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A Multi-Modular Neutronically Coupled Power Generation SystemPatel, Vishal 2012 May 1900 (has links)
The High Temperature Integrated Multi-Modular Thermal Reactor is a small modular reactor that uses an enhanced conductivity BeO-UO2 fuel with supercritical CO2 coolant to drive turbo-machinery in a direct Brayton cycle. The core consists of several self-contained pressurized modules, each containing fuel elements in pressurized channels surrounded by a graphite moderator, and Brayton cycle turbo-machinery. Each module is subcritical by itself, and when several modules are brought into proximity of one another, a single critical core is formed.
The multi-modular approach and use of BeO-UO2 fuel with graphite moderator and supercritical CO2 coolant leads to an inherently safe system capable of high efficiency operation. The pressure channel design and multi-modular approach eliminates engineering challenges associated with large pressure vessels. The subcriticality of the modules ensures inherent safety during construction, transportation, and after decommissioning.
Serpent, a continuous-energy Monte-Carlo reactor physics burnup calculation code, was used to develop a critical configuration of the subcritical modules using UO2 fuel enriched with 5 wt% 235U with a 5 wt% BeO additive. The core lifetime was found to be 14.6 years operating at 10 MWth, though the U enrichment and power can be altered to achieve desired core lifetimes. Negative fuel and moderator temperature coefficients of reactivity were found that could maintain safety during operation.
The multi-modular design was found to be beneficial compared to a core with all fuel elements in one module. Batch battery type refueling was found to be beneficial and the feasibility of controlling the reactor was demonstrated through the use of control shells that surround each module.
The HT-IMMTR design is an inherently safe, highly efficient, economically competitive, and most important, feasible reactor design that takes advantage of proven technologies to facilitate the demonstration of a successful commercial deployment.
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Developmental Analysis and Design of a Scaled-down Test Facility for a VHTR Air-ingress AccidentArcilesi, David J., Jr. 26 June 2012 (has links)
No description available.
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The influence of thorium on the temperature reactivity coefficient in a 400 MWth pebble bed high temperature plutonium incinerator reactor / Guy Anthony RichardsRichards, Guy Anthony January 2012 (has links)
Social and environmental justice for a growing and developing global population requires
significant increases in energy use. A possible means of contributing to this energy increase
is to incinerate plutonium from spent fuel of pressurised light water reactors (Pu(PWR)) in
high-temperature reactors such as the Pebble Bed Modular Reactor Demonstration Power
Plant 400 MWth (PBMR-DPP-400). Previous studies showed that at low temperatures a
3 g Pu(PWR) loading per fuel sphere or less had a positive uniform temperature reactivity
coefficient (UTC) in a PBMR DPP-400. The licensing of this fuel design is consequently
unlikely. In the present study it was shown by diffusion simulations of the neutronics, using
VSOP-99/05, that there is a fuel design containing thorium and plutonium that achieves a
negative maximum UTC. Further, a fuel design containing 12 g Pu(PWR) loading per fuel
sphere achieved a negative maximum UTC as well as the other PBMR (Ltd.) safety limits of
maximum power per fuel sphere, fast fluence and maximum temperatures. It is proposed
that the low average thermal neutron flux, caused by reduced moderation and increased
absorption of thermal neutrons due to the higher plutonium loading, is responsible for these
effects. However, to fully understand the mechanisms involved a detailed quantitative
analysis of the roll of each factor is required. A 12 g Pu(PWR) loading per fuel sphere
analysis shows a burn-up of 180.7 GWd/tHM which is approximately double the proposed
PBMR (Ltd.) low enriched uranium fuel burn-up. The spent fuel has only a decrease of
24.5 % in the Pu content which is sub-optimal with respect to proliferation and waste
disposal objectives. Incinerating Pu(PWR) in the PBMR-DPP 400 MWth is potentially
licensable and economically feasible and should be considered for application by industry. / MIng (Nuclear Engineering), North-West University, Potchefstroom Campus, 2012
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The influence of thorium on the temperature reactivity coefficient in a 400 MWth pebble bed high temperature plutonium incinerator reactor / Guy Anthony RichardsRichards, Guy Anthony January 2012 (has links)
Social and environmental justice for a growing and developing global population requires
significant increases in energy use. A possible means of contributing to this energy increase
is to incinerate plutonium from spent fuel of pressurised light water reactors (Pu(PWR)) in
high-temperature reactors such as the Pebble Bed Modular Reactor Demonstration Power
Plant 400 MWth (PBMR-DPP-400). Previous studies showed that at low temperatures a
3 g Pu(PWR) loading per fuel sphere or less had a positive uniform temperature reactivity
coefficient (UTC) in a PBMR DPP-400. The licensing of this fuel design is consequently
unlikely. In the present study it was shown by diffusion simulations of the neutronics, using
VSOP-99/05, that there is a fuel design containing thorium and plutonium that achieves a
negative maximum UTC. Further, a fuel design containing 12 g Pu(PWR) loading per fuel
sphere achieved a negative maximum UTC as well as the other PBMR (Ltd.) safety limits of
maximum power per fuel sphere, fast fluence and maximum temperatures. It is proposed
that the low average thermal neutron flux, caused by reduced moderation and increased
absorption of thermal neutrons due to the higher plutonium loading, is responsible for these
