Author: Timothy Mason Ault
Publisher:
ISBN:
Category : Nuclear fuels
Languages : en
Pages :
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Book Description
The environment, health, and safety properties of thorium-uranium-based ( thorium ) fuel cycles are estimated and compared to those of analogous uranium-plutonium-based ( uranium ) fuel cycle options using a structured assessment methodology. Thorium resource recovery as a measure of environmental sustainability is described in terms of resource availability, chemical processing requirements, and radiological impacts. Results indicate that near-term thorium recovery will occur as a by-product of mining for other commodities, particularly titanium, and could satisfy even the most intensive nuclear demand for thorium six times over. Chemical flowsheet and radiological process analyses show greater, but not insurmountable, impacts for thorium recovery compared to uranium recovery. Four fuel cycle options are compared: a modified-open uranium option, a modified-open thorium option, a closed uranium option, and a closed thorium option. The options are compared on the bases of resource sustainability, waste management (both low- and high-level waste), and occupational radiological impacts. At steady-state, occupational doses somewhat favor the closed thorium option while low-level waste slightly favors the closed uranium option, although uncertainties are significant. The high-level waste properties favor the closed options (especially with thorium), but uranium options produce slightly less I-129 and may present less risk in a repository environment. Resource requirements are much lower for the closed options and are relatively similar between thorium and uranium. In addition to the steady-state results, several potential transition pathways are considered for closed uranium and thorium end-states. For dose, low-level waste, and fission products contributing to repository risk, the differences among transition impacts largely reflect the steady-state differences. However, the high-level waste properties show the opposite result in transition (strongly favoring uranium, whereas thorium is strongly favored at steady-state), since used present-day uranium fuel is disposed in transitions to purely thorium-based options. Resource consumption was the only metric was strongly influenced by specific transition pathways, favoring the most rapid transitions regardless of whether thorium or uranium was used.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
This report compares the radiological impacts of a fuel cycle in which only uranium is recycled, as presented in the Final Generic Environmental Statement on the Use of Recycle Plutonium in Mixed Oxide Fuel in Light Water Cooled Reactors (GESMO), with those of the light-water breeder reactor (LWBR) thorium/uranium fuel cycle in the Final Environmental Statement, Light Water Breeder Reactor Program. The significant offsite radiological impacts from routine operation of the fuel cycles result from the mining and milling of thorium and uranium ores, reprocessing spent fuel, and reactor operations. The major difference between the impacts from the two fuel cycles is the larger dose commitments associated with current uranium mining and milling operations as compared to thorium mining and milling. Estimated dose commitments from the reprocessing of either fuel type are small and show only moderate variations for specific doses. No significant differences in environmental radiological impact are anticipated for reactors using either of the fuel cycles. Radiological impacts associated with routine releases from the operation of either the thorium or uranium fuel cycles can be held to acceptably low levels by existing regulations.
Author: Donald W. Kuhn
Publisher:
ISBN:
Category : Thorium
Languages : en
Pages : 42
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Thorium has been widely considered an alternative to uranium fuel because of its relatively large natural abundance and its ability to breed fissile fuel (233U) from natural thorium (232Th). Possible scenarios for using thorium in the nuclear fuel cycle include use in different nuclear reactor types (light water, high temperature gas cooled, fast spectrum sodium, molten salt, etc.), advanced accelerator-driven systems, or even fission-fusion hybrid systems. The most likely near-term application of thorium in the United States is in currently operating light water reactors (LWRs). This use is primarily based on concepts that mix thorium with uranium (UO2 + ThO2), add fertile thorium (ThO2) fuel pins to LWR fuel assemblies, or use mixed plutonium and thorium (PuO2 + ThO2) fuel assemblies. The addition of thorium to currently operating LWRs would result in a number of different phenomenological impacts on the nuclear fuel. Thorium and its irradiation products have nuclear characteristics that are different from those of uranium. In addition, ThO2, alone or mixed with UO2 fuel, leads to different chemical and physical properties of the fuel. These aspects are key to reactor safety-related issues. The primary objectives of this report are to summarize historical, current, and proposed uses of thorium in nuclear reactors; provide some important properties of thorium fuel; perform qualitative and quantitative evaluations of both in-reactor and out-of-reactor safety issues and requirements specific to a thorium-based fuel cycle for current LWR reactor designs; and identify key knowledge gaps and technical issues that need to be addressed for the licensing of thorium LWR fuel in the United States.
