[opensource]

I’m interested. Is this an online discussion? If so, then can you post a link to it?
Thanks!

[opensource]

What we’re talking about I think – to be quite vague – is a technology that best converts between energy and matter. The more of the latter you have, the more effective the propulsion system will be in this sea of gas and gravitation. Sound right?

[opensource]

Thanks for the clarification!

In terms of radioactive waste, if something were to brake open even a very large FF reactor, then – as I understand it – the radioactive waste is minimal because it is pulsed and because there isn’t an accumulation of it over time. So in this paradigm, you start with fuels that are not radioactive, you end up making no long term reactants, but you do make radioactive byproducts with very short half lives (10 hours, or so). Correct?

Also, the shielding is only necessary for the first reaction (11B + α → 14N + n + 157 keV) created. And the second reaction (11B + p → 11C + n − 2.8 MeV) does not emanate beyond which sector of the reactor? That is, does the first reaction require a lot more shielding than the second?

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Joeviocoe wrote:
I think what opensource may be getting at is this:
Are there any downplayed drawbacks to the DPF shielding requirements that might make DPF a much less attractive solution in the future?

Such as how Nuclear Fission Power was once regarded as silver bullet to energy needs. It produced LOTS of power in a very small reactor (compared to other power plants at the time). And the fuel was VERY abundant too. But dealing with radiation (both in the reactor and the fuel itself) proved to be more problematic than many early claims indicated. Shielding, safety systems, fuel handling, separation of water cycles, waste handling…. were all problems created due to radioactivity. And those problems made Fission power plants MUCH larger and MUCH more expensive. So now, Nuclear power makes up only 20% of the electric power in the U.S.

It is a very pertinent question to ask about the exact requirements for shielding. We have already eliminated most concerns; the fuel (decaborane is toxic but non-radioactive), no radioactive water cycles, and waste is inert helium. The only concerns left are the safety systems of High electrical power (easy) and shielding from possible radiation from side reactions.

Indeed, and I still get a variety of different answers on the main forum focused on the best fusion power DPF out there.
I’m trying to get an exhaustive list of the reactions that cause the theoretically safest DPF (pB11 fuel, etc) to require shielding around humans.

[opensource]

So Lerner,

The above list of reactions creating neutrons and ionizing radiation is exhaustive?

An the second one (11B + p → 11C + n − 2.8 MeV) is the only one you think can’t be avoided?

I’m focusing on the need for shielding, not byproducts that affect maintenance. To me this is a bigger issue affecting my investment in DPF research.

[opensource]

Using water and lead shielding will make applications in transportation more difficult. Lerner said the main reaction does not produce any, so do we have a list of the (side) reactions that are producing the neutrons?

[opensource]

Let’s not hi-jack my thread, guys. It’s not even been stated explicitly yet (in this thread) whether DPFs will always require neutron shielding – and, furthermore, there have been several conflicting posts on this. Lerner clarified some, but this is something that I think needs to be spelled out.

[opensource]

Wow! Couldn’t the “onion” catch most of the X-rays? Judging by your description, these gamma rays aren’t really rare enough to ever justify zero shielding on a FF reactor, even if it’s running on pB11…

[opensource]

Lerner wrote: We have a document on this but I have to find it. There are two minor reactions. In one, the alphas, which are still trapped in the plasmoids, undergo another reaction with the boron and produce very low energy neutrons, which must be shielded against but are too feeble to create activation in the materials we are using. We calculated that you could carry the Be anode in your pocket after it was exposed for a year. The other is a very high energy p B11 reaction which produces C11, with a very short lifetime (20 minutes). That is what has to decay before the device can be serviced. I know of no other fuel that produces fewer neutrons, and the main reaction pB11->3 He4 does in fact produce none.

So, to be clear, would a pB11 FF reactor definitely need shielding to be around humans, or not?

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I’ll start an IRC channel if we can sticky a thread or put something on focusfusion.org about how to use IRC and that it’s #focusfusion on freenode or something.

[opensource]

I realize x-rays travel at c, of course, I was just referring to the experiments where c was changed using thick gases. Just think of far out ways to reduce the xray cooling effect.

On another note, what kinds of simple plasma experiments would benefit DPF understanding? Do they all have to be expensive experiments done at high temperatures?

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Thanks James, you always clear things up…
Can some gas be used to slow the x-rays to decrease reactivity and cooling?

[opensource]

Sorry; don’t know how a double post occurred. Please remove this post moderator.

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So if using x-rays forces us to work against the bremsstrahlung cooling effect in designing a DPF, then maybe we shouldn’t use x-rays? Have there been any clever proposals for dealing with bremsstrahlung cooling besides just scaling to work against it?

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We never got to the bottom of this. So, JamesR, who was right – zapkitty or delt0r? Is the amount of radiation 20 minutes after shutdown the same as background?

Furthermore, I feel the need to lay rest to the OP, whose question was not adequately answered. There are breakthroughs necessary before aneutronic fusion is feasible and cost-effective – but I don’t think one of them is the confinement of the plasma. I’m only talking about DPF technology here – fusion power that is based upon confinement (like Tokamaks) may require better confinement.

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