mdsolar's point isn't that we should build no new nuclear, at least not in this thread. His point is that nuclear can't, in and of itself, decarbonize the electric sector. We simply don't have the capacity to build that many nuclear power plants simultaneously, nor do we have the fuel, nor do we have the money.
The first one might be overcome. After all, if world leaders were able to simultaneously lay out this plan and get political support for it, part of the plan would include training more engineers, trades, and other jobs necessary. We might not be able to build 100 per year in 2016 (or even 2020), but we could ramp up.
The second one might be overcome. After all, with pressure for more fuel, we might go out and find more fuel, develop new techniques to find, recover, and process more fuel, etc. I doubt we could overcome it, but generally speaking if we went "long" on nuclear, at least some more fuel would turn up.
The third one is the toughest. Nuclear power, today, is more expensive than wind and in some places, more expensive than solar. Given that wind and solar don't have the political opposition, don't have 10-15 year lags from "let's build it" to "let's turn it on", and can be built in more places at far smaller increments, it's really tough to argue that we should spend the money on nuclear when there are cheaper options. But -- that could change. Improving the regulatory climate could help lower construction costs, as could improvements in design. Wind and solar $/kW will continue to fall for a while, but perhaps their supply inputs will become scarce and, at least for wind, the locations for the best wind become scarce. At some point in the future it's possible that the $/kWh for nuclear will become cheap enough, but it's not there now.
My view: don't put any option off the table, but let's spend our money to get the most decarbonization per buck. Right now, that means going long on energy efficiency, retiring the old coal units, building wind and solar where we can, and keeping (most) nuclear units already built up and running, so long as their safety is secure. Simultaneously, we should price carbon appropriately, eliminate subsidies on oil, coal, and gas, and be working to lower the cost of all no-carbon generating options using both technology and regulatory approaches. All of those things, together, will result in a steady least cost decarbonization of our electric sector, and if/when/where nuclear can beat out wind and solar, so be it.