Let's take an example. Here's the list of the 7 long-lived fission products [1]. The nastiest appears to be Caesium-135 [2]. If you zap this with a proton it b

Let's take an example. Here's the list of the 7 long-lived fission products [1]. The nastiest appears to be Caesium-135 [2]. If you zap this with a proton it becomes Barium-136, which is a stable element (the half-life is so long that it cannot be estimated; probably it is in the trillions of years). [1] https://en.wikipedia.org/wiki/Long-lived_fission_product#The_7_long-lived_fission_products https://en.wikipedia.org/wiki/Long-lived_fission_product#The... [2] https://en.wikipedia.org/wiki/Isotopes_of_caesium#Caesium-135 https://en.wikipedia.org/wiki/Isotopes_of_caesium#Caesium-13...