Environmental monitoring results around Tsuruga Nuclear Power Plant

The radioactive nuclides in the air have been mainly measured as the environmental monitoring around the Tsuruga Nuclear Power Plant, utilizing a high volume air sampler, and the tested results are presented. The measuring equipments consist of the high volume air sampler made by the STAPLEX Company in the USA with a large intake adapter having the intake of 8 inch x 10 inch, mesh filter papers (TFAGF No. 810), an active carbon cartridge, a Ge (Li) detector and 1024 and 4096 channels pulse height analyzers. The measuring system was calibrated with the standard radiation sand which was composed of 90% KCl/0.01% 232Th/0.0004% 238U before the test. The monitoring was conducted in the summer of 1978 and in the winter of 1979. The sampling points surrounding the plant and the sampling conditions are shown. Concerning the measured results, the concentrations and the spectra of detected radioactive nuclides in the air are presented. The concentrations are about 9 pCi/m3 for 60Co, 8 pCi/m3 for 54Mn, 9 pCi/m3 for 137Cs, 4 pCi/m3 for 125Sb, 5 pCi/m3 for 144Ce, 6 pCi/m3 for 7Be and 10 pCi/m3 for 106Ru, 60Co and 54Mn, which had not been detected in the past, were detected, utilizing the high volume air sampler in this monitoring. On the other hand, the sand of sea bottom, seaweeds and mugwort were sampled and monitored near the plant. Relating to these monitoring, the sampling dates, the sampling points, and the sampling conditions are tabulated. The concentrations of radioactive nuclides were about 6 pCo/g for 60Co, 9 pCi/g for 54Mn, 9 pCi/gr for 137Cs, 6 pCi/g for 40K, 8 pCi/g for 106Ru, 6 pCi/g for 7Be, 7 pCi/g for 125Sb and 4 pCi/g for 144Ce. These values are comparative to the existing data. (Nakai, Y.)