Nuclear power is not as reliable as you might think.

Capt'n Midnight

If you have to shut down a reactor for more than a few hours you can't restart it for several days. Xenon-135 poisoning and all that. So if you want to improve nuclear reliability then you better have a way to sink 100's of megawatts close to the power plant.

cba checking out the exact statistics - we've heard the scare stories about earthquake shields being build backwards, (and Indian reactors being unusable) so I'm resonably sure that even if exaggerated the claims are in the right ballpark - this wikipedia article claims that 48% of reactors in the US have had outages of over a year or more, it probably includes early reactors which wern't as reliable and no doubt will include many closed for political reasons. But if you take account the time it takes to build a reactor it's quite sobering, even if the figure isn't half it still means you probably need to have contingency plans to build a power station.


http://en.wikipedia.org/wiki/Intermittent_energy_source

in the United States, 132 nuclear plants were built, and 21% were permanently and prematurely closed due to reliability or cost problems, while another 27% have at least once completely failed for a year or more. The remaining U.S. nuclear plants produce approximately 90% of their full-time full-load potential, but even they must shut down (on average) for 39 days every 17 months for refueling and maintenance.[32] To cope with such intermittence by nuclear (and centralized fossil-fuelled) power plants, utilities install a “reserve margin” of roughly 15% extra capacity spinning ready for instant use.[32]

Lovins says that nuclear plants have an additional disadvantage: for safety, they must instantly shut down in a power failure, but for nuclear-physics reasons, they can’t be restarted quickly. For example, during the Northeast Blackout of 2003, nine perfectly operating U.S. nuclear units had to shut down and were later restarted. Lovins states that "twelve days of painfully slow restart later, their average capacity loss had exceeded 50 percent. For the first three days, just when they were most needed, their output was below 3% of normal"

Macha

Indeed, this was also seen across Europe during the heat wave of 2003 when river levels were too low and nuclear plants had to be shut down.

Every form of power generation has its advantages and disadvantages.