People are not getting killed by the heat, but by the radiation needed to do that. My math on radiation is a bit shaky, but to heat water by 20 degrees, it need

People are not getting killed by the heat, but by the radiation needed to do that. My math on radiation is a bit shaky, but to heat water by 20 degrees, it needs to absorb 80000 Grey, isn't it. Now we can also assume that most radiation was not confined to the water. The dose to get a person sick is 2 Grey and 10 Grey (full body) is almost always fatal. Making a few leaps in logic here and it depends on how much water was heated, assuming it was in the litre range, then beeing close to such a device seems likely to be unhealthy.