Anything that allows you to live longer also increases your risk of developing cancer, or suffering from any other disease. Potential causes of death are a natural hazard of being alive.

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Developmental neurobiology? Can you recommend any good books? Seriously--even without plans of becoming an expert, I enjoy learning new things.

That's exactly right, but people prefer letting the papers think for them. In a nutshell: If the thing didn't go critical, it would not be a viable power source. Criticality is the condition where, on average, each fission begets one further fission--this is how a constant power level is maintained. Further, supercriticality corresponds to increasing power output, and subcriticality to decreasing output. All of these conditions are necessary for the reactor to respond to changing power demands, and none of them is inherently bad.

"Quantum diamonds are forever. Or are they?" --Lord Nimula