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: Armenian-2 NPP, Armenia

Latitude (decimal degrees N or S): 40.18 N

Longitude (decimal degrees E or W): 44.15 E

Height of the site (m): 25m

Start of release (date/time, UTC): 19-May-2026 07:30 UTC

Duration (hours): 0.5hours, or

End of release (date/time, UTC): 19-May-2026 08:00 UTC

Radionuclide species: CS-137

Total release quantity (Becquerel): 1, or

Pollutant release rate (Becquerel/hour): Click or tap here to enter text.

Effective height of release:

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

Release height:

Base (m): 25 m

Top (m): 500 m

Response Details

Request sent by: IAEA

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

Contact Details for RA II

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: Partly cloudy, light precipitation, northwesterly wind at 2-4 m/s.

Surface weather and outlook: The NWP of Japan and Russian: A low pressure system over near the northwestern coast of the Caspian Sea is remaining almost stationary and will be slowly weakening until Wednesday 20 May, 2026. Precipitation is expected around this low pressure system from 20 May to 21 May. Weak northwest wind about 4m/s is expected over Armenia from between 20 to 21 May, the wind field will be weak and temperature will rise in 22 May. The NWP of China, a low pressure system is passing away in 20 May. Precipitation is expected around this low pressure system from 20 May. Weak southeast wind is expected over Armenia in next 72hours.

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.

Within the first 24 hours, RSMC Beijing, Tokyo and Obninsk have similar exposure patterns. After the release, southern or southeastern Armenia, western Azerbaijan, the eastern border region of Turkey and northern Iran will be affected. On the second day, RSMC Tokyo and Obninsk predict the the impact zone is predicted to expand in all directions. Southeastern Georgia, southern regions of the Russian Federation (Republic of Dagestan), Azerbaijan, eastern Turkey, northern Iran, eastern Iraq, and the southwestern Caspian Sea will be impacted On the third day, RSMC Tokyo and Obninsk predict that the impact zone will continue to expand and affect southern Russia, eastern Turkey, northern and central Iran, the southern Caspian Sea, and the eastern border region of Turkmenistan. RSMC Beijing predicts that the pollutants will spread northwest covering the parts of Eastern Europe from 48 t0 72 hour.

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.

For RSMC Tokyo and Obninsk, the deposition area on the first day will be located southeast of the release source and will cover part of Armenia, the western border region of Azerbaijan, northern Iran, and the eastern border region of Turkey. On the second day, the deposition area will expand in all directions. However, it will be primarily located southeast of the release source and will affect southern Georgia, most of Azerbaijan, northern Iran, eastern Turkey, and the southwestern Caspian Sea. On the third day, the impact area will continue to expand across the same countries.

For RSMC Beijing, the deposition area will spread around in all directions in first day. Then, it will spread to northwest covering the parts of Eastern Europe.

Which variations of flow with altitude do the trajectories indicate?

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

For RSMC Tokyo and Obninsk, tracers from 500 m to 1500 m above the ground will move southeastward for the first 24 hours, and then will move northeastward accompanied with the low pressure system. Tracers from 3000 m above the ground will move south east for 24-48 hours, and then will move east-southeastward.

For RSMC Beijing, tracers from 500 m to 3000m m above the ground will move northeastward accompanied with the low pressure system in next 72hours

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.