Spanish Experience on Modeling of Environmental RadioactiveContamination Due to Fukushima Daiichi NPP Accident UsingJRODOSAlla Dvorzhak,* Carlos Puras, Milagros Montero, and Juan C. Mora

CIEMAT, Radiation Protection for the Public and the Environment, Av. Complutense 40, E-28040 Madrid, Spain

*S Supporting Information

ABSTRACT: Since the Chernobyl Nuclear Power Plant accident,decision support systems (DSS) for supporting response of the decisionmakers in emergencies have been developed and refined. Data availablefrom real accidents are used to validate these systems, thusdemonstrating their real capabilities and finally to improve them. Thisarticle presents the findings of the simulation exercises using JRODOSDSS performed in Spain after the first days of the accident in theFukushima Daiichi Nuclear Power Plant. The investigation was carriedout in two phases. The first phase is considered the early phase of theaccident when few details of the real emissions are known (operationalmodeling). The second phase demonstrates how real measurementscould be used (reconstructive modeling) to improve model predictions.Only major releases to the atmosphere, occurring during the first twoweeks, were taken into account. Validation of the model was performedby direct comparison of the modeled results with real measurements.

1. INTRODUCTIONAt 2:46 pm on the March 11th of 2011 (Japanese local time), inthe northeast coast of Japan, a 9.0 degree on the Richter scaleearthquake occurred. At that time, reactors 1−3 of theFukushima Daiichi Nuclear Power Plant (FNPP) were inoperation while reactors 4−6 were being subjected to periodicinspection and refueling. Once the earthquake was detected,units 1−3 were automatically stopped with emergencyshutdown (SCRAM). The earthquake damaged the electricitytransmission towers. Then, a tsunami submerged the seawatersystems that cooled the Emergency Diesel Generators and theelectrical switchgear. This resulted in all alternating current(AC) power supply being lost at units 1−5. Because of thecomplete power failure, the cooling systems failed and thereforethe temperature of the reactor and fuel pools increased. Thisincrease in temperature triggered all the events which finallyproduced the hydrogen explosions and release of radioactivematerial into the environment.After the announcement of the nuclear accident, the Spanish

Emergency Center (SALEM) of the Spanish regulatoryauthority the Nuclear Safety Council (CSN) begancarrying out operational modeling (early phase) of possiblescenarios to analyze the situation and every possibleconsequence. For this objective the Decision Support System(DSS) JRODOS, previously installed in the CSN installationsby our group, was used.RODOS is the European Real-time On-line DecisiOn

Support System for off-site emergency management whichprovides consistent and comprehensive information on the

present and future radiological situation, the extent and thebenefits and drawbacks of emergency actions and counter-measures, and methodological support for taking decisions onemergency response strategies.1−4 Over the last years, RODOSsystem has been re-engineered and in 2008 JRODOS − a Java-based product − was released.5,6 The implementation of theRODOS and JRODOS systems in the emergency center inSpain was performed by our group.7−9

To apply JRODOS system for the evaluation of the FNPPaccident, configuration and updating for Japan was fulfilled bythe JRODOS development team of Institute for Nuclear andEnergy Technologies (IKET).10 During this adaptation, keydata of the FNPP: coordinates, type of reactors, possibleinventories, site maps (land use and soil type, elevation,population) were incorporated into the system and especiallyJRODOS release for Japan application was prepared by IKETgroup and then installed and used by the CIEMAT groupduring operational modeling in the first days after the beginningof the accident.The aim of this article is to present some of the results

obtained in operational modeling and in reconstructivemodeling coupled with a description of the hypothesis takenin the different phases. All of the work was focused on the studyand modeling of atmospheric dispersion of radioactive materials

Received: April 27, 2012Revised: July 21, 2012Accepted: September 24, 2012Published: October 15, 2012

