Results 1 - 10 of 110
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[en] This paper explains the key activities that International Nuclear Services undertakes to consistently deliver high quality and reliable international marine transports of Category I to III nuclear materials. (author)
[en] This article has been retracted: please see Elsevier Policy on Article Withdrawal ( (http://www.elsevier.com/locate/withdrawalpolicy)). This article has been retracted at the request of the Publisher. This document was mistakenly published instead of the editorial of this special issue. The correct editorial is published in J. Nucl. Mater., 419 (2011) 398, (http://dx.doi.org/10.1016/j.jnucmat.2011.11.033). Apologies are offered to the guest editors and to readers of the Journal that this error was not detected during the production process.
[en] Provisions of the EURATOM Treaty are described with focus on Chapter VIII (Ownership of special fissile materials), Chapter VI (Common Supply Policy), and Chapter VII (Safeguards). The distribution of competencies among the Council, Commission and Member States in those areas is also discussed.
[en] The long-term wide development of nuclear power requires new approaches towards the realization of nuclear fuel cycle, namely, closed nuclear fuel cycle (CNFC) with respect to fission materials. Plant nuclear fuel cycle (PNFC), which is in fact the reprocessing of spent nuclear fuel unloaded from the reactor and the production of new nuclear fuel (NF) at the same place together with reactor plant, can be one variant of CNFC. Developing and projecting of PNFC is a complicated high-technology innovative process that requires modern information support. One of the components of this information support is developed by the authors. This component is the programme conducting calculations for various variants of process flow sheets for reprocessing SNF and production of NF. Central in this programme is the blocks library, where the blocks contain mathematical description of separate processes and operations. The calculating programme itself has such a structure that one can configure the complex of blocks and correlations between blocks, appropriate for any given flow sheet. For the ready sequence of operations balance calculations are made of all flows, i.e. expenses, element and substance makeup, heat emission and radiation rate are determined. The programme is open and the block library can be updated. This means that more complicated and detailed models of technological processes will be added to the library basing on the results of testing processes using real equipment, in test operating mode. The development of the model for the realization of technical-economic analysis of various variants of technologic PNFC schemes and the organization of 'operator's advisor' is expected. (authors)
[en] The U.S. Department of Energy (DOE) Nuclear Criticality Safety Program (NCSP) mission is to provide sustainable expert leadership, direction, and the technical infrastructure necessary to develop, maintain, and disseminate the essential technical tools, training, and data to support safe, efficient fissionable material operations within the DOE. The NCSP Website site makes a variety of information available to the criticality safety practitioner, including reference materials, training modules and links to related sites. It assists criticality safety personnel to keep abreast of NCSP activities or current developments in criticality safety via a 'What's New' section within the Website. Convenient access to the many useful features of the Website is available via drop-down menus. The Website is also available to non-DOE and international professionals tasked with ensuring safe operations involving fissionable nuclear materials. (author)
[en] The purpose of this paper is to review the lessons learnt on the use of advanced materials on the design and operation of components in fission reactors and to consider how these lessons can be employed to benefit the use of advanced structural and, to a certain extent, coolant channel materials in the design and qualification of the in-vessel and containment vessel components for the DEMO fusion reactor. The focus is on lessons learnt on methodologies that need to be applied, and a number of specific recommendations are made. (paper)
[en] It is shown in this work that the physical nature of the longevity of light actinides under extreme conditions in a range of nonequilibrium states of t ∼ 10"–"6–10"–"1"0 s is determined by the time needed for the formation of a critical concentration of a cascade of failure centers, which changes connectivity of the body. These centers form a percolation cluster. The longevity is composed of waiting time t_w for the appearance of failure centers and clusterization time t_c of cascade of failure centers, when connectivity in the system of failure centers and the percolation cluster arise. A unique mechanism of the dynamic failure process, a unique order parameter, and an equal dimensionality of the space in which the process occurs determine the physical nature of the longevity of metals, including fissionable materials
[en] The International Atomic Energy Agency (IAEA) must ensure the peaceful use of all nuclear materials with a budget that has been compared in size to that of the police department in Vienna. This includes, for example, coverage of nearly 1,300 nuclear facilities spread around the globe and verification of over 200,000 significant quantities of nuclear material. The amount of information the IAEA collects is on an upward trajectory, and data overload is poised to be an ever-increasing stress on the IAEA’s ability to perform its safeguards mission. Los Alamos National Laboratory (LANL) has been investing over the past several years in experimental studies within a number of its unique facilities to characterize activity patterns and operational modes using automated methods for disparate data integration. Building on the success of these preliminary studies, there is currently an effort funded by LANL’s Laboratory-Directed Research and Development (LDRD) program to develop a testbed at one of the Laboratory’s radiological facilities for advancing this work, specifically aimed at safeguards-relevant data streams. The overarching goal of this work is to develop and experimentally validate methods to improve the efficiency and effectiveness of safeguards verification at nuclear facilities, which will allow the IAEA to better utilize the data it is already collecting. This paper describes work that has been done to date as well as implications for future areas of research. (author)
[en] Highlights: • Critical mass of Pu-239 is calculated. • MCNP is utilized to demonstrate that sphere is the optimal shape to reach criticality. • The critical masses from five polyhedrons and sphere are compared. - Abstract: In introductory courses for nuclear engineering, the concept of critical dimension and critical mass are introduced. Students are usually taught that the geometrical shape which needs the smallest amount of fissionable material to reach criticality is a sphere. In this paper, this concept is explored further using MCNP code. Five different regular polyhedrons (i.e., the Platonic solids) and a sphere have been examined to demonstrate that sphere is indeed the optimal geometrical shape to minimize the critical mass. For illustration purpose, the fissile isotope used in this study is 239Pu, with a nominal density of 19.8 g/cm3