Properties of fine-grained graphites based on two-component fillers

The effect of the nature of two-component fillers on the physical and mechanical properties of finegrained graphites was studied using highly oriented needle coke and nearly isotropic synthetic graphite as components of fillers. Each filler was prepared in the form of coarse (-120 µm) and fine (-10 µm) powders. Different mixtures of these components were used in producing graphite samples, which were then characterized by density, thermal expansion, compressive strength, and modulus of elasticity measurements. The results demonstrate that the thermal expansion, compressive strength, and modulus of elasticity of the graphites thus prepared depend on the microtexture, size, and shape of the filler particles.Translated from Neorganicheskie Materialy, Vol. 40, No. 12, 2004, pp. 1448–1454.Original Russian Text Copyright © 2004 by Samoilov.     

Mixing in processing of thermoplastics by extrusion

Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 8, pp. 9–11, August, 1993.     

VBÉR-300 reactor system and power-generating units for regional nuclear power production

The basic design solutions and characteristics of the VBéR-300 reactor system for the power-generating units of 150–300 MW(e) nuclear power plants and regional nuclear heat-and-electricity plants are described. The reactor system implemented as a unit is based on the technologies and solutions used for marine nuclear power systems, which have been corroborated by experience in operating nuclear-powered icebreakers. The technical-economic advantages of floating power-generating units are substantiated. __________ Translated from Atomnaya énergiya, Vol. 102, No. 1, pp. 35–39, January, 2007.     

Lanthanides in phosphates with the structure of whitlockite mineral [analog of β-Ca3(PO4)2]

Data on phosphates with the structure of biogenic whitlockite mineral [analog of low-temperature modification of β-Ca₃(PO₄)₂] were analyzed. The possibility of isomorphic substitution of cations in phosphates with whitlockite structure was evaluated and formation of solid solutions of various compositions involving elements in oxidations states 1+, 2+, 3+, and 4+, including lanthanides and other elements and isotopes occurring in wastes from radiochemical plants, was studied. Phosphates of Ca, Mg, and lanthanides (Sm, Eu, Gd) were prepared by the sol-gel procedure, and their thermal, thermomechanical (thermal expansion), and hydrolytic properties were determined. The results of hydrothermal and thermal experiments were compared with published data for calcium phosphate and other matrices for immobilization of radioactive wastes (RAW).     

Dynamic response analysis of pyroelectric sensitive element for thermal imaging

Temperature distributions under periodic thermal excitations and the responsivity of a pyroelectric device consisting of a cover layer, infrared absorber, metal contact, sensitive pyroelectric element, interconnecting column, and bulk silicon are found. Some results of numerical thermal modeling and analysis of exact expressions for a few extreme cases are presented. Pyroelectric responses of real structures are compared with the response of a single pyroelectric element in air as a limiting case of maximum sensitivity. The analytical approximations and numerical simulation show that the frequency response of the multilayered structure consists of different parts with simple frequency dependencies. In the region of high frequencies of light modulation, the responsivity is proportional to /spl omega//sup -1/, at low frequencies /spl sim/ /spl omega//sup -0.5/, and, in the region of intermediate frequencies, the voltage responsivity is independent of frequency.     

Tests of a Two-Stage Core at the KV-1 Test Facility: Physical Aspects and Results

Atomic Energy - The physical aspects and main results of reactor tests of a two-stage core consisting of fresh fuel assemblies and a significant number of fuel assemblies from the previous core,...