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[en] The current management system in the United States for commercial spent nuclear fuel does not emphasize integration among storage, transportation, and disposal. The large containers in use for dry-storage remain at high temperatures for decades and, thereby, delay removal from decommissioned reactors. The large containers also have no easy path to disposal unless (1) disposal is delayed (up to 150 years for some geologic media); (2) the contents are repackaged into smaller, cooler packages; or (3) the high temperatures are used as de facto site-selection criteria for a repository. Implementing consolidated interim storage could address many issues that exist because of this lack of integration. A consolidated interim storage facility that includes appropriate capabilities acts as a universal coupler that allows existing disparate parts to integrate as a system. Previous agencies and commissions have noted this theme before as a way to provide flexibility in the waste management system. This rationale is elaborated upon here. (author)
[en] A national debate has been launched about the 5. national plan for the management of radioactive wastes (PNGMDR). The PNGMDR is re-assessed every 3 years and it is the second public debate about it. The purpose of the PNGMDR is: to make an audit of what has been made in the previous years concerning the management of radioactive wastes, to assess the future needs in terms of storage and disposal, to launch studies on specific issues of radioactive waste managing and to give recommendations in implementing new modes of management or in modifying existing installations. The aim of the public debate is to make people interested and involved in an important issue that concern themselves and future generations. Around 25 public meetings are scheduled from april to september 2019. (A.C.)
[en] Dismantling, clean-up, decontamination and radioactive waste managing are the components of a mature and growing nuclear decommissioning market in France. It is known that these activities do not require as much staff as a nuclear facility in operation but some related projects like the recycling of very low level radioactive wastes or the implementation of smart grids can create jobs locally. A feature of the nuclear industry is that it is spread all across the country and the response in terms of jobs to the definitive closure of a facility should be found locally so that the local economic tissue is preserved. For instance in the region where the Fessenheim nuclear power plant is about to shutdown definitely, an industrial tissue is being developed. Another example is the CIGEO facility that is being built with the aim of disposing high level radioactive waste in deep geological layers. A nearby industrial activity zone has been created where local enterprises have moved in in order to favor synergy and industrial development. (A.C.)
[en] Radioactive waste repositories are designed to isolate waste from the living environment without human intervention over extended periods of time. Nevertheless, the intention is not to abandon the repositories, but to provide the oversight that is necessary to ensure that they are not forgotten by society. In response to this challenge, the Nuclear Energy Agency launched the international initiative 'Preservation of Records, Knowledge and Memory (RK and M) Across Generations'. As a result, an in-depth understanding of this issue was developed, as well as a specific methodology to address it. The RK and M preservation toolbox, for example, offers a menu with 35 different preservation mechanisms and guidelines on how to combine and implement them. This report may be used as a general guide to the RK and M preservation topic. It presents a historical review, addresses ethical considerations, analyses the fundamentals of RK and M preservation, outlines various mechanisms and indicates how to develop these mechanisms into a systemic RK and M preservation strategy. The report aims to inspire and assist a variety of actors so that they can discuss and develop national and repository-specific RK and M preservation strategies
[en] This paper presents a nuclear criticality safety analysis of an operation to recover containers from a 30-year-old storage site. There are 145 containers containing waste from fuel elements with fissile material. The storage consists of 15 cement wells, 7 m deep and 0.4 m in diameter. Each well contains up to 10 60-liter containers stacked on top of each other. Waste containers contain mixtures of various fuel element sections and samples which have various shapes (rods, needles, bars, etc.), different physical or chemical forms (metal, oxide) and variable isotopic compositions. The analysis is based on an inventory of the quantities of fissile material and their composition, which are well known. Given the duration of storage and the possibility of dropping a container during handling, two methods of taking up containers are envisaged. The first one is handling the container as a whole (without opening the container), and the second is opening the container inside the well and recovering the waste directly into the container. For the recovery of the containers, nuclear critical safety of the operation is ensured by limiting the masses of handled fissile material. These masses must remain below the safe masses under normal condition (gripping of a container) or under an abnormal situation (falling of a container on the one below with grouping of the fissile material of the two containers). These safe masses are calculated at optimal moderation for homogeneous or heterogeneous media with reflection by concrete. Different criteria are used for normal and abnormal situations. The paper presents the method for determining a reference fissile medium that bounds all fissile material present in the two containers without being too penalizing. It takes into account the nature of the fissile material (oxide or metallic, homogeneous or heterogeneous), 235U enrichment and the moderating material. The paper also presents calculations of critical and safe mass limits of fissile material for all the reference fissile media. For each grouping of two containers, the paper presents the calculations of an equivalent mass of fissile material in both containers and then verifies that it is below the safe mass limit. Thanks to this method, it is possible to handle a majority of containers (90%) as a whole (without opening) thus saving time and reducing worker exposure for the operation all the while ensuring nuclear criticality safety control.
