| Project summary |
The activity aims to conduct a coordinated Nordic benchmark study comparing different Atmospheric Transport and Dispersion (ATD) and dose calculation tools used for evaluation of offsite consequences to the public and emergency preparedness and response to nuclear accidents.
Participating organizations will apply their respective tools (e.g., LENA, MACCS, JRODOS, ARGOS, ARANO, VALMA, ESS-Doctor and others) to identical or comparable accident and meteorological scenarios, jointly selected as benchmark exercises for the project. The benchmark will assess the ability of different models to predict plume transport and dispersion, ground deposition, and radiological doses to the public through various exposure pathways, and will evaluate the impact of modelling assumptions and parameter selections on code predictions.
The project will be implemented in three phases where the goal of the first phase (2026) is:
(i) to perform a detailed literature review and in-depth analysis of the models employed in the codes selected by the participating organizations, identifying key assumptions and limitations and their potential impact on results. Examples include modelling approaches for plume rise, plume meander, plume dispersion, and treatment of atmospheric conditions - to identify the phenomena and respective modelling approaches implemented in the codes.
(ii) to select the benchmark exercise(s) for the code-to-code comparison, including, at minimum, selection of the reactor type, accident scenario, source term(s), weather conditions, and dose conversion factors.
To perform a meaningful comparison, the ATD and dose assessment tools must be applied to the same problem. The benchmark selection will therefore be based on a set of hypothetical accident scenarios and source terms generated with integral plant response codes (such as MAAP or MELCOR).
(iii) to select the main figures of merit (FOMs) for the analysis (e.g., maximum air and ground concentrations around the facility, total effective dose, thyroid dose at specified distances from the release source, exceedance of emergency response levels, etc.). The selection of FOMs is an important step to ensure that the analysis covers all relevant aspects related to ATD phenomena and dose calculations.
(iv) to conduct the initial benchmarking of the ATD and dose assessment tools on the selected benchmark exercises. This step will include initial model setup in the ATD and dose assessment tools and calculations of atmospheric transport, dispersion, and evaluation of the main FOMs using standard (best-estimate) modelling parameters and assumptions in the respective tools.
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NKS-B 