Given the insane amounts of iodine released,
Again, that's because the initial assumption was "everything gets released." Since basically all the gaseous products were released, those projections line up relatively well. However, nothing else does. That's why the total dose projections are way, way off. To the point that they add negative value because people try to take them in any way seriously.
The actual contaminated land that should have required actual evacuation was much smaller, but a severely bungled response by TEPCO and Japan prevented a reasonable evacuation. Hell, there's currently restricted land that could be safely inhabited right now.
But seriously, what parameters would you put in RASCAL that would end up with real world survey verified areas 40 miles out needing to be evacuated?
Personally? None, because I think Fukushima showed that doesn't actually happen.
But, ignoring that, how about the ones that actually existed? Impossible to do at the time, though, since Japan and TEPCO bungled the response and sucked at communication. That was the whole reason entirety unrealistic projections were made.
Side note: there were few areas (none I'm aware of) 40 miles away that actually needed to be evacuated (except in the ocean, I'd guess).
I'm not an EP or HP guy, so I could be talking out of my ass, but here's a rundown as I understand it:
UNSCEAR estimates are that, if you assume 80-year post-accident lifetimes, a person living inside the 20 km zone (but outside the closer zones) would get a lifetime dose of 100-150 mSv in the most contaminated townships.
For reference, natural background radiation in the US is about 2.4 mSv per year, so 150 mSv is about equal to the lifetime background dose of a typical American.
Fukushima was a human failure. The technology did great given the circumstances. Shitty regulation, shitty emergency response, shitty operations, and shitty everything else and still it posed surprisingly low risk outside of its nearby surroundings.
Compare that to a coal plant. The EPA estimated a few years ago that they cause about 7,000 to 14,000 early deaths a tear domestically when they operate normally. Possibly the worst modern nuclear accident feasible caused zero. And should have resulted in way less than the 120,000 or so evacuees that it produced.