Laser Inertial Fusion Energy
LIFE used the same basic concepts as NIF, but aimed to lower costs using mass-produced fuel elements, simplified maintenance, and diode lasers with higher electrical efficiency.
Through 2011 and into 2012, NIF ran the "national ignition campaign" to reach the point at which the fusion reaction becomes self-sustaining, a key goal that is a basic requirement of any practical IFE system.
[2][3] The basic idea was to use a driver to compress a small pellet known as the target that contains the fusion fuel, a mix of deuterium (D) and tritium (T).
[8] At the time, a number of different drivers were considered, but the introduction of the laser later that year provided the first obvious solution with the right combination of features.
This is potentially attractive because this burns off many of the long lived radioisotopes in the process, producing waste that is only mildly radioactive and lacking most long-lived components.
The designer has to choose which is more important; burning up the fuel through fusion neutrons, or providing power through self-induced fission events.
Following consultations with their partners in the utility industry, the project was redirected toward a pure fusion design with a net electrical output around 1 gigawatt.
[30] One of the cost concerns for MCF designs like ITER is that the reactor materials are subject to the intense neutron flux created by the fusion reactions.
In most MFE designs, the reactor is constructed in layers, with a toroidal inner vacuum chamber, or "first wall", then the lithium blanket, and finally the superconducting magnets that produce the field that confines the plasma.
Disassembling a toroidal stack of elements would be a time-consuming process that would lead to poor capacity factor, which has a significant impact on the economics of the system.
[31] As a natural side-effect of the size of the fuel elements and their resulting explosions, ICF designs use a very large reaction chamber many meters across.
The reaction chamber is, on the whole, dramatically simpler than those in magnetic fusion concepts, and the LIFE designs proposed building several and quickly moving them in and out of production.
When originally conceived by Nuckols, laser-driven inertial fusion confinement was expected to require lasers of a few hundred kilojoules and use fuel droplets created by a perfume mister arrangement.
[39] Several other projects running in parallel with Mercury explored various cooling methods and concepts allowing many laser diodes to be packed into a very small space.
[39] LIFE was essentially a combination of the Mercury concepts and new physical arrangements to greatly reduce the volume of the NIF while making it much easier to build and maintain.
Each module was completely independent, unlike NIF which is fed from a central signal from the Master Oscillator, allowing the units to be individually removed and replaced while the system as a whole continued operation.
[42] Each driver cell in the LIFE baseline design contained two of the high-density diode arrays arranged on either side of a large slab of laser glass.
This would mean that a complete LIFE plant would require about $600 million worth of diodes alone, significant, but within the realm of economic possibility.
In order to efficiently convert the driver laser's light to the x-rays that drive the compression, the cylinder has to be coated in gold or other heavy metals.
[37] To address this concern, a considerable amount of LIFE's effort was put into the development of simplified target designs and automated construction that would lower their cost.
Working with General Atomics, the LIFE team developed a concept using on-site fuel factories that would mass-produce pellets at a rate of about a million a day.
In MFE, a relatively large amount of fuel is prepared and put into the reactor, requiring much of the world's entire civilian tritium supply just for startup.
These systems looked like a scaled down version of NIF, with beamlines about 100 metres (330 ft) long on either side of a target chamber and power generation area.
The fission processes triggered by the fusion would add an additional energy gain of 4 to 10 times, resulting in a total thermal output between 2000 and 5000 MWth.
Using high efficiency thermal-to-electric conversion systems like Rankine cycle designs in combination with demonstrated supercritical steam generators would allow about half of the thermal output to be turned into electricity.
[51] Over a year, LIFE would produce 365 days x 24 hours x 0.9 capacity factor x 1,000,000 kW nameplate rating = 8 billion kWh.
LLNL calculated the LCOE of LIFE.2 at 9.1 cents using the discounted cash flow methodology described in the 2009 MIT report "the Future of Nuclear Energy".
[61] LLNL projected that further development after widespread commercial deployment might lead to further technology improvements and cost reductions, and proposed a LIFE.3 design of about $6.3 billion CAPEX and 1.6 GW nameplate for a price per watt of $4.2/W.
[65] NIF construction was completed in 2009 and the lab began a long calibration and setup period to bring the laser to its full capacity.
[70] LLNL's acting director, Bret Knapp, commented on the issue stating that "The focus of our inertial confinement fusion efforts is on understanding ignition on NIF rather than on the LIFE concept.
