The European Journal of Physics N (EPJ-N)
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European collaborative efforts to achieve effective, safe, and cost-controlled dismantling of nuclear facilities
No full textThis paper aims to give an overview of very recent European coordinate efforts to implement technologies of the “4.0 Industry” in the nuclear deconstruction sector. This objective aims to benefit from the lever of efficiency and reliability represented by innovative technologies on all the value chain of the dismantling, from early characterization to the dismantling operations themselves through engineering studies, waste management, project management and coordination of multiple stakeholders of each project. The outcomes of five projects (INNO4GRAPH, LD-SAFE, PLEIADES, CLEANDEM and INSIDER) are summarized here. They result in a unique data and knowledge common base, as well as in a significant sharing of experience based on dismantling projects already carried out or to come. They also result in designing new tools or methods natively taking into account the needs of a maximum of dismantling operators, as well as new test facilities. This will allow the undertaken joint work and collaboration to be continued. All of this paves the way to further collaborative projects and developments, in order to continue to implement reliable new technologies and processes in European dismantling projects to make future dismantling operations more efficient, safer and more cost-effective
A novel 3D-imaging and characterisation technique for special nuclear materials in radioactive waste
No full textA novel technique for non-destructive assay (NDA) of radioactive waste called ARCTERIX (Advanced Radwaste Characterisation based on Tomographically Enhanced Radiation Imaging without X-rays) is presented. The concept is based on a 3D-tomographic imaging technique for special nuclear materials – neutron-gamma emission tomography (NGET). ARCTERIX takes the NGET principle from its original application area of nuclear security systems into the realm of radioactive waste assay with its special characteristics and challenges. By adding localisation and imaging of SNM inside shielded waste containers to the array of existing techniques used for radioactive waste characterisation, ARCTERIX complements the state of the art in passive and active NDA interrogation methods. It is aimed primarily at the class of mixed, long-lived radioactive waste that is commonly called “legacy” or “historic” waste which has special safety, security and safeguards concerns due to its mixed composition, commonly poor documentation, and the frequent presence of SNM. The ARCTERIX concept provides rapid imaging and characterisation of nuclear materials in radioactive waste with a high degree of automation and high throughput capabilities, making it possible to quickly scan large radioactive waste inventories for the presence of special nuclear materials with minimal manual intervention. The first ARCTERIX prototype system has demonstrated a high technological readiness for the implementation of the technique in a commercial stand-alone system for rapid assessment of radioactive waste drums or in a system operating in conjunction with established techniques
Radioactivity and health risk assessments in cement samples commonly used as construction materials in the case of South Gondar Zone, Ethiopia
No full textThis work deals with the measurement of the radioactivity concentrations from different cement samples collected from the South Gondar Zone, Ethiopia. The measurement of naturally occurring radioisotopes and radiation health impact indices caused by these nuclides in cement samples are indisputable in the dwellings. Specifically, the average concentrations for 226Ra, 232Th and 40K were estimated as 76.53, 81.67, and 407 Bq kg−1, respectively. It was seen that all the measured mean values were greater than the world’s limited levels. External and internal hazard indices are calculated as defined by the European Commission from the corresponding concentrations of 226Ra, 232Th and 40K nuclides. Moreover, the natural radionuclides have variety of concentrations which must be caused by the types of raw materials used in the industries for the production of cement
Coupling reactor design and scenario calculations: a promising method for scenario optimization
No full textThe link between reactor design studies and scenarios calculations is usually sequential. From a list set of objectives, a reactor design is produced and passed to the scenarist in the form of a numeric irradiation model. This approach assumes that the reactor design is fixed from the scenarist perspective. The method presented in this article proposes to use a flexible reactor model, built with artificial neural networks, that gives the possibility to the scenarist to change a reactor design directly during the scenario calculations. Doing so, the reactor design is no longer an imposed parameter but a tool to find new optimal trajectories. Moreover, this flexible model is able to exploit the historical loaded fuel compositions generated by the scenario calculations in order to monitor the reactor performances over time. In this paper, the flexible reactor model construction is detailed and the interest of such method is highlighted with an application case that consists in the transition from a PWR fleet, similar to the French one, towards a PWR − SFR fleet stabilizing plutonium inventory
Methodologies for efficient and reliable NPP polymer ageing management
No full textThe lifetime of existing Nuclear Power Plants (NPPs) can potentially be extended to between 60 and 80 years if safety and operability of facilities can be guaranteed. This requires efforts in terms of equipment qualification and ageing management to support stakeholders and decision makers. Polymer ageing is of concern due to their widespread use in NPPs (e.g. each NPP contains approximately 1500 km of cables). Predicting their lifetime and monitoring their integrity remain a challenge. Here, we present a cross-cutting review of two on-going Horizon 2020 projects (TeaM Cables and El Peacetolero). The combination of these 2 projects allows to provide the community with non-destructive and predictive tools that can help assess the reliability and functionality of polymer-based components such as cables or pipes. The paper discusses scientific challenges faced in the beginning and achievements made throughout the projects, including the industrial impact and lessons learnt. Two specific aspects highlighted concern the way the projects sought contact with end users and the balance between industrial and academic partners. The paper concludes with an outlook on follow-up issues related to the long-term operation of NPPs
Start-up, operation and thermal-hydraulic analysis of a self-propelling supercritical CO
No full textThe supercritical carbon dioxide (sCO2