Article

pubs.acs.org/est

© 2012 American Chemical Society 11887 dx.doi.org/10.1021/es301687t | Environ. Sci. Technol. 2012, 46, 11887−11895

released during the accident and the ground deposition afterthe release, those being the main results needed for consideringthe major exposure pathways for the first phases of a nuclearaccident. Those models are strongly dependent on factors as agood consideration of the events (time of each release),estimation of the source term (radioisotopes to be consideredand quantities released), weather measurements and forecast-ing, and so forth.Also, contaminations in the ecological/food chains and doses

burdens were calculated with JRODOS, however; those resultsare not presented in this article, as they are not its objective. Toproperly model both concentrations in foodstuff and doses, acorrect modeling of air dispersion and deposition is alsonecessary.

2. METHODOLOGY

Modeling of nuclear accidents is performed using twoapproaches: the first an operational modeling during thedevelopment of accident (early phase) where only approximatedata and reasonable hypothesis can be used and the second areconstructive modeling (intermediate phase) after thecompletion of the accident where real measurements anddata can be used.The first approach is characterized by the scarcity of

information, mainly about the source term (quantity andperiod of each release, radionuclides released, etc.).The second approach is where a greater quantity of

information is available after the completion of the accidentbased mainly on measurements. This information can be used

in the models and assessments, although uncertaintiesassociated with these data are still considerable.In the case of FNPP, several types of events with releases of

radiation from the different damaged reactors occurred. Thiswork distinguishes 11 events occurring from 06:15 UTC 12thto 13:00 UTC 24th of March, 2011. To model these events andto estimate the source terms, the sequence of events in theirentirety was studied.The scenarios, hypothesis, and assumptions were developed

based on the knowledge and information published by officialmeans in the hours and days after the accident.

2.1. Meteorological Data.Weather (forecast and measure-ments) is extremely important in the modeled scenarios.Observed meteorological data are usually measured only in alimited number of points, whereas forecasted data represent 3Dcalculated data fields in each cell of a calculated domain.In the exercise performed during operational modeling,

weather forecast data from the European Centre for Medium-Range Weather Forecasts (ECMWF) at the point ofFukushima (37°25′17″ N 141°01′57″ E) was obtained byCSN and computationally adapted for their use in JRODOSsystem. After that, meteorological preprocessor of JRODOSprepared the data in each cell of the domain by interpolationsand extrapolations.For reconstructive modeling (considering releases from 12th

to 24th of March of 2011), weather forecast obtained throughthe model WRF from the Deutsche WetterZentrale andadapted by Institute for Meteorology and Climate Research -Troposphere Research (IMK-TRO) and IKET of KarlsruheInstitute of Technology (KIT)10 was used. These files, with a

Figure 1. Representation of the chosen release pathway to model the accidental scenario in the Fukushima Daiichi NPP unit 2 using RASCAL v3.0.5.12

Environmental Science & Technology Article

dx.doi.org/10.1021/es301687t | Environ. Sci. Technol. 2012, 46, 11887−1189511888

horizontal resolution of about 10 km grid spacing and with 27vertical levels, included the following data:Fields of singular level:

• fraction of the earth,• roughness,• precipitation,• height of atmospheric boundary layer.

Fields of multi levels (vertical):

• temperature,• wind speed and direction,• geopotential height.

The range for meteorological data was one day expandedwith respect to the temporal range used for considering theevents in the accident. The data used from 12th to 18th ofMarch of 2011 are reanalyses performed with information ofthe measurements to refine the forecast data, whereas the datafrom 19th to 25th of March of 2011 are the forecast itself.2.2. Source Term. The estimation of the source term is the

key point for proper modeling and reconstruction of theenvironmental contamination.In the FNPP accident, the information about status of the

reactors and source term could not be obtained in the earlyphase.11 Therefore to estimate source term for the operationalmodeling the RASCAL version 3.0.5 code (RadiologicalAssessment System for Consequence AnaLysis) was used.12

