I would assume that if you took a poll of cleared RCT's, 90% of them are working.
The only way a company would get that cleared RCT to work for them would be by offering them a little extra hourly, diem, and incentive bennies.
Then, that RCT would take the company with more money. This business isn't any different now than it was in the 80's, when you are talking about taking the higher bidder for your services.
If the DOE would set up a program where you could pay a reasonable price to get and keep your clearance, they could recoup some of their losses when they do the investigations, and the "cleared RCT" population would rise significantly.
I don't ever see it happening, but it sounds good.