Study on the Small Pressurized Water Reactor Based on Fully Ceramic Microencapsulated Fuel

After Fukushima nuclear power plant disaster, the efforts to overcome these defects of PWRs were carried out, such as replacing the cladding and fuel materials. One of these feasible efforts is using Fully Ceramic Microencapsulated (FCM) fuel replacement traditional UO2 pellets fuel into PWR. The FCM fuels are composed of Tri-structural-isotropic (TRISO) particles embedded in silicon carbide matrix. The TRISO fuel can hold its containment integrity and without fission production releases under the design temperature limit of 1600 °C. Furthermore, the silicon carbide matrix will benefit the thermal conductivity, radiation damage resistance, environmental stability and proliferation resistance. Consequently, the safety of the reactor could be significantly improved with FCM fuel instead of the conventional UO2 pellet fuel in PWR. We also analyzed the temperature distribution for the FCM fuel compared the traditional UO2 pellets, the calculation indicated that the centerline temperature is lower than UO2 pellets due to FCM higher thermal conductivity. The calculation demonstrated that, utilizing FCM replacement of conventional UO2 fuel rod is feasible and more security in a small pressurized water reactor. In this paper, a small pressurized water reactor utilizing FCM fuel is considered. A 17 × 17 fuel assemblies with Zircalloy cladding was applied in conceptual design through a preliminary neutronics and thermal hydraulics analysis. The reactor physics is accomplished, including the refuel cycle length, the effective multiplication factor, power distribution analysis being discussed. The Soluble Boron Free (SBF) concepts are introduced in small PWR, as a result, it makes the nuclear power plant more simpler and economical. FCM fuel loading has a very high excess reactivity at the beginning of reactor core life, and it is important to flat reactivity curve during operation, or to minimize excess reactivity during the core life. Consequently, conventional burnable poison configurations were introduced to suppress excess reactivity control at beginning of cycle.

Characteristics of the Evolution of Carbide Morphology in the Haynes® 230® Alloy as a Result of High Temperature Annealing

In this work, results of an investigation of the microstructure evolution in Haynes® 230® alloy are presented. The morphological and chemical compositions of the chosen microstructure’s constituents, such as the primary and secondary carbides, were analyzed based on tests in the temperature range 700–800 °C for 1000–3000 h. The prediction of phase evolution within the microstructure was proposed based on the analysis of mutual replacement of carbide-forming elements at the carbide/matrix interface. Based on the results, some complementary markers were considered to describe Haynes® 230® microstructure evolution. Qualitative markers, i.e., defined morphological features, were related to the shape and distribution of microstructure constituents. The study also used quantitative markers related to the local chemical compositions of carbide particles, determined as the ratio of the concentrations of carbide-forming elements Crc/Wc, Crc/CrM and Wc/WM. Microstructure maps created on the basis of these complementary markers for the successive annealing stages reflected the course of its morphological evolution.

Features of induction heating during hardening of tools from high-speed steel

The fundamental differences in the kinetics of transformations of high-speed steels during heating by high-frequency induction currents (HFC) and in salt baths are considered. At HFC, the high temperature at the "carbide — matrix" boundaries promotes more complete dissolution of carbides in austenite, which improves the quality of the tool. Keywords: high frequency current, salt bath, hardening, high speed steel, interphase boundary. [email protected]

Microstructure of WC–Co–VN carbide catrix for drilling tools diamond-containing materials

The results of studies aimed at improving the structure and performance characteristics of carbide matrices WC-Co samples, formed by cold pressing and thereafter hot pressing, for drilling tools diamond-containing materials. It is shown that the introduction of vanadium nitride in an amount of 3% into the composition of the starting materials 94WC-6Co provides an increase in the hardness of the sample from 22.8 to 34.2 GPa, the strength limit in compression from 4800 to 5340 MPa and bending from 2200 to 2280 MPa, as well as reduction of wear intensity from 1710×10-6 to 5200×10-6 g/m. The revealed effect of the formation of a fine-grained structure of a carbide matrix WC-Co-VN with increased mechanical and operational characteristics indicates the need for their use in the development of effective tools for drilling oil and gas wells.

The use of high-resolution methods of research in the design of the diamond-matrix interface to increase the durability of the diamond tool

The results of studying fundamental and applied problems regarding the formation of boundary layers between diamond and carbide matrix are presented with the goal to develop a highly resistant diamond tool. The new approaches to the synthesis of diamond-carbide materials combining diamond metallization and sintering in a single-stage technology are presented. The developed technology eliminates the re-heating of a metallized coatings which results in their destruction and enhanced graphitization of diamond (these phenomena restrict using metallization procedure to improve diamond retention and synthesis of high-functional composites for diamond tools). The goal of the study is analysis the structural and phase state of the «diamond – carbide matrix» interface in a diamond tool obtained by the new technology and the main factors determining the level of diamond retention in the presence of a metallized coating. Unique opportunities provided by modern high-resolution methods of research were used in the study. The elemental composition and morphological features of the diamond-matrix interface were studied using the methods of scanning electron microscopy, atomic force microscopy, X-ray microanalysis and Raman spectroscopy. Identification of the reaction products, including non-diamond carbon was performed. It is shown that the introduction of the powder-metallizer significantly modified the contact boundaries and provide conditions for improving the chemical and mechanical adhesion of the diamond-matrix system. The formation of the well-developed nano- and sub-microscale roughness of the diamond surface and dense filling of the existing voids with nanoscale layers of metal-infiltrate was revealed. The multilevel organization of highly structured elements of the transition zone with the minimal graphitization ensured the monolithic character and strength of the diamond-matrix bond. Comparative service tests of preproduction and control samples of diamond dressers proved the efficiency of developed hybrid technology (the specific performance of diamond tools increased by 39 – 45%). New fundamental and applied results have been obtained in the field of studying interface zones in crystalline multiphase systems that can be used to regulate adhesion phenomena at the interphase boundaries and develop highly efficient composite materials.