[2C10-16] Fukushima 2

3:00 PM - 3:15 PM JST(6:00 AM - 6:15 AM UTC)

[2C11] Investigation on distribution of radioactive substances in Fukushima(6) Analysis of the source of cesium discharge from the Fukushima Daiichi Nuclear Power Plant to the ocean

*Yuichi Onda¹, Hikaru Sato¹, Daisuke Tsumune¹, Katsuhiko Kohata², Tomomi Okamura² (1. Center for Research in Radiation, Isotopes and Earth System Sciences, 2. Tokyo Electric Power Company Holdings)

Keywords:

Cs-137,Fukushima Daiichi Nuclear Power Plant,Tritium

Minimizing radionuclide release is crucial for the decommissioning and ecological restoration of post-accident nuclear sites. At Fukushima Daiichi Nuclear Power Plant, despite a seaside impermeable wall, Caesium-137 (137Cs) continues leaking into the ocean with seasonal fluctuations. The origins and factors driving these variations are poorly understood. We investigated the K discharge channel, a significant route for 137Cs transfer from land to sea. Using tritium (3H) as a hydrologic tracer, we differentiated base flow from total channel discharge and applied an effective rainfall method. Findings indicate that reactor building roofs are the primary 137Cs source. Seasonal variations are linked to temperature effects on base flow and rainfall-driven runoff. This tracer approach provides novel insights for sustainable remediation of nuclear sites.