Full out nuclear war, mushroom clouds sprouting all over... probably not worth preparing for unless you have an underground base with a recycling plant, hydroponic garden, perpetual motion machine to run a generator, et cetera, et cetera.
Regular radiation shit like after the Japan earthquake... maybe.
Assess your area for likely radiation sources. Do you live near INEL or another facility like it? If so then it may not be too 'out there' to take some precautions. If not, then maybe a tad too far when the money spent for a full NCB suit for each family member could go further and better in other preps like larger water purification system, long(er) term food storage, long term medical supplies, and stuff like that.
Just my 2/100 of a FRN.