Problems as a consequence of underground nuclear tests

During surveys of the territories of Semipalatinsk nuclear test site by Amer­ican satellites NOAA-14 and NOAA-15, experts at the National Nuclear Centre of Kazakhstan detected large-scale surface temperature changes (Zakarin et al., 1997; Sultangazov et al., 1997). Their findings indicated the presence of a regional thermal anomaly with a surplus temperature of about 10°C in an area which was over 20,000 km2, i. e., the entire area of the landfill including the sites of Degelen and Balapan. The presence of such a thermal anomaly was assured to be associated with increased activity of the earth surface and the active mechanism of ‘smoldering’ reactions of nuclear fission. It is hypothesized that, under the influence of gamma radiation in the atmospheric boundary layer, reactions occur that result in a certain part of the oxygen being converted into ozone (Melent’ev and Velikhanov, 2003). Since ozone is heavier than air, it is concentrated at the surface of the Earth and, having been an active oxygenator, produces detrimental effects on biological systems. This effect is confirmed by the images obtained from satellites: there is practically no vegetation in the places that experi­enced these higher temperatures. Publications on this issue are the subject of much scientific debate. It is clear that the parts of the Earth’ s surface exposed to nuclear explosions should be looked at in more detail to examine the structure of the thermal field at the landfill, in order to draw attention to the complex combination of natural conditions and radiation effects, taking into account the low spatial resolution of the apparatus of NOAA satellites.

In addition, these influences are manifested at the ground surface (under certain conditions they can be observed visually, such as when snow melts in the warmer parts of the area). However, all processes associated prima­rily with the underground migration of radioactive products in the aqueous and hydrocarbon layers (including the partitioning of radioactive products in the area of the boiler cavity from a melt solution, and their contamination of surface and groundwater) and changes in the hydrological regime of aquifers are hidden from the naked eye.

The articles by Kiryukhina and Shahidzhanov (2003) and Bakharev et al. ( 2002 ) specifically note the possible effects of long-term exposure of ele­ments of the cavity to radionuclides and the post-explosion collapse of aquifers after different times. In this case, additional man-made caverns and aquifers contaminated with radionuclides may produce an ever-expanding contaminated area in concert with the natural aquifer system. It is noted that the radiation risk can increase substantially if the boiler starts to accu­mulate karst cavities or other water, that interacts with calcium oxide which can serve as a basis for the formation of liquid radioactive brine (calcium hydroxide), which is able to penetrate sufficiently large distances, up to the upper layers of aquifers. With technological processes occurring near such cavities, the removal of radioactive material to the surface should not be excluded. In limestone-containing rocks, these processes can be exacer­bated by the fact that it is likely that the crushed pile containing calcium oxide and carbon dioxide will expand and will be distributed through per­meable systems and brought to the surface through increased fracturing.

Observations on the migration of radioactive products from underground nuclear explosions carried out in permafrost conditions have been described by Golubov et al. (2003) and Kozhukhov and Kukushkin (2003). The distri­bution of radon, tritium, strontium and other radionuclide contents in the water, and gamma radiation in the vicinity of the explosion ‘Crystal’, carried out in 1974 in Yakutia near the diamond-mining quarry known as ‘Udachnyi’, were studied. Measurements were carried out from the epicenter to the quarry (about 5 km) and showed the following:

1. The level of gamma radiation ranged from 9 to 14 micro-R/h, i. e. it did not exceed natural background levels when the whole area was surveyed.

2. The volume of the radon activity in the epicenter, at a distance of 2.5 km, ranged from 400-500 to 1,300-1,400 Bq/m3.

3. In the area of the quarry, the radon content was 200-700 Bq/m3, suggest­ing that the rate of migration of radon in the local soil is low.

4. There is increased concentration of tritium to 220 Bq/l in the epicenter of the explosion.

5. Concentrations of radioactive carbon and strontium in the drained brines on the side quarry of ‘Udachnyi’ are on average 2-3 times higher than the corresponding concentrations in groundwater from technologi­cal wells close to the background level.

6. It cannot be excluded that the permeability of permafrost rocks in this area caused the working quarry horizons to drop to a much greater depth than that of the cavity created by the nuclear explosion, thereby promoting the drainage of underground brines in the vicinity of the cavity wall of a quarry with the formation of the network of flooded cracks with dissolved radioactive products.

Thus, according to Bakharev et al. (2002), each underground nuclear explo­sion site creates a self-generating uncontrolled dumping of radioactive products into the environment that can have a permanent impact on nature and mankind and, therefore, should be regarded as a functioning ‘radiation — dangerous’ object. Evaluation of radiation and ecological safety in this case is connected with the prediction of the secondary impacts of the residual effects of an explosion on the environment and should be based analysis of situations that could lead to further dissemination and redistribution of the radioactive products.

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