Neutronicity

[Transmute]

It has at least been admitted that there will be some neutron production from side reactions and contaminants in B11+P fusion. How much radioactivity could this cause from neutron activation? Will close loop cooling be required rather then cheaper open loop?

[Lerner]

The cooling system will be open loop, and there just won’t be enough activation of impurities in the water to worry about. Exposure times will be very short to the small amount of residual neutrons. The shielding water will be separate from the cooling water and will be distilled water.

[JRandall]

So, the main reaction itself is expected to be aneutronic. I say expected to be, because I do not know if anyone has actually caused this reaction to happen in the real world.

Could someone please tell me if anyone has actually achieved boron-hydrogen fusion in the laboratory?

However, it is admitted that the side reactions WILL produce “slow” neutrons. Much like in chemistry, obviously everything possible will be done to reduce unwanted side reactions. That still leaves FF generating radioactivity, though. I understand that this radioactivity is expected to be very short-lived, but the fact of its presence will most likely cause it to have to be regulated in some way. No big deal, really: lots of businesses deal with regulation and still operate effectively.

My question is whether or not it is fair to call the device “aneutronic” under these circumstances.

Don’t get me wrong: I believe in the project and support it wholeheartedly. I certainly do my part to spread word-of-mouth about it. But I, personally, have stopped characterizing it to my friends as aneutronic, saying instead that it is expected to produce several orders of magnitude less radioactivity, and that its waste products will have half-lives measured in seconds rather than millenia. 😉 This seems fair to me, and also more accurate. I can certainly point to lots of figures suggesting that FF is obviously better than our current policy of dumping gigatons of carbon into the air, and also safer in regards to waste than traditional fission reactors OR the expected waste stream from a tokamak or a spheromak. (if nothing else, the reactor vessel of a traditional fusion plant is expected to become hopelessly contaminated after a period of some decades, and must be disposed of just like a fission reactor.) FF doesn’t have this problem.

Final question, perhaps not related to this thread (I will gladly move it on request, or not object if the admin moves it): has anyone thought of doing (or actually done) a DT reaction, or even a plain old hydrogen-hydrogen reaction inside an FF device? It seems to me that an FF device could reach 100 million degrees or thereabouts much more easily than a tokamak or spheromak, and in tests I believe the device has already demonstrated this capacity. Of course it would be radioactive as all heck, but it seems to me that this would be a more sensible route for the HH and DT fans out there than any of the mainstream alternatives. I mean, these people have already decided that they can live with the radioactivity so why not produce it in a more cheap and effective manner?

Thank you for your attention.

-Jay

[Brian H]

JR;
don’t know the details, but I suspect that the ionized plasma wouldn’t behave properly. Everything has to link together just right, and the neutron flux from the HH and DT paths is a major carrier of the energy of fusion. Saying, “several orders of magnitude” doesn’t quite capture the difference. It’s a whole ‘nother ball game. The shielding is measured in 100s of tons and meters of thickness. You can’t do that stuff on a “small” scale.

[JimmyT]

Actually a lot of the development and testing work on focus fusion will be done using hydrogen or deuterium. This is one way to measure the “success” of the fusion reaction. By measuring the number of neutrons produced. Somewhere in the development plan Eric outlines this rather concisely. You will find it on LPP’s website.

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