It's not competitive and not needed.
1) Free market has not and cannot support it--too many liabilities, too big, too complex, too risky in its current forms.
2) Other renewables are free market supported, affordable and a good investment. As a result, true renewables jumped from supplying 2% of new energy growth in the US in 2004 to 55% in 2009.
3) Nuclear power is too risky of a technology: it's so unforgiving that a failure of a backup energy supply at Fukushima AFTER the nukes were shut down ended up destroying 4 out of 6 reactors and costing 20-100 Billion dollars. Who wants to take on risks like that, even with the Price Anderson Act limitation on liability?
4) New nukes--and old ones for that matter--have a consistent history of huge cost overruns. And what do you think will happen to the already-sky-high 8 billion dollar pricetag of the new nukes planned in Texas and Georgia after Fukushima?
5) It is far cheaper for a utility to invest in negawatts, i.e. in saving energy and promoting energy efficiency as a means to meet its future needs, rather than investing in a new power plant. This gives them time for renewable energy technologies to mature and so when it's time for existing power plants to retire, low carbon alternatives will be even more affordable.
6) Centralized power plants are like mainframe computers: no longer necessary. Just as the desktop/laptop/smart phone sequence is infinitely more adaptable, affordable and versatile than the mainframe, so it is with energy. New buildings and subdivisions can generate their own power needs through locally controlled, decentralized power sources, added to the existing grid in modular ways that the transmission system knows how to adapt to, and the grid is getting smarter and smarter every day.
Will nuclear ever be relevant? Who knows what the future will bring? Some folks are enamored with thorium, which eliminates many of the proliferation/contamination/accident potential, tho not completely. One thing is for certain: nobody in their right minds should be trying to build more of the water cooled reactors, complete with adjacent spent fuel pools. Time to move on. The same amount of money can and should be spent much more productively pursuing other energy paths.
For an interesting summary, check out Amory Lovins' Economist magazine article:
http://www.rmi.org/rmi/Library/2011-03_EconomistDebate 
