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In the article there are presented data of the study of the radiation situation on the territory and at premises of the “Electric Mechanical Plant” Company, one of the units of the former uranium mining and milling facility of the former Lermontov Almaz Production Association. At the area of waste rock dumps and off-balance ores, the radiation situation was shown to meet requirements of health regulations SP LKP-91.The radiation situation in 14 out of 15 observed workshops and office premises meets the requirements for the limitation of the public exposure to natural radiation sources in occupational conditions established by health regulations and norms SanPiN 2.6.1.2800-10. In one building (warehouse premises), the requirements for equivalent equilibrium volumetric activity of radon (EEVA) in indoor air are exceeded. Based on the annual EEVA of radon values the assessment of effective doses in the work of the personnel over the one shift, was shown to be overestimated up to 7 times due to the daily variation of radon volumetric activity concentration.

Evolution of the integral intensity of the photoluminescence (IIPL) of untreated and treated (48% HF etched) porous silicon (PS) samples is studied in samples stored in the air both in the dark and in daylight. It is established that IIPL of the illuminated samples rises with time more rapidly for the etched samples than for the untreated ones. The luminescence efficiency of the unilluminated samples practically does not change. The mechanism of the light effect on sample photoluminescence can be related to an increase of the ambient air ionicity, which is favorable to the reaction of atmospheric oxygen with silicon during the PS surface passivation and the oxide formation. The influence of HF etching duration on sample IIPL is also studied. The effect of HF on the luminescent properties depends on the treatment time and the initial intensity of sample photoluminescence.

The effect of chemical treatment of porous silicon samples by HF on its photoluminescence and its evolution with time in sample aging in air is investigated. It is shown that the effect of HF on the luminescence parameters depends on the duration of the treatment and the initial photoluminescence intensity of the sample. It is found that chemical etching in HF accelerates the growth of the total luminescence intensity in aging of the sample in air. The evolution of the photoluminescence spectrum in aging of the sample in air after chemical etching can be explained within the framework of the quantum-size model of the luminescence of porous silicon.

The effect of boron diffusion on the microhardness and photoluminescent properties of porous silicon layers obtained conventionally by anode etching is studied. By means of angle lap, it was found that the samples have a three-layer structure: the upper layer is a transparent film, the middle—actually porous silicon, and the lower layer is a single-crystal substrate. It is established that boron diffusion into the cathode surface increases the luminescence intensity, while diffusion into the anode surface decreases it, and the thickness of both the porous and surface silicon compound layers increased in both cases. A conclusion is drawn that the gradient of internal stresses in the substrate produces a positive effect on the luminescence intensity of the porous layer grown on it. A luminescence model allowing for both the role of silicon compounds and the quantum-size hypothesis is proposed.

The substructure and cleavage fracture in two types of polycrystalline B4C specimens are investigated. It is shown that in specimens hot-pressed below 2000°C twins in poreless grains are effective barriers for cleavage cracks. Cleavage fracture occurs in planes of the type {10\(\bar 1\)1}. There are twins and faceted pores in grains of specimens sintered below 2200°C. In these grains cleavage is along the twinning planes. Pores eliminate the effect of twins as crack stoppers.