The sight of Japan's Fukushima #3 nuclear reactor exploding is chilling (Youtube video pasted below.) When the remaining best-case scenario involves pumping seawater into a nuclear reactor and venting off the radioactive steam in a highly populated area, you have to wonder "how the hell did we get here?"'
Critics have long contended that Japan high level of seismic activity makes it a poor place for nuclear power, while nuclear proponents have been equally confident that it is safe. Judging from the island nation’s dependency on nuclear energy (roughly 1/3 of power generation), it seems clear that the optimists' arguments have (until now) carried the day.
The same confidence in the safety of Japan's nuclear plants led to the loading last fall of a new fuel type called MOX (mixed-oxide) into the core of the Fukushima #3 reactor. In contrast to the Uranium that powers most reactors, MOX is basically a Uranium cocktail spiked with Plutonium. Greenpeace reports that using MOX in a reactor is less safe because "plutonium is more reactive and this hotter fuel can cause increased localised melting of fuel in the reactor." A release or accident is also more severe, since plutonium is one of the nastiest and most toxic substances around, and MOX reactors have a lot more of it.
So what would have prompted officials to make an already risky proposition even riskier? The answer of course is that they don't (or at least didn’t) believe that the risk exists. Overconfidence leads to poor decision making.