Jr, my guess is that it wasn't the "blemish" on your background check that caused your UA denial but rather the lack of disclosure of it. If I am wrong or jumping to conclusions, I apologize since I don't know the specific nature of this discrepency. When applying for unescorted access at a nuclear facility you should disclose EVERYTHING that even has the potential to be found on a background check. If they find something you didn't disclose, they will almost always deny you unescorted access. However, if you disclose something that is no longer in the forefront of your life, i.e. past DUI, fitness-for-duty violation, etc., they will usually grant you access with minimal grief. It would be a rare event you find someone that has a 'not-so-perfect' background, that was not disclosed on a Personnel History Questionnaire working at a plant. If you do find someone like that, they would hardly be willing to come forward. In any event, I wish you luck. I know the unescorted access requirements seem a bit overboard, but that's the way it is.