While the japanese government agreed to consider the worker's lung cancer, four year afterwards, as having been caused by his heroic efforts so that his family would get benefits, there's very real doubt as to whether it actually was. However, there's no point in arguing over that one death since it doesn't matter at all for the question of whether harmful radiation was released or not. His situation wasn't exactly the norm.
https://en.wikipedia.org/wiki/Fukushima_nuclear_accident#Fatalities