Tuesday, October 21, 2014

Comparing Fukushima and Chernobyl

Data are slippery and estimates diverge greatly for Fukushima and Chernobyl source terms. There exist no definitive figures for atmospheric emissions, only estimates. Here are some data points I've found:

CHERNOBYL Atmospheric Estimates
Estimates for Cesium-137 range from 70-280 PBq

Estimates for Iodine-131 range from 1760 PBq to 4000 PBq

FUKUSHIMA Atmospheric Estimates
Estimates for Cesium-137 range widely but in Schöppner et al. estimates range from 100-1000 PBq

Estimates for Iodine-131 range widely but Schöppner estimates 10,000 PBq


OECD Nuclear Energy Agency Radiological protection > Chernobyl: Assessment of Radiological and Health Impact 2002 Update of Chernobyl: Ten Years On. https://www.oecd-nea.org/rp/chernobyl/c02.html
[Excerpted] In their 1988 Report (UN88), the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) gave release figures based not only on the Soviet data, but also on worldwide deposition. The total 137Cs release was estimated to be 70 petabecquerels (PBq) of which 31 PBq were deposited in the Soviet Union.
[Chart for current estimates of releases put cesium 137 at 280PBq]
[Chart for Iodine-131 put total release For Iodine-131 1760 PBq]

Additional source: FRANCE’S IRSN estimates total Iodine-131 from Chernobyl at 4008 PBq SOURCE Fukushima's nuclear contamination levels 'chronic and lasting' http://www.france24.com/en/20120228-fukushima-japan-nuclear-radiation-tsunami/

Range of findings described by du Bois et al:

Pascal Bailly du Bois, Pierre Garreau, Philippe Laguionie, Irène Korsakissok (2014) Comparison between modelling and measurement of marine dispersion, environmental half-time and 137Cs inventories after the Fukushima Daiichi accident. Ocean Dynamics 64, Issue 3, pp 361-383.
“The 137Cs total atmospheric source term varies from 10 to 36PBq, (Schöppner et al 2012) implies a much higher activity (1,000 to 10,000 PBq in the total inventory of radionuclides released.”
Let us look at the source for the 1,000 to 10,000 PBq:

Michael Schöppner, Wolfango Plastino, Pavel P. Povinec c, Gerhard Wotawa, Francesco Bella, Antonio Budano, Mario De Vincenzi, Federico Ruggieri (2012) Estimation of the time-dependent radioactive source-term from the Fukushima nuclear power plant accident using atmospheric transport modelling. Journal of Environmental Radioactivity 114 (2012) 10e14 http://ac.els-cdn.com/S0265931X1100275X/1-s2.0-S0265931X1100275X-main.pdf?_tid=4b7ed0f6-9995-11e3-b127-00000aacb362&acdnat=1392835404_5fad3a3eec5a5966cd6b60c28b44f13b

[excerpted] A worst case scenario of the emission of 1019 Bq/day for both 137Cs and 131I (constant release on the 12 March 2011) was used and the resulting estimations were compared with real measurements. First estimations of worst case emissions served as input data for atmospheric simulations. These estimations were then compared with the actual IMS measurements. Further, an approach is presented to determine the time dependent source term for 137Cs and 131I at the FD-NPP. (p. 12)

…It can be concluded from the other two contemplated stations that the real source-term at the FD-NPP emitted fewer particles in the case of 137Cs than assumed in the worst case scenario. Based on these results a source term of 1017–1018 Bq/day seems reasonable. For 131I, however, these first results suggest a source term not too different from the worst case scenario of 1019 Bq/day. (p. 13)[end]
10 to the 17th power for cesium-137 (1.0E+17) = 100 PBq

10 to the 18th power for cesium-137 (1.0E+18) = 1000 PBq

100 – 1000 PBq Cesium 137

10 to the 19th power for Iodine-131 (1.0E+19) = 10,000 PBq

10,000 PBq Iodine 131



  1. The most recent work by Schoppner and colleagues was published in November 2013:

    Estimation of the radioactive source dispersion from Fukushima nuclear power plant accident. Applied Radiation and Isotopes
    Volume 81, November 2013, Pages 358–361
    DOI: 10.1016/j.apradiso.2013.03.070

    Their 2011 paper that you quote above was a real outlier to the high end of release estimates when it was first published. They have lowered their Fukushima release estimates from the study that you post above which were in error. From their new paper, based on more observations in the environment, they report:

    "The time-dependent source terms of 131I and 137Cs following the Fukushima accident have been established previously with a similar method (Schoeppner et al., 2011). Thus, it is possible to compare how the Fukushima source term is seen by different stations and isotopes. From the previous results the 137Cs and 131I source terms have been overestimated, and therefore down-scaled to fit more recent estimations of 3.5–27 PBq for 137Cs and 152–160 PBq for 131I (Hirose et al., 2012).”

    These source term estimates are much more in line with what other international investigators have been reporting and are consistent with a Fukushima source term for 131-I and 137-Cs that is about 10-fold lower than Chernobyl. This is what is summarized in the two most recent, up to date, review articles that I sent to you before you authored this post (e.g. Steinhauser and others Comparison of the Chernobyl and Fukushima nuclear accidents: A review of the environmental impacts, Science of the Total Environment Volumes 470–471, 1 February 2014, Pages 800–817 DOI: 10.1016/j.scitotenv.2013.10.029.

  2. Jay can you provide any figures for the ongoing atmospheric emissions I've documented here in my blog and the ongoing ocean contamination reported by TEPCO.

    We've had 3 years of leaks.

    Additionally, there were reports by Japanese scientists of radiation spikes from Fukushima in the fall of 2011 (I'll have to dig up source but they monitored air levels for over a year after the disaster).

    Additional evidence of fall 2011 emissions can be found in the EPA Radnet charts for west coast cities under the jet stream. Beta data indicate off the chart spikes during periods from Oct 2011 to Jan 2012.

    Webcam watchers saw what looked like fires during this period.

    1. It will be important to characterize how large were the spikes later in 2011. Deposition rates of 137-Cs to land in March were on the order of 3000 Bq/m2/day (Amano et al. 2012) http://www.sciencedirect.com/science/article/pii/S0265931X11002657

      What kind of spikes in count rates or deposition were measured later in 2011, 2012?

    2. Amano study was for Chiba, much higher deposition rates and activities in areas near to Fukushima-Daiichi.

  3. I would suggest that read the Steinhauser paper which documents CTBT data tracking the global dispersion of the atmospheric plume. The great bulk of releases occurred in the week following the disaster. Similar to ocean releases the rates are now are very small compared to the March-April 2011 period.

    Please note that the release estimate you list above was corrected by the authors of the original study. Consensus is on the order of 20 PBq of 137-Cs released to the atmosphere. Suggest that you read here http://www.dailykos.com/story/2014/09/08/1328170/-How-Much-Radioactive-Material-Was-Released-by-Fukushima

    Comprehensive review of atmospheric and ocean releases.

  4. I will check out the article

    Beta charts for Phoenix in nov 2011 through Jan 2012 were MUCH higher than during march 2011.

    Same for nearly all cities under jet stream in US during that time. I have sample charts.

    Webcam data suggested gas or fire in units 3 and perhaps 4.