Organizational Unit:

Fusion Research Center

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https://hdl.handle.net/1853/70733

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Organizational Unit

George W. Woodruff School of Mechanical Engineering

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https://finding-aids.library.gatech.edu/agents/corporate_entities/1150

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Publication Search Results

Now showing 1 - 10 of 31

A sub-critical, He-cooled, fast reactor for the transmutation of spent nuclear fuel (DOE Grant ER54350)

(Georgia Institute of Technology, 2005-10) Stacey, Weston M.

A design concept and supporting analysis are presented for a He-cooled, fast reactor for the transmutation of spent nuclear fuel. Coated TRU fuel particles in a SiC matrix are used. The reactor operates sub-critical (k ≤ 0.95), with a tokamak D-T fusion neutron source, to achieve > 90% TRU burnup in repeated 5-batch fuel cycles, fissions 1.1 MT/FPY, and produces 700 MWe net electrical power. The reactor design is based on nuclear, fuels, materials and separations technologies being developed in the GEN-IV, NGNP and AFCI Programs and similar international programs, and the fusion neutron source is based on the physics and technology supporting the ITER design.
Calculation of toroidal rotation profiles in DIII-D using neoclassical viscosity (DoE Grant ER54538)

(Georgia Institute of Technology, 2005-10) Stacey, Weston M. ; Johnson, R. W. ; Mandrekas, John

Momentum and particle balance and neoclassical viscosity were applied to calculate the radial profile of toroidal rotation in several DIII-D [J. Luxon, Nucl. Fusion, 42, 614 (2002)] discharges in a variety of energy confinement regimes (Low-mode, Low-mode with Internal Transport Barrier, Highmode, and High-mode with Quiescent Double Barrier). Calculated toroidal rotation velocities were found to over-predict measured values most in the center—by factors of 1.5 to 3--with the over-prediction generally decreasing with increasing radius, for the L, H and ITB mode shots, but the single impurity species approximation could not properly model the multiple Ni and Cu charge states in the QDB shots.
Rotation velocities and radial electric field in the plasma edge

(Georgia Institute of Technology, 2005-10) Stacey, Weston M.

The toroidal and poloidal rotation and related radial electric field observed in the edge (and core) of tokamak plasmas are of interest for several reasons, not least of which is what they reveal about radial momentum transport, but also because of their apparent role in the L-H transition and the edge pedestal. It was recently shown that if the heat transport coefficients and rotation velocities are taken from experiment, then the particle, momentum and energy balance equations and the conductive heat conduction relation are sufficient to determine the observed edge pedestal profile structure in the density and temperature profiles in several DIII-D discharges. Thus, it would seem that understanding the edge pedestal structure is a matter of understanding the edge rotation profiles. We present a practical computational model for the rotation and the radial electric field profiles in the plasma edge that is based on momentum and particle balance, includes both convective (including anomalous) and neoclassical gyroviscous momentum transport, and incorporates atomic physics effects associated with recycling neutrals.
Investigation of edge pedestal structure in DIII-D (DoE Grant ER54538)

(Georgia Institute of Technology, 2005-10) Stacey, Weston M. ; Groebner, Rich J.

A calculation based on the requirements of particle, momentum and energy conservation, conductive heat transport and atomic physics resulting from a recycling and fueling neutral influx was employed to investigate the experimental density, temperature, rotation velocities and radial electric field profiles in the edge of three DIII-D [J. Luxon, Nucl. Fusion, 42, 614 (2002)] high-mode plasmas. The calculation indicated that the cause of the pedestal structure in the density was a momentum balance requirement for a steep negative pressure gradient to balance the forces associated with an edge peaking in the inward pinch velocity (caused by the observed edge peaking in the radial electric field and rotation velocity profiles) and, to a lesser extent, in the outward radial particle flux (caused by the ionization of recycling neutrals). Thermal and angular momentum transport coefficients were inferred from experiment and compared with theoretical predictions, indicating that thermal transport coefficients were of the magnitude predicted by neoclassical and ion-temperature-gradient theories (ions) and electrontemperature- gradient theory (electrons), but that neoclassical gyroviscous theory plus atomic physics effects combined were not sufficient to explain the inferred angular momentum transfer rate throughout the edge region.
2005 Annual Report Fusion Research Center Georgia Institute of Technology [Title page and table of contents]

(Georgia Institute of Technology, 2005-10) Stacey, Weston M.
Investigation of the cause of the High-to-Low mode confinement transition following MARFE formation in DIII-D (DoE Grant ER54538)

(Georgia Institute of Technology, 2005-10) Stacey, Weston M. ; Friis, Zachary Ward ; Petrie, Thomas W. ; Leonard, Anthony W.

