Shielding isn't going to be a major portion of the cost. Exposure is from stuff that leaks, not stuff that comes through the walls. And the cost overruns are

Shielding isn't going to be a major portion of the cost. Exposure is from stuff that leaks, not stuff that comes through the walls. And the cost overruns are to a large degree due to regulations--specifically, changing regulations. The environmentalists have destroyed nuclear by forcing delays and changes, that is the *majority* of the cost. Especially the delays.