Abstract
Since 1994, environmental radioactive contamination levels in the vicinity of Semipalatinsk nuclear test site (SNTS) have been studied by our field mission.
The village of Dolon is located about 100 km north-east of the hypocenter and is well known for receiving heavy exposure from radioactive fallout due to the 1st nuclear detonation on 29 August 1949. As one of the available methods external dose other than TL and/or ESR, there is a model calculation based on the long-lived radionuclide 137Cs (T1/2 = 30.17 y) in soil. Some investigators have reported the contamination levels of 90Sr, 137Cs and 239,240Pu in the area of Dolon settlement. But, the number of samples monitored was too scant to estimate the radiation dose around there. Furthermore, the assessment of plutonium isotopes (239,240Pu and 238Pu) is also important from the aspect of internal radiation. Such situation encouraged us to investigate in more detail the present situation of radioactive contamination of 137Cs and Pu isotope (239,240Pu and 238Pu).
In this paper, we report the current radiological situation at Dolon and its adjoining three villages Mostik, Cheremshki and Budene. Emphasis was placed on (1) reevaluation of accumulated levels and (2) distributions of residual long-lived radionuclides 137Cs and Pu isotope in soil using long core samples up to a depth of 30 and 100 cm, and (3) characteristics of Pu in soil by using sequential leaching, particle size discrimination and a-track methods.
