RC: I have no doubt they'll round up quite a few citizens to act as guinea pigs to test the radiation effects.
Indeed. Also helps to explain the contradiction of evacuating a province but building a reviewing stand within a few clicks. After all, what's to see with an underground explosion? A "captive audience" makes sense, probably including the engineers who built the test site, but not to risk too many peasants if there are crops to work. Then again, perhaps the purchasers are demanding to see the demo.
Also, what is the probability of using conventional explosives to fake a nuke shot? There is the chance that this is all Kabuki.
BTTT
A big puff of dust, and a subsidence crater. That's if the nuke goes 'boom' properly, anyway ...