G.L. Kulcinski

Energy from Inertial Fusion

Fusion is potentially a safe clean source not limited by political boundaries. Magnetic and inertial fusion share this promise, but there are differences between them. An inertial fusion power plant is based on different physics and technology from a magnetic fusion power plant and therefore presents somewhat different benefits and challenges. The facilities required to demonstrate inertial fusion power are potentially much smaller. In this article we describe concepts for such a power plant, its beneficial features and a low‐cost reactor test facility for developing practical fusion power.

Birth to death analysis of the energy payback ratio and CO2 gas emission rates from coal, fission, wind, and DT-fusion electrical power plants☆

The amount of electrical energy produced over the lifetime of coal, LWR fission, UP fusion, and wind power plants is compared to the total amount of energy required to procure the fuel, build, operate, and decommission the power plants. The energy payback ratio varies from a low of 11 for coal plants to a high of 27 for DT-fusion plants. The magnitude of the energy investment and the source of the various energy inputs determine the CO2 emission factor. This number varies from a low of 9 to a high of 974 tonnes of CO2 per GWeh for DT-fusion and coal plants, respectively.

Surface melting and evaporation during disruptions in magnetic fusion reactors

Abstract Disruptions in tokamaks lead to high energy deposition for short times on in-vessel components. Melting and evaporation may then occur. A comprehensive model to evaluate the extent and duration of melting, the amount of evaporation, and the time for resolidification is presented. This model entails the solution of a heat conduction problem with two moving boundaries, the liquid surface and the melt—solid interface with a surface boundary condition determined by the dynamics of evaporation. Extensive numerical results are presented for in-vessel components made of stainless steel, molybdenum, or graphite. The effects of vapor shielding, pulse shape, and pulse duration are also investigated.

Microstructure of copper following high dose 14-MeV Cu ion irradiation

Abstract High-purity copper has been irradiated with 14-MeV Cu ions to peak doses of 40 dpa over the temperature range of 100–500°C. Examination of the foils in a transmission electron microscope revealed that no significant amount of void formation had occurred, in conflict with previous irradiation studies. Instead, a high density of stacking fault tetrahedra (SFT) were observed. The defect cluster density is constant for irradiation temperatures ⩽ 200°C, and the density decreases rapidly with irradiation temperature ⩾ 300°C. It is postulated that the absence of voids is due to the low oxygen content of the copper foils (

The depth dependent damage profile in nickel irradiated with nickel or copper ions

Abstract High purity nickel samples have been irradiated with high energy (> 14 MeV) heavy ions and the resultant microstructure examined in cross section (i.e., in a plane parallel to the incident ions). The microstructure observed after irradiation with copper ions was not significantly different from that observed after nickel ion irradiation. Swelling near the ion end-of-range was less than that in the mid-range in both the self-ion and copper ion irradiated samples. A 100 nm void denuded zone was observed at the front surface in samples irradiated at 525 °C, and voids were observed at depths ≈ 15% greater than the calculated damage curves. An irradiation at 200 °C produced a loop lattice structure aligned along {001} with a spacing of ≈40 nm. The steady-state rate equations were formulated and solved to give the depth dependent defect concentrations. The calculated void growths rate was found to qualitatively fit the experimental results. A depth dependent radiation enhanced diffusion model predicted the result that for ion fluences used in this study, the injected copper impurities were confined to the end-of-range region.

The Science and Technologies for Fusion Energy With Lasers and Direct-Drive Targets

We are carrying out a multidisciplinary multi-institutional program to develop the scientific and technical basis for inertial fusion energy (IFE) based on laser drivers and direct-drive targets. The key components are developed as an integrated system, linking the science, technology, and final application of a 1000-MWe pure-fusion power plant. The science and technologies developed here are flexible enough to be applied to other size systems. The scientific justification for this work is a family of target designs (simulations) that show that direct drive has the potential to provide the high gains needed for a pure-fusion power plant. Two competing lasers are under development: the diode-pumped solid-state laser (DPPSL) and the electron-beam-pumped krypton fluoride (KrF) gas laser. This paper will present the current state of the art in the target designs and lasers, as well as the other IFE technologies required for energy, including final optics (grazing incidence and dielectrics), chambers, and target fabrication, injection, and tracking technologies. All of these are applicable to both laser systems and to other laser IFE-based concepts. However, in some of the higher performance target designs, the DPPSL will require more energy to reach the same yield as with the KrF laser.

First wall surface problems for a D-T tokamak reactor

The effects of deuterium, tritium, helium and neutron bombardment on surface degradation of the first wall of a 5000 MWth D-T reactor have been analyzed. The effects of both sputtering and blistering have been analyzed and the results applied to 316 stainless steel wall operating at temperatures from 300 to 500°C. It has been calculated that the total wall erosion rate is 0.22 mm/year and that 14 MeV neutron sputtering accounts for two thirds of this number. Sputtering from all neutrons results in ≈0.17 mm/year erosion. The calculated erosion rate is 2–3 times that which would be allowable for a 30 year first wall lifetime.

Overview of University of Wisconsin Inertial-Electrostatic Confinement Fusion Research

Abstract In Inertial Electrostatic Confinement (IEC) devices, a voltage difference between concentric, nearly transparent spherical grids accelerates ions to fusion-relevant velocities. The University of Wisconsin (UW) operates two IEC devices: a cylindrical aluminum chamber and a spherical, water-cooled, stainless-steel chamber, with a power supply capable of 75 mA and 200 kV. The research program aims to generate fusion reaction products for various applications, including protons for creating radioisotopes for nuclear medicine and neutrons for detecting clandestine materials. Most IEC devices worldwide, including the UW devices, presently operate primarily in a pressure range (1-10 mtorr) that allows ions to make only a few passes through the core before they charge exchange and lose substantial energy or they collide with cathode grid wires. It is believed that fusion rates can be raised by operating at a pressure where neutral gas does not impede ion flow, and a helicon ion source has been developed to explore operation at pressures of ~0.05 mtorr. The UW IEC research group uses proton detectors, neutron detectors, residual gas analyzers, and spectroscopic diagnostics. New diagnostic techniques have also been developed, including eclipse disks to localize proton production and chordwires to estimate ion fluxes using power balance.

Apollo - An advanced fuel fusion power reactor for the 21st century

A preconceptual design of a tokamak reactor fueled by a D-He-3 plasma is presented. A low aspect ratio (A=2-4) device is studied here but high aspect ratio devices (A > 6) may also be quite attractive. The Apollo D-He-3 tokamak capitalizes on recent advances in high field magnets (20 T) and utilizes rectennas to convert the synchrotron radiation directly to electricity. The overall efficiency ranges from 37 to 52% depending on whether the bremsstrahlung energy is utilized. The low neutron wall loading (0.1 MW/m/sup 2/) allows a permanent first wall to be designed and the low nuclear decay heat enables the reactor to be classed as inherently safe. The cost of electricity from Apollo is > 40% lower than electricity from a similar sized DT reactor.

Transmutations, Radioactivity, and Afterheat in a Deuterium-Tritium Tokamak Fusion Reactor

Calculations have been performed to assess the effects of fast-neutron-induced transmutation reactions in the blanket region surrounding the plasma in a Tokamak fusion reactor. The production of bo...