White Beard, Roshi, All Might. (Great physical strenght, been able to shoot Ki or producing shockwaves and earthquakes doesn't protect you from radiation)
Characters that maybe die, maybe not, but high likelyhood of dying:
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Naruto (Can chakra cloack block radiation? Probably not)
Gojo (Can infinity block radiation? Probably not).
Toriko (some gourmet cells might or might not give him the power to survive radiation or regen, Probably not).
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Might possibly survive but get affected or die after a while:
Luffy (while he is weaker than Naruto, Toriko and Roshi, Luffy is made of rubber, not normal human flesh as we understand, so maybe, he might be able to survive, but several studdies suggest that Gamma radiation still affects rubber and it degradates it's flexibility and mechanical properties, so it would still hut Luffy, even if he's made of rubber, whether it would permanently affect him or he might heal afterwards it's unknown, but he might have greater chances of survival than the other above just because of been made out of rubber rather than normal flesh)
Boros (alien physiology and regen might allow him to survive).
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Ichigo ( it is unlikely that something like pure normal (non spiritual) gamma radiation can even affect Souls or Ghosts, gamma radiation photons simply may not be able to interact with Ichigo the same way it interacts with normal humans made of physical matter)
MCU Thor (he was already directly blasted by the energy emissions of a Neutron Star to forge Stormbringer).
Jin Mori (too many haxes, can probably survive due to some of them)
Aizen (Not only gamma radiation might not be able to hurt him because of not been made of physical matter, he is also inmortal, so he would survive anyway)
Sailor Moon (I honestly don't know, but isn't she like universal or multiversal, with her magic and crystals, and becomming Queen Serenity or something)
Super Man (most comic book versiosn of Super Man regularly fly through outer space, have Dipped inside of the Sun, etc... Superman in general even gets more powerful from radiations in general unless it was red sun light)