Reply To: Animated plasma.

[vansig]

it isn’t about fast versus slow neutrons, it’s about neutron flux. both short-lived and long-lived isotopes are little or no concern. it’s only medium-lived isotopes, with half-lives in years to centuries, that would be any worry, at all. but these are not produced in greater than trace amounts. and remember to compare this to that produced by cosmic rays naturally.

the anode could make:
Be-10 1.5 My

the onion could make:
Al-28 2.2 minutes
Si-31 157 minutes

steel structure could make:
Fe-59 44.5 days
Ti-51 5.76 minutes
Cr-55 3.5 minutes
V-52 3.7 minutes

high Tc superconductor could make:
Y-90 3.9 hours
Cu-66 5.1 minutes
Ba-139 83 minutes
O-19 26.4 seconds

PVC insulation could make:
Cl-36 301 ky
C-14 5.7 ky
H-3 12.3y (trace)

gases in switches:
S-35 87.5 days
F-20 11.1 seconds

electrolyte:
?

what you might expect, after years of use, is embrittlement of components, only, as nearly all these isotopes will have decayed. tritium buildup in the water shield will not be a problem, as this can be drained and replaced easily.

Fe-59 or S-35 buildup, maybe? but again, it depends on the rate of neutron production.

tritium buildup within the insulation, maybe? but this will be in trace amounts anyway, as tritrium would require double-neutron absorption.

if these are a concern, then different structural materials, and different insulation, such as teflon, could be used.