[zapkitty]

Brian H wrote: Actually, Zapkitty, considering the benefits of moderate radiation (the hormesis phenomenon), operators of FFs should charge admission for a few hours exposure to the gamma in their containment buildings. 🙂

Errr…. what FF containment buildings?

Anyways, people can get that sort of stuff for free by sunbathing on granite outcroppings and they’d get a wider selection as well :coolgrin:

[zapkitty]

Henning wrote: That x-ray transparent fluid (helium gas, I don’t know at which pressure it gets fluid

It doesn’t, not even at the multi-megapascal pressures that were researched for certain other fission and fusion reactors. “Fluid” in this usage is a generic term the same as “working fluid”… the He will still be gaseous

I think those extreme He pressures required for other, more widely known applications were why Lerner-hakase specifically pointed out that in an FF the He pressure would only be a few bar.

[zapkitty]

Henning wrote: Can’t access Flickr at the moment, but I suspect it’s the knife-edge of the DPF you’re refering to:

Nope… it’s a collar around the electrode rods at the business end of the core.

I’ll swipe it and post it here.

(I didn’t even notice the collar until the text in the flickr captions clued me in )

Attached files

[zapkitty]

Do note that the exhaust temp of 200 C for the cooling system was for a proposed portable 2 MWe FF unit housed in a shipping container. That’s an entirely different setup than the classical 5 MWe power unit you are using for your examples.

200 C was appropriate for the lower output unit and enabled a generator that could be placed almost anywhere. A fixed installation such as the 5 MWe station “the size of a two-car garage” would have a higher upper limit on its exhaust… temps in excess of 700 C 🙂

And in the “garage” style station the cooling system need not be crammed into the same shipping container as an FF. So the intermediate water or oil loop can also be omitted. Direct air cooling for the heat sink where the helium dumps the core heat..

[zapkitty]

benf wrote:
Correct me if I’m wrong with this information: With Focus Fusion (using hydrogen and pB11), you won’t be using radioactive materials that can spread into the environment.

Correct.

short description relevant to current events

A Focus Fusion unit is technically a type of aneutronic fusion reactor that uses boron and hydrogen for fuel.

It fuses ions of Hydrogen (p) and Boron 11 (B11) to generate energy and neither of those elements are radioactive and they do not produce any radioactive waste that has to be stored… much less stored and kept under constant cooling.

The p and B11 are forced together using a device called a dense plasma focus or DPF. The DPF is powered in pulses by jolts of electricity supplied by a bank of large capacitors. When the unit is running some of the energy generated by fusion is used to recharge the capacitors and complete the circle.

But the concepts of “chain reaction”, “critical mass” or “decay heat” that are currently wreaking havoc in Fukushima are simply not relevant in fusion reactors.

Instead it goes like this: a proton (the Hydrogen atom’s nucleus) is fused with a Boron 11 nucleus to form a Carbon 12 nucleus (C12). But although the C12 atom is very stable and not radioactive in and of itself, the C12 thrown together by the FF unit is rockin’ out with the energy of the fusion process that created it… and it breaks apart into 3 helium nuclei (He4) carrying a lot of energy and some X-rays.

And the He4 nuclei, which are called alpha particles when they’re out and about on their own, these can be directly converted into electricity as can the X-rays

No neutrons needed, no steam and no expensive turbines.

benf wrote: When it is running neutrons aren’t produced that would make materials radioactive.

Correct: An aneutronic reactor is one that has less than 1% of its output energy carried by neutrons. An FF unit meets that criteria by a large margin, with only 0.2% of its output energy carried by neutrons.

So while some neutrons are produced in an FF as the result of occasional secondary reactions they are a minor pest, something easily shielded against but otherwise ignored. These neutrons do not carry enough energy to make the FF core a radioactive hazard and FFs produce no radioactive waste. None whatsoever.

Now, technically speaking, an end-of-life FF core will be a bit more radioactive than when it started but the radiation would be about the same as…

… check this out…

… a classroom full of kindergarteners.

Terrifying, no? 🙂

Myself… I’d use it as a bookend or a paperweight but then I’m a silly person (FF cores are tiny things for all the power that they handle.) The actual plan is to recycle the core materials into new cores.

benf wrote: With Focus Fusion, you wouldn’t have a meltdown, it would simply stop working.

Correct. Full Stop. Period. Perambulate No Further. End Of Discussion.

Now, there is one detail about an FF that has been shut down (whether the shutdown was intentional or not) but it is truly a minor one: During FF operation an occasional nucleus of C11 is created instead of C12. This C11 is radioactive but the half-life is 20.38 minutes and it decays into not-radioactive B11. Back to where it started.

During operations this is unnoticeable compared to the main fusion process going on… but it is why you’d want to wait about 9 hours after shutdown before opening an FF for servicing.

But *after* that 9 hours has passed then there will be no radiation hazard in the core. None at all.

