Long-term integrated environmental radioactivity monitoring and public dose assessment across a full emergency planning zone.

This study presents an 8-y (2017-2024) integrated environmental radioactivity monitoring program and public dose assessment conducted across the entire Emergency Planning Zone (EPZ) of the Hanbit Nuclear Power Plant in the Republic of Korea. Following the expansion of the EPZ to a 30 km radius, a comprehensive multi-media monitoring framework was established, covering rainwater, surface soil, seawater, and locally produced foodstuffs. To our knowledge, this study represents one of the first EPZ-scale, integrated multi-media environmental radioactivity datasets in Korea, enabling a systematic evaluation of spatial and temporal variability across multiple environmental pathways. Radionuclides of interest included beta activity, cesium-137, and tritium, analyzed under metrologically validated conditions in accordance with ISO 11929 and IAEA guidelines. Temporal and spatial analyses indicated that radionuclide concentrations across all environmental matrices remained within the range of natural background variability, with no statistically significant long-term trends (P > .05). Occasional fluctuations were attributed to environmental factors such as precipitation patterns and marine dynamics rather than anthropogenic releases. Public radiation dose assessments, based on realistic exposure pathways including ingestion and external exposure, showed that the annual effective dose to residents within the EPZ was well below regulatory limits and international reference levels. The integration of long-term, multi-media monitoring data with dose assessment provides a robust framework for distinguishing natural background variability from potential anthropogenic contributions. These findings demonstrate the radiological safety and environmental stability of the Hanbit EPZ and highlight the value of EPZ-scale, system-based monitoring approaches for nuclear facility surveillance and public reassurance.