fissile vs fissionable

fissile

adj

  • Capable of sustaining a nuclear fission chain reaction. 

  • Able to be split. 

  • Easily split along a grain. 

fissionable

adj

  • Capable of undergoing nuclear fission; fissile. 

noun

  • Any fissile or fissionable substance. 

How often have the words fissile and fissionable occurred in a corpus of books? (source: Google Ngram Viewer )