Very good answer to a nuclear accidents question by Kai Vetter, professor in nuclear engineering at UC-Berkeley in his reddit AMA. No doubt that the Dai-ichi nuclear power accident was a very significant event that has and will continue to impact particularly Japan economically, politically, and with respect to society. There are still more than 90,000 people evacuated due to the radiological contamination close and north-west of the site. However, in contrast to for example, Chernobyl, the Japanese government did immediately respond to the releases of radioactivity and evacuated large parts of the population close to the site to minimize the risk for potential health effects. Compared to the 28 radiation induced deaths in Chernobyl within the first 4 months no life has been lost yet in Fukushima due to radiation. Yes, some of the radiological and emergency workers have experienced increased exposure, but they are closely monitored. The three main nuclear disasters often discussed are Three-Mile Island (TMI), Chernobyl, and Fukushima. TMI did lead to only small amounts of releases of radioactivity and no health effects have been observed. Chernobyl can indeed be seen as the biggest nuclear disaster as large parts of the radioactivity contained in one of the reactors and the explosion led to releases of large amounts of fission fragments into the atmosphere and therefore led to the contamination of large areas in Europe. Due to the lack of protection and information, I-131 contaminated milk was consumed particularly by children in the Ukraine leading to about 6000 cases of thyroid cancer resulting in about 15 deaths. The nuclear accident in Fukushima was quite different and did result in significantly less releases of radioisotopes into the atmosphere. Overall, the total releases in Fukushima, e.g. in I-131 or Cs-137 were factor 10 and 5 smaller than in Chernobyl, respectively. The releases into the atmosphere were significantly smaller. To date, Fukushima has not resulted in any death due to radiation. Many health experts expect not to be able to detect any health impact in the future. The reason is that the average cancer incident rate in Japan is about 40-50% and to-date there is no scientific way to distinguish in the causes of cancer (although research is being done on this topic e.g. at Berkeley Lab). The population in Japan close to Fukushima is and will be closely monitored and will provide very useful data on the impact and more in general to better understand the relationship between radiation levels/ dose and health effects. Contaminated water continues to be leaking into the Ocean, however, the observable levels beyond the close vicinity are very small. This is due to the enormous dilution effect of the Ocean and the fact that Cs settles to the sediment quickly. Significant efforts are underway to build a barrier around the site to prevent further leakage into the ground water and ultimately into the Ocean. On the West Coast of the US seafood or any food will remain very safe to eat. The measurements to date and the projections show that the levels of radioactivity due to Fukushima will remain far below the levels due to naturally occurring radioisotopes. We are exposed to these varying levels in our daily live which are also not posing a health risk. Just to put Fukushima into the context of the impact of the root cause which is the earthquake and the subsequent tsunami. The impact of the tsunami was enormous. Still about 170,000 people are evacuated as their homes are still destroyed (in addition to the 90,000 evacuated due to the radioactivity). More than 18,000 people have been killed and or are still missing and are assumed dead. Again, no radiation induced death have been observed to-date, three years after the accident. Even if thyroid cancer will be detected in children, it will be recognized at a very early stage and will be treated.
Posted on: Fri, 14 Mar 2014 06:55:57 +0000
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