This publication presents the material properties of all unirradiated Uranium-Molybdenum (U-Mo) fuel constituents that are essential for fuel designers and reactor operators to evaluate the fuel's performance and safety for research reactors. Many significant advances in the understanding and development of low enriched uranium U-Mo fuels have been made since 2004, stimulated by the need to understand irradiation behavior and early fuel failures during testing. The publication presents a comprehensive overview of mechanical and physical property data from U-Mo fuel research
This book is the product of a congressionally mandated study to examine the feasibility of eliminating the use of highly enriched uranium (HEU2) in reactor fuel, reactor targets, and medical isotope production facilities. The book focuses primarily on the use of HEU for the production of the medical isotope molybdenum-99 (Mo-99), whose decay product, technetium-99m3 (Tc-99m), is used in the majority of medical diagnostic imaging procedures in the United States, and secondarily on the use of HEU for research and test reactor fuel. The supply of Mo-99 in the U.S. is likely to be unreliable until newer production sources come online. The reliability of the current supply system is an important medical isotope concern; this book concludes that achieving a cost difference of less than 10 percent in facilities that will need to convert from HEU- to LEU-based Mo-99 production is much less important than is reliability of supply.
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Over the past decade significant progress has been achieved in the development of waste characterization and control procedures and equipment as a direct response to ever-increasing requirements for quality and reliability of information on waste characteristics. Failure in control procedures at any step can have important, adverse consequences and may result in producing waste packages which are not compliant with the waste acceptance criteria for disposal, thereby adversely impacting the repository. The information and guidance included in this publication corresponds to recent achievements and reflects the optimum approaches, thereby reducing the potential for error and enhancing the quality of the end product. -- Publisher's description.
This publication reports on the results of a coordinated research project on advances in high temperature gas cooled reactor (HTGR) fuel technology and describes the findings of research activities on coated particle developments. These comprise two specific benchmark exercises with the application of HTGR fuel performance and fission product release codes, which helped compare the quality and validity of the computer models against experimental data. The project participants also examined techniques for fuel characterization and advanced quality assessment/quality control. The key exercise included a round-robin experimental study on the measurements of fuel kernel and particle coating properties of recent Korean, South African and US coated particle productions applying the respective qualification measures of each participating Member State. The summary report documents the results and conclusions achieved by the project and underlines the added value to contemporary knowledge on HTGR fuel.
Research reactor fuel technology continues to evolve, driven in part by international efforts to develop high density fuels to enable the conversion of more reactors from highly enriched uranium (HEU) to low enriched uranium (LEU) fuels. These high density fuels may offer economic benefits for research reactors, despite being more expensive initially, because they offer the prospect of higher per-assembly burnup, thus reducing the number of assemblies that must be procured, and more flexibility in terms of spent fuel management compared to the currently qualified and commercially available LEU silicide fuels. Additionally, these new fuels may offer better performance characteristics. This publication provides a preliminary evaluation of the impacts on research reactor performance and fuel costs from using high density fuel. Several case studies are presented and compared to illustrate these impacts.
The implementation of advanced nuclear systems requires that new technologies associated with the back end of the fuel cycle are developed. The separation of minor actinides from other fuel components is one of the advanced concepts being studied to help close the nuclear fuel cycle and to improve the long-term effects on the performance of geological repositories. Separating spent fuel elements and subsequently converting them through transmutation into short-lived nuclides should considerably reduce the longterm risks associated with nuclear power generation.
By the second half of the twentieth century, a new branch of materials science had come into being — crystalline materials research. Its appearance is linked to the emergence of advanced technologies primarily based on single crystals (bulk crystals and films). At the turn of the last century, the impending onset of the “ceramic era” was forecasted. It was believed that ceramics would play a role comparable to that of the Stone or Bronze Ages in the history of civilization. Naturally, such an assumption was hypothetical, but it showed that ceramic materials had evoked keen interest among researchers. Although sapphire traditionally has been considered a gem, it has developed into a material typical of the “ceramic era.” Widening the field of sapphire application necessitated essential improvement of its homogeneity and working characteristics and extension of the range of sapphire products, especially those with stipulated properties including a preset structural defect distribution. In the early 1980s, successful attainment of crystals with predetermined char- teristics was attributed to proper choice of the growth method. At present, in view of the fact that the requirements for crystalline products have become more str- gent, such an approach tends to be insufficient. It is clear that one must take into account the physical–chemical processes that take place during the formation of the real crystal structure, i.e., the growth mechanisms and the nature and causes of crystal imperfections.