effects. However, to fully understand the mechanisms involved a detailed quantitative
analysis of the roll of each factor is required. A 12 g Pu(PWR) loading per fuel sphere
analysis shows a burn-up of 180.7 GWd/tHM which is approximately double the proposed
PBMR (Ltd.) low enriched uranium fuel burn-up. The spent fuel has only a decrease of
24.5 % in the Pu content which is sub-optimal with respect to proliferation and waste
disposal objectives. Incinerating Pu(PWR) in the PBMR-DPP 400 MWth is potentially
licensable and economically feasible and should be considered for application by industry. / MIng (Nuclear Engineering), North-West University, Potchefstroom Campus, 2012
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Deep burn strategy for the optimized incineration of reactor waste plutonium in pebble bed high temperature gas–cooled reactors / Serfontein D.E.Serfontein, Dawid Eduard. January 1900 (has links)
In this thesis advanced fuel cycles for the incineration, i.e. deep–burn, of weapons–grade
plutonium, reactor–grade plutonium from pressurised light water reactors and reactor–grade
plutonium + the associated Minor Actinides in the 400 MWth Pebble Bed Modular Reactor
Demonstration Power Plant was simulated with the VSOP 99/05 diffusion code. These
results were also compared to the standard 9 g/fuel sphere U/Pu 9.6% enriched uranium
fuel cycle. The addition of the Minor Actinides to the reactor–grade plutonium caused an
unacceptable decrease in the burn–up and thus an unacceptable increase in the heavy metal
(HM) content in the spent fuel, which is intended for direct disposal in a deep geological
repository, without chemical reprocessing. All the Pu fuel cycles failed the adopted safety
limits in that either the maximum fuel temperature of 1130°C, during normal operation, or the
maximum power of 4.5 kW/sphere was exceeded. All the Pu cycles also produced positive
Uniform Temperature Reactivity Coefficients, i.e. the coefficient where the temperature of the
fuel and the graphite moderator in the fuel spheres are varied together. these positive
temperature coefficients were experienced at low temperatures, typically below 700°C. This
was due to the influence of the thermal fission resonance of 241Pu. The safety performance of
the weapons–grade plutonium was the worst. The safety performance of the reactor–grade
plutonium also deteriorated when the heavy metal loading was reduced from 3 g/sphere to 2
g or 1 g.
In view of these safety problems, these Pu fuel cycles were judged to be not licensable in the
PBMR DPP–400 reactor. Therefore a redesign of the fuel cycle for reactor–grade plutonium,
the power conversion system and the reactor geometry was proposed in order to solve these
problems. The main elements of these proposals are:
v
1. The use of 3 g reactor–grade plutonium fuel spheres should be the point of departure.
232Th will then be added in order to restore negative Uniform Temperature Reactivity
Coefficients.
2. The introduction of neutron poisons into the reflectors, in order to suppress the power
density peaks and thus the temperature peaks.
3. In order to counter the reduction in burn–up by this introduction of neutron poisons, a
thinning of the central reflector was proposed. / Thesis (PhD (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2012.
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Deep burn strategy for the optimized incineration of reactor waste plutonium in pebble bed high temperature gas–cooled reactors / Serfontein D.E.Serfontein, Dawid Eduard. January 1900 (has links)
In this thesis advanced fuel cycles for the incineration, i.e. deep–burn, of weapons–grade
plutonium, reactor–grade plutonium from pressurised light water reactors and reactor–grade
plutonium + the associated Minor Actinides in the 400 MWth Pebble Bed Modular Reactor
Demonstration Power Plant was simulated with the VSOP 99/05 diffusion code. These
results were also compared to the standard 9 g/fuel sphere U/Pu 9.6% enriched uranium
fuel cycle. The addition of the Minor Actinides to the reactor–grade plutonium caused an
unacceptable decrease in the burn–up and thus an unacceptable increase in the heavy metal
(HM) content in the spent fuel, which is intended for direct disposal in a deep geological
repository, without chemical reprocessing. All the Pu fuel cycles failed the adopted safety
limits in that either the maximum fuel temperature of 1130°C, during normal operation, or the
maximum power of 4.5 kW/sphere was exceeded. All the Pu cycles also produced positive
Uniform Temperature Reactivity Coefficients, i.e. the coefficient where the temperature of the
fuel and the graphite moderator in the fuel spheres are varied together. these positive
temperature coefficients were experienced at low temperatures, typically below 700°C. This
was due to the influence of the thermal fission resonance of 241Pu. The safety performance of
the weapons–grade plutonium was the worst. The safety performance of the reactor–grade
plutonium also deteriorated when the heavy metal loading was reduced from 3 g/sphere to 2
g or 1 g.
In view of these safety problems, these Pu fuel cycles were judged to be not licensable in the
PBMR DPP–400 reactor. Therefore a redesign of the fuel cycle for reactor–grade plutonium,
the power conversion system and the reactor geometry was proposed in order to solve these
problems. The main elements of these proposals are:
v
1. The use of 3 g reactor–grade plutonium fuel spheres should be the point of departure.
232Th will then be added in order to restore negative Uniform Temperature Reactivity
Coefficients.
2. The introduction of neutron poisons into the reflectors, in order to suppress the power
density peaks and thus the temperature peaks.
3. In order to counter the reduction in burn–up by this introduction of neutron poisons, a
thinning of the central reflector was proposed. / Thesis (PhD (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2012.
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