Assessment of the Implications of Conversion of University Research and Training Reactors to Low Enrichment Uranium Fuel PDF Download

Author: LEU Study Group (U.S.)
Publisher:
ISBN:
Category : Nuclear fuels
Languages : en
Pages : 161

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Author: United States. Congress. House. Committee on Science and Technology. Subcommittee on Energy Development and Applications
Publisher:
ISBN:
Category : Nuclear engineering
Languages : en
Pages : 2246

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Author: Russian Academy of Sciences
Publisher: National Academies Press
ISBN: 0309253209
Category : Science
Languages : en
Pages : 126

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Highly enriched uranium (HEU) is used for two major civilian purposes: as fuel for research reactors and as targets for medical isotope production. This material can be dangerous in the wrong hands. Stolen or diverted HEU can be used-in conjunction with some knowledge of physics-to build nuclear explosive devices. Thus, the continued civilian use of HEU is of concern particularly because this material may not be uniformly well-protected. To address these concerns, the National Research Council (NRC) of the U.S. National Academies and the Russian Academy of Sciences (RAS) held a joint symposium on June 8-10, 2011. Progress, Challenges, and Opportunities for Converting U.S. and Russian Research Reactors summarizes the proceedings of this joint symposium. This report addresses: (1) recent progress on conversion of research reactors, with a focus on U.S.- and R.F.-origin reactors; (2) lessons learned for overcoming conversion challenges, increasing the effectiveness of research reactor use, and enabling new reactor missions; (3) future research reactor conversion plans, challenges, and opportunities; and (4) actions that could be taken by U.S. and Russian organizations to promote conversion. The agenda for the symposium is provided in Appendix A, biographical sketches of the committee members are provided in Appendix B, and the report concludes with the statement of task in Appendix C.

Author: United States. Congress. House. Committee on Science and Technology. Subcommittee on Energy Development and Applications
Publisher:
ISBN:
Category : Nuclear engineering
Languages : en
Pages : 1968

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Author: National Academies of Sciences, Engineering, and Medicine
Publisher: National Academies Press
ISBN: 0309379210
Category : Science
Languages : en
Pages : 205

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The continued presence of highly enriched uranium (HEU) in civilian installations such as research reactors poses a threat to national and international security. Minimization, and ultimately elimination, of HEU in civilian research reactors worldwide has been a goal of U.S. policy and programs since 1978. Today, 74 civilian research reactors around the world, including 8 in the United States, use or are planning to use HEU fuel. Since the last National Academies of Sciences, Engineering, and Medicine report on this topic in 2009, 28 reactors have been either shut down or converted from HEU to low enriched uranium fuel. Despite this progress, the large number of remaining HEU-fueled reactors demonstrates that an HEU minimization program continues to be needed on a worldwide scale. Reducing the Use of Highly Enriched Uranium in Civilian Research Reactors assesses the status of and progress toward eliminating the worldwide use of HEU fuel in civilian research and test reactors.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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The highly-enriched uranium (HEU) fuel used in twenty United States university reactors can be viewed as contributing to the risk of theft or diversion of weapons-useable material. The US Nuclear Regulatory Commission has issued a policy statement expressing its concern and has published a proposed rule on limiting the use of HEU in NRC-licensed non-power reactors. The fuel options, functional impacts, licensing, and scheduling of conversion and standardization of these reactor fuels to use of low-enrichment uranium (LEU) have been assessed. The university reactors span a wide range in form and function, from medium-power intense neutron sources where HEU fuel may be required, to low-power training and research facilities where HEU fuel is unnecessary. Conversion provides an opportunity to standardize university reactor fuels and improve reactor utilization in some cases. The entire program is estimated to cost about $10 million and to last about five years. Planning for conversion and standardization is facilitated by the US Department of Energy. 20 refs., 1 tab.

Author: Dakota J. Allen
Publisher:
ISBN:
Category :
Languages : en
Pages : 109

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In the framework of non-proliferation policy, the Massachusetts Institute of Technology Reactor (MITR) is planning to convert from highly enriched uranium (HEU) to low enriched uranium (LEU) fuel. A new type of high-density LEU fuel based on a monolithic U-10Mo alloy is being qualified to allow the conversion of all remaining U.S. high performance research reactors including the MITR. The purpose of this study is to understand the impact of proposed MITR LEU "FYT" fuel element fabrication tolerances on the operation and safety limits of the MITR. Therefore, the effects of fabrication specification parameters on all levels of the core, ranging from full-core alterations to individual spots on the fuel plates were analyzed. Evaluations at the design tolerances, and beyond, were conducted through neutronics and thermal hydraulics calculations. The first step was analyzing the separate effects that parameters, including enrichment, fuel mass loading, fuel plate thickness, and impurities, have on the reactor physics of the core. These analyses were used to develop curve fits to predict the effect of these parameters on the excess reactivity of fresh fuel inserted into the LEU core. These models could then be used to estimate the effect on fuel cycle length to ensure the tolerances would not cause significant changes to the operating cycle of MITR. These analyses estimated the margin to criticality present in the core and ensured that the reactivity shutdown margin (SDM) was not violated. Other parameters such as coolant channel gap and local fuel homogeneity cause primarily local impacts including the power distribution within the fuel element, and related impacts to thermal hydraulic margins. This modeling was necessary to ensure that these parameters would not cause the margin to MITR's thermal hydraulic safety limit, the onset of nucleate boiling (ONB), to be violated. The final step was a covariance analysis of the combined effects at a full-core and element level. This combined effect analysis assured that the core would maintain proper safety and operational margins with a realistic distribution of off-nominal parameters. Given the comprehensive analysis performed, the current design fabrication tolerances were determined to provide acceptable fuel cycle length and safety margins consistent with the MITR LEU preliminary safety analysis report, and a basis for updating these tolerances during planned manufacturing-scale plate fabrication demonstrations has been established.

Author: International Atomic Energy Agency
Publisher:
ISBN: 9789201018182
Category : Technology & Engineering
Languages : en
Pages : 0

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This publication was developed based on the results of an IAEA coordinated research project (CRP) and will serve as a reference to those potentially involved in conversion of research reactors from high enriched uranium (HEU) to low enriched uranium (LEU). The publication contains comprehensive design and safety analyses for the conversion of miniature neutron source reactors (MNSRs) and includes analyses that were performed by MNSR operating organizations participating in the CRP using data specific to their MNSR. The outcome of this CRP can therefore be used to provide best practice guidelines in preparation for conversion of research reactors by individual research reactor operating organizations, and as a procedural and methodological reference for regulatory bodies and other stakeholders involved in the conversion of research reactors.

Author: John E. Stoddard
Publisher:
ISBN:
Category : Nuclear fuels
Languages : en
Pages : 320

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Author: Leo M. Bobek
Publisher:
ISBN:
Category :
Languages : en
Pages : 5

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The process for converting the University of Massachusetts Lowell Research Reactor (UMLRR) from high-enrichment uranium (HEU) fuel to low-enrichment uranium (LEU) fuel began in 1988. Several years of design reviews, computational modeling, and thermal hydraulic analyses resulted in a preliminary reference core design and configuration based on 20 standard, MTR-type, flat-plate, 19.75% enriched, uranium silicide (u3Si2) fuel elements. A final safety analysis for the fuel conversion was submitted to the Nuclear Regulatory Commission (NRC) in 1993. The NRC made two additional requests for additional information and supplements were submitted in 1994 and 1997. The new UMLRR Reactor Supervisor initiated an effort to change the LEU reference core configuration to eliminate a complicated control rod modification needed for the smaller core.