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Liquid polysulfide rubbers (thiocols) are widely used in practice to regulate properties of epoxy com posite materials. It has been established [1][2][3] that, in the case of composites cured without heat input from outside, i.e., when a quite large amount of rubber should be added in order to achieve maximal values of the adhesion strength at room temperature (about 60 wt %/100 wt % of epoxy oligomer), which, consid ering the high cost of thiocol, leads to a quite signifi cant rise in the cost of the material. In addition, with such a large content of the modifier, the cohesive strength, modulus of elasticity, and water and wear resistance significantly decrease in comparison with the basic epoxy polymer.By analogy with liquid oligobutadiene rubbers with end carboxyl groups [4][5][6], it was assumed that this disadvantage can be avoided if there is preliminary carrying out (before introduction of a curing agent) of the interaction reaction of mercaptan groups and oxirane cycles at the elevated temperature and, then, the product of this thioetherification reaction is used as the resin part for curing at room temperature: According to data [3] obtained with the use of dif ferential scanning calorimetry, such interaction occurs in a wide temperature interval of 80-180°C.In the present work, an attempt was made to com paratively investigate the properties of polymers based on epoxy-thiocol composites obtained via simplemechanical mixing of the components at room tem perature or after preliminary thioetherification reac tion (PTER). Epoxy polymers based on epoxy diane resin of Epikote 828 trademark (Hexicon Co.) with 22.8% content of epoxy groups were chosen as the objects of the investigation. The modifier was the liquid thiocol of I trademark with viscosity of 28 Pa s at 25°C and 3.1% content of sulfhydryl groups. The mechanical mixtures were obtained via thorough mixing of epoxy oligomer (EO) with thiocol at 60°C for ~10 min. The products of PTER were obtained via mixing from 30 min to 10 h at temperatures from 90 to 180°C. The compositions were cured in a stoichiometric amount of diethyltriamine DETA at (22 ± 2)°C (cold curing) over 240 h. The samples were thermally treated at 120°C for 3 h.The samples' tensile strength (σ b ) and deformation at break (ε b ) were measured on films (150 μm thick ness) and block samples of standard sizes (according to GOST (State Standard) 11262-80 (type 2)). The modulus of elasticity (E) was calculated by the inclina tion angle of the initial part of the stress-strain curve. A fracture work (A b ) was measured by the area under the σ-ε curve. The ultimate compression strength (σ com ) was determined by GOST (State Standard) 4651-82, the specific impact viscosity (a) by GOST (State Standard) 4647-80, the wear factor (I) by GOST (State Standard) 11012-69, and the adhesive shear strength (τ sh ) by GOST (State Standard) 14759-69.The dynamic mechanical characteristics (dynamic modulus of elasticity (E'), loss modulus (E'') and mechanical loss tangent (tanδ)) were measured on the Abstr...

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The theory of checking statistical hypotheses is used to elaborate the probabilistic approach to establishing the reference levels of emissions and discharges from nuclear power plants. Expressions are obtained and a scheme is proposed for establishing these levels. The scheme is based on optimizing the indicator and control functions and the monitoring sensitivity. For more effective monitoring, it is proposed that when the reference levels are established the operating regimes of the power-generating units of a nuclear power plant be divided into operation at power and a regime of planned preventative maintenance. Using as an example the first unit of the Khmel'nitsk nuclear power plant, the characteristics of the statistical distribution of the various components of real gas-aerosol emissions are determined and the corresponding reference levels are calculated.The establishment of standard levels of emissions and discharges of radionuclides is the most important measure for ensuring the radiological safety of a nuclear power plant. Being distinctive threshold values, they perform an important indicator function in the system that monitors the state of a very complex object -a nuclear power plant. In addition, they are important control parameters of the radiation state in the system nuclear power plant + environment, playing a key role in ensuring that the radiation effect of emissions and discharges from a nuclear power plant on the environment and the public does not exceed the regulation level.The effectiveness of implementing the indicator and control functions indicated above depends directly on the optimality of their values. The best approach must take into account the real properties of the parameters monitored and the characteristics of the measurement means used (sensitivity, accuracy, and masurement limits) and the checking procedure (check points, periodicity, measurement time). The factors indicated can be taken into account in such a comprehensive manner on the basis of an analysis of the data from real measurements, which are a convolution of the intrumental function of the measurement system used and the function characterizing the physical quantity being monitered. Since the processes resulting in the formation of emissions and discharges for a nuclear power plant are stochastic, the function characterizing the physical quantity being monitored should be interpreted as a density distribution function. Indeed, because they are affected by many factors which vary conitnually in time the emissions and discharges from a nuclear power plant are stochastic quantitites, which makes the probabilistic approach better substantiated and more suited for establishing the reference levels.The need to use the results of a stochastic analysis of real emissions in order to establish the reference levels has been pointed out in [1,2]. It has been shown for radioactive inert gases that the distribution of the normalized emissions (presented per unit of energy generated) in the normal operating regime of a nuclea...