C.G. Bathke

Overview of the ARIES-RS reversed-shear tokamak power plant study

The ARIES-RS tokamak is a conceptual, D‐T-burning 1000 MWe power plant. As with earlier ARIES design studies, the final design of ARIES-RS was obtained in a self-consistent manner using the best available physics and engineering models. Detailed analyses of individual systems together with system interfaces and interactions were incorporated into the ARIES systems code in order to assure self-consistency and to optimize towards the lowest cost system. The ARIES-RS design operates with a reversed-shear plasma and employs a moderate aspect ratio (A4.0). The plasma current is relatively low (Ip11.32 MA) and bootstrap current fraction is high ( fBC 0.88). Consequently, the auxiliary power required for RF current drive is relatively low ( 80 MW). At the same time, the average

Single and multiple helicity Ohmic states in reversed‐field pinches

The properties of single helicity and multiple helicity Ohmic states in reversed‐field pinches (RFP’s) are investigated by a combination of analytic and numerical methods. The single helicity results show that toroidal field reversal can be provided in a helical Ohmic equilibrium driven by a toroidal loop voltage, and that reversal in helical symmetry is related to stellarator transform. Nevertheless, a constant λ≡j∥/B state cannot be sustained because λ must reverse at the toroidal field reversal surface. This helical equilibrium can be thought of as the saturated state of an unstable tearing mode. For a force‐free plasma, helical reversal can be maintained by a relatively small value of δB/B because it is accompanied by an inward paramagnetic pinch velocity. Conversely, in models with △⋅v=0, a large outward diffusive velocity must build up to balance the inward paramagnetic pinch velocity, requiring poloidal beta to be of order unity. It is shown that in three dimensions no multihelical Ohmic equilibriu...

The ARIES-I Tokamak Reactor Study †

The ARIES research program is a multi-institutional effort to develop several visions of tokamak reactors with enhanced economic, safety, and environmental features. Three ARIES visions are currently planned for the ARIES program. The ARIES-I design is a DT-burning reactor based on modest extrapolation from the present tokamak physics data base; ARIES-II is a DT-burning reactor which will employ potential advances in physics; and ARIES-III is a conceptual D-3He reactor. The first design to be completed is ARIES-I, a 1000 MWe power reactor. The key features of ARIES-I are: (1) a passively safe and low environmental impact design because of choice of low activation material throughout the fusion power core, (2) an acceptable cost of electricity, (3) a plasma with performance as close as possible to present-day experimental achievements, (4) a high performance, low activation, SiC composite blanket cooled by He, and (5) an advanced Rankine power cycle as planned for near term coal-fired plants. The ARIES-I research has also identified key physics and technology areas with the highest leverage for achieving attractive fusion power system.

Physics basis for a reversed shear tokamak power plant

The reversed shear plasma configuration is examined as the basis for a tokamak fusion power plant. Analysis of plasma equilibrium and ideal MHD stability, bootstrap current and current drive, plasma vertical stability and position control, divertor physics and plasma power balance are used to determine the operating point parameters that maximize fusion power density and minimize the recirculating power fraction. The final plasma configuration for the ARIES-RS power plant obtains b of 4.96%, plasma driven current fraction of 91%, plasma current of 11.3 MA, toroidal field of 8.0 T and major and minor radius of 5.5 and 1.4 m. The current drive system utilizes fast wave, lower hybrid and high frequency fast wave current drive to obtain maximum current profile flexibility, requiring 5 80 MW of power. A divertor solution is found which employs neon impurity injection to enhance the radiation in the scrape-off layer (SOL) and divertor and results in a combined particle and heat load in the divertor of5 6M W m 2 . The plasma is driven with a Q of 25 and is at a thermally stable operating point. The plasma is assumed to be in an ELMy H-mode, with low amplitude and high frequency ELMs.

The Attractiveness of Materials in Advanced Nuclear Fuel Cycles for Various Proliferation and Theft Scenarios

We must anticipate that the day is approaching when details of nuclear weapons design and fabrication will become common knowledge. On that day we must be particularly certain that all special nuclear materials (SNM) are adequately accounted for and protected and that we have a clear understanding of the utility of nuclear materials to potential adversaries. To this end, this paper examines the attractiveness of materials mixtures containing SNM and alternate nuclear materials associated with the plutonium-uranium reduction extraction (Purex), uranium extraction (UREX), coextraction (COEX), thorium extraction (THOREX), and PYROX (an electrochemical refining method) reprocessing schemes. This paper provides a set of figures of merit for evaluating material attractiveness that covers a broad range of proliferant state and subnational group capabilities. The primary conclusion of this paper is that all fissile material must be rigorously safeguarded to detect diversion by a state and must be provided the highest levels of physical protection to prevent theft by subnational groups; no “silver bullet” fuel cycle has been found that will permit the relaxation of current international safeguards or national physical security protection levels. The work reported herein has been performed at the request of the U.S. Department of Energy (DOE) and is based on the calculation of “attractiveness levels” that are expressed in terms consistent with, but normally reserved for, the nuclear materials in DOE nuclear facilities. The methodology and findings are presented. Additionally, how these attractiveness levels relate to proliferation resistance and physical security is discussed.

