Actually the radioactivity does go away after some sim years but you can make that land into an industrial area.
Industrial radioactive exports.
Nice. In my region I a. can't afford it and b. have dumb sims, so they'll be all 'derp what's this button do? *nuclear meltdown*'
I kinda like my large small town though! No nukes here!
Whatever I do it goes abandoned due to being radioactive. I'm toying with putting a hospital on top of it