Of the first 10,000 people exposed to radioactive plumes in the wake of the Fukushima accident—those assumed to have the highest levels of radiation exposure—only 73 had exposure higher than 10 millisieverts.
Average annual background radiation is about 3-4mSv, in Denver that rises to 1.8 (and oddly Boston hovers around 1.0.) The world leader on background radiation seems to be Iran, where in one town, Ramsar, annual background radiation of 130mSv or more have been measured--the population there appears to be healthy. So, the workers got about as much exposure as people in Boston do in 10 years. Not bad.
The strangest line in the piece, though was this one:
In comparison, the half-million workers who entombed Chernobyl had average exposures more than ten times as high.
It's not the radiation dose that caught my eye, but the idea that it took 500,000 people to drop concrete on a single site. How could it possibly take that many people?