Siro Abe

An electrostatic integrating 222Rn monitor with cellulose nitrate film for environmental monitoring.

This paper describes a new type of electrostatic integrating 222Rn monitor designed for the environmental 222Rn monitoring. The window area of the monitor was selected to make the exchange rate optimal. The collecting electrode was positioned on the basis of calculating the internal electric field. A drying agent, P2O5, was placed in the bottom of the monitor, since the collection efficiency of 218Po+ atoms depends on the humidity of the air. The monitors have been calibrated against known 222Rn exposures. The detection limit is 1.2 Bq m-3 for an exposure time of 2 mo. In a small survey, annual mean 222Rn concentrations between 3.7 and 9.5 Bq m-3 in outdoor air and between 6.4 and 11.9 Bq m-3 in indoor air were measured.

A mysterious spot on the outdoor concentration of radon isotopes

Abstract Temporal and spatial distribution of 222 Rn and 220 Rn and their progeny concentrations in the open atmosphere, 222 Rn and 220 Rn exhalation rates, radioactivities in soil and underground water, including some meteorological factors, were measured at a spot of high 222 Rn and 220 Rn concentrations to investigate the source and occurrence mechanism. Hourly mean concentrations of 222 Rn and 220 Rn during August 1993 were about 230 Bq m −3 and 130 Bq m −3 at 1 m above ground surface. Diurnal variations were high at daytime and low at nighttime, which gives an inverse variation compared with the typical variation in the normal environment. 222 Rn concentrations varied quickly in a few minutes and reached a maximum of about 14 kBq m −3 . The maximum daily mean 222 Rn concentration at 5 cm above ground surface was 11 kBq m −3 . Concentrations of 218 Po, 214 Pb, 214 Bi, and 220 Rn progeny were 8∼61 Bqm −3 , 1∼7 Bqm −3 , 0.5∼5 Bq m −3 , and 0.02∼0.14 Bq m −3 , respectively. The equilibrium factor for 222 Rn was estimated to be 0.01∼0.2. The main source of the mysterious spot of high 222 Rn and 220 Rn concentrations was a small but deep channel between the basement of the building and the surrounding soil, and the extremely localized weather condition.

Sex-Specific per capita Dose due to Background Radiation in Japan

The collective dose due to the background radiation outdoors in Japan was analyzed, and the influence of the time trend of the population movement on the per capita dose was estimated. Only the external dose was considered. It was previously shown that the per capita dose calculated for each year between 1952 and 1980 by the use of the surveyed background levels along with the registered population data has been decreasing continuously. In this work, the latest data in 1981 was added, and male and female statistics were processed separately. The result showed that the male values of the per capita dose have been always lower than the female values, if the deficit is small. It was also shown previously that the prevailing population movement from countryside toward urban areas (often plains of volcanic ash) would be the cause which have changed the per capita dose, i.e. population-weighted mean dose of the whole country. In this work, it was anticipated that the gross population movement from the South-Wes...

VERY LOW LEVEL

第1段階として, 簡単でしかも微量Poに対しても化学的収率の高い電気化学的置換法により, 不純物を含まない極微量 (10-12～10-14Ci) 210Poの酸性溶液について, 化学的収率を求めた。使用した実験条件下においては, 210Po量が10-12～10-14Ciという極微量においてすら, 90%以上の化学的収率が得られることがわかった。