Coal plants give off several times the radiation of any nuclear power plant. Plus, they vent a LOT of thorium directly into atmo. You're more likely to get mutated off a coal plant than a nuclear power plant. Even the law is as dumb as most people are. If any nuke plant was giving off the radiation of a coal plant, they'd have the NRC on site demanding a LOT of answers.
This.
Heck, the COMPANY would have been all over us, if we exceeded company discharge limits (which were well below state and federal limits), when I worked at North Anna.
They don't want that kind of attention!
I seem to recall some of the most modern reactor designs now are self-limiting, in that you have to actively push them up to criticality, and if you left them alone they would default to a sub-critical state pretty much no matter what. It has been a few years since I've read much about them though, does anyone else have any info? (As has been stated, these reactors having the problems are "old tech," and not likely to be self-limiting.)
Reactors in the US are required by law to have negative reactivity coefficients in the power range (when at normal operating conditions between ~0-100% of rated power, as opposed to the Intermediate or Startup Ranges, which are many orders of magnitude lower). What that means is, as you suggest, they are "self-limiting". With no action, the plant will seek to shut itself down from the Power Range. Chernobyl, as a counter-example, had a POSITIVE reactivity coefficient - once they got themselves in trouble, the reactor ran away from them and went prompt-critical. Near-instantaneous spike orders of magnitude above 100%-power, steam explosion, rod ejection, containment breach, meltdown ... Nasty. The report from the Russian Academy of Sciences about that incident read like a comedy of errors - they did EVERYTHING wrong leading up to the actual incident. Wish I still had a copy of it, but it's been quite some time (I got it from work, when I was at North Anna). Not sure what Japan permits for their reactors, but if the designs are the same as our BWRs here in the US, I'd think they'd have to have the same negative reactivity coefficients as ours.
Unfortunately, the Gen-2 reactors, like the Fukushima plants and pretty much every plant in the US, use active safety systems, which require power and/or operator action in many cases to shut down and maintain safe-shutdown conditions. The Gen-3 designs, which are just starting to get approved here in the US, are designed to use PASSIVE safety systems - no power or operator action required. But people are still standing in the way of those being built.
Because, y'know, it'd just be STUPID to build safer plants...
