What degrees are needed, and how much experience.

If you have some experience in the field could you tell them what the prefrences are for employeers?

First, a nuclear engineer or physicist has to know how to spell.

Your questions can be answered by this article in the current Occupational Outlook Handbook:

Nuclear Engineers (http://www.bls.gov/oes/current/oes172161.htm)

Apart from the masters and PhD degrees, you need to be focused and committed to what you are doing. Paul Halpern, Ph.D Physicist (http://www.superscholar.org/interviews/paul-halpern/), says physicists need considerable focus and either strong mathematical abilities for theorists or superb technical and computer skills for experimentalists. It's not easy, if you want to get into physics, learn as much math and computational skills as possible.