Radiological Event Details

Note: This is a summary of the contents in a request form. Therefore, the fields will be filled only if the corresponding information is provided in the request form.

Name of the release site and country: Zwentendorf, Austria

Latitude (decimal degrees N or S): 48.355 N

Longitude (decimal degrees E or W): 15.886 E

Height of the site (m): Click or tap here to enter text.

Start of release (date/time, UTC): 18 August 2026 0500 UTC

Duration (hours): , or

End of release (date/time, UTC): 18 August 2026 0720 UTC

Radionuclide species: I-131

Total release quantity (Becquerel): 10e15, or

Pollutant release rate (Becquerel/hour): 1.0E+18

Effective height of release:

Surface: Click or tap here to enter text., or

Release height:

Base (m): 15

Top (m): Click or tap here to enter text.

Response Details

Request sent by: IAEA

Additional information (Optional): Click or tap here to enter text.

Contact Details for Select WMO Region

Note: The following table shows all RSMCs’ contacts. Please refer to the contacts relevant RSMCs in your Region.

RSMC	E-Mail	Telephone No.
RA I and VI
Exeter, United Kingdom	EMARC@metoffice.gov.uk	+44 330 135 4267
Toulouse, France	cmc@meteo.fr	+33 5 6107 8540
Offenbach, Germany	Mvd@dwd.de met.Leitstand@dwd.de	+49 69 8062 2591 +49 69 8062 2530
Vienna, Austria	rsmc-vienna@geosphere.at	+43 1 36026 2311
RA II
Beijing, China	rsmc@cma.gov.cn	+86 10 5899 3295
Tokyo, Japan	era-tokyo@met.kishou.go.jp	+81 3 3434 9102
Obninsk, Russian Federation	rsmc@feerc.ru	+7 484 394 4950
RA III and IV
Montreal, Canada	rsmc.montreal@ec.gc.ca	+1 514 421 4635
Washington, USA	SDM@noaa.gov arl.emerg@noaa.gov	+1 301 683 1500
RA V
Melbourne, Australia	rto@bom.gov.au	+61 3 9669 4010

For more detailed contact information, see https://wmo.int/contact-points-nuclear-and-non-nuclear-environmental-emergency-response.

Meteorological situation and expected development over the next 72 hours in the area:

Surface observations at the release site: Winds from the northwest at roughly 8 knots. Temperature of 18 degrees Celsius. Partly cloudy skies and no precipitation.

Surface weather and outlook: The next 3 days will see a warming trend at the site, with temperatures initially around 18 C rising to 22, 28 and then 32 C for the coming days. Winds will generally be from the west or southwest during the period. Winds will be around 25 knots during the afternoon but weakening to calm overnight Wednesday into Thursday. Some light rain is forecast Tuesday afternoon, but the rest of the period is expected to be dry.

Meteorological forecast model details

Details regarding the models of each RSMC, including the name of the NWP model, native horizontal resolution, cycle run, and forecast time interval, can be found in Section 5, Annex 4 at https://community.wmo.int/technical-document-no-778-documentation-rsmc-support-environmental-emergency-response-targeted.

Time-integrated air concentrations (Exposure): Does the dispersion modelling output from the RSMCs differ significantly, and what are the possible reasons for these differences?

Description and analysis of the concentration results (gathering the information from the different results, describing the most likely outcome and explaining the differences in the results), and some interpretation of these.

Exposures for both models are very similar. The CA exposure pattern extends further to the northeast into southwestern Russia, however. It also extends further south, reaching Crete, contrary to the US model. Maximum amounts are very similar between both models for the third day (8.77e+04 vs 7.6e+04 Bq*s/m3 for the CA and US models, respectively).

Total deposition: Does the dispersion modelling output from the RSMCs differ significantly, and what are the possible reasons for these differences?

Description and analysis of the total deposition results (gathering the information from the different results and describing the most likely outcome), their differences and some explanations on why the differences arise.

Deposition patterns are very similar between both models, extending into southwestern Russia and northwestern Turkey. It is noted that the maximum amount of deposition in the US model is two orders of magnitude larger than its CA counterpart (4.9e+05 Bq/m2 vs. 3.4e+03 Bq/m2).

Which variations of flow with altitude do the trajectories indicate?

Some information on the expected flow with altitude collected from the different trajectory results.

While the trajectories forecast by both the US and CA models are initially alike, the US low-level trajectories ultimately stay over Hungary and Serbia, contrary to the CA trajectories, which make it to the western Black Sea. Conversely, while the US mid-level trajectories end up almost over the Black Sea, the CA ones remain over Romania. The upper-level trajectories are more similar, making it to northwestern Turkey.

Note:

At a particular location, any model dispersion/deposition differences can be attributed to differences in the flow driving meteorological models and differences in the formulation of the dispersion models. Until updated meteorological data and sufficient radiological monitoring information become available, it is suggested that the higher comparative values of the time-integrated concentrations and total depositions presented above be considered.

Trajectories represent material released from discrete levels. The limited number of trajectories displayed may be used to evaluate the general material flow beginning at each level. Still, it should not be used to determine pollutant time-integrated concentration patterns or total deposition patterns, since these levels may not be representative of all interacting levels where pollutants are being transported, diffused and deposited. The concentration/deposition model results and comparisons are a more appropriate guide for decision-making.

Concentration results represent the total air concentration present in the area in the corresponding time interval, i.e. the time-integrated concentration over the first 24 hours, second 24 hours and third 24 hours.

Deposition is the process where material leaves the atmosphere either by the uptake at the surface (dry deposition) or by the absorption into droplets and the following precipitation (wet deposition). Wet deposition is highly related to the forecast and may therefore lead to bigger deviations in the results due to variations in forecasts of different meteorological models. The results depict the total deposition (i.e. sum of dry and wet deposition).

Details on the mandatory products and general rules for displaying products can be found in Appendix 2.2.22 of the Manual on the WMO Integrated Processing and Prediction System (WIPPS) at https://library.wmo.int/records/item/35703-manual-on-the-wmo-integrated-processing-and-prediction-system?offset=2.