Monster Island News linked to this article here about a fan theory that the reason Indiana Jones survived his ride in the nuked refrigerator in Indiana Jones and the Kingdom of the Crystal Skull was because he had drunk from the correct Holy Grail in the prior movie. It's actually a stroke of minor genius to suggest this, I think....it explains a lot!
Despite that, I also love the explanation posted by Reel Physics, which actually argues that our assumption about the non-survivability of a nuked lead-lined fridge being tossed away via nuclear detonation is possibly a tiny bit off-base:
If you combine fan theory with Reel Physics then I think you get a plausible explanation for the entire scene!
I guess you could call this one a case of....fridge logic....
(Disclaimer: I actually liked Kingdom of the Crystal Skull, and am a big Indie fan. I think using 50's era thematics such as the soviets, aliens, crystal skulls, MKUltra style mind control and UFOs was a stroke of mad genius in showing how the very nature of the pulp and weird was transforming, and that Indie is the guy who gets to experience all of it. My biggest gripe was --like most-- the trauma of having to watch Shia Labeouf swinging on vines).