Systems analysis in support of the selection of the ARIES-RS design point

Systems analysis has been instrumental in the determination of the ARIES-RS reference design point through the evaluation of design options and the economic optimization of design variables. The ARIES-RS reference design point is described as modeled by the ARIES systems code. Parametric sensitivities about the ARIES-RS reference design point are presented that illustrate the economic impact of various design choices considered within the ARIES-RS design study.

The ARIES-III D-/sup 3/He tokamak reactor: design-point determination and parametric studies

The multi-institutional Advanced Reactor Innovation and Evaluation Study (ARIES) has examined the physics, technology, safety, and economic issues associated with the conceptual design of a tokamak magnetic-fusion reactor. The ARIES-I variant envisions a deuterium-tritium (D-T) fueled device based on advanced superconducting coil, blanket, and power-conversion technologies and a modest extrapolation of existing tokamak physics. Key aspects of the ARIES-I physics model are summarized, and the engineering and costing models are discussed. Results of parametric studies leading to the identification of a design point to be subjected to detailed analysis and integration as well as to characterize the ARIES-I operating space are presented.<<ETX>>

Lessons learned from the Tokamak Advanced Reactor Innovation and Evaluation Study (ARIES)

Lessons from the four-year ARIES (Advanced Reactor Innovation and Evaluation Study) investigation of a number of commercial magnetic-fusion-energy (MFE) power-plant embodiments of the tokamak are summarized. These lessons apply to physics, engineering and technology, and environmental, safety, and health (ES&H) characteristics of projected tokamak power plants. Summarized herein are the composite conclusions and lessons developed in the course of four conceptual tokamak power-plant designs. A general conclusion from this extensive investigation of the commercial potential of tokamak power plants is the need for combined, symbiotic advances in both physics, engineering, and materials before economic competitiveness with developing advanced energy sources can be realized. Advances in materials are also needed for the exploitation of environmental advantages otherwise inherent in fusion power.

NFCSim : A dynamic fuel burnup and fuel cycle simulation tool

NFCSim is an event-driven, time-dependent simulation code modeling the flow of materials through the nuclear fuel cycle. NFCSim tracks mass flow at the level of discrete reactor fuel charges/discharges and logs the history of nuclear material as it progresses through a detailed series of processes and facilities, generating life-cycle material balances for any number of reactors. NFCSim is an ideal tool for analysis - of the economics, sustainability, or proliferation resistance - of nonequilibrium, interacting, or evolving reactor fleets. The software couples with a criticality and burnup engine, LACE (Los Alamos Criticality Engine). LACE implements a piecewise-linear, reactor-specific reactivity model for its criticality calculations. This model constructs fluence-dependent reactivity traces for any facility; it is designed to address nuclear economies in which either a steady state is never obtained or is a poor approximation. LACE operates in transient and equilibrium fuel management regimes at the refueling batch level, derives reactor- and cycle-dependent initial fuel compositions, and invokes ORIGEN2.x to carry out burnup calculations.

The ARIES-III D-3He tokamak-reactor study

A description of the ARIES-III research effort is presented, and the general features of the ARIES-III reactor are described. The plasma engineering and fusion-power-core design are summarized, including the major results, the key technical issues, and the central conclusions. Analyses have shown that the plasma power-balance window for D-/sup 3/He tokamak reactors is small and requires a first wall (or coating) that is highly reflective to synchrotron radiation and small values of tau /sub ash// epsilon /sub e/ (the ratio of ash-particle to energy confinement times in the core plasma). Both first and second stability regimes of operation have been considered. The second stability regime is chosen for the ARIES-III design point because the reactor can operate at a higher value of tau /sub ash// tau /sub E// tau /sub E/ approximately=2 (twice that of a first stability version), and because it has a reduced plasma current (30 MA), magnetic field at the coil (14 T), mass, and cost (also compared to a first-stability D-/sup 3/He reactor). The major and minor radii are, respectively 7.5 and 2.5 m.<<ETX>>