Oceanic Dispersion Simulations of 137Cs Released from the Fukushima Daiichi Nuclear Power Plant

Masumoto, Yukio; Miyazawa, Yasumasa; Tsumune, Daisuke; Tsubono, Takaki; Kobayashi, Takuya; Kawamura, Hideyuki; Estournel, Claude; Marsaleix, Patrick; Lanerolle, Lyon W. J.; Mehra, Avichal; Garraffo, Zulema

doi:10.2113/gselements.8.3.207

Cited by 100 publications

(71 citation statements)

References 10 publications

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“…However, it agrees well with the estimate of 11 to 16 PBq reported by Charette et al (2013), is consistent with the 14.8 PBq estimate obtained by Masumoto et al (2012) based on the JCOPE model results, and is within the 10-34 PBq range reported by Bailly du Bois et al (2012). As a consistency check, combining the total 137 Cs inventory of 2 PBq reported by Buesseler et al (2011) with our model-based percentage of 137 Cs left in the KOK area from the oceanic (17.5 %) and atmospheric (4.5 %) sources, and making use of the notion that about 95 % of the measured 137 Cs inventory comes from the oceanic source, one can obtain an estimate of the total source amplitude of about 11 PBq for the oceanic and 2.2 PBq for the atmospheric sources.…”

Section: Summary and Discussionsupporting

confidence: 92%

“…Second, the largest concentrations of 137 Cs were shown to be associated with the semi-permanent near-shore eddy that was entraining 137 Cs-rich coastal waters from the FNPP vicinity and retaining them through stirring around the eddy perimeter. This is in general agreement with Masumoto et al (2012) who also commented on the importance of the mesoscale current structures for the spreading of Fukushima-derived radionuclides. Finally, the intermediate 137 Cs concentrations at the westernmost meridional column of stations were explained by the fact that these stations contained the more recent coolant water that had continued to leak from the reactor after the initial discharge.…”

Section: Summary and Discussionsupporting

confidence: 91%

“…Over the last two years there have been a number of numerical modeling studies aimed at assessing the aftermath of the Fukushima disaster (e.g., Tsumane et al, 2011Tsumane et al, , 2013Kawamura et al, 2011;Estournel et al, 2012;Miyazawa et al, 2012;Masumoto et al, 2012;Bailly du Bois et al, 2012). Forward numerical models have allowed simulation of the spread of radioactive waters into the ocean.…”

Section: Modeling the Spreading Of 137 Csmentioning

confidence: 99%

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Short-term dispersal of Fukushima-derived radionuclides off Japan: modeling efforts and model-data intercomparison

et al. 2013

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The Great East Japan Earthquake and tsunami that caused a loss of power at the Fukushima nuclear power plants (FNPP) resulted in emission of radioactive isotopes into the atmosphere and the ocean. In June of 2011, an international survey measuring a variety of radionuclide isotopes, including ¹³⁷Cs, was conducted in surface and subsurface waters off Japan. This paper presents the results of numerical simulations specifically aimed at interpreting these observations and investigating the spread of Fukushima-derived radionuclides off the coast of Japan and into the greater Pacific Ocean. Together, the simulations and observations allow us to study the dominant mechanisms governing this process, and to estimate the total amount of radionuclides in discharged coolant waters and atmospheric airborne radionuclide fallout. The numerical simulations are based on two different ocean circulation models, one inferred from AVISO altimetry and NCEP/NCAR reanalysis wind stress, and the second generated numerically by the NCOM model. Our simulations determine that > 95% of ¹³⁷Cs remaining in the water within ~600 km of Fukushima, Japan in mid-June 2011 was due to the direct oceanic discharge. The estimated strength of the oceanic source is 16.2 ± 1.6 PBq, based on minimizing the model-data mismatch. We cannot make an accurate estimate for the atmospheric source strength since most of the fallout cesium had left the survey area by mid-June. The model explained several key features of the observed ¹³⁷Cs distribution. First, the absence of ¹³⁷Cs at the southernmost stations is attributed to the Kuroshio Current acting as a transport barrier against the southward progression of ¹³⁷Cs. Second, the largest ¹³⁷Cs concentrations were associated with a semi-permanent eddy that entrained ¹³⁷Cs-rich waters, collecting and stirring them around the eddy perimeter. Finally, the intermediate ¹³⁷Cs concentrations at the westernmost stations are attributed to younger, and therefore less Cs-rich, coolant waters that continued to leak from the reactor in June of that year