In this case, different levels of damage to the nuclear powerplant were considered using expert judgment.For reconstructive modeling, the source term was obtained

based on assumptions and estimation of total radioactivedischarge by correlating real on-field dose measurements.A complete description of the calculation of source term in

both phases is provided.2.2.1. Operational Modeling. For the operational modeling,

source term for the event occurred in unit 2 (hydrogenexplosion) on March 14th at 21:10 UTC was estimated usingRASCAL where the NPP Cooper (Nebraska) 4 BWR Mark I,which has the same electrical and thermal power as unit 2 ofFNPP, was used. Some parameters used in RASCAL can beseen in Figure S1 of the Supporting Information. Dispersion ofthe release and radioactive contamination was modeled usingJRODOS.The characteristics taken into account for calculations were:

burn-up of 45 GWd/T,13 probable damage in the suppressionpool, and uncontrolled release of gases from containment. Arepresentation of most probable available release pathwaysselected in RASCAL for this scenario is shown in Figure 1. Asource term of about 50 radionuclides was obtained but in

JRODOS the main 25 radionuclides were selected according totheir contribution (Table 1). Atmospheric transport anddispersion and deposition of released radioactive materialwere modeled, being the first results of deposition fulfilled onMarch 16th, 2011, in the CSN.Further calculations, assuming an emission of the same

source term in the days following the accident, were done toestimate the possible location of the radioactive cloud withchanging weather conditions.

2.2.2. Reconstructive Modeling. Once the accident waspractically dominated, completion of the entire situation wasconsidered and the scenario was modeled using all eventsoccurred during the accident. Thus, an estimation of the sourceterm for the whole period for which the accident occurred wasperformed. In this phase, more information was available.On April 12th of 2011, according to the results of analysis of

the reactors, Nuclear and Industrial Safety Agency (NISA) andNuclear Safety Commission (NSC) estimated the totaldischarge of 137Cs and 131I11,14 and, subsequently, the JapanNuclear Safety Organization (JNES) and NISA reanalyzed thestate of reactors and re-estimated the release. NSC used for thisestimation monitoring data with atmospheric diffusionsimulations, being 137Cs and 131I supposed to be dominantcomponent to the dose around the area of FNPP, whereasother radioisotopes as noble gases were also admitted to beemitted. NSC together with Japan Atomic Energy Agency(JAEA) estimated the total amount of radioisotopes dischargedto the atmosphere within March 11th to April 5th based onenvironmental monitoring data and calculations of atmosphericdispersion (a compilation is given in Table S1 of theSupporting Information). It was assumed that the dischargebegan to decline steadily since early April reaching valuesaround 1011 to 1012 Bq/h equivalent to 131I.11

In this study, re-estimated total activity released: 1.6 × 1017

Bq for 131I and 1.5 × 1016 Bq for 137Cs, was considered. Thisinformation is important to compare with similar accidents anda proper modeling requires accurate knowledge of the temporaldistribution of release during the development of the accident.This is especially important because weather data (mainly winddirection and velocity) change continuously determiningtransport radioactive material and subsequent contaminationof soil. To obtain this distribution, major events occurredduring the accident in all units of FNPP and estimation ofduration of each of them was taken into account.11,14−16

Measurements of dose rate routinely published by TokyoElectric Power Company (TEPCO) between March 11th andMarch 27th in the monitoring points for gamma dose ratesaround FNPP (ref 17 and Figure S2 of the Supporting

Table 1. Source Term Used. The Selected Radionuclides Include the 97% of the Total Release Estimated by RASCAL

radionuclide total activity released (TBq) % to total estimated release radionuclide total activity released (TBq) % to total estimated release

Xe-133 3.69 × 106 93.04 Cs-137 4.21 × 103 0.11I-131 3.27 × 104 0.83 Cs-136 1.30 × 103 0.03Kr-85 2.79 × 104 0.70 Sr-90 6.32 × 102 0.02I-132 2.27 × 104 0.57 Ru-103 4.56 × 102 0.01Te-132 1.42 × 104 0.36 Te-131 m 3.96 × 102 0.01Xe-135 1.42 × 104 0.36 Ru-106 1.74 × 102 0.00Ba-140 1.37 × 104 0.34 I-135 6.42 + 100 0.00Sr-89 9.31 × 103 0.24 Kr-85 m 8.25 × 10−1 0.00Cs-134 6.57 × 103 0.17 Kr-88 8.96 × 10−4 0.00I-133 4.50 × 103 0.11 Rb-88 9.90 × 10−6 0.00Total 3.84 × 106 96.91

