Radiation effects of sic on nuclear reactors

Silicon carbides have enjoyed both fundamental study and practical application since the early days of nuclear materials science. In the past decade, with the increased interest in increasing efficiency, solving the real issues of waste disposal, and the constant mission to improve safety of nuclear reactors, silicon carbide has become even more attractive. This ceramic material has wide range of applications due to its high strength, low density, thermal shock resistance. The purpose of this paper is to discuss recent research that does not only strives to understand the remarkable radiation stability of SiC but the radiation effect of SiC under high temperature. This article will expound on the fabrication of SiC, the mechanical behavior and thermaity with regards to the phase transformation which occurs at refractory temperature

Development of Cost Analysis Process based on the Supply Chain Strategy

Abstract— This paper discusses the methodology of research and development costs analysis through the supply chain management. Peculiarities of costs formation at early stages of development life cycle are defined, aims and tasks of analysis, method of cost budget analysis in terms of responsibility centers, individual projects and cost items are disclosed. The supply chain management discipline suggests that information sharing is paramount when attempting to achieve cost reductions and quality improvements. Factors have been identified and impact of such factors on costs assessed. Special attention is devoted to the ratio between costs and results and to the ratio between costs and work duration. The analysis of plan and fact costs of separate projects is carried out in supply chain process and by examples of projects creation is considered. Besides that, the algorithm of average costs estimation through the determination of dependence between costs and work duration are presented by formula. The research identifies a theoretical model that can be used to explain the relationships and themes associated with supply chain costing and strategic decision making. Evidence suggests that there is some movement to implement managerial accounting techniques within these two industries to capture supply chain costing information. The results of this study allow to make decisions by supply chain managers for increasing of research and development work efficiency and for cost reduction

Investigative study of the radiation damage on fuel clad of miniature neutron source reactor using computational tools

Core conversion requires some evaluation of the reactor safety. Changes to the reactivity worth, shutdown margin, power density and material properties are crucial to the proper functioning of the reactor. The focus of this article is to study the neutron flux distribution in the reactor core and radiation damage on candidate clads. The Ghana Research Reactor-1 (GHARR-1) operates at maximum power of 30 kW in order to attain a flux of 1.0? 1012 n·cm–2·s for the high enriched uranium core. Using the GHARR-1 core geometry, considering 348 fuel pins, the multiplication factor (Keff) is calculated at enrichments of 10%, 12.5%, 16%, 20%, 30% and 90.2%. The spectrum of neutron flux generated in the 26 group is also calculated at the specified enrichments. The ion/particle interactions with the targets (clad) were studied in the Stopping and Range of Ion in Matter code to establish the best clad material based on recorded defects and vacancies generated. From the calculations and simulations, the best choice from the candidate clads based on the assessment is SiC. The calculation of the fuel campaign length gives 7.5 years. The defects sustained by the prospective clad showed low susceptibility to swelling and other forms of deformation

Comparative analysis of using natural and radiogenic lead as heat-transfer agent in fast reactors

Fast reactors with lead coolant have several advantages over analogues. Performance can be further improved by replacement of natural composition lead with radiogenic one. Thus, two main issues need to be addressed: induced radioactivity in coolant and efficient neutron multiplication factor in the core will be changed and need to be estimated. To address these issues analysis of the scheme of the nuclear transformations in the lead heat-transfer agent in the process of radiation was carried out. Induced radioactivity of radiogenic and natural lead has been studied. It is shown that replacement of lead affects multiplication factor in a certain way. Application of radiogenic lead can significantly affect reactor operation

Ultrasound coagulation in Venturi scrubbers: features of implementation and efficiency of application

Актуальность исследования обусловлена экологическими требованиями к дымовым газам предприятий ТЭЦ и ТЭС, работающих на угле. Обеспечение экологических требований осуществляется с помощью ультразвуковой коагуляция твердых золовых частиц с каплями жидкости, которая реализуется в устройствах мокрой очистки газов - в скрубберах Вентури. Цель: увеличение эффективности скрубберов Вентури для мокрой очистки газов за счет улучшения условия поглощения золовых частиц каплями жидкости в акустических полях, которые создаются при ультразвуковой коагуляции. Объекты: процессы ультразвуковой коагуляции золовых частиц с каплями орошаемой жидкости в скруббере Вентури. Методы. Теоретические методы основывались на численном решении уравнений, описывающих движение газодисперсного потока в скруббере Вентури и коагуляцию золовых частиц в акустическом поле. Экспериментальные результаты были получены при проведении промышленных испытаний на котлоагрегате БКЗ-220-100Ф ТЭЦ, работающем на угле Харанорского месторождения, по утвержденной стандартом методике РД 153-34.1-27.301-2001. Результаты. Разработана физико-математическая модель, описывающая движение газодисперсного потока в скруббере и взаимодействие дисперсных частиц между собой в акустическом поле. Модель позволила рассчитать эффективность газоочистки в различных условиях и определить оптимальные режимы ультразвукового воздействия: уровень звукового давления не менее 145 дБ, частота 22 кГц, зона воздействия во всем объеме скруббере Вентури, направление акустического поля перпендикулярно потоку газа. Критериями оптимальности являлись максимальная эффективность коагуляции золовых частиц в скруббере Вентури и максимальная степень очистки дымовых газов. Проведены испытания созданного ультразвукового оборудования на котлоагрегате БКЗ-220-100Ф ТЭЦ в золоулавливающей установке: в акустическом поле уменьшается концентрация золовых частиц в отводящих газах до четырех и более раз (эффективность не менее 98 %), процентное содержание золовых частиц (размером менее 5 мкм) снижается до 15 раз.The relevance of the research is caused by environmental requirements for flue gases from coal-fired TPPs and TPPs. Environmental requirements are ensured by ultrasonic coagulation of solid ash particles with liquid droplets, which is realized in devices for wet gas purification - in Venturi scrubbers. The main aim of the research is to increase the efficiency of Venturi scrubbers for wet gas purification by improving the conditions for absorption of ash particles by liquid droplets in acoustic fields created by ultrasonic coagulation. Objects: processes of ultrasonic coagulation of ash particles with drops of irrigated liquid in a Venturi scrubber. Methods. Theoretical methods were based on the numerical solution of equations describing the motion of a gas-dispersed flow in a Venturi scrubber and the coagulation of ash particles in an acoustic field. Experimental results were obtained during industrial tests at the boiler unit BKZ-220-100F CHP, operating on the coal of the Kharanorsk deposit, according to the approved methodology RD 153-34.1-27.301-2001. Results. The authors developed the physical and mathematical model that describes the gas-dispersed flow motion in a scrubber and the interaction of dispersed particles with each other in an acoustic field. The model made it possible to calculate the efficiency of gas purification under various conditions and determine the optimal modes of ultrasonic exposure: the sound pressure level is not less than 145 dB, the frequency is 22 kHz, the exposure zone in the entire volume of the Venturi pipe, the direction of the acoustic field is perpendicular to the gas flow. The maximum efficiency of ash particles coagulation in the Venturi scrubbers and the maximum degree of purification of flue gases were the criteria of optimality. The created ultrasonic equipment was tested at the BKZ-220-100F CHP unit in an ash collecting unit: the concentration of ash particles in the exhaust gases in the acoustic field decreases by four or more times (efficiency not less than 98 %), the percentage of ash particles (size less than 5 microns) is reduced to 15 times