[en] The objective of this study is the operational verification of an environmental dose rate monitoring network composed by several sensors. The verification of the study has been tested on the CIEMAT's Radiological Network, establishing a records quality assurance of the detectors using the covariance matrix and the eigenvalues. The technique has revealed an underlying records malfunction, which have not been appreciated by applying conventional surveillance. In this sense, the malfunction has economic and security consequences, which can be minimized with an alternative methodology, which guarantees the radiological protection of a local area according to the Regulatory Agency. (authors)
[en] The technologies of knowledge representation and inference in an artificial intelligence system focused on the domain of nuclear physics and nuclear power engineering are considered in the paper. The possibilities of description logics and graph databases of nuclear knowledge for the generation of cognitive hypotheses, using in addition to deduction and other ways of reasoning, such as inductive inference and reasoning based on analogies, are also discussed
[ru]В работе рассматриваются технологии представления знаний, модели рассуждений и методы генерации когнитивных гипотез в системах искусственного интеллекта. Практический акцент сделан на применении проблемно-ориентированных графов знаний как образовательной технологии при подготовке специалистов в области ядерной физики и атомной энергетики
[en] A historical Magnox fuel element debris storage facility presents one of the highest radiological hazards on the Sellafield Site. Preparations to retrieve the solid radiological inventory into waste packages and put these into modern storage facilities are reaching fruition, with retrievals due to commence later this year. The vast majority of the Magnox fuel fissile waste in the facility presents no credible criticality risk. A very small mass fraction of the waste, Enriched Fissile Tippings (EFT), presents a theoretical criticality risk during the operations to retrieve and safe-store the waste. At the onset of work on the criticality safety case the understanding of the EFT inventory was inadequate and it appeared that the criticality risk could be near to a level regarded as intolerable in UK custom and practice. The criticality safety case has required a detailed investigation of the records concerning the EFT. This has been a challenging task requiring expert identification, interpretation and reconciliation of records from multiple archives and document stores. As this work has progressed, our understanding of the uncertainties in the data and our level of confidence in the data has improved, to the extent that it is now considered adequate to underpin the criticality safety case. Various theoretical accumulations and arrangements of the EFT have been modelled and used to map a 'criticality safety envelope'. The developed EFT inventory (with uncertainties) has then been compared against the safety envelope and it has been demonstrated that the likelihood of sufficient EFT accumulating in an arrangement that could cause criticality is very low. The criticality risk is now demonstrated to be tolerably low within the context of the overwhelming need to reduce the high radiological risk as soon as reasonably practicable. Furthermore, the susceptibility of criticality to uncertainties and unknown factors is considered so low that there would be no benefit from having a Criticality Emergency Plan (CEP) and hence no requirement for a Criticality Warning System. The paper will discuss the investigation of the EFT inventory, the development of the criticality safety case and the consideration of the need for a CEP. (author)
[en] Due to the length of the article, the article is published in four parts. The authors and editor hope you will enjoy and look forward to reading the entire article, as each portion is published. Part I provides the background to the discussion. Part II considers nuclear waste management from the perspective of Russia, Part III the perspective of Asia, while Part IV considers those States in the Southern Hemisphere.