B. Grant Logan

Exploring the Competitive Potential of Magnetic Fusion Energy: The Interaction of Economics with Safety and Environmental Characteristics

The Senior Committee on Environmental, Safety, and Economic Aspects of Magnetic Fusion Energy (ESECOM) summarizes its recent assessment of magnetic fusion energys (MFEs) prospects for providing energy with economic, environmental, and safety characteristics that would be attractive compared with other energy sources (mainly fission) available in the time frame of the year 2015 and beyond. Accordingly, ESECOM has given particular attention to the interaction of environmental, safety, and economic characteristics of a variety of magnetic fusion reactors, and compared those fusion cases with a variety of fission cases. Eight fusion cases, two fusion-fission hybrid cases, and four fission cases are examined, using consistent economic and safety models, to permit exploration of the environmental, safety, and economic potential of fusion concepts using a wide range of possible materials choices, power densities, power conversion schemes, and fuel cycles.

A plan for the development of fusion energy

This is the final report of a panel set up by the U.S. Department of Energy (DOE) Fusion Energy Sciences Advisory Committee (FESAC) in response to a charge letter dated September 10, 2002 from Dr. Ray Orbach, Director of the DOEs Office of Science. In that letter, Dr. Orbach asked FESAC to develop a plan with the end goal of the start of operation of a demonstration power plant in approximately 35 years. This report, submitted March 5, 2003, presents such a plan, leading to commercial application of fusion energy by mid-century. The plan is derived from the necessary features of a demonstration fusion power plant and from the time scale defined by President Bush. It identifies critical milestones, key decision points, needed major facilities and required budgets. The report also responds to a request from DOE to FESAC to describe what new or upgraded fusion facilities will “best serve our purposes” over a time frame of the next twenty years.

Assessment of Potential for Ion-Driven Fast Ignition

Abstract Critical issues and ion beam requirements are explored for fast ignition using ion beams to provide fuel compression using indirect drive and to provide separate short-pulse ignition heating using direct drive. Several ion species with different hohlraum geometries are considered for both accelerator-produced and laser-produced ion ignition beams. Ion-driven fast ignition targets are projected to have modestly higher gains than with conventional heavy ion fusion and may offer some other advantages for target fabrication and for use of advanced fuels. However, much more analysis and additional experiments are needed before conclusions can be drawn regarding the feasibility for meeting the ion beam transverse and longitudinal emittances, focal spots, pulse lengths, and target standoff distances required for ion-driven fast ignition.

The US inertial confinement fusion (ICF) ignition programme and the inertial fusion energy (IFE) programme

There has been rapid progress in inertial fusion in the past few years. This progress spans the construction of ignition facilities, a wide range of target concepts and the pursuit of integrated programmes to develop fusion energy using lasers, ion beams and z-pinches.Two ignition facilities are under construction, the national ignition facility (NIF) in the United States and the laser megajoule (LMJ) in France, and both projects are progressing towards an initial experimental capability. The laser integration line prototype beamline for LMJ and the first four beams of NIF will be available for experiments in 2003. The full 192 beam capability of NIF will be available in 2009 and ignition experiments are expected to begin shortly after that time.There is steady progress in target science and target fabrication in preparation for indirect-drive ignition experiments on NIF. Advanced target designs may lead to 5–10 times more yield than initial target designs. There has also been excellent progress on the science of ion beam and z-pinch-driven indirect-drive targets.Excellent progress on direct-drive targets has been obtained on the Omega laser at the University of Rochester. This includes improved performance of targets with a pulse shape predicted to result in reduced hydrodynamic instability. Rochester has also obtained encouraging results from initial cryogenic implosions.There is widespread interest in the science of fast ignition because of its potential for achieving higher target gain with lower driver energy and relaxed target fabrication requirements. Researchers from Osaka have achieved outstanding implosion and heating results from the Gekko XII Petawatt facility and implosions suitable for fast ignition have been tested on the Omega laser.A broad-based programme to develop lasers and ion beams for inertial fusion energy (IFE) is under way with excellent progress in drivers, chambers, target fabrication and target injection. KrF and diode pumped solid-state lasers are being developed in conjunction with dry-wall chambers and direct-drive targets. Induction accelerators for heavy ions are being developed in conjunction with thick-liquid protected wall chambers and indirect-drive targets.

A Slot Divertor for Tokamaks with High Divertor Heat Loads

AbstractA new divertor configuration is suggested as a possible solution to the problems of high heat flux and erosion at the divertors in large high-power tokamaks. The proposed configuration is a toroidally symmetrical slot in the divertor that allows part of the edge plasma and most of its power to enter a cavity in a thin annular sheet. The large surface area of the sheet is exposed to interaction with gas in the cavity. This results in radiation and a reflux of fast neutral atoms, both of which transport power to the cavity walls. The heat flux is reduced because the power is spread over a much larger area. Erosion due to sputtering is also reduced because the decreased power flux reduces the sheath potential and, therefore, the average ion impact energy. Sputtering by fast neutrals should not be a serious problem because neutrals are not accelerated by a sheath as are ions. Helium ash and impurity atoms that are ionized within the cavity tend to be trapped there by the electric field that must exist...

