Computation and Analysis of the Global Distribution of the Radioxenon Isotope 133Xe based on Emissions from Nuclear Power Plants and Radioisotope Production Facilities and its Relevance for the Verification of the Nuclear-Test-Ban Treaty

Wotawa, Gerhard; Becker, Andreas; Kalinowski, Martin; Saey, Paul R. J.; Tuma, Matthias P.; Zähringer, Matthias

doi:10.1007/s00024-009-0033-0

Cited by 68 publications

(27 citation statements)

References 21 publications

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“…This model was originally developed for calculating the dispersion of radioactive material from nuclear emergencies, but since then it has been used for many other applications as well. Nuclear emergency applications include simulations of the transport of radioactive materials from NPPs and other facilities (Andreev et al, 1998;Wotawa et al, 2010) or from nuclear weapon tests . The model has a detailed description of particle dispersion in the boundary layer and a convection scheme to describe particle transport in clouds (Forster et al, 2007).…”

Section: Methodsmentioning

confidence: 99%

Inverse modeling of the Chernobyl source term using atmospheric concentration and deposition measurements

et al. 2017

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Abstract. This paper describes the results of an inverse modeling study for the determination of the source term of the radionuclides 134 Cs, 137 Cs and 131 I released after the Chernobyl accident. The accident occurred on 26 April 1986 in the Former Soviet Union and released about 10 19 Bq of radioactive materials that were transported as far away as the USA and Japan. Thereafter, several attempts to assess the magnitude of the emissions were made that were based on the knowledge of the core inventory and the levels of the spent fuel. More recently, when modeling tools were further developed, inverse modeling techniques were applied to the Chernobyl case for source term quantification. However, because radioactivity is a sensitive topic for the public and attracts a lot of attention, high-quality measurements, which are essential for inverse modeling, were not made available except for a few sparse activity concentration measurements far from the source and far from the main direction of the radioactive fallout.For the first time, we apply Bayesian inversion of the Chernobyl source term using not only activity concentrations but also deposition measurements from the most recent public data set. These observations refer to a data rescue attempt that started more than 10 years ago, with a final goal to provide available measurements to anyone interested. In regards to our inverse modeling results, emissions of 134 Cs were estimated to be 80 PBq or 30-50 % higher than what was previously published. From the released amount of 134 Cs, about 70 PBq were deposited all over Europe. Similar to 134 Cs, emissions of 137 Cs were estimated as 86 PBq, on the same order as previously reported results. Finally, 131 I emissions of 1365 PBq were found, which are about 10 % less than the prior total releases.The inversion pushes the injection heights of the three radionuclides to higher altitudes (up to about 3 km) than previously assumed (≈ 2.2 km) in order to better match both concentration and deposition observations over Europe. The results of the present inversion were confirmed using an independent Eulerian model, for which deposition patterns were also improved when using the estimated posterior releases. Although the independent model tends to underestimate deposition in countries that are not in the main direction of the plume, it reproduces country levels of deposition very efficiently. The results were also tested for robustness against different setups of the inversion through sensitivity runs. The source term data from this study are publicly available.

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Section: Methodsmentioning

confidence: 99%

Inverse modeling of the Chernobyl source term using atmospheric concentration and deposition measurements

et al. 2017

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“…The CTBTO network records 133 Xe "pollution episodes" regularly, especially at stations downwind of the known sources of radioxenon (Wotawa et al, 2010). This known background is on the order of some mBq m À3 and was determined here by averaging all measured concentrations for each station for the period 1 January till 11 March 2011.…”

Section: Measurements Of Xe-133mentioning

confidence: 99%

The total release of xenon-133 from the Fukushima Dai-ichi nuclear power plant accident

