Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 11 10 2011 10.5194/acpd-11-28319-2011 http://www.atmos-chem-phys-discuss.net/11/28319/2011/ http://www.atmos-chem-phys-discuss.net/11/28319/2011/acpd-11-28319-2011.html http://www.atmos-chem-phys-discuss.net/11/28319/2011/acpd-11-28319-2011.pdf 28319 28394 2011-10-20 Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant: determination of the source term, atmospheric dispersion, and deposition A. Stohl P. Seibert G. Wotawa D. Arnold J. F. Burkhart S. Eckhardt C. Tapia A. Vargas T. J. Yasunari NILU – Norwegian Institute for Air Research, Kjeller, Norway Institute of Meteorology, University of Natural Resources and Life Sciences, Vienna, Austria Central Institute for Meteorology and Geodynamics, Vienna, Austria Institute of Energy Technologies (INTE), Technical University of Catalonia (UPC), Barcelona, Spain Department of Physics and Nucelar Engineering (FEN),Technical University of Catalonia (UPC), Barcelona, Spain Universities Space Research Association, Goddard Earth Sciences and Technology and Research, Columbia, MD 21044, USA On 11 March 2011, an earthquake occurred about 130 km off the Pacific coast of Japan's main island Honshu, followed by a large tsunami. The resulting loss of electric power at the Fukushima Dai-ichi nuclear power plant (FD-NPP) developed into a disaster causing massive release of radioactivity into the atmosphere. In this study, we determine the emissions of two isotopes, the noble gas xenon-133 (¹³³Xe) and the aerosol-bound caesium-137 (¹³⁷Cs), which have very different release characteristics as well as behavior in the atmosphere. To determine radionuclide emissions as a function of height and time until 20 April, we made a first guess of release rates based on fuel inventories and documented accident events at the site. This first guess was subsequently improved by inverse modeling, which combined the first guess with the results of an atmospheric transport model, FLEXPART, and measurement data from several dozen stations in Japan, North America and other regions. We used both atmospheric activity concentration measurements as well as, for ¹³⁷Cs, measurements of bulk deposition. Regarding ¹³³Xe, we find a total release of 16.7 (uncertainty range 13.4–20.0) EBq, which is the largest radioactive noble gas release in history not associated with nuclear bomb testing. There is strong evidence that the first strong ¹³³Xe release started very early, possibly immediately after the earthquake and the emergency shutdown on 11 March at 06:00 UTC. The entire noble gas inventory of reactor units 1–3 was set free into the atmosphere between 11 and 15 March 2011. For ¹³⁷Cs, the inversion results give a total emission of 35.8 (23.3–50.1) PBq, or about 42% of the estimated Chernobyl emission. Our results indicate that ¹³⁷Cs emissions peaked on 14–15 March but were generally high from 12 until 19 March, when they suddenly dropped by orders of magnitude exactly when spraying of water on the spent-fuel pool of unit 4 started. This indicates that emissions were not only coming from the damaged reactor cores, but also from the spent-fuel pool of unit 4 and confirms that the spraying was an effective countermeasure. We also explore the main dispersion and deposition patterns of the radioactive cloud, both regionally for Japan as well as for the entire Northern Hemisphere. While at first sight it seemed fortunate that westerly winds prevailed most of the time during the accident, a different picture emerges from our detailed analysis. Exactly during and following the period of