You had an experience that traumatized you. It may or may not be something that you will overcome, but you are trying to come to terms with what you saw, and that is good. Everyone needs to know that self preservation is inherent to the human being, and we at times do things in that interest when other actions are warranted. It is just who we are. That said, the Navy did the right thing in your situation. There is no room in engineering spaces for an unreliable, unpredictable engineer, no matter what the cause or the effort to mitigate it.
You need to come to terms with yourself that working in your trade is not something that you can continue to do until your fears are understood and put in their proper place. Keep in mind, that therapy may get you off the meds, but until you can demonstrate that you can work on electrical equipment, no amount of progress will be meaningful. What that means is to get well, you need to work in your environment, but to work in your environment, you need to be well. You have a hard road to travel and may in the end, even if cured, preclude an employer from taking the chance that you are not 'well'.
My advice is that you get on with your life. Upon discharge, get the disability, no matter how minimal it is, just so you can get VA Hospital care and continued therapy. Take advantage of the education benefits available to you and look forward.
By the way, from what you said about the accident, it looks to me like the Chief ignored safety procedures of which he should have known. What happened was of his own doing, and while tragic, is yet another lesson that assumptions and short cuts can be fatal. What happened, should not have happened. Whether that helps you put your experience into context is up to you.
Oh, nuclear power, or for that matter, conventional power generation is not the all there is in the world. I was an RO and became an accountant. What you have learned in the nuclear navy is more then just the plant. Put the effort you put into your navy job into another field (or one not involving maintenance), and you will be fine.
Good luck to you.