Author: International Atomic Energy Agency
Publisher: IAEA Tecdoc
ISBN: 9789201007155
Category : Science
Languages : en
Pages : 0
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Book Description
This publication is the outcome of an IAEA coordinated research project on near term and promising long term options for deployment of thorium based nuclear energy. It is based on the compilation and analysis of available results on thorium tristructural isotropic (TRISO) coated particle fuel performance in manufacturing during irradiation and accident condition heating tests. As a result, the project participants concluded that the performance statistics for the high enriched thoria urania TRISO fuel system are in perfect concert with those state of the art requirements for present day high temperature reactor concepts.
Author: Raymond G. Wymer
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 870
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
A renewed interest in thorium-based fuels has arisen lately based on the need for proliferation resistance, longer fuel cycles, higher burnup and improved wasteform characteristics. Recent studies have been directed toward homogeneously mixed, heterogeneously mixed, and seed-and-blanket thorium-uranium fuel cycles that rely on "in situ" use of the bred-in U-233. However, due to the higher initial enrichment required to achieve acceptable burnups, these fuels are encountering economic constraints. Thorium can nevertheless play a large role in the nuclear fuel cycle; particularly in the reduction of plutonium. While uranium-based mixedoxide (MOX) fuel will decrease the amount of plutonium, the reduction is limited due to the breeding of more plutonium (and higher actinides) from the U-238. Here we present calculational results and a comparison of the potential burnup of a thorium-based and uranium-based mixed oxide fuel in a light water reactor (LWR). Although the uranium-based fuels outperformed the thorium-based fuels in achievable burnup, a depletion comparison of the initially charged plutonium (both reactor and weapons grade) showed that the thorium-based fuels outperformed the uranium-based fuels by more that a factor of 2; where more than 70% of the total plutonium in the thorium-based fuel is consumed during the cycle. This is significant considering that the achievable burnup of the thorium-based fuels were 1.4 to 4.6 times less than the uranium-based fuels. Furthermore, use of a thorium-based fuel could also be used as a strategy for reducing the amount of long-lived nuclides (including the minor actinides), and thus the radiotoxicity in spent nuclear fuel. Although the breeding of U-233 is a concern, the presence of U-232 and its daughter products can aid in making this fuel self-protecting, and/or enough U-238 can be added to denature the fissile uranium. From these calculations, it appears that thorium-based fuel for plutonium incineration is superior as compared to uranium-based fuel, and should be considered as an alternative to traditional MOX in both current and future reactor designs.
Author: Allan S. Krass
Publisher: Routledge
ISBN: 100020054X
Category : Political Science
Languages : en
Pages : 325
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Book Description
Originally published in 1983, this book presents both the technical and political information necessary to evaluate the emerging threat to world security posed by recent advances in uranium enrichment technology. Uranium enrichment has played a relatively quiet but important role in the history of efforts by a number of nations to acquire nuclear weapons and by a number of others to prevent the proliferation of nuclear weapons. For many years the uranium enrichment industry was dominated by a single method, gaseous diffusion, which was technically complex, extremely capital-intensive, and highly inefficient in its use of energy. As long as this remained true, only the richest and most technically advanced nations could afford to pursue the enrichment route to weapon acquisition. But during the 1970s this situation changed dramatically. Several new and far more accessible enrichment techniques were developed, stimulated largely by the anticipation of a rapidly growing demand for enrichment services by the world-wide nuclear power industry. This proliferation of new techniques, coupled with the subsequent contraction of the commercial market for enriched uranium, has created a situation in which uranium enrichment technology might well become the most important contributor to further nuclear weapon proliferation. Some of the issues addressed in this book are: A technical analysis of the most important enrichment techniques in a form that is relevant to analysis of proliferation risks; A detailed projection of the world demand for uranium enrichment services; A summary and critique of present institutional non-proliferation arrangements in the world enrichment industry, and An identification of the states most likely to pursue the enrichment route to acquisition of nuclear weapons.
Author:
Publisher:
ISBN: 9780982800843
Category : Energy policy
Languages : en
Pages : 237
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Book Description
"In this analysis we have presented a method that provides insight into future fuel cycle alternatives by clarifying the complexity of choosing an appropriate fuel cycle in the context of the distribution of burdens and benefits between generations. The current nuclear power deployment practices, together with three future fuel cycles were assessed."--Page 227.
Author: Anthony V. Nero
Publisher: Univ of California Press
ISBN: 9780520036611
Category : Technology & Engineering
Languages : en
Pages : 312
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Book Description
Provides a detailed introduction to nuclear reactors, describing the four commercial types and discussing uranium resources, fuel cycles, advanced reactor systems, and issues and problems concerning the use of nuclear power
