10 research outputs found
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Fusion reactors: a remote possibility
The next generation of controlled thermonuclear reactor experiments will be faced with the handling problems of tritium and neutron activation that will dominate the safety and maintenance problems of future fusion reactors. The nuclear industry has been working with highly radioactive systems for many years and has developed the tools and methods to do safely productive work in the presence of high radiation fields. These methods can be applied to CTR work by extending them to the unique problems associated with fusion reactors. (auth
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Fusion Power Demonstrations I and II
In this report we present a summary of the first phase of the Fusion Power Demonstration (FPD) design study. During this first phase, we investigated two configurations, performed detailed studies of major components, and identified and examined critical issues. In addition to these design specific studies, we also assembled a mirror-systems computer code to help optimize future device designs. The two configurations that we have studied are based on the MARS magnet configuration and are labeled FPD-I and FPD-II. The FPD-I configuration employs the same magnet set used in the FY83 FPD study, whereas the FPD-II magnets are a new, much smaller set chosen to help reduce the capital cost of the system. As part of the FPD study, we also identified and explored issues critical to the construction of an Engineering Test Reactor (ETR). These issues involve subsystems or components, which because of their cost or state of technology can have a significant impact on our ability to meet FPD's mission requirements on the assumed schedule. General Dynamics and Grumman Aerospace studied two of these systems, the high-field choke coil and the halo pump/direct converter, in great detail and their findings are presented in this report
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Studies for a fusion Technology Development Facility
We have been studying small, driven fusion reactors as candidates for a Technology Development Facility (TDF) to be used for testing reactor subsystems, components, and materials. Magnetic mirror systems are particularly interesting for this application because of their inherent steady-state operation, potentially high wall loading, and relatively small size. The systems so far studied have 14-MeV neutron wall loads ranging from 1 to 3 MW m/sup -2/ on testing surface areas of 2 to 5 m/sup 2/ with annual fluences as high as 10/sup 21/ neutrons cm/sup -2/. These devices are based on physics and engineering that has been demonstrated or is scheduled for demonstration in the next year
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TIBER II configuration and structural design
The TIBER-II machine is a minimum-size steady-state tokamak with sufficient fusion power, wall flux, and fluence to be used for undertaking a nuclear test mission. Although the machine is envisioned as an engineering device, it will demonstrate reactor-relevant physics. To achieve the small size and high performance goals of TIBER II, the engineered systems must be based on aggressive assumptions. In addition, the machine must be designed for ease of maintenance to ensure reaching the fluence goal of 5 MW yr/m/sup 2/ in a design lifetime of 13 years. This paper concentrates on the configuration and structural issues of designing a small, high-field, and high-flux device
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Options to upgrade the Mirror Fusion Test Facility
In this document we describe three options for upgrading MFTF-B, and the nomenclature used for these options is shown on the chart, MFTF-B Upgrade Options. We propose to add a 4-m-long reactor-like insert to the central cell, or to change the end plugs to the new MARS-type configuration, or both. LLNL prefers the third option, labeled MFTF-..cap alpha../sup +/T in the chart, in which both the central cell insert is added and the end plugs are modified. All options are long-pulse or steady-state DT burning experiments. Those upgrades with the insert would be constructed beginning in FY 86, with operation beginning in mid-FY 92. Confirmation of our intent to modify the end plugs would be sought in FY 88 based on positive results from MFTF-B experiments. The upgrade with only the end plug modification would not start until MFTF-B data are available. The timeline for constructing and operating the MFTF-B Upgrade included at the end of this preface is for reference while reading the text. The various modes of operation shown on the chart are described later
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Engineering of beam direct conversion for a 120-kV, 1-MW ion beam
