Ionizing radiation as it affects people is what is important and today it is measured in Sieverts. It used to be measured in REMs which stands for Rontgen Equivalent Man – 1 milliSevert (1 mSv)is 0.1 REM.
Radiation comes in several forms and is measured several ways.
Alpha radiation can be stopped with a piece of thin paper but inhaling an alpha emitter is dangerous.
Gamma is the most dangerous, equivalent to what you get in X-rays or airport Scanners.
A mammogram generates about 3 mSv. Other common X-ray studies range up to 15 mSv.
At Three Mile Island the peak (maximum) radiation dose was 1 mSv. A mile or so away the absolute maximum exposure was about 0.1 mSv. Greater than a dental X-ray but less than a chest X-ray or the amount you might experience during a 6000 mile airplane ride.
The background radiation from any environment on planet Earth is between 2 and 6 mSv per year with a few higher and a few lower areas.
1,000 mSv (1 Sv) is a dangerous dose.
So far the disaster in Japan had a peak reading of 400 mSv/hr for a few minutes and that was at the reactor plant.
At Chernobyl the highest recorded radiation level was about 300 Sieverts (not milliSeverts) per hour. About 100X a probably fatal dose so some workers such as firefighters nearby were probably getting a fatal dose about every 2-10 seconds.
For adult humans (children are more at risk and the elderly are generally at lower risk if they are otherwise in good health) the risk from TOTAL dose over a short time is:
>1,000 to 3,000 mSv (1-3 Sv) is a dangerous dose
>3,000 to 6,000 mSv could be fatal
>6,000 to 10,000 mSv is usually fatal
But remember that the peak 400 mSv per hour at Fukushima 1 was PER HOUR, divide that by 60 for how much radiation you would get in one minute if you stood in the worst place at the reactor building for a minute. You wouldn’t get 400 mSv even there because that peak didn’t last an hour, just a few minutes.
No one has ever died as a result of a nuclear power plant accident in the United States and we have more than 100 old units still operating.
35,000 to 45,000 people are killed in highway accidents each year.
It has been estimated that between 200 and 1000 people die each year from accidental suffocation during sex (erotic or autoerotic asphyxia.
Consider some actual facts before deciding that it is better to huddle hungry and cold in the dark because nuclear power is just too dangerous. Too dangerous compared to WHAT exactly? More workers have died by falling from wind turbines.