TRITIUM IN AIR AND ENVIRONMENTAL WATER IN JIUQUAN DISTRICT AND ITS DOSE TO POPULATION

From July 1987 to Novermber 1989, the monitoring of the tritium in air and environmental water in Jiuquan District was made for the first time. The results show that the average tritium concentrations of surface water in this region remained 4.6—9.6 Bq/1 in recent years. However, these values are still an order of magnitude higher than those before thermonuclear tests era in 1952. The tritium concentration in air was approximately twice as much as that of surface water. HTO values in air exhibit a higher peak in summer. The total tritium ingested by residents of Jiuquan was 1.12×10~4 Bq. The collective dose equivalent was equal to 0.25 man·Sv per year. Because of taking environmental tritium in the area, the annual committed effective dose equivalent was 0.19 μSv which is only one five thousandth of annual limited dose to the public proposed by ICRP and one ten thousandth of the natural background estimated by UNSCEAR in 1982.