Practical systems for beam direct conversion are required to recover the energy from ion beams at high efficiency and at very high beam power densities in the environment of a high-power, neutral-injection system. Such an experiment is now in progress using a 120-kV beam with a maximum total current of 20 A. After neutralization, the H/sup +/ component to be recovered will have a power of approximately 1 MW. A system testing these concepts has been designed and tested at 15 kV, 2 kW in preparation for the full-power tests. The engineering problems involved in the full-power tests affect electron suppression, gas pumping, voltage holding, diagnostics, and measurement conditions. Planning for future experiments at higher power includes the use of cryopumping and electron suppression by a magnetic field rather than by an electrostatic field. Beam direct conversion for large fusion experiments and reactors will save millions of dollars in the cost of power supplies and electricity and will dispose of the charged beam under conditions that may not be possible by other techniques
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Tokamak ignition/burn experimental research device
As part of a continuing effort by the Office of Fusion Energy to define an ignition experiment, a superconducting tokamak has been designed with thin neutron shielding and aggressive magnet and plasma parameters. By so minimizing the inner radial dimensions of the tokamak center post, coil, and shielding region, the plasma major radius is reduced with a corresponding reduction in device costs. The peak nuclear-heating rate in the superconducting TF coils is 22 mW/cm/sup 3/, which results in a steady heat load to the cryogenic system of 50 kW. Fast-wave, lower-hybrid heating would be used to induce a 10-MA current in a moderate density plasma. Then pellet fueling would raise the density to achieve ignition as the current decays in a few hundred seconds. Steady-state current drive in subignited conditions permits a 0.8 MW/m/sup 2/ average wall loading to study plasma and nuclear engineering effects
Antiinflammatory therapy with canakinumab for atherosclerotic disease
BACKGROUND: Experimental and clinical data suggest that reducing inflammation without affecting lipid levels may reduce the risk of cardiovascular disease. Yet, the inflammatory hypothesis of atherothrombosis has remained unproved. METHODS: We conducted a randomized, double-blind trial of canakinumab, a therapeutic monoclonal antibody targeting interleukin-1β, involving 10,061 patients with previous myocardial infarction and a high-sensitivity C-reactive protein level of 2 mg or more per liter. The trial compared three doses of canakinumab (50 mg, 150 mg, and 300 mg, administered subcutaneously every 3 months) with placebo. The primary efficacy end point was nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death. RESULTS: At 48 months, the median reduction from baseline in the high-sensitivity C-reactive protein level was 26 percentage points greater in the group that received the 50-mg dose of canakinumab, 37 percentage points greater in the 150-mg group, and 41 percentage points greater in the 300-mg group than in the placebo group. Canakinumab did not reduce lipid levels from baseline. At a median follow-up of 3.7 years, the incidence rate for the primary end point was 4.50 events per 100 person-years in the placebo group, 4.11 events per 100 person-years in the 50-mg group, 3.86 events per 100 person-years in the 150-mg group, and 3.90 events per 100 person-years in the 300-mg group. The hazard ratios as compared with placebo were as follows: in the 50-mg group, 0.93 (95% confidence interval [CI], 0.80 to 1.07; P=0.30); in the 150-mg group, 0.85 (95% CI, 0.74 to 0.98; P=0.021); and in the 300-mg group, 0.86 (95% CI, 0.75 to 0.99; P=0.031). The 150-mg dose, but not the other doses, met the prespecified multiplicity-adjusted threshold for statistical significance for the primary end point and the secondary end point that additionally included hospitalization for unstable angina that led to urgent revascularization (hazard ratio vs. placebo, 0.83; 95% CI, 0.73 to 0.95; P=0.005). Canakinumab was associated with a higher incidence of fatal infection than was placebo. There was no significant difference in all-cause mortality (hazard ratio for all canakinumab doses vs. placebo, 0.94; 95% CI, 0.83 to 1.06; P=0.31). CONCLUSIONS: Antiinflammatory therapy targeting the interleukin-1β innate immunity pathway with canakinumab at a dose of 150 mg every 3 months led to a significantly lower rate of recurrent cardiovascular events than placebo, independent of lipid-level lowering. Copyright © 2017 Massachusetts Medical Society