Why don't we build more nuclear power plants?

Prospects for Nuclear Power
Lucas W. Davis

Abstract: The prospects for a revival of nuclear power were dim even before the partial reactor meltdowns at the Fukushima nuclear plant. Nuclear power has long been controversial because of concerns about nuclear accidents, proliferation risk, and the storage of spent fuel. These concerns are real and important. In addition, however, a key challenge for nuclear power has been the high cost of construction for nuclear plants. Construction costs are high enough that it becomes difficult to make an economic argument for nuclear, even before incorporating these external costs. This is particularly true in countries like the United States where recent technological advances have dramatically increased the availability of natural gas.

Understanding Nuclear Accidents

As if the direct damages from the Sendai earthquake / tsunami weren't enough, there's now ample concern that one of the nuclear power plants damaged by the quake might melt down. Ed Lyman of the Union of Concerned Scientists' All Things Nuclear blog has an overview of what's going on and how this could make an already horrific disaster worse:

I have done considerable analysis on the safety risks associated with using MOX fuel in light-water reactors. The use of MOX generally increases the consequences of severe accidents in which large amounts of radioactive gas and aerosol are released compared to the same accident in a reactor using non-MOX fuel, because MOX fuel contains greater amounts of plutonium and other actinides, such as americium and curium, which have high radio-toxicities.

Because of this, the number of latent cancer fatalities resulting from an accident could increase by as much as a factor of five for a full core of MOX fuel compared to the same accident with no MOX. Fortunately, as noted above, the fraction of the fuel in this reactor that is MOX is small. Even so, I would estimate this could cause a roughly 10% increase in latent cancer fatalities if there were a severe accident with core melt and containment breach, which has not happened at this point and hopefully will not.

They also have an excellent two page pdf describing how nuclear power plants work and why they can be so unstable.

More broadly, one of our better estimates of the long-term impacts of nuclear fallout was actually done by Doug Almond, one of the SDev Ph.D. program's core faculty. From his 2009 Quarterly Journal of Economics article with Lena Edlund and Mårten Palme:

We use prenatal exposure to Chernobyl fallout in Sweden as a natural experiment inducing variation in cognitive ability. Students born in regions of Sweden with higher fallout performed worse in secondary school, in mathematics in particular. Damage is accentuated within families (i.e., siblings comparison) and among children born to parents with low education. In contrast, we detect no corresponding damage to health outcomes. To the extent that parents responded to the cognitive endowment, we infer that parental investments reinforced the initial Chernobyl damage. From a public health perspective, our findings suggest that cognitive ability is compromised at radiation doses currently considered harmless.

There's accompanying video of the Chernobyl plume's spread here. And not to be terribly alarmist, but western North America is directly downwind from Japan.