they are in very early development stages - rather less developed
This is true. John Slough, the man behind this effort, is working to scale up the fusion reaction by increasing the magnetic confinement up to the 10 T field he envisions for a hybrid thorium reactor.
John Slough's philosophy is one that I am sure would appeal to the engineers in this forum. Although it would, of course, be nice to understand what is going on in scientific detail, he doesn't waste time worrying about it. He tries things out, and if it works, he builds on it. For example, they did an experiment where they smashed two FRCs into each other. You might expect that they would squish past each other, or tip, or disrupt, and do any number of deleterious things, but in fact they stopped and stuck, even when the experimenters weren't careful about alignment. I probably would have been so worried about all the bad things that could happen, and maybe even theoretically should happen, that I would never have done the experiment.
It seems to me that this thorium hybrid concept is in disfavor from all sides of the nuclear community , both the fission and fusion community dislikes this approach.
The fusion community wants a steady state device. They have an aversion to pulsed devices. They don't even want a tokamak reactor to power up and down in a 24 hour cycle, although that would probably make a lot of sense.
They like machines that make a big bang even less. Pulse power puts strain on the reactor structure. You have to pay a lot of attention to cycle fatigue and arcing and all.
But if that's where the physics leads you, good engineering and experience will probably let you make a home there. John is thinking in the 10 Hertz range and a natural fusion power level like 10 MW, but there may be a lot of freedom to choose your operating point. With thorium as a fusion energy multiplier, the hybrid power heat output will be a few hundred times that level.
At this time the design goal is to get to fusion breakeven i.e. ”Q = 1”. IMHO, this is good enough for a successful thorium hybrid. The next step is to get the fusion people up to speed on all the off the self advancements that will have occurred on thorium fission reactors like AHTR and LIFE.
Are you saying you expect this device to manufacture all the startup fissile?
Do you have any numbers that suggest it could possibly do such a thing?
The design goal of 10e17 neutrons per second per pulse is very possible to achieve. At 100 pulses per second, that gives 10e19 neutrons per second total fluence. Over a short time span of a few months, that will build up a working inventory of U233. When enough U233 is produced, the neutron production rate from fusion can be decreased to sustain a steady state hybrid reaction… say down to a fusion pulse rate of a few pulses per second or less. The hybrid will produce heat and power all through this U233 buildup phase, however.
After U233 buildup, lowering the neutron steady state rate produced from fusion will extent the working lifetime of the fusion first wall proportionately.
• The elimination of the Lftr core through the replacement with a fusion based neutron point source.
How does this align with your title Neutron supplemented LFTR?
What is eliminated is the 5% U235 Light Water Reactor fuel in the core of a two fluid Lftr as a neutron source. Because U235 must be denaturized by IAEA rule, there will always be U238 to deal with. In easy to acquire light water reactor fuel, 95% of that core salt is U238. It is this U238 that produces all the transuranic waste.
You say “Some of the uranium fails to fission and generates plutonium, americum, and californium.”
In a pure thorium fuel cycle, only a trace of PU239 and higher waste products are generated.
So far as I can tell this design will have a core wall problem 100x worse. You earlier post about a similar accelerator stream with swirling molten salt around would be less tough on the wall - though it does sound fairly impressive to have 100 tonnes of material swirling in a whirlpool that gets completely changed out every 5-10 seconds.
I see the core of this type of fusion hybrid as an easily replaceable diamond pipe that holds vacuum. This tube runs down the center axis of a long cylinder enclosing the liquid thorium blanket salt; a tube in shell configuration if you please.
The fusion accelerators are at either ends of the diamond tube well out of the region of fission and are easy to operate an maintain. These two accelerators shot T-D plasma down the evacuated diamond tube to and adjustable point of fusion anywhere down the entire length of the long diamond tube.
By adjusting the timing of the pulses from the two counter-facing plasma accelerators, the point of fusion can be moved along the entire length of the diamond tube where no one tube location is used more than another in a ware balancing strategy. This will greatly extend the life of the first wall.
I believe you are referring to startup fissile charge requirements. It takes an awful lot of neutrons to manufacture fissile. The most likely path to generating the fissile startup charge is mined u235. LFTR startup charge requirements are similar to an LWR (possibly less). Roughly 3 years worth of fuel for an LWR.
In a thorium fission reactor, the breeding ratio is very tight. One of the design risks on a thorium reactor is that it may not always achieve a breeding ratio greater than 1 due to unexpected loss of neutrons. Adding additional Light Water Reactor fuel to provide the possibility of supplemental neutrons may always be needed.
Clearly getting from a breeding ratio of .95 to 1.01 is a disproportionate cost and design expense that a low cost fusion neutron source can eliminate. The adjustable fusion source can be turned on and off as needed to keeps the hybrid reaction going. For example, there is no pressing need to aggressively remove waste from the hybrid to save neutrons. Keep the solid waste in the reactor until they stabilize, and then remove them.
Tritium is only a problem until it is captured. It has marketplace value now. If the day comes when tritium has no value the half-life is only 11 years and once combined chemically it can be reasonably stored. The whole trick with tritium is to be sure you capture it before it escapes. You fusion machine will generate much more tritium than will a fission machine so it has to do a much better job of collecting it. There is no information on the website to give any idea how they intend to collect the tritium.
This type of FRC fusion can burn deuterium exclusively in a pure D-D fuel cycle. But if some tritium is produced in the fission process, then burn it. No harm done.
I am quite confident that the NRC will manage to be sure they get to regulate any fusion machine that generates lots of neutrons. If there is a loophole now that avoid it they will plug it quick enough once they think someone will actually build the machine.
Laser Inertial Fusion Engine (LIFE) at the the National Ignition Facility (NIF), will be the test case. We will see.