear data easy and accessible for students, while the C++ interface gives experienced researchers easy access to continuous-energy physics when writing Monte Carlo codes to test new computational methods
Benefits from power and heat cogeneration
No full textA large fraction of heat production from power sources is wasted in the environment, despite its numerous potential energy uses, for example, district heating, seawater desalination, or hydrogen production. In this paper, we use the MIXOPTIM methodology to evaluate performance indicators of mixes of electric power sources with and without cogeneration of heat to assess the benefits it entails. It appears from the study that the cogeneration option is highly interesting for mixes with a large nuclear share. The case of France is analyzed in detail, with an evaluation of the overall potential of cogeneration in terms of economic competitiveness as well as in terms of greenhouse gas emission reduction
EURAD EC project – overview of the routes work package: identified key issues and open questions about waste management routes in Europe, from cradle to grave
No full textThe ROUTES Work Package (WP) is one of the two strategic studies being conducted as part of the European Joint Programme on Radioactive Waste Management (EURAD). ROUTES’ objectives are (i) to provide a framework for European Union’s member states (MS) to share methodologies, experiences, and knowledge in situations in which a waste management strategy is difficult to define as well as to (ii) to compare national approaches and strategies of waste management. The work considers national programmes at different stages of their development and deals with different amounts and types of radioactive waste. The expected output is identifying Research & Development (R&D) needs and opportunities for collaboration between MS, which need not be confined to ROUTES or EURAD frameworks. This work has enabled ROUTES partners to identify key issues such as retrieving poorly characterised legacy waste from a predisposal or disposal facility, implementing specific waste management solutions in the absence of well-defined WAC or developing innovative or shared solutions for MS that have only limited amounts of waste to manage. Discussion of these questions is illustrated through some of the case studies identified and analysed under the ROUTES WP