[zapkitty]

Ivy Matt wrote: …The bad news is that the technology appears to be the tokamak only, and apparently you can’t start building working reactors until around 2100…

A tok? By 2100? That explains it… they’re thinking of ITER 🙂

[zapkitty]

Uh… FWIW, I don’t think a DPF will work with this.

From the description of lots of neutrons they were speaking of toks and similar low-density plasma.

I don’t think that sophisticated LCD is going to survive in a core for more than one pulse and I don’t think it could project anything through the dense plasmoid… and even if it could I’d think that the results would lost in the midst of the extreme plasma and current conditions that far outstrip what happens in a tok.

[zapkitty]

What are the basic parameters of your helium system?

[zapkitty]

Breakable wrote: Probably we would need to work something out, I would love to speculate on this idea. Basically all it boils down is cheap energy == affordable space flight.

It depends as well on the readiness level of the technology for a given application. For example my FOOF stuff was about getting a grip on how FFs work and how quickly test units might be validated in space using current tech.

At the moment I’m trying integrating custom shielding for aircraft power containment systems using the default FF stats while verifying my ideas on subsonic transports. (Oh damnable C11, why do you torment me so?…)

[zapkitty]

Rezwan wrote: Looks good to me!

Perhaps a box on the side with some links to info about fusion and space flight could be handy. Speaking of which, what are some definitive links to info on fusion and space flight?

Since NASA was banned from the fusion arena all that’s left is a variety of threads on different forums and an assortment of papers, most of which are dated by now.

[zapkitty]

Rezwan wrote:

With the “emergency brake on”, I don’t think anything will be rammed down anyone’s throat. This has a while to unfold. Assuming funding stabilizes, then assuming the concept is proven, there’s still the engineering development phase, and throughout this time, as noted elsewhere, many industries will be feeling threatened and likely challenging the concept “with extreme prejudice.”

I think skeptics needs will be well taken care of.

Errrr…. you seem to be assuming that those threatened by the technology will be deterred by a masterful display of the facts which will also convince the honest skeptics.

What happens when instead they play to the worst fears of the anti-nukes and have them amplify those fears to the public with a half-billion dollar campaign against the radioactive poison-spewing monsters that those terrorist-enabling crazies want to install in every neighborhood and contaminate the houses for thousands of years?

The oligarchs don’t have too strong a connection to reality at best and are not shy about callously jettisoning it entirely where profits are involved.

[zapkitty]

Rezwan wrote:
Yes. Fusion has a ways to go. And we have a duty to do everything to make it happen. The erratic and pathetic funding to date is a big part of the problem. If there is a solution to be found, it will take commitment to find it.

While I hesitate at the thought of adding to the ziggurat that is the FFS Forums main page, is there a dedicated area where admitted skeptics can come ask questions?

The questions will undoubtedly range from the basics to advanced subjects that are covered in other topics… but all will have the same basis as the skeptics seek to assure themselves that there are no hidden “gotchas”… that as aneutronic fusion advocates we aren’t giving the world the same bum rush that got the uranium fission plants rammed down our throats.

[zapkitty]

Rezwan wrote:
Then again, if someone is in screech mode, it’s a lost cause.

Yes, I’m referring to techniques to get factual information past the screechers to those in the same forum who can still listen.

[zapkitty]

Been dealing with this on various forums myself.

Most people will listen if you explain the facts, but an unfortunate portion of the anti-nuke crowd senses that there is blood in the water (literally, sad to say) and will not stop screeching.

And of that group a smaller portion will screech anything that pops into their heads.

Have to deal with them as best as can be done while not letting them derail the subject with their fantasies. (latest: spent fuel rods in cooling ponds have been launched like ballistic missiles into the atmosphere)

I wonder if they will ever be able to realize that, as well-meaning as they may be, they are dancing to a tune the oligarchs arranged?

[zapkitty]

vansig wrote:

Here are some numbers that Lerner-hakase tossed out during his Space Show appearance and my patella-twitching responses to a few of them are in parantheses:

50 kj pulse = 500 hz

(isn’t this supposed to be about 10 kj now? 50 kj at 500 hz gives us 25 megawtfs… )

nominal 5 to 20 MW has been talked about for some time.. with possible impact on cooling and anode wear.

… but a 5 mw FF is what he discusses and is the current proposed baseline, correct?

vansig wrote:

5 mw genset @ 3 tons and 2 meters wide

(Unshielded mass? He uses 3 tons as current mass of LPPX-1 but then uses this # for mass for FFs in general use… and they will need shielding )

current LPPX-1 has shielding. maybe the 3 tons includes that?

… it does? I thought that LPPX-1 had no integral rad shielding and it’s the room it’s in that has the shielding.

Minimum mass spherical shielding according to the LPP descriptions would be still be well over 4 tons.

zapkitty wrote: output =

1/3 x-rays – caught by PV with thousands layers of metal

2/3 beam

(this needs confirmed please)

This is also a puzzle. Was previously stated to be approx 50/50.

While in theory it makes no difference in total output it makes a big difference in application… and in applications.

Also inspires daydreaming of brem suppression in excess of expectations 🙂

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