There is the possibility that this may "un-nerve" a small percentage of potential buyers. On the positive side, it demonstrates that when you become aware of a problem, you address it. Another plus: The number of buyers who will "back away" is much smaller than if this were discovered during a home inspection.
Certainly, the existence of the system should be disclosed. Meanwhile, if the amount of electricity being used is insignificant, don't be shy about pointing out this fact. Actually, you could demonstrate it by showing prospects the electric bills for the past year.
My advice: If a potential buyer is "put off" by the Radon situation, smile and let them go. They'd probably find a half-dozen OTHER things to grumble about, also. [Grin.]