That is a somewhat silly statement; obviously it only makes sense to build nuclear plants if the resulting energy is cheaper than the alternatives. And nuclear power is as the most environmentally friendly source of energy we know of.

The argument, as it has been for about 40 years now, is that the people saying it is not cost competitive tend to have high overlap with people who are changing regulations to ... make it very expensive. If the regulatory framework was sane, it'd be quite cost competitive.

The problem nuclear has is the economic learning curve has been inverted. That can only be caused by overregulation.