Comment on "Global risk of radioactive fallout after major nuclear reactor accidents" by Lelieveld et al. (2012)

Abstract

In the above mentioned article we assessed the worldwide risk of exposure to radioactivity due to the atmospheric dispersion of gases and particles following severe nuclear accidents, using particulate 137 Cs and gaseous 131 I as proxies for the fallout. To evaluate the global risks, we applied empirical evidence to estimate the probability of severe accidents. Our results and the methods used have been subject of scientific and public debate. For this reason, we re-opened the discussion and offered the possibility to contribute comments. We used Atmospheric Chemistry and Physics Discussions as a transparent, public and archived forum, through the submission of a standard "peer-reviewed commentary", which is directly linked to the original scientific publication. Commentaries, clarifications and corrections of this nature are a standard procedure in other journals, although most do not require peer review of such commentaries as in ACP; we note that this is not, as asserted in some of the comments, a submission intended as a new scientific publication. We have also used the opportunity of this forum to provide some additional information and explanation about the assumptions and methods basic to our work. Answers to frequently asked questions about this article:Q1. Why did you adopt the Chernobyl accident as a source of radioactivity in your model?The Chernobyl accident was at the time of our manuscript's publication (and is still) the only INES 7 accident for which a broad consensus exists about the emissions. The emissions by Chernobyl have been adopted in many previous publications and were presented as "revised estimates" by IAEA (2006). Furthermore, Davoine and Bocqet (2007) re-assessed the Chernobyl source term by inverse modeling and found that their results are in good agreement with the latest reported emission estimates with only a minor difference in their temporal representation. Nevertheless, it may be assumed that substantial uncertainties remain. We only used 131 I and 137 Cs sources from Chernobyl, as these isotopes are typically emitted from any type of nuclear reactor after a major accident. For the other reactors accounted for in our global model the emissions were scaled by their gross capacity to account for the different amounts of nuclear fuel. Q2. Why didn't you adopt Fukushima as a source of radioactivity in your model?The emissions from Fukushima are associated with a significant degree of uncertainty, and are subject of scientific debate. Nevertheless, the order of magnitude of the Fukushima emissions is meanwhile reasonably well known, at least for certain species, indicating that they are generally lower than from Chernobyl. Table 1 in our article presents a range of emissions based on the two references available at the time of publication, Chino et al. (2011) andStohl et al. (2012). If the Fukushima emissions per reactor would be a factor of ten less than of Chernobyl, and if they would also be more representative for major accidents than Chernobyl, the calculated risk Published by...

Global risk from the atmospheric dispersion of radionuclides by nuclear power plant accidents in the coming decades

“…(Christoudias and Lelieveld, 2013). To obtain the overall probabilistic risk, one would also need to account for the accident and emission risk of each individual plant or an average risk of all plants, which is speculative, as such information is not publicly available (Lelieveld et al, , 2013. Therefore, the results presented here compare the relative impacts of different radioactivity emission sources based on meteorological conditions rather than the risks of individual nuclear power plant accidents, as we assume the same source for each plant, regardless of local accident risk factors, number of reactors, capacity, etc.…”