I work at all three DOE sites in Oak Ridge. I don't know if you'll get your DOE Q clearance. Having been through it, I'm not sure what the process is to award them. Having been through both the NRC and DOE clearance processes, I can tell you that there are very few similarities between them [if any].
I know that, for a DOE clearance, they do pretty thorough background checks. So, what you divulge needs to be in line with the people that they talk with who know you. They'll interview your references, then ask them for references, then ask them for references. They're looking for inconsistencies [which are their primary concern, I think]. As far as how they decide who gets one and who doesn't, I think that it might involve three monkeys in a room with a Magic 8-Ball. I can tell you, that I' don't know anyone personally who was turned down for a clearance, just people who took very long times to get them [which can exceed the employee's lifetime in some cases]. This time to clearance award, also seems to be a totally random process based upon whose desk your paperwork gets lost. Some people get them in six months, some people in three years, and I know some who have been waiting for over ten years. I had a couple of employees who worked for me for years and left for other jobs without their clearances ever coming through.
In my own case, my job had the same requirement to be able to obtain a Q clearance. So, when I hired on I filled out my application. Within three months, I received my L Clearance. Within the next three months, I had a dozen people from my past contact me that they'd been interviewed. A year later, I was called in for an interview to go over some questions that some reviewer had identified. A year and a half after that ( over three years total), I got my Q clearance.
The point to all of this is that, provided you explain to the hiring manager and HR all of the stuff that you told us [and will divulge on your clearance application], then whether or not you actually ever get your clearance is a random process of indeterminate timespan [they understand this]. If the employer is willing to hire someone who doesn't yet have a clearance, then that means that they have plenty of uncleared work for you to do while you wait for it to come through [which could take forever]. In the mean time your work history will speak for itself. If you do good work and they like you, then, even if you're eventually rejected [after three to ten years], they'll probably either: (a) change your job position requisition to not require a clearance; OR (b) bring you back as an uncleared subcontractor making twice as much money.
Therefore, I say divulge everything, and if they still hire you, then don't worry about when or whether you ever get the clearance. Focus on doing good work and getting along with everyone. About the time that you stop caring whether you ever get the clearance, they'll give it to you, whether you want it or not.
Good luck,
mgm