Laser Inertial Fusion-based Energy (LIFE) - Developing Manufacturing Technology for low cost and high volume fusion fuel is critical to our future energy needs
Sustainably providing for the world’s energy needs is one of the most urgent – and difficult – challenges facing today’s society. Worldwide electric power demand is expected to double from its current level of about two trillion watts (TW) to four TW by 2030 and could reach eight to ten TW by 2100. As many as 10,000 new one-gigawatt (GW) power plants will be needed to keep up with this demand. Yet fossil-fuel supplies, such as coal and natural gas, are limited, and the environmental effects of that many additional fossil-fuel plants could be devastating. Conventional nuclear power could provide clean energy, but poses waste-disposal and proliferation concerns. All available energy options have limitations and liabilities, so revolutionary responses must be pursued in parallel with evolutionary ones. The Laser Inertial Fusion Energy concept, or LIFE, is one such revolutionary response.
Today, researchers at the Lawrence Livermore National Laboratory are close to demonstrating the scientific basis required to make LIFE a reality. The capability of lasers to create the conditions required for ignition and thermonuclear burn in the laboratory with inertial confinement fusion (ICF) is expected to be demonstrated on the National Ignition Facility (NIF) located in the U.S. during fiscal years 2010 or 2011. With the appropriate research, development and engineering program, LIFE power plants could begin to provide electricity to U.S. consumers within 20 years and could provide a very significant fraction of U.S. and international electricity demand by 2050. See Figure 1.
At the heart of the LIFE power plant is a fuel capsule containing a tiny amount of solid deuterium-tritium (DT) which is compressed to high density by lasers, and then a short-pulse laser beam delivers energy to ignite the compressed core until a fusion reaction is initiated – analogous to a sparkplug in an internal combustion engine. The fission reaction produces thermal energy for electricity generation. The fuel capsule consists of a spherical shell with an internal layer of foam that retains the DT within its pores. The capsule is attached to the hohlraum, which converts laser light into x-ray energy to compress the DT, and a cone that injects energy directly to the center of the imploding capsule to hasten the fusion reaction. The fuel capsule components shown in Figure 2 would be fabricated in a central factory and then assembled at the LIFE power plant. Fuel capsules would be injected into the target chamber at a rate of 10 to 20 targets per second. The current fuel capsule fabrication techniques are unsuitable for low-cost, high throughput. For ICF fusion energy to be cost-competitive with other forms of energy, the high-precision fuel capsules must be manufactured in quantities of about 1.73 million per day per plant and at unit costs of less than $0.25 USD.
The challenge is to develop inexpensive processes that can be used to meet the specified tolerances of the fuel capsule. The fuel capsule must be made to micrometer tolerances to attain a stable contraction of the fusion fuel. The fuel must align to the laser centroid to within 50 μm. Manufacturing methods such as injection moulding or the development of new processes based on chemical engineering massproduction principles are examples. The greatest probability of success lies with a simple fuel capsule design using a minimal number of parts and materials that accommodate the component fabrication and assembly operations. The final fuel capsule design will be the result of an optimization effort in which all factors are weighed and new solutions are explored to improve the overall target cycle.
This paper outlines the requirements, the current state-of-the-art and research plan for several aspects of the fuel capsule fabrication. A fuel manufacturing R&D is being planned with a goal of demonstrating the unit processes needed for a prototype LIFE power plant. R&D efforts will be conducted in collaboration with industrial partners.
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