Environmental Science & Technology Article

dx.doi.org/10.1021/es301687t | Environ. Sci. Technol. 2012, 46, 11887−1189511889

Information) were considered. On March 28th TEPCOupdated the information, being the last data incorporated inthis study.18,19 In total, nearly 4000 measurement data wereanalyzed (details provided in Table S2 of the SupportingInformation).Figure 2 shows dose rate measurements performed at

different points during the considered period. Peaks in thegraph represent the different accidental events occurred alongthe time. Correlating the time period of main events11,14−16

with dose rate peaks, releases of radioactive material for eachevent were defined (a summary of obtained data is presented inTable 2). Each event was related to a point of measurementassuming a correlation between the monitoring data at thatpoint and the amount discharged of radioactive material duringthe time period of the event. As each point is located atdifferent distance and direction from point of emission,measurements in different points might not be totallycorrelated. Source term was estimated neglecting this effectbut being conscious of the uncertainty this hypothesis may

introduce. The estimated source term was normalized to thetotal estimated release reported by NISA.To define the source term related to all major events, gamma

dose rate data were analyzed considering following assumptionsand relationships:The dose rate measurements made by TEPCO were carried

out with different time steps (e.g., 2, 10, 30 min, etc.) or wereinterrupted for a temporary period, so integrated dose in eachevent was used to estimate the contribution of each of theseevents in the total discharge occurred during the accident. Thefollowing expressions describe the assumptions carried out toevaluate these contributions:

∫ τ= =D t t i N( )d , 1...it

t

ii

i

,1

,2

(1)

Being:

N - total number of events;i - index of event,τi (t) - dose rate of event i;ti,1 - lower limit of event i;

Figure 2. Gamma dose rate measurements in the monitoring points around FNPP from March 11th to March 27th, 2011.17

Table 2. Events Considered in the Scenario for Reconstructive Modeling

event possible reason of release (number of Unit) period (UTC) duration, hours relation with point of measurement

1 explosion (U1) 12/3/11 06:15 − 06:45 0.5 MP-42 venting (U3) 12/3/11 23:20 − 13/3/11 00:00 0.7 MP-43 (U3) 13/3/11 04:50 − 05:20 0.5 MP-44 explosion (U3) 14/3/11 00.00 − 02:10 2.2 MP-35 venting (U2) 14/3/11 12:30 − 13:40 1.2 Main gate6 explosion (U2) and pool fire (U4)a

preliminary estimation 14/3/11 21:10 − 15/3/11 05:10 8 Main gatebest estimation 14/3/11 21:10 − 15/3/11 11:00 14 Main gate

7 injection of water into the pool (U4) 15/3/11 14:00 − 20:00 6 Main gate8 (U4) 16/3/11 01:10 − 07:10 6 Main gate9 (U3, U4) 17/3/11 0:30 − 21/3/11 7:30 103 Admin building North side10 venting (U2, U3) 21/3/11 08:50 − 10:50 2 Main gate11 (U3) 23/3/11 20:30 − 24/3/11 13:00 16.5 Admin building South side

aRelease was extended using the latter analysis of the data.20,26

Environmental Science & Technology Article

dx.doi.org/10.1021/es301687t | Environ. Sci. Technol. 2012, 46, 11887−1189511890

ti,2 - upper limit of event i;Di - integrated dose of event i

∑==

D Di

N

ia1 (2)

Da - total integrated dose (all events);

α =DDi

i

a (3)

∑ α ==

1i

N

i1 (4)

αi - ratio of integrated dose of event i;Then activity emitted during each event was estimated as:

α=Q Qi i a (5)

Being:

Qi - emission during event i andQa - total emission during the accident.11

Figure 3. Estimation of the 137Cs and 131I release reconstructed by correlation with gamma dose rate measurements.

