From what i can gather the Gabon had an output of 100kW, compared to the following figures I got from
http://www.fissilematerials.org/blog...of_unit_4.html
"Fukushima-I (Daiichi) has six boiling water reactors (BWR), ranging from 460 MW to 1100 MW, started up between 1970 and 1979. Fukushima-II (Daini) has four 1100 MW BWRs, commissioned between 1981 and 1986. Eleven nuclear reactors were in operation and three in planned outage in the coastal areas of Japan...when the tsunami struck (my words)..... All units had emergency shutdowns. In the follow-up, seven reactors declared a nuclear emergency, in particular because of lack of power supply and deficient cooling systems.
So, I'm not sure if comparing the environmental impact of a 100kW reactor to at least 5 1100MW and 5 at least 460MW reactors has any real validity here.
As far as the Hiroshima and Nagasaki situations, I reckon there would be a huge difference in the effects of an atmospheric explosion compared as opposed to a partial meltdown. Also, the amounts of fissile material would be far greater in the case of 10 reactors plus 40 years of waste.
As far as getting perspective about nuclear materials and the harm they can cause, here's some perspective from someone who has experienced the harm they can do first-hand....
http://www.bbc.co.uk/news/science-environment-12344861
Cheers
Stephen