Steve may well be right that we need nuclear and that new designs are much better. I am inclined to believe that when he speaks, he knows what he's talking about. But the nuclear industry has only itself to blame for the highly negative public opinion.
As far as I know the economics of nuclear power have never been discussed on SGU. Steve has impressive credentials but I don't believe they include expert knowledge of power generation distribution and sales.
I'm not much of an expert on those either but I am in a unique position of being both a solar panel installer on the side as well as being currently employed in the nuclear industry. Over the last five years I've watched with amazement as the cost of solar and storage have become cheaper than I had optimistically predicted. I'm helping a friend install a 26kW PV system that will cost ~$0.70/w. That's <$0.02/kWh over 20 years. Costs are still falling. At the same time the construction of new plants at Vogtle and Summer seen massive cost overruns and threatened the solvency of their builder. This isn't a one-off event. It's rare to find a nuclear plant built since 1980 that wasn't massively over budget and behind schedule.
The main economic problem with nuclear is that compared to the capital and O&M cost, fuel is a rounding error. A nuclear power plant is massively expensive to build and maintain. They must be kept online to stay viable. As wind and solar grow they will force the curtailment of other generators. A nuclear power plant that can't be operated with a high capacity factor isn't worth keeping.
It's true that solar and wind alone can't support the grid. It's also true that storage still needs decades to scale to a level that fossil fuels can be fully displaced from the grid. But a $1 invested in solar, wind, storage and demand response is far more effective than a $1 invested in new nuclear. We will need load following gas plants for decades to come... even if we were able to build more nuclear.
The new reactors are less prone to a "China Syndrome" type accident, where the radioactive rods collapse into a critical mass in case of a meltdown. They are also simpler, their cooling systems less prone to leaking radioactive gasses or water. And they are more reliable. But, the new reactors still generate a a lot of waste.
We generate and have to store tons and tons of waste.
Following the earthquake and Tsunami in Japan it was the nuclear waste stored on-site that caused most of the issues. Waste storage and maintenance issues of issues don't go away with the new plants, and no one in our democracy wants the radio active waste transported to and stored in their back yards.
Coal is only worse in the very short term. Nuclear waste is forever.
IMO safety isn't the issue. It's cost. New reactors are safe and have fewer parts but the cost has still gone up.
It's important to make the distinction between short term storage and long term storage. It was the fuel pools in Japan that created the problem. Long term waste storage is very secure and as far as I'm aware there has never been an issue.