the strongest ¹³⁷Cs emissions on 14 and 15 March as well as after another period with strong emissions on 19 March, the radioactive plume was advected over Eastern Honshu Island, where precipitation deposited a large fraction of ¹³⁷Cs on land surfaces. The plume was also dispersed quickly over the entire Northern Hemisphere, first reaching North America on 15 March and Europe on 22 March. In general, simulated and observed concentrations of ¹³³Xe and ¹³⁷Cs both at Japanese as well as at remote sites were in good quantitative agreement with each other. Altogether, we estimate that 6.4 TBq of ¹³⁷Cs, or 19% of the total fallout until 20 April, were deposited over Japanese land areas, while most of the rest fell over the North Pacific Ocean. Only 0.7 TBq, or 2% of the total fallout were deposited on land areas other than Japan. Becker, A., Wotawa, G., Ringbom, A., and Saey, P. R. J.: Backtracking of noble gas measurements taken in the aftermath of the announced October 2006 event in North Korea by means of PTS methods in nuclear source estimation and reconstruction, Pure Appl. Geophys., 167, 581–599, 2010 Bowyer, T. W., Biegalski, S. R., Cooper, M., Eslinger, P. W., Haas, D., Hayes, J. C., Miley, H. S., Strom, D. J., and Woods, V.: Elevated radioxenon detected remotely following the Fukushima nuclear accident, J. Environ. Radioactivity, 102, 681–687, 2011. Brandt, J., Christensen, J. H., and Frohn, L. M.: Modelling transport and deposition of caesium and iodine from the Chernobyl accident using the DREAM model, Atmos. Chem. Phys., 2, 397–417, http://dx.doi.org/10.5194/acp-2-397-2002doi:10.5194/acp-2-397-2002, 2002. Central Institute for Meteorology and Geodynamics (ZAMG): Accident in the Japanese NPP Fukushima: Spread of radioactivity/first source estimates from CTBTO data show large source terms at the beginning of the accident/weather currently not favourable/low level radioactivity meanwhile observed over US East Coast and Hawaii, http://www.zamg.ac.at/docs/aktuell/Japan2011-03-22_1500_E.pdf, last download on 28 September 2011. Chino, M., Ishikawa, H., and Yamazawa, H.: SPEEDI and WSPEEDI: Japanese Emergency Response Systems to Predict Radiological Impacts in Local and Workplace Areas due to a Nuclear Accident, Radiat. Prot. Dosimetry, 50, 145–152, 1993. Chino, M., Nakayama, H., Nagai, H., Terada, H., Katata, G., and Yamazawa, H.: Preliminary estimation of release amounts of $^131$I and $^137$Cs accidentally discharged from the Fukushima Daiichi nuclear power plant into the atmosphere, J. Nuc. Sci. Tech., 48, 1129–1134, 2011. Davoine, X. and Bocquet, M.: Inverse modelling-based reconstruction of the Chernobyl source term available for long-range transport, Atmos. Chem. Phys., 7, 1549–1564, http://dx.doi.org/10.5194/acp-7-1549-2007doi:10.5194/acp-7-1549-2007, 2007. Devell, L., Güntay, S., and Powers, D. A.: The Chernobyl Reactor Accident Source Term: Development of a Consensus View, CSNI Report, Organisation for Economic Co-Operation and Development (OECD), OCDE/GD(96)12, 1995. Eckhardt, S., Stohl, A., Wernli, H., James, P., Forster, C., and Spichtinger, N.: A 15-year climatology of warm conveyor belts, J. Climate 17, 218–237, 2004. Eckhardt, S., Prata, A. J., Seibert, P., Stebel, K., and Stohl, A.: Estimation of the vertical profile of sulfur dioxide injection into the atmosphere by a volcanic eruption using satellite column measurements and inverse transport modeling, Atmos. Chem. Phys., 8, 3881–3897, http://dx.doi.org/10.5194/acp-8-3881-2008doi:10.5194/acp-8-3881-2008, 