Safety features of commercial aneutronic fusion

[rashidas]

Here are some questions for FF devotees:

What sort of safety features would a prototype focus fusion reactor have? For example X-ray emission could be a problem.
How much would these features cost? What sort of training would power plant operators need? How long would state and federal permitting take?

[Aeronaut]

rashidas wrote: Here are some questions for FF devotees:

What sort of safety features would a prototype focus fusion reactor have? For example X-ray emission could be a problem.
How much would these features cost? What sort of training would power plant operators need? How long would state and federal permitting take?

Great questions. The biggest operational safety challenge that I can see is the potential lack of industry-standard NEMA and possibly IEEE approved enclosures and procedures for working with the high voltage pulses and the associated RF noise.

The unavoidable X-ray emissions will be contained within the outermost shield layer, comprised of ~2cm of lead.

The neurotoxin decaborane will also be confined to within the apparently massive shielding assembly, and limited to only a few pounds per year- probably less than a pound of solid fuel per maintenance cycle. The actual gas would be confined in a multi-walled fuel system within the core and vacuum chamber.

Since this fuel is a solid anywhere near room temperature, the gas should revert to solid form long before the core can be safely removed, which would eliminate the X-ray threat and all but residual capacitor charge issues if not engineered out of the system design.

Bottom line should be no realistic threat to industrial or neighborhood health not already faced by transformer substations and chemical plants or detergent manufacturers.

[emmetb]

Bottom line should be no realistic threat to industrial or neighborhood health not already faced by transformer substations and chemical plants or detergent manufacturers.

That, at least, is good news. One concern remains though: how hard is it to breed fissile material using a (modified) plasma focus device?

[vansig]

Aeronaut wrote:
The biggest operational safety challenge that I can see is the potential lack of industry-standard NEMA and possibly IEEE approved enclosures and procedures for working with the high voltage pulses and the associated RF noise.

This reminds me of EMP produced by nuclear explosions and lightning strikes, so let’s examine the declassified TEMPEST protection guidelines. These specify that the protective shielding must have 90 dB attenuation, if i recall, which is attainable with enclosures that are bolted to ground each 0.9m, and similar minimum separation between hot electric sources and cool signal paths.

[vansig]

emmetb wrote: how hard is it to breed fissile material using a (modified) plasma focus device?

for that, you need lots of neutrons. DPF isn’t an appreciable neutron source, but that might depend on what fuel you use

[Aeronaut]

Wow. 90dB sounds fantastic, but achieving it sounds like a mechanical nightmare. Would welding the enclosures to ground achieve the same results? Also, would locating the DPF below grade increase attenuation enough to be worth considering?

[emmetb]

vansig wrote:

how hard is it to breed fissile material using a (modified) plasma focus device?

for that, you need lots of neutrons. DPF isn’t an appreciable neutron source, but that might depend on what fuel you use
I came across this, admittedly old, paper that seems to propose using the energetic ion beam directed at a spallation target as a neutron source:
http://ci.nii.ac.jp/naid/110000011602/en/
More recent research seems to focus on subcritical fission reactors which can burn long lived actinides. So this would actually be a great options for disposing of nuclear waste. No idea if a plasma focus is powerful enough to be used directly here… They need particles with energies approaching the GeV range:
http://www.world-nuclear.org/info/inf35.html
This BTW seems to be related to older threads on this forum:
https://focusfusion.org/index.php/forums/viewthread/216

[vansig]

Aeronaut wrote: Wow. 90dB sounds fantastic, but achieving it sounds like a mechanical nightmare. Would welding the enclosures to ground achieve the same results? Also, would locating the DPF below grade increase attenuation enough to be worth considering?

I imagine welding would be okay. The specification prohibits soldering, because high currents will melt it.

You want to make wires as short as is feasible, (including ground wires) to avoid any antenna-like effects. Each device and signal path has its own enclosure, and you want all the enclosures firmly grounded. So if the entire structure is enclosed in a shield, and located below-grade, then yes, that will probably help.

[vansig]

emmetb wrote: No idea if a plasma focus is powerful enough to be used directly here… They need particles with energies approaching the GeV range: http://www.world-nuclear.org/info/inf35.html

It seems ion energies in the reactor will fall short of that range by a couple orders of magnitude

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