Stohl

Seibert

Wotawa

2012

Journal of Environmental Radioactivity

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The accident at the Fukushima Dai-ichi nuclear power plant (FD-NPP) on 11 March 2011 released large amounts of radioactivity into the atmosphere. We estimate the total emission of the noble gas xenon-133 ( 133 Xe) using global atmospheric concentration measurements. We estimate the emissions using three different methods, one using a multi-box model, the other a dispersion model driven with two different meteorological input data sets. The three methods yield total 133 Xe releases of 16.7 EBq±1.9 EBq, 14.2±0.8 EBq and 19.0±3.4 EBq, respectively. These values are substantially larger than the entire 133 Xe inventory of FD-NPP of 12.2 EBq derived from calculations of nuclear fuel burn-up. Additional release of 133 Xe due to the decay of iodine-133 ( 133 I), which can add another 2 EBq to the 133 Xe FD-NPP inventory, is required to explain the atmospheric observations. Two of our three methods indicate even higher emissions, but this may not be a robust finding given the uncertainties. The result was a massive discharge of radionuclides. In the atmosphere, the 10The total amount of radioactivity released into the atmosphere is still 100At Darwin in the SH (Fig. 2, bottom where N is the number of stations (latitude bands) used, A i the area of (not shown). Estimates using the central ten 5-day intervals show relatively 151 little variability, suggesting that the method works best during that period. 152The overall negative trend during that period can be explained by leakage The results, again averaged over 5-day intervals, are shown in Fig. 4. 182Using model results based on ECMWF data, the release estimates until early in building up and maintaining its global radio-xenon measurement network. 228ECMWF and met.no granted access to ECMWF analysis data.

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“…Field experiments have been used to validate the performance of FLEXPART (Stohl et al, 1998;Forster et al, 2007). FLEXPART has also been used in a wide variety of dispersion applications, including the transport of air pollutants Avey et al, 2007), of radiological releases from nuclear power plants and radioisotope production facilities (Andreev et al, 1998;Wotawa et al, 2010;Stohl et al, 2012), of volcanic plumes (Stohl et al, 2011), and of noble gases produced from nuclear weapons tests .…”

Section: Flexpartmentioning

confidence: 99%

Bayesian inverse modeling of the atmospheric transport and emissions of a controlled tracer release from a nuclear power plant

et al. 2017

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Abstract. Probability distribution functions (PDFs) of model inputs that affect the transport and dispersion of a trace gas released from a coastal California nuclear power plant are quantified using ensemble simulations, machine-learning algorithms, and Bayesian inversion. The PDFs are constrained by observations of tracer concentrations and account for uncertainty in meteorology, transport, diffusion, and emissions. Meteorological uncertainty is calculated using an ensemble of simulations of the Weather Research and Forecasting (WRF) model that samples five categories of model inputs (initialization time, boundary layer physics, land surface model, nudging options, and reanalysis data). The WRF output is used to drive tens of thousands of FLEXPART dispersion simulations that sample a uniform distribution of six emissions inputs. Machine-learning algorithms are trained on the ensemble data and used to quantify the sources of ensemble variability and to infer, via inverse modeling, the values of the 11 model inputs most consistent with tracer measurements. We find a substantial ensemble spread in tracer concentrations (factors of 10 to 10 3 ), most of which is due to changing emissions inputs (about 80 %), though the cumulative effects of meteorological variations are not negligible. The performance of the inverse method is verified using synthetic observations generated from arbitrarily selected simulations. When applied to measurements from a controlled tracer release experiment, the inverse method satisfactorily determines the location, start time, duration and amount. In a 2 km × 2 km area of possible locations, the actual location is determined to within 200 m. The start time is determined to within 5 min out of 2 h, and the duration to within 50 min out of 4 h. Over a range of release amounts of 10 to 1000 kg, the estimated amount exceeds the actual amount of 146 kg by only 32 kg. The inversion also estimates probabilities of different WRF configurations. To best match the tracer observations, the highest-probability cases in WRF are associated with using a late initialization time and specific reanalysis data products.

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Computation and Analysis of the Global Distribution of the Radioxenon Isotope 133Xe based on Emissions from Nuclear Power Plants and Radioisotope Production Facilities and its Relevance for the Verification of the Nuclear-Test-Ban Treaty

Cited by 68 publications

References 21 publications

Inverse modeling of the Chernobyl source term using atmospheric concentration and deposition measurements

Inverse modeling of the Chernobyl source term using atmospheric concentration and deposition measurements

The total release of xenon-133 from the Fukushima Dai-ichi nuclear power plant accident

Bayesian inverse modeling of the atmospheric transport and emissions of a controlled tracer release from a nuclear power plant

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