"but your assumptions just don't jive with what I've read are the true costs of nuclear power plants. The huge construction and operating costs without massive governmental subsidies make the payback time for a private firm way too long to be commercially viable."

You can make laws that cause a hamburger joint's "true costs" be so high that "huge construction and operating costs without massive governmental subsidies make the payback time for a private firm way too long to be commercially viable."

There is no doubt that in the American political environment the true cost of building a nuclear power plant is too expensive- hence few are being built. But in terms actual or reasonable "true costs" without addition of psychotic regulation and laws [which are deliberately designed to inhibit building and maintaining nuclear power]
nuclear power can be cost effective [not require any tax dollars to subsidize.

Reference:
The report of a major European study of the external costs of various fuel cycles, focusing on coal and nuclear, was released in mid 2001 - ExternE. It shows that in clear cash terms nuclear energy incurs about one tenth of the costs of coal. The external costs are defined as those actually incurred in relation to health and the environment and quantifiable but not built into the cost of the electricity. If these costs were in fact included, the EU price of electricity from coal would double and that from gas would increase 30%. These are without attempting to include global warming.
"http://www.uic.com.au/nip08.htm

"France has 59 nuclear reactors operated by Electricité de France (EdF) with total capacity of over 63 GWe, supplying over 430 billion kWh per year of electricity, 78% of the total generated there. In 2005 French electricity generation was 549 billion kWh net and consumption 482 billion kWh - 7700 kWh per person. Over the last decade France has exported 60-70 billion kWh net each year and EdF expects exports to continue at 65-70 TWh/yr.

The present situation is due to the French government deciding in 1974, just after the first oil shock, to expand rapidly the country's nuclear power capacity. This decision was taken in the context of France having substantial heavy engineering expertise but few indigenous energy resources. Nuclear energy, with the fuel cost being a relatively small part of the overall cost, made good sense in minimising imports and achieving greater energy security.

As a result of the 1974 decision, France now claims a substantial level of energy independence and almost the lowest cost electricity in Europe. It also has an extremely low level of CO2 emissions per capita from electricity generation, since over 90% of its electricity is nuclear or hydro. "
http://www.uic.com.au/nip28.htm

"In France, unlike in America, nuclear energy is accepted, even popular. Everybody I spoke to in Civaux loves the fact their region was chosen. The nuclear plant has brought jobs and prosperity to the area. Nobody I spoke to, nobody, expressed any fear. From the village school teacher, Rene Barc, to the patron of the Cafe de Sport bar, Valerie Turbeau, any traces of doubt they might have had have faded as they have come to know plant workers, visited the reactor site and thought about the benefits of being part of France's nuclear energy effort."

"http://www.pbs.org/wgbh/pages/frontline/shows/reaction/readings/french.html

"Because nuclear plants emit no greenhouse gases, France has the cleanest air in the industrialized world, and because the price of oil is now around $60 a barrel, it has the lowest electric bills in Europe. In fact, France has so much cheap electricity, it exports it to its European neighbors. French nuclear plants supply power to parts of Germany, Italy and help light the city of London.

"It is a very competitive way of producing electricity when oil prices are beyond, I would say, around $40 a barrel," Gadonniex tells Kroft.
http://www.cbsnews.com/stories/2007/04/06/60minutes/main2655782.shtml

These are first 5 hit on google search: "France cost nuclear energy"

The 4th hit is negative, it's dated 1999:
http://www.worldwatch.org/node/1646
Quote from Worldwatch Mission Statement:
"The Worldwatch Institute is an independent research organization that works for an environmentally sustainable and socially just society, in which the needs of all people are met without threatening the health of the natural environment or the well-being of future generations."

In other words they are against nuclear power. And no doubt coal and oil too.
They want the world run on wind mills.
I have nothing against wind mills- they are govt subsidized, but they can better then solar power in terms of costs. And it might be possible that without any govt subsidy they might be profitable in some locations. But they simply can't provide in a significant fraction of our energy needs- and in some locations which don't have good wind condition they are complete waste of money.