Reply To: Competition from the Thorium reactor

[texaslabrat]

Axil, you want FF to be a Tokamak when it really, really isn’t for a very good reason. You’ve completely missed the point and the elegance of aneutronic fusion. Deuterium may be the “holy grail” for you…but it’s not for those who want fusion without the downsides that D-D fusion brings.

Neutrons are not to be feared from an engineering et al perspective? Yeah, I guess if you don’t mind the structure turning brittle and becoming long-lived radioactive waste..I suppose that’s true. Good luck finding someone who wants to maintain your gear in that scenario though…and the long-term radioactivity will GREATLY reduce the appeal and rate of adoption of the technology into the mainstream. Nobody wants a fission reactor in their neighborhood…and a D-D FF reactor would have many of the same negative traits.

Great idea about thermalizing the neutrons with heavy water so the reactor vessel won’t be damaged. So, instead of just going with nice and clean aneutronic Boron-Hydrogen reactions and getting a direct-to-electric conversion in a setup that has such simplistic elegance that a refrigerator factory should be able to mass produce it…you want to try and put a heavy water shield around the plasmoid (which is a pumped vacuum, btw), and THEN capture the energy as heat (and requiring all structural components be designed to withstand the high temperatures that you want to transfer to the molten salt loop..and what happens to the heat captured in the heavy water shield if you want to eventually heat salt to 700C? You putting in an electric heat pump to step up the temperature too or do you plan to run it at earth-core pressure?) and THEN run everything through a Carnot-limited heat engine attached to a mechanical generator to eventually produce….wait for it….electricity? Great solution if you were the captain of your school’s “Rube Goldberg” device team. And then there’s the tremendous additional capital costs of such a setup that is orders of magnitude higher than the as-envisioned FF system. Ever priced a gas turbine engine?

Let’s just assume for a moment that a Brayton-cycle based power generation scheme WAS more efficient overall from a pure watts produced from a certain amount of fuel burned (and I’m not convinced that it is..just playing devil’s advocate as you are) perspective. Is that the metric you are using? Ok…assuming that’s the case…and let’s say it’s even 10 times more efficient. Heck, let’s say the deuterium is FREE in this scenario. What does a year’s worth of Boron fuel cost versus a year’s worth of deuterium? Congratulations..you’ve saved a couple thousand dollars a year (or in that ballpark). In the process, you’ve made the actual total device 10 times larger (at least), made it far more complicated to manufacture, and thus at *least* 10 times as expensive (or if you forgo the neutron shielding, you’ve now made the manufacture a little cheaper but now the NRC requirements will make it 100 times more expensive due to the radioactive waste you will create over time). It’s going to take a lot of years of that few thousand bucks/year to make up for the additional $3million-plus you’ve sunk into the system (compared to a $300k FF system of equal electrical generation capacity). Nevermind the huge increase in ongoing maintenance costs for all the additional mechanical components (and very tight-tolerance, expensive ones at that). Or you could have just built 10 FF systems and had 10 times the power output for a nominal increase in fuel costs (either way the fuel costs are negligible in the larger scheme of things when you are talking a few kg a year that produces millions of kilowatt-hours of sellable power).

I know if I had $3million to invest in one setup versus the other..I know which one I’d pick. I’d pick the one that put out more power and made the most profit for me for that $3 million spent…and that one sure as heck isn’t the one that requires a gas turbine engine 😉