ARNECC Paper Talks #10: The Inter-comparison of transboundary atmospheric dispersion calculations: A Summary of outputs from the ASEAN NPSR benchmark exercise

Online, 16 Dec 2021

The ASEAN Researchers Network on Energy and Climate Change (ARNECC) Paper Talks has reached the 10th series with the discussion of nuclear technology to close 2021! The discussion was about an article “The Inter-comparison of transboundary atmospheric dispersion calculations: A Summary of outputs from the ASEAN NPSR benchmark exercise”, which was published in the journal of Progress in Nuclear Energy as part of the activity of ASEAN Network on Nuclear Power Safety Research (ASEAN NPSR). This topic was presented on 16 December 2021 by the lead researcher, Dr Kampanart Silva, and Mr Wasin Vechgama, who both are authors of this study. The event was moderated by ACCEPT Research Analyst, Ms Monika Merdekawati. 

Ever since the Fukushima nuclear accident, there was a growing concern in the ASEAN region when it comes to installing nuclear power plants and some projects were abandoned during construction phase. ASEAN NPSR, established in the year 2017, conducted research on nuclear accidents and consequences through inter-comparison tasks among ASEAN Member States (AMS). This is one of the action plans of ASEAN sub-committee on Sustainable Energy Research in 2017. 

This study provides a better understanding of four calculation codes and two dispersion models that could predict the transboundary atmospheric dispersion from a hypothetical accident at Vietnam’s Fangchenggang nuclear power plant. The main dispersion models of this paper are the Lagrangian particle model and Gaussian puff model where they can determine the radionuclide concentration or radiation dose at specific locations in a 24-hour timeframe. 

The research suggests that both models show minor differences in both dry and wet seasons. The meteorological data is the major factor in the diffusion of radionuclides. In addition to that, radionuclide types, extreme weather and the existence of rainfalls do not affect significantly in the results. However, strong wind could extend the radioactive exposure distance further.  

Despite the radiation reaches Southeast Asian countries within 24 hours, the radiation dose rate amounts to 0.1 µSv/h. This gives a total of 0.9 mSv/year, which is still smaller than the recommended exposure level (so-called reference level) for normal exposure of the International Commission on Radiological Protection (ICRP) at 1 mSv/year. Whereas the reference level for emergency exposure, such as radiological accidents, is 20-100 mSv/year which is way higher than the result.

The paper concludes the best practice is to utilize Gaussian Puff model to get an initial information before employing the Lagrangian particle model to confirm the results. These calculation codes and dispersion models can be used by the authorities to make informed decisions to design appropriate risk communication strategies, dispel unnecessary public anxiety and deploy more extensive radiation monitoring system. This approach is more cost-efficient compared to the conventional evacuation and sheltering procedures that can be very disruptive to the general public.  

In the Q&A sessions, there were questions related to the evacuation procedures and planning and designing phase.  

Dr Kampanart explained the evacuation procedures in terms of distance, depending on the severity of the nuclear accident, for neighboring countries and countries who own the NPP. Mr Wasin added on the fact that there is a document listing the potential impact from past NPPs. Therefore, future NPP projects can be designed with less consequences in case an accident does happen. 

Regarding planning and designing phase, there are several aspects that needed to be complied before predicting the radioactive dispersions such as safety, stable ground, nearby existing grid, cooling source and people who accept NPP installation. After selecting a location, core inventories can be requested from vendors for accurate simulation results. 

Ms Monika closed the event by promoting ARNECC, which links to a group of scholars, analysts and other stakeholders across ASEAN to broaden knowledge and insights on energy and climate change. This will bridge the gap between the ASEAN energy and climate policies, contributing to more climate-friendly development of the energy sector. 

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