Figure 4. Modeling of 137Cs deposition accumulated during 48 h (for 21:10 h March 16th), max value 3.99 × 107 Bq/m2.

Environmental Science & Technology Article

dx.doi.org/10.1021/es301687t | Environ. Sci. Technol. 2012, 46, 11887−1189511891

Taking into account 137Cs release (estimated by NISA, JNET)and eqs 1−5, release for each event was calculated. Figure 3shows the emission rate of 137Cs and 131I for the consideredperiod. For this estimation, original data in every point ofmeasurement, as measured around FNPP, were considered.17

Future work will deal with refinement of estimations by takinginto account the influence of distances and meteorologicalconditions for the time period of the releases, among otherfactors. Accumulated emission of 137Cs and 131I estimated inthis work was compared with estimation performed by NSC21

showing good agreement (Figures S3 and S4 of the SupportingInformation). More precise further studies could improveestimations.

2.3. Other Parameters and Framework of Modeling.The framework of modeling as calculation domain, precision ofthe cell, time period, grid resolution, and others, can be checkedin Table S3 of the Supporting Information. Other parameterspresented and used in the models were selected by expertjudgment: deposition velocity, height of the emission, durationof release, or period of modeling. After iterative trials, a generalunderestimation of the deposition values was observedconsidering two explanations: the existence of heavy particlesand the effect of forest canopy, predominant in the area.Deposition velocity was increased in order to take into accountboth phenomena as currently JRODOS cannot use differentparticle sizes in the models.

Figure 5. Results of 137Cs ground concentration (dry and wet) at (a) 21:15 h March 14th, (b) 12:15 h March 15th, (c) 20:15 h March 15th, (d) 5:15h March 20th, (e) 12:15 h March 21st, (f) 23:15 h March 24th (UTC).

Environmental Science & Technology Article

dx.doi.org/10.1021/es301687t | Environ. Sci. Technol. 2012, 46, 11887−1189511892

3. RESULTS AND DISCUSSION

The results are focused on the atmospheric dispersion andground deposition as other results such as activities infoodstuffs or dose burden are dependent on the quality andprecision of these values.3.1. Operational Modeling. During operational modeling,

several calculations were carried out in the first days of theaccident in CSN. First of all, existing operational informationwas analyzed to be used in the modeling of the releaseproduced on March 14th, 2011, corresponding to a hydrogenexplosion in unit 2. Figure 4 shows the result of the 137Csdeposition obtained during the period of the release beginningat 21:10 h UTC of March 14th, 2011, and lasting almost eighthours.Additional calculations for next days were performed using

hypothetical releases (using RASCAL v. 3.0.5) and beginning at00:00 h UTC provided possible location of the clouddependent on meteorological conditions. Selection of calcu-lations is included in Figure S5 of the Supporting Information.On March 20th, the predominant wind direction was towardinhabited areas at northwest of FNPP, which could partlyexplain the contamination measured in these areas. Source ofmeteorological data was ECMWF, using 6 h time step of thepredicted data. Results are not always comparable withreconstructive modeling based on WRF meteorological dataprediction with a one hour time step.In general, the preliminary estimations of air concentrations

and ground deposition obtained in the first days after thebeginning of the accident by using RASCAL coupled withJRODOS provided acceptable guidance for early phase of theemergency showing the location and importance of theradioactive cloud after the emission produced in each episodeof the accident. During this phase, the usefulness of this systemfor decision makers was evident.

Two points are considered primordial in this case: properquantification of the source term (by the use of monitoringdata, estimation by computer code, expert judgment, etc.) andthe capability to assimilate this source term by available DSSand models of atmospheric dispersion.

