the nuclear option?

http://politicalticker.blogs.cnn.com/2013/11/21/harry-reid-likely-to-go-nuclear-today/?hpt=hp_t1

this post is about a bill trying to be past that is called the nuclear option I am a little lost on the subject but the republicans are saying its just something to hide the Obama care debacle what has my ears perks is the word nuclear I read a little bit on the matter but I am confused on it but this sound like a serious matter that needs to be discussed if you have anymore information about it please give it to me in your comments thanks.