Identification of tritium-contaminated areas using a tritium survey on the snow cover, the case of Semipalatinsk test site.

The article presents research findings on the content of tritium in the snow cover of test locations 'Balapan' and 'Sary-Uzen' in the territory of the Semipalatinsk Test Site. Based upon results, a number of tritium-contaminated areas were revealed. At the 'Balapan' site, elevated tritium concentrations in the snow were revealed in the vicinity of the 'Atomic lake' close to the 'Karazhyra' deposit and at the location of Lake 'Kishkensor'. At the 'Sary-Uzen' site, elevated tritium concentrations in the snow were discovered near borehole 101, at object 'Lazurite' and at an unnamed creek outflowing from the mountain range. Maximal of tritium activity concentration in the snow were 45 Bq/kg and 36 Bq/kg at the 'Balapan' and 'Sary-Uzen' sites, respectively. Background tritium concentrations in the snow cover of the STS territory were found to be 4.6-12 Bq/kg.

Peculiarities of radioactive soil contamination in places of underground nuclear tests in the Semipalatinsk test site.

The article highlights the results of a radioecological survey of the surface areas of combat boreholes at the Sary-Uzen site located on the territory of the Semipalatinsk Test Site (STS), where underground nuclear tests in these boreholes were conducted earlier. The surface areas of boreholes were examined the levels of radioactive contamination of the soil were determined. A total of 2 main groups were identified. The first group includes boreholes with radioactive contamination of the soil on the surface area. The second group includes boreholes with no radioactive contamination of the surface soil layer. The first group can be divided into boreholes with a deformation of the ground surface and without it. For each variety, depending on the specifics of the nuclear test, the characteristic features of radioactive contamination were determined. Based on the results of the survey, the ranges of specific activity values were established.

Characterization of area radioactive contamination of near-surface soil at the Sary-Uzen site in the Semipalatinsk test site.

The paper provides study of the radioactive contamination of near-surface soil at the Sary-Uzen site in the Semipalatinsk test site (STS). Increased values of natural radionuclides in the studied area were not detected, which indicates the absence of possible geochemical anomalies that could create an elevated radiation background. Radioactive contamination by technogenic radionuclides is caused by two factors. The first factor is fallout of radioisotopes from the atmosphere because of an explosion on September 24, 1951 at the "Experimental field" site. The fallout plume extended from the north-western part of the site to the very south. The range of activity concentration values for 241Am in soil varies from <0.3 Bq/kg to 390 Bq/kg, with an average value of 5 Bq/kg; for 137Cs from <1.1 Bq/kg to 330 Bq/kg, with an average value of 55 Bq/kg. A second, but more significant factor is the fallout of radioisotopes due to underground nuclear tests with radioactive release that took place in boreholes on the site itself. The largest area of contamination (about 8 km) is the fallout from testing borehole No. 101 (241Am to 920 Bq/kg and 137Cs to 12150 Bq/kg).

Transfer parameters of radionuclides from soil to plants at the area of craters produced by underground nuclear explosions at the Semipalatinsk test site.

A study to determine 137Cs, 90Sr, 241Am, 239+240Pu radionuclides in vegetation cover of the area of craters produced by underground nuclear explosions at the Semipalatinsk test site (STS) is summarised in this paper. Transfer factors (Tf) required for the quantitative description of the radionuclides transition from the soil to aboveground plant parts were found to be highest for sagebrush (Artemisia sublessingiana), Tf values for 90Sr were gradually decreasing with increasing distance from the dump zone. When arranging the radionuclide transferring factors in descending order, the following sequence was obtained: 90Sr Tf > 137Cs Tf > 241Am Tf > 239+240Pu Tf, which is consistent with International data. All Tf derived are much higher than those ones derived earlier for epicenters of aboveground nuclear tests and are closest to values for conventionally "background" areas at the Semipalatinsk test site.

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).