3.2. Reconstructive Modeling. Once releases from theaccident finished, a reconstruction of the processes thatinfluence the contamination of environment (considering allsignificant releases occurred from the beginning to stabilizedsituation) was carried out.Modeling with real meteorological conditions and based on

prognosis meteorological data of WRF was performed. Theresults of this modeling reflect adequate orientation of thecloud toward inhabited areas in the dominant northwestdirection, as obtained by measurements of DOE andNNSA16,22−24 and in good agreement with modelingperformed by Visible Information Center, Genki K. et al. orYasunari T. J. et al.25−27 Figure 5 presents the results of 137Csdeposition modeling (dry and wet) accumulated from March12th to March 24th, 2011. Red circles mark 20 and 30 kmradius (restricted zone and extended evacuation zone).Environmental contamination by cesium and iodine, for the

considered period (March 12th to March 24th, 2011), wasreconstructed using JRODOS, the estimated source term forthis period, and the meteorological data and forecast obtainedby WRF model. Source term was calculated by correlating on-field dose measurements, this correlation being important toprove the usefulness of the radiation survey emergency systeminstalled around Spanish Nuclear Installations (RadioactivityAlert Network) based on electronic dosimeters connected toemergency centers.Modeling of 137Cs showed significant wet deposition during

the period of release (Figure 6). This result depends on rainrate in given location and time. Of course, the wet depositionpattern follows the meteorological conditions dominant in each

Figure 6. Results of 137Cs ground concentration (wet). Max value, corresponding to the release point: 4.11 × 105 Bq/m2.

Environmental Science & Technology Article

dx.doi.org/10.1021/es301687t | Environ. Sci. Technol. 2012, 46, 11887−1189511893

simulated instant. For that reason, spots of higher depositioncan be found in some locations as happened in NNW direction.Comparison of the pattern of contamination related to

topographic maps within the modeled domain (Figure S6 in theSupporting Information) shows that potentially contaminatedair masses were dispersed and deposited mainly before and overthe mountains ranges Jyoshin-etsu (∼2568 m) on thenorthwest and Yatsugatake (∼2899 m) on the south.Reconstruction modeling shows that most of the releasedmaterial from the Fukushima accident was transported towardPacific Ocean and so most deposition occurred far frompopulated areas due to existing meteorological conditionsduring the events.Further fitting of source term, weather conditions, and

comparison with dynamics of measurements in time and spacewill raise more accurate results.3.3. Validation. After the accident events, results of

modeling could be validated by comparison with availablemeasurements, those being:

• Dose rate measurements published by TEPCO or• Measurements of environmental radioactivity levels

published by Ministry of Education, Culture, Sports,Science & Technology in Japan (MEXT) (air, fallout,soil, milk, and vegetables).

The latter were compared with modeled results.JRODOS DSS can perform such comparisons by adding

georeferenced layers with values of measurements. Figure 7shows the map of the results of accumulated depositionmeasurements of 137Cs from 20th to 24th March in the points(marked in Figure 7) − only available measurements pointswithin the computational range − and results of modeleddeposition from 12th to 24th March, in this stage of the study:Ibaraki (measured, 25 531; modeled, 8140); Yamagata(measured, 6510; modeled, 954); Tachigi (measured, 929;

modeled, 118) (all values given in Bq/m2, Table S4 of theSupporting Information).Although measured and modeled values were in the same

order of magnitude, modeled values were below measurementsin a factor up to eight. A more exhaustive analysis will beperformed with additional data (as new data of the deposition)and improving modeling, both spatially and temporally, toidentify the source of the found uncertainties. Further researchusing additional measurements and tuning critical parameterswould allow an improvement of the modeled results. In a firstapproximation, several factors were identified as especiallyimportant: source term (time, number of events, releasedquantities), size of the released particles, or the use of distancesto monitors for normalizing source term estimations. Thenumerical weather prediction data is also a very critical factorfor such modeling as, for such a long time of emission, thepossible variability in this data may lead to differences of ordersof magnitude in results.During the FNPP accident, JRODOS DSS was shown to be a

quickly adaptable system for modeling in specific conditions,although originally designed for its application in Europe. Thesystem showed a stable performance during operationalmodeling and a good capability to incorporate results fromother models of weather forecast.

