The Relationship between the Surface Current Offshore Tokai and the Wind Field

Nakano, Masanao ; Isozaki, Hisaaki; Isozaki, Tokuju; Ao, Hidetoshi*; Nemoto, Masashi*

The marine observation has been performed along the coast of JNC Tokai Reprocessing Plant (TRP) that discharges low level radioactive effluent. Recently the underslung electromagnetic flow-meter measured the current field at the very surface layer (depth: 0.5m, 1.0m, 3.0m). Then, the characteristic of the surface current field was analysed with correlation to the wind field that observed at 20m above sea level in Tokai Works. The tidal component is apparently detected by the harmonic analysis since the diel contents (land and sea breeze) is included in the wind that drives the surface seawater. However it is not the tidal current but the wind current. As the result, it made sure that the surface current is induced by the wind. Especially the wind current develops at the thin surface (skin) layer with pycnocline. The effluent from TRP has no salt and relatively high temperature, and it induces pycnocline near the discharge port. Assessing the marine diffusion of the radioactive materials from TRP, it is important to consider wind current especially.