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.
Transport of La, Nd, Eu, Tb, Tm and Lu through a supported liquid membrane (SLM) was investigated by using di(2,4,4-trimethylpentyl)phosphinic acid (DTMPPA) as a mobile carrier. Lanthanoid elements in the feed solution were quantitatively transported and concentrated into the product solution of mild acidity. The transport rates increased with increasing atomic number of lanthanoids in the low pH region of the feed solution. Separation factors evaluated from the transport rates for lanthanoids were close to those from the distribution ratios in liquid-liquid extraction.
Authors:M. Takeyasu, T. Iida, H. Watanabe, M. Takeishi, and A. Yamamoto
The performance of the computer code system, SIERRA-II, for calculating the environmental radiation dose due to an accident
was assessed over a coastal area, using the environmental monitoring data around the coastally located Tokai Reprocessing
Plant (TRP) when 85Kr was discharged during its operation. The agreement within a factor of 5 between the calculated and observed air concentrations
of 85Kr in areas of a few km from the TRP was achieved in 57% of the comparison data, disregarding the internal boundary layer.
The mean fraction bias was −0.6, which meant a slight overestimation. According to the vertical profile of the atmospheric
temperatures, the internal boundary layer was modeled with the SIERRA-II and the agreement became better than when the internal
boundary layer was not considered.