Having sat in the 4-star's chair, I can tell you that the interviews are nothing to sweat, especially if you have a good record of prior nuclear experience to back you up. In my power school class we had a LT who failed out of his flight school, and was no worse off than anyone else. One thing that hurt him though was making O4 without a dept head tour under your belt is almost impossible in the submarine community, just something to think about, in your case you may be able to squeeze in 20 before your HYT. Also, I can tell you that you are probably more capable academically than you may realize by making it through the pipeline, enlisted or EOOW. The only difference in curriculum is on the third floor, they derive the equations. Just keep in mind that as an EOOW student, you don't actually operate anything, given that, your enlisted experience should put you at an advantage. If you fail out, given the state of the nuclear officer community, I don't think it would be a stretch to send you back to a submarine.