How is it less expensive then solar??? Are you using solar panels from 1970?
It has always been highly subsidized. And there is also cost to keep it working. Fuel rods and people... And if you include "persistent waste storage costs" and force them to pay money into a fund that will be used in case of a rare catastrophy, combined with the prediction of solar getting cheaper and cheaper, no one with the intention to gain money would invest in that.
But what's the radius of the balls?