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Abstract WA163Full Paper + Presentation
Identifying dominant phenomena in the dose-distance curve for optimization of Japanese emergency planning
Understanding the dose-distance curve is essential for determining the emergency planning zone. It is known that dose variation with distance is influenced by a combination of multiple phenomena, each characterized by either a power law or an exponential decay law. In our previous study, we examined the range of applicability of the power law by focusing on various accident scenarios and meteorological conditions. However, further investigation was needed to clarify which phenomenon becomes dominant under different conditions. Therefore, the objective of this study is to clarify the relative importance of each phenomenon depending on the conditions.
For accident scenarios, containment failure, hardened containment venting, and filtered containment venting were considered under various assumed timings. For meteorological conditions, 8,760 cases were analyzed using one year of site data from Japan. In addition, release height and finite cloud correlation factors, which were not addressed in the previous report, were incorporated as parameters, thereby enabling a more detailed discussion at short distances.
Through this analysis, the relative importance of each phenomenon was identified under the respective conditions. Criteria for power-law dominance and exponential-law dominance were also clarified. Furthermore, based on annual data in Japan, the statistically dominant phenomenon at real Japanese sites was identified.
Based on these findings, a decision-making framework for determining the emergency planning zone was examined and proposed. The power law describes the scaling relationship between distance and dose and supports decision-making for defining the emergency planning zone based on proportional changes of reactor thermal power. In contrast, the exponential law describes a constant proportional change in dose per unit distance and allows assessment of the marginal dose-reduction benefit per unit distance increment.
Future work will focus on formulating a more universal expression of dose-distance curve and developing a rigorous theoretical framework. The elasticity discussion of the formulated universal dose-distance curve could be utilized as a technical basis for prioritizing protective measures and determining emergency planning zone.
← Check another abstractFor accident scenarios, containment failure, hardened containment venting, and filtered containment venting were considered under various assumed timings. For meteorological conditions, 8,760 cases were analyzed using one year of site data from Japan. In addition, release height and finite cloud correlation factors, which were not addressed in the previous report, were incorporated as parameters, thereby enabling a more detailed discussion at short distances.
Through this analysis, the relative importance of each phenomenon was identified under the respective conditions. Criteria for power-law dominance and exponential-law dominance were also clarified. Furthermore, based on annual data in Japan, the statistically dominant phenomenon at real Japanese sites was identified.
Based on these findings, a decision-making framework for determining the emergency planning zone was examined and proposed. The power law describes the scaling relationship between distance and dose and supports decision-making for defining the emergency planning zone based on proportional changes of reactor thermal power. In contrast, the exponential law describes a constant proportional change in dose per unit distance and allows assessment of the marginal dose-reduction benefit per unit distance increment.
Future work will focus on formulating a more universal expression of dose-distance curve and developing a rigorous theoretical framework. The elasticity discussion of the formulated universal dose-distance curve could be utilized as a technical basis for prioritizing protective measures and determining emergency planning zone.