Kodama Tatsuhiko, Professor and head of the Radioisotope Center at the University of Tokyo addressed the Committee on Welfare and Labor of the House of Representatives on July 27, 2011. Below is an excerpt from his comments on Fukushima "source" terms and fallout longevity:
CITATION: Kodama Tatsuhiko (trans Kyoko Selden) Radiation Effects on Health: Protect the Children of Fukushima. The Asia Pacific Journal Vol 9, Issue 32 No 4, August 8, 2011, http://japanfocus.org/-Kodama-Tatsuhiko/3587
When we calculate on the basis of the knowledge available at our Radioisotope Center, in terms of the quantity of heat, the equivalent of 29.6 Hiroshima a-bombs leaked.
Converted to uranium, an amount equivalent to 20 Hiroshima a-bombs is estimated to have leaked.
What is further dreadful is that, according to what we know so far, when we compare the amount of radiation that remained after the a-bomb and that of radiation from the nuclear plant, that of the former goes down to one-thousandth after one year whereas radioactive contaminants of the latter are reduced to only one-tenth.
In other words, in thinking about the Fukushima nuclear power plant disaster, the first premise is that, as in the case of Chernobyl, an amount of radiation equivalent to tens of a-bombs was released and far greater contamination remains afterward compared with the a-bomb.Keep in mind that he is describing the "initial" atmospheric release. His estimate does not include ongoing atmospheric emissions, nor does it include contamination of the ocean and aquifer.