2008. Furuta, S., Sumiya, S., Watanabe, H., Nakano, M., Imaizumi, K., Takeyasu, M., Nakada, A., Fujita, H., Mizutani, T., Morisawa, M., Kokubun, Y., Kono, T., Nagaoka, M., Yokoyama, H., Hokama, T., Isozaki, T., Nemoto, M., Hiyama, Y., Onuma, T., Kato, C., and Kurachi, T.: Results of the Environmental Radiation Monitoring Following the Accident at the Fukushima Daiichi Nuclear Power Plant – Interim Report (Ambient Radiation Dose Rate, Radioactivity Concentration in the Air and Radioactivity Concentration in the Fallout), Radiation Protection Department, Nuclear Fuel Cycle Engineering Laboratories, Tokai Research and Development Center, Japan Atomic Energy Agency, JAEA-Review 2011-035 (Draft). Galmarini, S., Stohl, A., and Wotawa, G.: Fund experiments on atmospheric hazards, Nature, 473, 285, 2011. Gauntt, R. O., Cole, R. K., Erickson, C. M., Gido, R. G., Gasser, R. D., Rodriguez, S. B., Young, M. F., Ashbaugh, S., Leonard, M., and Hill, A.: MELCOR Computer Code Manuals, Vol. 3: Demonstration Problems, Version 1.8.5 May 2001, Sandia National Laboratories, SAND2001-0929P, Albuquerque, USA, 2001. Gudiksen, P. H., Harvey, T.F., and Lange, R.: Chernobyl source term, atmospheric dispersion, and dose estimation, Health Phys., 57, 697–706,1989. Hartley, D. and Prinn, R.: Feasibility of determining surface emissions of trace gases using an inverse method in a three-dimensional chemical transport model, J. Geophys. Res., 98, 5183–5197, 1993. Hass, H., Memmesheimer, M., Geis, H., Jakobs, H. J., Laube, M., and Ebel, A.: Simulation of the Chernobyl radioactive cloud over Europe using the EURAD model, Atmos. Environ., 24A, 673–692, 1990. Hertel, O., Christensen, J. Runge, E. H., Asman, W. A. H., Berkowicz, R., Hovmand, M. F., and Hov, O.: Development and testing of a new variable scale air pollution model – ACDEP, Atmos. Environ., 29, 1267–1290, 1995. Hoffmann, W., Kebeasy, R., and Firbas, P.: Introduction to the verification regime of the Comprehensive Nuclear-Test-Ban Treaty, Physics of the Earth and Planetary Interiors, 113, 5–9, 2000. Institut de Radioprotection et de Surete Nucleaire (IRSN): IRSN publishes assessment of radioactivity released by the Fukushima Daiichi Nuclear Power Plant (Fukushima I) through 22 March 2011, http://www.irsn.fr/EN/news/Documents/IRSN_fukushima-radioactivity-released-assessment-EN.pdf, last download on 28 September 2011, 2011. Kristiansen, N. I., Stohl, A., Prata, A. J., Richter, A., Eckhardt, S., Seibert, P., Hoffmann, A., Ritter, C., Bitar, L., Duck, T. J., and Stebel, K.: Remote sensing and inverse transport modeling of the Kasatochi eruption sulfur dioxide cloud, J. Geophys. Res., 115, D00L16, http://dx.doi.org/10.1029/2009JD013286doi:10.1029/2009JD013286, 2010. Mahowald, N. M., Prinn, R. G., and Rasch, P. J.: Deducing CCl₃F emissions using an inverse method and chemical transport models with assimilated winds, J. Geophys. Res., 102, 28153–28168, 1997. Masson, O., Baeza, A., Bieringer, J., Brudecki, K., Bucci, S., Cappai, M., Carvalho, F. P., Connan, O., Cosma, C., Dalheimer, A., Didier, D., Depuydt, G., De Geer, L. E., De Vismes, A., Gini, L., Groppi, F., Gudnason, K., Gurriaran, R., Hainz, D., Halldorsson, O., Hammond, D., Hanley, O., Holey, K., Homoki, Zs., Ioannidou, A., Isajenko, K., Jankovic, M., Katzlberger, C., Kettunen, M., Kierepko, R., Kontro, R., Kwakman, P. J. M., Lecomte, M., Leon Vintro, L., Leppänen, A.