Ok, I think I'm pushing the envelope on this one: I bought a roll of 400TX (or Tri-X Pan 400) film dating to June 1972. From what I've heard, black and white films last longer than their color counterparts, because they lack color dyes. Just the silver.

@wiltw: Can you send me a link to the Kodak tech pub discussing the accumulation of radioactivity on films?

If you really wanted to halt radiation fogging, you may want to put the film in lead-lined boxes/bags.