Fusion Reactor Musings

[mmartin798]

I have again given some thought to the size, configuration and so on the MP Vehicle Reactor. Assuming it uses H2 for fuel and is only 25% efficient, the tank for the H2 would be about the size of a large scuba tank for 18 months of continuous output at 1.5MWH. I pick 1.5MW since I seem to recall that is about the output of an M1's gas turbine. Would the reactor casing encompass the fuel tank or would the tank be separate? If it were separate, refueling would be a non-trivial but easy operation.

Step 1) Power down reactor
Step 2) Close internal fuel valve
Step 3) Remove old tank
Step 4) Connect new tank
Step 5) Attach vacuum pump to supply line
Step 6) Evacuate air from supply line
Step 7) Open both internal and tank valves
Step 8) Restart reactor

This would allow for a top off in just a couple hours. This is also something that potentially could be cobbled together by a motivated team. Thoughts?

[kato13]

Given the small size (and therefore lack of shielding) I always assumed it was He3 fusion that was accomplished by some trick like the palladium used in cold fusion research.

[mmartin798]

He3 is harder to come by than D2 as the primary fuel. The D2+D2 reaction takes off in two paths. If we assume the innovation was the ability to strip out the T3 that results from one of the paths, then we only have to deal with low energy neutrons around 2.4MeV. The other reaction path produces He3 and we fuse that with D2 and get no neutrons from a secondary reaction. This would require the team to vent the radioactive T3 from time to time, but it does have a really short half-life.

[kato13]

Interesting. Would you have heat exchangers to capture the energy of the D2 + D2 reaction in addition to the direct proton capture from the D2 + He3. The heat exchange was one major issue I saw when using such a small device.
(edit see my post below)

That is why I liked the pure He3 + He3 Reaction. Twice the number of protons and a estimated capture of 95% of the energy. If you can trick your way around the coulomb barrier (like the cold fusion people tried to do) you can get a ton of energy from a very small package.

I could not come up with a source for the He3 without going to the moon so I guess there would have to be a breakthrough in Li6 -> T3 -> He3 conversion. If you could convert one of the Li6 neutrons to an anti-neutron you might get spontaneous decay to T3 (in addition to the antimatter reaction). Then you just need to figure out how to reduce the half life to a more manageable timeframe.

Yes this involves a lot of handwaveium, but is on a believability level as Star Trek science IMO (I stole the creation of the anti-neutron conversion from the startrek tech manual).

Well, if I had all the answers I would be at fermilab right now (and a billionaire )

[kato13]

http://sciencenordic.com/plastic-can...at-electricity

This actually might solve the heat exchange issue. I remember reading about it several. years ago, but it looks closer to being a refined technology.

[mmartin798]

I got talking with a friend of mine and came up with an interesting spin on this whole discussion. In an ideal world, the portable reactors would be He3+He3. Minimal shielding needed because of no neutrons, direct electricity from the protons and we have to assume the existence of some efficient high energy/high temperature thermoelectric generator for the waste heat. What if the Project planned to have He3 production centers? Just a few around the country to send He3 canisters to refuel the team?

Such a center would have ready access to sea water and a D+D fusion reactor. The sea water undergoes electrolysis, the D is captured for fuel and the H is burned in co-generation manner to help keep electrolysis going. The D is then used in the fusion reactor and the He3 harvested from the reactor. The T can also be stored and more He3 collected as it decays. This way, we have these reactors running underground where the neutron release can be more easily managed and the Projects He3 needs can be met.

If these centers were located near proposed refugee centers and manufacturing centers thought likely to be easily repairable, the electricity from the reactor making the He3 can also be sent out by just running some copper. It is an interesting idea at least.