The common observation that the onset of a core MARFE (Multifaceted Asymmetric Radiation From Edge) is followed immediately by a H-L (High-to-Low) confinement mode transition in DIII-D [J. Luxon, Nucl. Fusion, 42, 614 (2002)] was investigated by comparing a theoretical prediction of the threshold non-radiative power across the separatrix needed to maintain H-mode with an experimental determination of the non-radiative power flowing across the separatrix. It was found that in three shots with continuous gas fueling the increased neutral influx associated with the MARFE formation caused a sharp increase in the predicted threshold non-radiative power crossing the separatrix that was required for the plasma to remain in H-mode to a value comparable to the experimental power crossing the separatrix.
Improvements in the 2D TEP Neutral Particle Transport Calculation in Edge Plasmas (DoE Grant ER54538)

(Georgia Institute of Technology, 2005-10) Zhang, Dingkang ; Mandrekas, John ; Stacey, Weston M.

Extensions of the 2D Transmission and Escape Probability neutral particle transport method in treating the spatial non-uniformity of collision sources and neutral energy effects are presented. These extensions have been tested by benchmarks against Monte Carlo calculations for specially designed models and for realistic DIII-D discharges. The comparisons indicate these extensions improve accuracy of the TEP method.
Application of a particle, momentum and energy balance model to calculate the structure of the edge pedestal in DIII-D

(Georgia Institute of Technology, 2005-04) Stacey, Weston M. ; Groebner, Rich J.

A calculation of edge density and temperature profiles based on "classical" physics - particle, momentum and energy balance, heat conduction closure relations, neutral particle transport - yielded a pedestal structure that is qualitatively and quantitatively similar to that found experimentally in five DIII-D [J. Luxon, Nucl. Fusion,42, 614 (2002)] discharges, when experimental radial electric field and rotation profiles and experimentally inferred heat transport coefficients were used. The principal cause of the density pedestal was a peaking of the inward pinch velocity just inside the separatrix caused by the negative well in the experimental electric field, and the secondary cause was a peaking of the radial particle flux caused by the ionization of incoming neutrals. There is some evidence that this peaking of the radial particle flux just inside the separatrix may also be responsible in part for the negative electric field in that location.
Sub-critical Transmutation Reactors with Tokamak Fusion Neutron Sources

(Georgia Institute of Technology, 2005) Stacey, Weston M. ; Mandrekas, John ; Hoffman, E. A. (Elisha Albright)

The principal results of a series of design scoping studies of sub-critical fast transmutation reactors (based on the nuclear and processing technology being developed in the USDoE Generation IV, Advanced Fuel Cycle and Next Generation Nuclear Plant programs) coupled with a tokamak fusion neutron source (based on the ITER design basis physics and technology) are presented.
Transmutation missions for fusion neutron sources

(Georgia Institute of Technology, 2005) Stacey, Weston M.

There are a number of potential neutron transmutation missions (destruction of long-lived radioisotopes in spent nuclear fuel, ‘disposal’ of surplus weapons grade plutonium, ‘breeding’ of fissile nuclear fuel) that perhaps best can be performed in sub-critical nuclear reactors driven by a neutron source. The requirements on a tokamak fusion neutron source for such transmutation missions are significantly less demanding than for commercial electrical power production. A tokamak fusion neutron source based on the current physics and technology database (ITER design base) would meet the needs of the spent nuclear fuel transmutation mission; the technical issue would be achieving ≥ 50% availability, which would require advances in component reliability and in steady-state physics operation.