Reactive armor slots on 'Mechs as described on p. 282 are a bit odd. On the one hand, they're obvious "roll again" candidates, so that means they can't technically suffer a critical hit themselves; on the other, whenever they are rolled while there's still armor in place in that location, there's that 1-in-36 chance of it blowing off in addition to the reroll.
So, what happens if a location that by dint of construction or previous damage contained only reactive armor slots at the start of the current phase suffers a "floating" critical hit? Per the usual "transferring criticals" rules on Total Warfare p. 125, that critical hit should transfer inwards if there are no slots that can be affected by a critical hit; but it's not quite clear whether reactive armor slots actually fall into that category. If the critical hit simply transfers as usual, there is obviously no risk of a chain reaction despite the presence of those armor slots; conversely, if it doesn't, then the same reaction would seem to be essentially guaranteed since for a sufficiently (arbitrarily) long chain of rerolls in place with the accompanying detonation checks the probability of never rolling a 2 on the latter would approach zero.
(Perhaps the most "natural" outcome would be to check for a possible chain reaction in that location once and then have the critical hit transfer inwards as per TW p. 125 whether the armor stays in place or not, I'm just having trouble actually arriving there strictly by the letter of the rules.)
