Nuclear power occupies a weird space in American politics. Environmental types tend to dislike it, despite the fact that it's almost entirely carbon-free. Conservatives love it, even though, with its heavy reliance on government funding, it's the most socialist power system imaginable.

But there's one aspect of nuclear that gets comparatively little attention: its inherent political vulnerability. This recent report offers a good example of why nuclear is so iffy:

Researchers say radioactive cesium isotopes from Japan's severely damaged Fukushima nuclear power plant have made their way to the waters just off the coast of Canada. [UPI]

That's right. Three years after the nuclear meltdown in Fukushima, we're pretty sure a radioactive plume just finished crossing the dang Pacific Ocean.

Luckily, the radioactive cesium is so diluted by this point that it poses no danger (so far anyway). But nuclear meltdowns freak people out, and for good reason. The hazards are obvious and easy to understand: Invisible poison! Cancer! Mutation! Early, painful death! And, it turns out, radioactive plumes stretching 4,800 miles across the ocean!

What's worse, meltdowns last forever, both in terms of the damage they inflict and their lifespan in the media. Chernobyl is still ring-fenced, and they'll be cleaning up Fukushima for decades, if not centuries. While most people have forgotten about the massive explosion at the fertilizer plant in West, Texas, nuclear meltdowns generate a steady stream of bad press for a long time.

Nuclear boosters argue that the dangers of Fukushima have been exaggerated, and don't apply anyway to the U.S., which isn't nearly so tsunami- or earthquake-prone. They make some good points. But one does have to make a concession to political reality. Just look at Germany, which got so unnerved post-Fukushima that it retired all its nuclear stock. Japan did the same, leading to a spike in oil consumption and imports.

In other words, for a supposedly clean and stable source of energy, nuclear is extremely unreliable.

It would be a different story if nuclear were super-cheap and political panic were the only obstacle preventing its deployment on a grand scale. But the opposite is true. While wind and (especially) solar have been crashing in price, nuclear has actually been getting more expensive. New nuclear plants are stupendously costly to build, maintain, and insure, which is why they can only be built with colossal government subsidies.

The point shouldn't be taken too far. I am still mildly pro-nuclear, because every carbon-free technology deserves thorough research and scrutiny. If it is a choice between coal and nuclear, nuclear is the obvious choice. But if it is a choice between nuclear and renewables, the choice is much less clear. Few things would be worse than going big on nuclear, only to abandon the endeavor halfway over political considerations.