■ ASSOCIATED CONTENT

*S Supporting InformationEstimated release, summary of analyzed data, framework formodeling, comparison of measured cumulative fallout withmodeling, input information in RASCAL, monitoring points,estimation of accumulated emission by NSC and this work,modeling of deposition using different weather conditions,topographical map. This material is available free of charge viathe Internet at http://pubs.acs.org.

Figure 7. Results of 137Cs ground concentration modeling (dry and wet) at 23:15 h March 24th (UTC).

Environmental Science & Technology Article

dx.doi.org/10.1021/es301687t | Environ. Sci. Technol. 2012, 46, 11887−1189511894

■ AUTHOR INFORMATION

Corresponding Author*E-mail: alla.dvorzhak@ciemat.es.

NotesThe authors declare no competing financial interest.

■ ACKNOWLEDGMENTS

This work was partially funded by Spanish R&D projectMATER (Development and Validation of Advanced Models ofAtmospheric Dispersion for Application to Studies of Radio-logical Emergency Systems) and project ACCROS (Actualiza-tion, Configuration and Basic Adaptation of JRODOS systeminstalled in the Emergency Center of CSN to Spanishconditions). The authors wish to thank Dmytro Trybushnyi(KIT, Karlsruhe) and Ievgen Ievdin, (UCEWP, Kiev) for theircooperation and operational assistance with the systemJRODOS and to Eduardo Gallego (UPM, Madrid) for hisconstructive discussions.

■ REFERENCES(1) Ehrhardt, J.; Weis, A. RODOS: Decision Support System for off-SiteNuclear Emergency Management in Europe, Report EUR 19144;European Commission: Brussels, 2000.(2) Schulte, E. H.; Nelly, G. N.; Jackson, C. A. Decision Support forEmergency Management and Environmental Restoration, Report EUR19793; European Commission: Brussels, 2002.(3) Raskob, W.; Gering, F.; Lochard, J.; Nisbet, A.; Starostova, V.;Tomic, B. Overview and main achievements of the EURANOSproject: European approach to nuclear and radiological emergencymanagement and rehabilitation strategies. Radioprotection 2010, 45(5), S9−S22.(4) RODOS home page. Available at: http://www.rodos.fzk.de/rodos.html (accessed March 20, 2011).(5) Ievdin, I.; Trybushnyi, D.; Zheleznyak, M.; Raskob, W. RODOSre-engineering: Aims and implementation details. Radioprotection2010, 45 (5), S181−S189.(6) Ievdin, I.; Trybushnyi, D.; Landman, C. JRodos CustomizationGuide. Version 2.1. 2010.(7) Dvorzhak, A.; Montero, M. Applicability of the Decision SupportSystem RODOS in situations of non nuclear emergencies. Radio-proteccion 2007, XIV (53 Ext), 359−363 (In Spanish).(8) Montero, M.; Dvorzhak, A.; Gallego, E. JRODOS system: anefficient and state of the art tools for nuclear and radiological accidentsmanagement and rehabilitation. Implementation in Spain. InProceedings of the 2nd Joint Congress of Spanish Society of RadiationProtection and Spanish Society of Medical Physics.Seville, Spain. May10−13, 2011; SEPR and SEFM: Seville, 2012; pp 575−587 (InSpanish).(9) Dvorzhak, A.; Puras, C.; Montero, M. Modeling of theFukushima accident with JRODOS system. 37th Annual meeting ofthe Spanish Nuclear Society. Burgos, Spain, September 28−30, 2011 (InSpanish).(10) Dmytro Trybushnyi from IKET Karlsruhe Institute ofTechnology (KIT). Personal communication. 2011 March 18th.Data from IMK-TRO (KIT).(11) Report of the Japanese Government to the IAEA MinisterialConference on Nuclear Safety. The Accident at TEPCO’s FukushimaNuclear Power Stations. Nuclear Emergency Response HeadquartersGovernment of Japan. 2011 June. Available at: http://www.iaea.org/newscenter/focus/fukushima/japan-report/ (accessed July 11, 2011).(12) McGuire, S. A.; Ramsdell, J. V.; Athey, G. F. Rascal 3.0.5:Description of Models and Methods. NUREG-1887, 2008. Availableat: http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1887/sr1887.pdf (accessed March 20, 2011).

