Reply To: Earthquake v. Powerplants

[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.