A rationale for fusion economies based on inherent safety

A comparison of the direct capital costs of recent light-water-reactor fission plants and recent magnetic fusion designs indicates that cost reductions by innovation in both the fusion reactor and the fusion balance of the plant (nonreactor part) will be required for fusion direct costs to become competitive. Both future fusion and future fission designs would benefit from modularity, standardization, and inherent safety (passive afterheat removal without damage in loss-of-coolant and loss-of-flow accidents) to improve their utility and public acceptance and to reduce nonreactor balance-of-plant costs, indirect costs, and time-related costs. If this can be achieved, inherently safe fusion and fission designs should have comparable reactor enclosure power densities, of the order of 1 MWth/m3. With a reduction by a factor of about 2 in the fusion magnet and heating-system cost per watt, such fusion and fission designs should also have comparable direct and total capital costs per watt, provided the fusion plants can be modularly built in somewhat larger units (300 to 600 MWe) than some of the modular fission units (100 MWe). With the eventual fusion capital cost per watt thus attaining parity with fission some decades later than the development and deployment of second-generation fission plants, the economic incentive for switching growth to new fusion electric plants would derive from lower fuel-cycle costs (fuel startup, operating, processing, and waste-disposal costs). At the same time, there would also be strong economic incentives to build hybrid fusion plants to supply fissile fuel for the established fission plants,

Quasispherical fuel compression and fast ignition in a heavy-ion-driven X-target with one-sided illumination

The HYDRA radiation-hydrodynamics code [M. M. Marinak et al., Phys. Plasmas 8, 2275 (2001)] is used to explore one-sided axial target illumination with annular and solid-profile uranium ion beams at 60 GeV to compress and ignite deuterium-tritium fuel filling the volume of metal cases with cross sections in the shape of an “X” (X-target). Quasi-three-dimensional, spherical fuel compression of the fuel toward the X-vertex on axis is obtained by controlling the geometry of the case, the timing, power, and radii of three annuli of ion beams for compression, and the hydroeffects of those beams heating the case as well as the fuel. Scaling projections suggest that this target may be capable of assembling large fuel masses resulting in high fusion yields at modest drive energies. Initial two-dimensional calculations have achieved fuel compression ratios of up to 150X solid density, with an areal density ρR of about 1 g/cm2. At these currently modest fuel densities, fast ignition pulses of 3 MJ, 60 GeV, 50 ps, a...

Progress towards a high-gain and robust target design for heavy ion fusion

Recently [E. Henestroza et al., Phys. Plasmas 18, 032702 (2011)], a new inertial-fusion target configuration, the X-target, using one-sided axial illumination has been explored. This class of target uses annular and solid-profile heavy ion beams to compress and ignite deuterium-tritium (DT) fuel that fills the interior of metal cases that have side-view cross sections in the shape of an “X.” X-targets using all-DT-filled metal cases imploded by three annular ion beams resulted in fuel densities of ∼50 g/cm3 at peak compression, and fusion gains of ∼50, comparable to heavy ion driven hohlraum targets [D. A. Callahan-Miller and M. Tabak, Phys. Plasmas 7, 2083 (2000)]. This paper discusses updated X-target configurations that incorporate inside the case a propellant (plastic) and a pusher (aluminum) surrounding the DT fuel. The updated configurations are capable of assembling higher fuel areal densities ∼2 g/cm2 using two annular beams to implode the target to peak DT densities ∼100 g/cm3, followed by a fast...

Inertial fusion reactors using Compact Fusion Advanced Rankine (CFARII) MHD conversion

Abstract This study evaluates the potential performance (efficiency and cost) of inertial fusion reactors assumed capable of vaporizing blankets of various working materials to a temperature (10,000-20,000 K) suitable for economical MHD conversion in a Compact Fusion Advanced Rankine II (CFARII) power cycle. Using a conservative model, 1-D neutronics calculations of the fraction of fusion yield captured as a function of the blanket thickness of Flibe, lithium and lead—lithium blankets are used to determine the optimum blanket thicknesses for each material to minimize CoE for various assumed fusion yields, “generic” driver costs, and target gains. Lithium-hydride blankets are also evaluated using an extended neutronics model. Generally optimistic (“advanced”) combinations of lower driver cost/joule and higher target gain are assumed to allow high enough fusion yields to vaporize and ionize target blankets thick enough to stop most 14 MeV neutrons, and to breed tritium. A novel magnetized, prestressed reactor chamber concept is modeled together with previously developed models for the CFARII Balance-of-Plant (BoP), consisting of a supersonic plasma jet, MHD generator, and “raindrop” condensor. High fusion yields (20 to 80 GJ) are found necessary to heat and ionize the Flibe, lithium, and lead-lithium blankets for MHD conversion, with initial solid thicknesses sufficient to capture most of the fusion yield. Much smaller fusion yields (1 to 20 GJ) are required for lithium-hydride blankets. For Flibe, lithium, and lead—lithium blankets, improvements in target gain and/or driver cost/joule, characterized by a “Bang per Buck” figure-of-merit of ≥ 20 joules yield per driver

Requirements for low-cost electricity and hydrogen fuel production from multiunit inertial fusion energy plants with a shared driver and target factory

, would be required for competitive CoE, while a figure-of-merit of ≥ 1 joule yield per driver