Development of measures for limiting negative impacts of the «Atomic¼ lake on population and environment.

In arid climate, economic activities at the territory of the "Atomic" lake is one of the topical issues for the Semipalatinsk test site (STS). Hence, the boundaries of areas with radionuclides contamination, which correspond to the level of radioactive wastes at the territory adjacent to the "Atomic" lake of STS, are to be determined. The territory around the lake is used for cattle breeding and the water of the "Atomic" lake that is the one large water source is used for livestock watering. It is important to develop measures that will limit possible negative impact on population and environment. In results of the conducted research were developed measures consisting of remediation and access limitation to the stockpile of soils with contamination level corresponding to the level of radioactive waste (RW).

90Sr/137Cs ratios in soil of epicentral zones of «Experimental Field¼ testing site of Semipalatinsk Test Site.

The paper presents the results of 90Sr/137Cs isotopic ratios in the soil surface layer in the venues of surface and atmospheric nuclear tests at the territory of the «Experimental Field ¼â€¯site of the Semipalatinsk Test Site. One of the main factors in the radiation impact of a nuclear explosion on the environment is the decay of fission products. The determination of 137Cs activity in soil is carried out by accurate, rapid and sufficiently cheap gamma-spectrometric method, while the existing methods of determining 90Sr activity are quite problematic: they either have sufficiently high detection limits or are time-consuming. As an alternative method, 90Sr activity can be determined using its correlation dependence with 137Cs activity. According to the literature, each test has its own fission product ratio, depending on the nuclear charge. As a result of the conducted research it was revealed that one epicenter is located at the technical site P-1, the ratio of 90Sr/137Cs is equal to 4,8; at the technical site P-3 - 2 epicenters, the ratio of 90Sr/137Cs is equal to 0,8 and 0,9; at the technical site P-5 - 6 epicenters, the ratio of 90Sr/137Cs is in the range of 0,9-2,1; at the technical sites P-2, P-7 - 19 epicenters, the ratio of 90Sr/137Cs is in the range of 0,6-2,1. It is assumed that the differences in the value of fission product ratios are due to different types and capacities of nuclear charges, as well as different explosion altitudes. The obtained ratios allow to calculate 90Sr by 137Cs activity in soil of the epicentral zones at the territory of the «Experimental Field ¼â€¯testing site by the computational method.

[Assessment of modern radioecological situation at nuclear explosion "Chagan" (Balapan Site, Semipalatinsk Nuclear Test Site, Kazakhstan)].

Results on estimation of modern radioecological situation at nuclear explosion "Chagan" based on large-scale cartographic studies (1:25000) of a test area (4 km2) are presented. Maximum gamma-irradiation doses were observed at bulk of ground surrounded a crater and at radioactive fall-outs extended to the North-East and to the SouthWest from the crater. Based on data on artificial radionuclide specific activity most part of soil samples were attributed to radioactive wastes according to IAEA (1996) and OSPORB (1999). Natural decrease of soil radioactivity up to safety level due to 60Co, 137Cs, 90Sr, 152Eu, 154Eu radioactive decay and 241Am accumulation-decay will not take place within the next 60 years at the studied area.