Modelling of the long-term evolution and performance of engineered barrier system
No full textComponents of the so-called “multiple-barrier system” from the waste form to the biosphere include a combination of waste containers, engineered barriers, and natural barriers. The Engineered Barrier System (EBS) is crucial for containment and isolation in a radioactive waste disposal system. The number, types, and assigned safety functions of the various engineered barriers depend on the chosen repository concept, the waste form, the radionuclides waste inventory, the selected host rock, and the hydrogeological and geochemical settings of the repository site, among others. EBS properties will evolve with time in response to the thermal, hydraulic, mechanical, radiological, and chemical gradients and interactions between the various constituents of the barriers and the host rock. Therefore, assessing how these properties evolve over long time frames is highly relevant for evaluating the performance of a repository system and safety function evaluations in a safety case. For this purpose, mechanistic numerical models are increasingly used. Such models provide an excellent way for integrating into a coherent framework a scientific understanding of coupled processes and their consequences on different properties of the materials in the EBS. Their development and validation are supported by R&D actions at the European level. For example, within the HORIZON 2020 project BEACON (Bentonite mechanical evolution), the development, test, and validation of numerical models against experimental results have been carried out in order to predict the evolution of the hydromechanical properties of bentonite during the saturation process. Also, in relation to the coupling with mechanics, WP16 MAGIC (chemo Mechanical AGIng of Cementitious materials) of the EURAD Joint Programming Initiative focuses on multi-scale chemo-mechanical modeling of cementitious-based materials that evolve under chemical perturbation. Integration of chemical evolution in models of varying complexity is a major issue tackled in the WP2 ACED (Assessment of Chemical Evolution of ILW and HLW Disposal cells) of EURAD. WP4 DONUT (Development and improvement of numerical methods and tools for modeling coupled processes) of EURAD aims at developing and improving numerical models and tools to integrate more complexity and coupling between processes. The combined progress of those projects at a pan-European level definitively improves the understanding of and the capabilities for assessing the long-term evolution of engineered barrier systems
Development of guidance documents in the EURAD and PREDIS projects
No full textParticular emphasis is dedicated to Knowledge Management activities within the EURAD (European Joint Programme on Radioactive Waste Management) and PREDIS (Pre-disposal management of radioactive waste) projects to ensure the capture of existing knowledge, transfer of knowledge between Members States and management of the knowledge for future generations. The EURAD project has three work packages dedicated to knowledge management. One of them, the EURAD Guidance work package (WP12) is developing a comprehensive suite of specific guidance documents that can be used by Members States with radioactive waste management (RWM) programmes that are at an early stage of development but can be beneficial also to more advanced programmes. The PREDIS project does not have a specifically allocated work package for guidance development. Rather, such activities are integrated within deliverables produced as part of the Strategic Implementation and State of Knowledge actions of the Roadmap contributions on predisposal waste management. The EURAD guidance work is based on the existing PLANDIS guide on RD&D planning, developed by the Implementing Geological Disposal of Radioactive Waste Technology Platform (IGD-TP). The guidance documents complement other documents prepared in parallel knowledge management activities inside EURAD project: the State of Knowledge documents. The differentiation is that guidance documents explain in more detail how the process can be established and performed, including illustrative examples. The guides are self-standing documents and integrated with the EURAD Roadmap. The target end users of the guidance are primarily programme owners and managers (i.e., governments/administrations, Waste Management Organisations, Research Entities and Technical Support Organisations) responsible for planning and implementing the RWM programme and the supporting RD&D activities at a national level, even though they might also be of use and interest to other interested stakeholders, such as representatives of civil society. To produce a first list of prioritised topics for guidance documents with the aim to select a topic for a pilot guide, the Guidance WP has developed a screening process that includes review by experts and end users. Based on the priority list, the first pilot guide was developed with the title “Cost Assessment and Financing Schemes of Radioactive Waste Management Programmes”. Experience gained during the selection of topics for the pilot guide and during its production are being incorporated into the procedure for identification of new topics for which guides will be developed. First, the degree of coverage of the EURAD Roadmap themes by suitable guide documents will be analysed by the WP 12 team. The analysis will be combined with feedback from experts verifying the needs for missing guides. Finally, the potential end user community representatives will be given the opportunity to comment on the prioritisation of selected guidance documents and make additional suggestions. The potential end users stay involved also during the production of the guides. This procedure aims to optimise the scarce expert resources in relation to the identified needs of guidance documents. This article explains the approach for selecting topics for guidance documents and the results obtained both in EURAD and PREDIS
The activity concentrations of radionuclides
No full textIn this paper, we have studied the concentration levels and corresponding radiological hazard indices of natural radioactive elements such as radium-226, thorium-232, and potassium-40 in soil samples collected from Metekel Zone, Ethiopia. We have determined the concentration levels with the help of gamma ray spectrometry. Accordingly, we obtained the average values for radioactive concentrations of radium, thorium, and potassium to be 64 Bq/kg, 70 Bq/kg, and 330 Bq/kg, respectively. The radiological hazard has been also determined from the pertinent concentration levels of radium, thorium and potassium isotopes. Therefore, we obtained that the radioisotopes have heterogeneous distribution which must be caused by the nature and types of the soil in the area where this investigation was conducted for