-P., Lind, B., Lujaniene, G., Mc Ginnity, P., Mc Mahon, C., Mala, H., Manenti, S., Manolopoulou, M., Mattila, A., Mauring, A., Mietelski, J. W., Møller, B., Nielsen, S. P., Nikolic, J., Overwater, R. M. W., Palsson, S. E., Papastefanou, C., Penev, I., Pham, M. K., Povinec, P. P., Ramebäck, H., Reis, M. C., Ringer, W., Rodriguez, A., Rulik, P., Saey, P. R. J., Samsonov, V., Schlosser, C., Sgorbati, G., Silobritiene, B. V., Söderström, C., Sogni, R., Solier, L., Sonck, M., Steinhauser, G., Steinkopff, T., Steinmann, P., Stoulos, S., Sykora, I., Todorovic, D., Tooloutalaie, N., Tositti, L., Tschiersch, J., Ugron, A., Vagena, E., Vargas, A., Wershofen, H., and Zhukova, O.: Tracking of airborne radionuclides from the damaged Fukushima Dai-Ichi nuclear reactors by European Networks, Environ. Sci. Technol., 45, 7670–7677, http://dx.doi.org/10.1021/es2017158doi:10.1021/es2017158, 2011. McMahon, T. A. and Denison, P. J.: Empirical atmospheric deposition parameters – a survey, Atmos. Environ., 13, 571–585, 1979. Medici, F.: The IMS radionuclide network of the CTBT, Radiation Physics and Chemistry, 161, 689–690, 2001. MEXT (Ministry of Education, Culture, Sports, Science and Technology): Results of the 2nd Airborne Monitoring by the Ministry of Education, Culture, Sports, Science and Technology and the U.S. Department of Energy, document available at: http://radioactivity.mext.go.jp/en/1270/2011/06/1304797_0616e.pdf, last access: 25 September 2011. Morino, Y., Ohara, T., and Nishizawa, M.: Atmospheric behavior, deposition, and budget of radioactive materials from the Fukushima Daiichi nuclear power plant in March 2011, Geophys. Res. Lett., 38, LOOG11, http://dx.doi.org/10.1029/2011GL048689doi:10.1029/2011GL048689, 2011. Nature News Blog: First estimates of total radioactive cesium and iodine emissions from Fukushima plant, http://blogs.nature.com/news/2011/03/first_estimates_of_radioactive.html, last download on 28 September 2011, 2011. Nuclear Energy Agency (NEA): Chernobyl: Assessment of Radiological and Health Impacts – 2002 Update of Chernobyl: Ten Years On, Organisation for Economic Co-Operation and Development (OECD) Publications, 155~pp., Paris, 2002. Nuclear Emergency Response Headquarters, Government of Japan: Report of the Japanese Government to the IAEA Ministerial Conference on Nuclear Safety. – The Accident at TEPCO's Fukushima Nuclear Power Stations, available at: http://www.iaea.org/newscenter/focus/fukushima/japan-report/, last retrieved: 7 October 2011. Oak Ridge National Laboratory: SCALE: A Modular Code System for Performing Standardized Computer Analyses for Licensing Evaluations, ORNL/TM-2005/39, Version 5, Vols. I–III, April 2005, Available from Radiation Safety Information Computational Center at Oak Ridge National Laboratory as CCC-725, 2005. Saey, P. R. J. and de Geer, L.-E.: Notes on radioxenon measurements for CTBT verification purposes, Appl. Radiat. Isot., 63, 765–773, 2005. Schulze, J., Auer, M., and Werzi, R.: Low level radioactivity measurement in support of the CTBTO, Appl. Radiat. Isot., 53, 23–30, 2000. Seibert, P.: Inverse modelling of sulfur emissions in Europe based on trajectories, in: Inverse Methods in Global Biogeochemical Cycles, edited by: Kasibhatla, P., Heimann, M., Rayner, P., Mahowald, N., Prinn, R. G., and Hartley, D. E., Geophysical Monograph 114, American Geophysical Union, 147–154, ISBN 0-87590-097-6, Washington, DC, USA, 2000. Seibert, P., Kristiansen, N. I., Eckhardt, S., Prata A. J., Richter, A., and Stohl, A.: Uncertainties in the inverse modelling of sulphur dioxide eruption profiles, Natural Hazards and Risk, 2, 201–216, http://dx.doi.org/10.1080/19475705.2011.590533doi:10.1080/19475705.2011.590533, 2011. Stohl, A. and Thomson, D. J.: A density correction for Lagrangian particle dispersion models, Bound.