Wick has been used for spent nuclear fuel flights for years. BAe146s to Carlisle, C-130s to Switzerland and elsewhere. Before that it was DanAir HS748s into half of the old WW2 runway (3000ft-ish) at Dounreay, using nothing more than an NDB approach with no DME. I think they also used Bandeirantes.
Seems to me the biggest concern about more nuclear flights at Wick ought to be the complete absence of controlled airspace and low level ATC radar cover there.