Distribution of natural #gamma# ray dose rates in a beach-dune system. A case study of the Tottori dune

Natural #gamma# ray dose rates were measured at 94 points in the Tottori Dune coast located in Tottori City, Tottori Prefecture. The dose rate increased gradually from the shoreline to the end of the beach, and revealed an approximately constant value on the slope and the entire area of the dune. As a result of spectrum measurements there, although the concentrations of both potassium and uranium in the beach amounted to almost the same levels as those in the dune, the concentrations of thorium in the dune were high compared to those in the beach. The peculiarity and commonality in natural #gamma# ray dose rate distribution in each beach-dune system were described by comparing with the cases of three dunes in the Enshu-nada coast measured so far. (author)