From what you were saying, if you are educated, and employed by the government - then you will be signing things to say that you will not disclose the information or you maybe tried for treason. So you have given your word not to do that in exchange for them GIVING you that knowledge as well as a wage. In effect - its NOT your knowledge to be giving away in the first place - so its treason.
Studying nuclear physics doesn't make you capable of building nuclear weapons - otherwise every country who wanted them would have them. They need to research, test and develop themselves! During your employment, they will be giving you access to the knowledge already gained. So you then claim its your knowledge to do with what you wish? Simply not true.
However, if you did research it all yourself, then you could claim that. At that point, the treason is due to you not doing what is in the best interest of your country - or betraying the countries wishes (as far as i am aware anyway - i am no lawyer!) Your giving away informatino that can be used to hurt/destroy the country = treason.