-Layer Meteorol., 90, 155–167, 1999. Stohl, A., Hittenberger, M., and Wotawa, G.: Validation of the Lagrangian particle dispersion model FLEXPART against large scale tracer experiment data, Atmos. Environ., 32, 4245–4264, 1998. Stohl, A., Eckhardt, S., Forster, C., James, P., and Spichtinger, N.: On the pathways and timescales of intercontinental air pollution transport, J. Geophys. Res., 107, 4684, http://dx.doi.org/10.1029/2001JD001396doi:10.1029/2001JD001396, 2002. Stohl, A., Forster, C., Frank, A., Seibert, P., and Wotawa, G.: Technical note: The Lagrangian particle dispersion model FLEXPART version 6.2, Atmos. Chem. Phys., 5, 2461–2474, http://dx.doi.org/10.5194/acp-5-2461-2005doi:10.5194/acp-5-2461-2005, 2005. Stohl, A., Seibert, P., Arduini, J., Eckhardt, S., Fraser, P., Greally, B. R., Lunder, C., Maione, M., Mühle, J., O'Doherty, S., Prinn, R. G., Reimann, S., Saito, T., Schmidbauer, N., Simmonds, P. G., Vollmer, M. K., Weiss, R. F., and Yokouchi, Y.: An analytical inversion method for determining regional and global emissions of greenhouse gases: Sensitivity studies and application to halocarbons, Atmos. Chem. Phys., 9, 1597–1620, http://dx.doi.org/10.5194/acp-9-1597-2009doi:10.5194/acp-9-1597-2009, 2009. Stohl, A., Prata, A. J., Eckhardt, S., Clarisse, L., Durant, A., Henne, S., Kristiansen, N. I., Minikin, A., Schumann, U., Seibert, P., Stebel, K., Thomas, H. E., Thorsteinsson, T., Tørseth, K., and Weinzierl, B.: Determination of time- and height-resolved volcanic ash emissions and their use for quantitative ash dispersion modeling: the 2010 Eyjafjallajökull eruption, Atmos. Chem. Phys., 11, 4333–4351, http://dx.doi.org/10.5194/acp-11-4333-2011doi:10.5194/acp-11-4333-2011, 2011. United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR): Annex C: Exposures to the public from man-made sources of radiation, in Sources and Effects of Ionizing Radiation, vol. 1, Sources, Report to the Gen. Assem., 291 pp., Vienna, Austria, 2000a. United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR): Annex J: Exposures and effects of the Chernobyl accident, in Sources and Effects of Ionizing Radiation, vol. 2, Effects, Report to the Gen. Assem., 115 pp., Vienna, Austria, 2000b. USGS (United States Geological Service): List of significant earthquakes. Magnitude 9.0 – NEAR THE EAST COAST OF HONSHU, JAPAN, 2011 March 11 05:46:23 UTC, available at: http://earthquake.usgs.gov/earthquakes/eqinthenews/2011/usc0001xgp/, retrieved 30 July 2011. Wernli, H. and Davies, H. C.: A Lagrangian-based analysis of ex-tratropical cyclones, I, The method and some applications, Q. J. Roy. Meteor. Soc., 123, 467–489,1997. Wotawa, G., Becker, A., Kalinowski, M., Saey, P., Tuma, M., and Zähringer, M.: Computation and analysis of the global distribution of the radioxenon isotope $^133$133 based on emissions from nuclear power plants and radioisotope production faclities and its relevance for the verification of the Nuclear-Test-Ban treaty, Pure Appl. Geophys., 167, 541–557, 2010. Vallés, I., Camacho, A., Ortega, X., Serrano, I., Blázquez, S., and Pérez, S.: Natural and anthropogenic radionuclides in airborne particulate samples collected in Barcelona (Spain), J. Environ. Radioact., 100, 102–107, 2009. Wernsberger, B. and Schlosser, C.: Noble gas monitoring within the international monitoring system of the Comprehensive Nuclear Test-Ban Treaty, Radiation Phys. Chem., 71, 775–779, 2004. Yasunari, T., Stohl, A., Hayano, R. S., Burkhart, J. F., Eckhardt, S., and Yasunari, T.: Cesium-137 deposition and contamination of Japanese soils due to the Fukushima nuclear accident, Proc. Natl. Acad. Sci., submitted, 2011.