The populations that appear to have been the most exposed to radioactive fallout as a result of nuclear weapons testing at the Semipalatinsk test site (STS) can be divided into two groups. The first group is located in the areas of the Republic of Kazakhstan in the vicinity of the STS and the second group is located in the Altai krai (i.e. Altai region) of the Russian Federation. The purpose of this paper is to estimate doses for the populations of the Republic of Kazakhstan that resided in the vicinity of the STS at the time when nuclear weapons tests were conducted in the atmosphere.The methodology that was used to estimate doses is based on the radiation measurements that were made after each test. It was developed by joint efforts of the sci-

1. In present-day blasting practice, increasing use is being made of straight undercuts, the effectiveness of which depends on the correct choice of distance between the charges and the timing of their detonations. From the viewpoint of cutting drilling costs, the distances between boreholes should be as large as possible. On the other hand, it must be such that the rock between the charges is broken when they are detonated. Consequently, the problem reduces to estimating the maximum distance R between the axes of long cylindrical charges such that all the rock is broken up between them.Many experiments have revealed that for simultaneously detonated charges, the maximum distance R between their axes is 2rf (where rf is the radius of the zone of fracture for explosion of a single charge).However, it has long been known from practice that explosion of charges with time intervals increases the total volume of broken rock, and thus increases the necessary spacing to R > 2rf. The cause of this may be an increase in the total local stress due to interference of oppositely directed compression waves from adjacent charges for some optimal phase difference, or formation of additional planes of exposure leading to phenomena of the spallation type.Thus previously discussed schemes of calculation have reduced to determination of the time interval which gives the maximum state of stress in the solid rock or which forms new free surfaces.2. In this article the author attempts to explain the phenomenon of short-delay blasting for the second case. Figure I shows in plan two parallel cylindrical charges with diameters d o and lengths l 0 separated from the wall of the borehole by an annular air gap h 1. If the delay is such that the process of formation of a zone of fracture of radius rf from the charge 1 in the rock has finished, then the action of charge 2 in the direction toward the "free" surface which has been formed and which bounds the zone of fracture will be similar to the rapid evolution of some quantity of energy on the surface of a barrier with a finite thickness h.Then to determine R we can use phenomenological theory to estimate the maximum depth of puncture h = hma x [1]. For the scheme of Fig. la, the estimates will certainly be approximate and qualitative; they are useful only because of their simplicity. The scheme of puncture for evolution of energy at point 0 is shown in Fig. lb [1]. Here it is assumed that the resistance to fracture due to tangential stresses is less than the resistance to direct pull. Since most materials become plastic under compression, puncture is largely determined by the process of pressing out the extruded part of the barrier (the "stopper").Here we are assuming that there are no phase transitions in the material of the barrier, and that consequently, the loading rates u x are less than the threshold velocities Uth. This has been verified for loading by the expanding explosion products (EP) [2].A crater first forms in the barrier (in the general case, it is ellipsoidal) with radius b ...

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The article deals with the issues of increasing the productivity of the process of applying the polymer shell to the abrasive. It is established that the performance of the abrasive encapsulation in the fluidized bed is achieved due to the selection of equipment, the type of polymer, the spray parameters and the properties of the abrasive material. The authors have developed a method for producing abrasive grain with a polymer coating using an installation that allows processing the initial particles in a fluidized bed.