Determination of the variation of environmental radiation due to the ground deposition of atmospheric 222Rn decay products during rainfall: utilization of the correlation between the variations observed at neighboring monitoring posts

Abstract

The increase of environmental radiation dose rate during rainfall at environmental monitoring posts (MPs) was calculated by using the correlation relationship with the dose rate at the neighboring MP. The calculated dose rate agreed with the observed one within less than 20% of the maximum increase height of the observed one for each rainfall. Furthermore, when the dose rate increased due to Krypton-85 (85Kr) discharged from the Tokai Reprocessing Plant (TRP) at the environmental monitoring station (MS) downwind of the stack during rainfall, the dose rate due to the 85Kr was tried to discriminate. The discriminated dose rate agreed with that calculated by the atmospheric dispersion calculation code system, SIERRA-II, using stack monitor data and local meteorological observation data.