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Section: Summary and Discussionsupporting

confidence: 92%

Section: Summary and Discussionsupporting

confidence: 91%

Section: Modeling the Spreading Of 137 Csmentioning

confidence: 99%

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Short-term dispersal of Fukushima-derived radionuclides off Japan: modeling efforts and model-data intercomparison

et al. 2013

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“…1). The amount of 137 Cs released is estimated to be about 3-27 PBq based on numerical models and observations (Kawamura et al, 2011;Bailly du Bois et al, 2011;Tsumune et al, 2012;Masumoto et al 2012;Miyazawa et al, 2012;Estournel et al, 2012), which is comparable to the amount that was released to the atmosphere (about 15 PBq, NERH, 2011). Recent studies, based on more rigorous calculation methods, tend to show an estimate around 5-6 PBq.…”

Section: The Release Of Radionuclides From the Coast Of Fukushimamentioning

confidence: 91%

The impact of oceanic circulation and phase transfer on the dispersion of radionuclides released from the Fukushima Dai-ichi Nuclear Power Plant

2013

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The mechanism behind the dispersion of radionuclides released from the Fukushima Dai-ichi Nuclear Power Plant on March 2011 is investigated using a numerical model. This model is a Lagrangian particle tracking–ocean circulation coupled model that is capable of solving the movement and migration of radionuclides between seawater, particulates, and bottom sediments. Model simulations show the radionuclides dispersing rapidly into the interior of the North Pacific once they enter a meso-scale eddy. However, some radionuclides also remain near the coast, with spatial distribution depending strongly on the oceanic circulation during the first month after the release. Major adsorption to bottom sediments occurs during this first month and many of these radionuclides remain on the sea floor once they are adsorbed. Model results suggest that weak offshore advection during the first month will increase the adsorption of radionuclides to bottom sediments and decelerate the dispersion to the open ocean. If vertical mixing is weak, however, fewer radionuclides reach the sea floor and adsorb to bottom sediments. More radionuclides will then quickly disperse to the open ocean

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“…2.9d ). Then, the amount of 134 Cs in the core of the western part of the NPSTMW in September 2012 was estimated to be 1.07 PBq, which accounts for 7-47 % of the total amount of 134 Cs released directly into the ocean from the FNPP (2.3-14.8 PBq of 137 Cs; 134 Cs/ 137 Cs ratio assumed to be 1.0 Masumoto et al 2012 ), or 10 % of the total deposition including direct release and atmospheric surface deposition (11 PBq 134 Cs; Kobayashi et al 2013 ). Although the estimation includes enormous uncertainties, it should be noted that a considerable amount of the FNPP-derived radioactive Cs had been dispersed in the southwestern portion of the North Pacifi c across the KC, which was considered to act as a barrier against the southward dispersion of FNPP-derived radionuclides (Sect.…”

Section: Amount Of 134 Cs In Subsurface Core Waters In the Southern Areamentioning

confidence: 99%

134Cs and 137Cs in the Seawater Around Japan and in the North Pacific

Kaeriyama

2015

Impacts of the Fukushima Nuclear Accident on Fish and Fishing Grounds

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Oceanic Dispersion Simulations of 137Cs Released from the Fukushima Daiichi Nuclear Power Plant

Cited by 100 publications

References 10 publications

Short-term dispersal of Fukushima-derived radionuclides off Japan: modeling efforts and model-data intercomparison

Short-term dispersal of Fukushima-derived radionuclides off Japan: modeling efforts and model-data intercomparison

The impact of oceanic circulation and phase transfer on the dispersion of radionuclides released from the Fukushima Dai-ichi Nuclear Power Plant

134Cs and 137Cs in the Seawater Around Japan and in the North Pacific

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