Confession is good for the soul
You confessed you are no nuke scientist, and you tell the truth.
But why would you not then have the integrity to pose your idea as a question, and then why not seek an answer sompleace like google?
Here is a link to a nuke scientist on google that shows your idea that 31 grams of matter is converted to energy is completely off base:
http://physics.bu.edu/py106/notes/RadioactiveDecay.html