i thought of the "radiation storm" too AWTGTS! :-D I think it is a great idea!
There is already a "rain storm" (with lightning! :->) so i think it will be confusing to add an "radiation rain" too IMO... But i was thinking of a "aurora/solar_flare event" (a good way to show a nice graphical effect here! hahaha) that is a "radiation event" too! In the beginning the aurora can be sweet green (pale, but greener & greener with time)... but at a random moment it turns violet/fushia (higher density/energy,;because red is lower than green in energy/frequency so it doesn't make sense lol) and damages the player little by little while outdoors (but no so much to kill it in one event; but in a weakened state, it could very be be fatal! :-X)
It should be a fun "OMG i MUST go to base NOW!" moment! hahaha! more fear than harm here lol X'D (even more if the player doesn't notice the faint green color at the beginning around the screen or "the special sun flare effect" hahaha; or forgot that the purple/violet/indigo/fushia one is dangerous after that! Maybe having a 25% chance that the "violent/violet one" after the green does not show up is a good trick too! B-] )
If in a vehicle in a long travel, the player could take (in inventory or trailer) a room & airlock just to survive/shelter the "bad aurora"... the aurora could boost the input of "solar panels" temporarily (150/200%!), even damage/break a random % of them (can repair it after, like the other event). It could be a nice touch! (taking a solar panel in case of an aurora/flare with a mini-base setup could save your life! and the smart ones could use the max output of panels to craft some heavy gears at once or max charge batteries! B-) )
Aurora should be occurring at night too (maybe only at night for the best visual?), to illuminate randomly a "dark moment" (the players don't like night! lol) with a strange/colorful atmospheric moment! ( a greenish/purplish halo night... :-O ) :-D It would be so cool! (and unexpected the first time!Panic guarantied! héhéhé)
=^^=