(13) Tokyo Electric Power Company (TEPCO). Available at:http://www.tepco.co.jp/nu/programs/viewf1-j.html (accessed March20, 2011).(14) Nuclear and Industrial Safety Agency (NISA). INES (theInternational Nuclear and Radiological Event Scale) Rating on theEvents in Fukushima Dai-ichi Nuclear Power Station by the TohokuDistrict - off the Pacific Ocean Earthquake. News Release. April 12,2011. Available at: http://www.nisa.meti.go.jp/english/files/en20110412-4.pdf (accessed April 12, 2011).(15) Nuclear and Industrial Safety Agency (NISA). Available at:http://www.nisa.meti.go.jp/english/files/en20110322-3-2.pdf (ac-cessed March 22, 2011).(16) Gesellschaft fur Anlagen- und Reaktorsicherheit (GRS).Available at: http://fukushima.grs.de/sites/default/files/ (accessedMay 25, 2011).(17) Tokyo Electric Power Company (TEPCO). Available at:http://www.tepco.co.jp/en/nu/fukushima-np/f1/index-e.html (ac-cessed March 17, 2011).(18) Gesellschaft fur Anlagen- und Reaktorsicherheit (GRS).Available at: http://fukushima.grs.de/sites/default/files/TEPCO_Nachtrag_ODL-Daten_20110607.pdf (accessed May 25, 2011)(19) Tokyo Electric Power Company (TEPCO). Available at:http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110528e14.pdf (accessed June 15, 2011).(20) Fukushima Prefecture, 2011. Available at: http://www.pref.fukushima.jp/j/20-50km0315-0331.pdf (accessed August 15, 2011).(21) Nuclear Safety Commission (NSC). Trial estimation ofemission of radioactive materials (I-131, Cs-137) into the atmospherefrom Fukushima Dai-ichi Nuclear Power Station. Press release. April12, 2011. Available at: http://www.nsc.go.jp/NSCenglish/geje/2011%200412%20press.pdf (accessed April 13, 2011)(22) U.S. Department of Energy (DOE). Available at: http://www.slideshare.net/energy/radiation-monitoring-data-from-fukushima-area-04182011 (accessed March 30, 2012)(23) Declan B. Radioactivity spreads in Japan. Nature, vol.471. Pp.555-556. 2011.(24) Daily Yomiuri Online, 2011. Available at: http://www.yomiuri.co.jp/dy/national/20110830dy05.htm (accessed August 31, 2011).(25) Visible Information Center Inc. (VIC). Simulation on 137Csdeposition due to the emission from Fukushima Daiichi Nuclear Plant.Available at: http://www.vic.jp/fukushima/global/global-e.html (ac-cessed May 31, 2011).(26) Genki, K.; Hiroaki, T.; Haruyasu, N.; Masamichi C. Numericalreconstruction of high dose rate zones due to the Fukushima Dai-ichinuclear power plant accident. J. Environ. Radioact.Vol. 111. pp 2-12.Sept. 2012.(27) Yasunari T. J., Stohl A., Hayano R. S., Burkhart J. F., Eckhardt S.,Yasunati T. Cesium-137 deposition and contamination of Japanesesoils due to the Fukushima nuclear accident, 2011 PNAS Early Edition.

Environmental Science & Technology Article

dx.doi.org/10.1021/es301687t | Environ. Sci. Technol. 2012, 46, 11887−1189511895