【Technical Introduction】
Based on the principle of prevention over response, the Nuclear Safety Commission (NSC) established Emergency Planning Zones (EPZs) to plan and prepare for disaster response, ensuring public safety and health. Concurrently, the NSC enacted the Nuclear Emergency Response Act, mandating Taiwan Power Company (TPC) to periodically review and revise the current EPZs. The National Atomic Research Institute (NARI) integrated the current nuclear energy safety and radiation protection analysis technology to develop a systematic evaluation approach for EPZs.
NARI developed an innovative systematic analysis technology that includes the calculations for inventories in reactor cores and spent fuel pools, severe accident analysis, design basis accident analysis and nuclear accident dose assessments. The system integrates upstream and downstream analytical tools (e.g., ORIGIN, MAAP, RADTRAD, and WinMACCS), as illustrated in Figure 1. This integrated technology combines the strengths of various analytical tools and ensures that each stage of the analysis is comprehensively considered and accurately calculated. The integrated system also provides an intuitive graphical interface, enabling faster data interpretation and assisting the decision makers make accurate judgement. This technology is critical for establishing EPZs and ensuring public safety.
Figure 1. Systematic analysis process and tool integration technology for EPZs
【Project Planning/Technical Applications】
The previous analytical technology for EPZs in Taiwan are based on the nuclear power plants (NPPs) during the full power operation. However, due to insufficient space in the spent fuel pools associated with Chin-shan and Kuo-sheng NPPs, some spent fuel remains temporarily stored in the reactors during the early stages of decommissioning. This is a unique situation internationally. The systematic analysis technology developed by NARI is suitable for NPPs during operation state and early stages of decommissioning. This achievement not only highlights the NARI's leading position in EPZ analytical technology in Taiwan but also completes the EPZs framework to ensure public health and property safety.
In accordance with the Nuclear Emergency Response Act, TPC is required to regularly review and revise the existing EPZs. The EPZ is defined as a circular area with a radius from the midpoint between the two reactor units. The assessment results indicate that the Maanshan NPP requires the largest EPZ (i.e., 2.5 km radius) during full power operation, as illustrated in Figure 2. Therefore, a conservative radius of 2.5 km is adopted for all NPPs. However, due to current administrative considerations by the NSC, the official EPZ remains set at 8.0 km radius for all NPPs. If future policies allow for the relaxation of EPZ requirements, the surrounding land near NPPs could be revitalized and better utilized, aligning with the nation’s best regulatory practices and maximizing public interest.
Figure 2. Annual probability of exceeding 50 mSv and 2 mSv in 2.5 km radius (using the Maanshan NPP as an example)
【Future Development】
To address the evolving trends in nuclear energy development and disaster prevention needs, this technology will continue to enhance model accuracy through the integration of advanced features, including Artificial Intelligence (AI)-assisted decision-making mechanisms, real-time coupling with meteorological data, automatic risk scenario identification and real-time decision support functions. These improvements aim to strengthen the timeliness and reliability of accident simulations and dose predictions.-
Looking ahead, this technology is expected to be extended to new nuclear facilities such as Small Modular Reactors (SMRs). The existing models will be modified to develop an EPZ assessment framework specifically suited for SMRs. Based on the assessment results generated by this enhanced technology, the new policy recommendations will be formulated for defining appropriate EPZs for SMRs, thereby laying a solid foundation for the deployment of next-generation nuclear energy systems. Whether applied to traditional nuclear reactors or SMRs, this technology is anticipated to serve as a key enabler in strengthening national sustainable development capabilities and enhancing global competitiveness.
【Contact Information】
Name：Cheng-Lun Yu
Tel：03-4711400 Ext. 6112
E-mail：fishcan@nari.org.tw
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