Nuclear ground-orbit vehicle

[DAT]

Originally Posted by theshadow99

Really this was just one within the US that went critical (three mile island), a few others with issues, and Russia's Chernobyl disaster... Oddly I learned the other day that they don't even teach why the US has stagnated on nuclear energy for the last 30 years, when a 2nd year political science major asked me what I was talking about when I said that nuclear energy had stagnated in the US... Though this is a repeated problem, the Hindenburg ended Blimps for around 70 years. Both are things we've rethought in the last decade, slowly realizing they weren't so bad.

The problem wasn't that TMI Unit 2 'went critical', nuclear fission reactors go critical to operate. The problem was that TMI had a loss of coolant accident and a portion of the core melted. When the fuel in the core melted, the fission products were released into the primary coolant. The radioactive fission products were spread into the containment building and into the secondary coolant. When the plant had to make a controlled vent to lower the containment building, a relatively small amount of radioactive steam was released. A measure of the radiation levels were made at the outlet of the stack and at the edge of the plant site. Due to the distance and air dispertion between the points, the radiation level at the plant site boundary is a thousand time or more less than the radiation levels measured at the stack outlet. When someone made the major goof of reporting the value from the stack as the value from the plant site boundary, a mandatory evacuation was called. By the time someone who knew an evacuation wasn't needed, it was too late.

That was probably more than what you wanted to know about the TMI accident.