Decontamination of Radionuclides from Concrete by Microwave Heating. I: Theory
نویسنده
چکیده
The paper analyzes a proposed scheme of decontamination of radionuclides from concrete structures, in which rapid microwave heating is used to spall off a thin contaminated surface layer. The analysis is split in two parts: ~1! the hygrothermal part of the problem, which consists in calculating the evolution of the temperature and pore pressure fields, and ~2! the fracturing part, which consists in predicting the stresses, deformations and fracturing. The former is assumed to be independent of the latter, but the latter is coupled to the former. The heat and moisture transfer governing the temperature and pore pressure fields induced by the decontamination process is analyzed using an improved form of Bažant and Thonguthai’s model for heat and moisture transfer in concrete at high temperatures. The rate of the distributed source of heat due to the interaction of microwaves with the water contained in concrete is calculated on the basis of the standing wave normally incident to the concrete wall. Since the microwave time period is much shorter than the time a heating front takes to propagate over the length of microwave, and since concrete is heterogeneous, the ohmic power dissipation rate is averaged over both the time period and the wavelength. The reinforcing bars parallel to the surface are treated as a smeared steel layer. The recently developed microplane model M4 serves as the constitutive model for nonlinear deformation and distributed fracturing of concrete. Application of the present model in numerical computations is relegated to a companion paper which follows. DOI: 10.1061/~ASCE!0733-9399~2003!129:7~777! CE Database subject headings: Concrete; Microwaves; Contamination; Contaminants; Heating; Diffusion; Thermal stresses; Pore
منابع مشابه
Decontamination of Radionuclides from Concrete by Microwave Heating. II: Computations
Based on a mathematical model developed in the preceding Part I of this study, a numerical analysis of the process of decontamination of radionuclides from concrete by microwave heating is conducted. The aim is to determine the required microwave power and predict whether and when the contaminated surface layer of concrete spalls off. As customary, the finite element method is used for the stre...
متن کاملProject Title : Decontamination of Radionuclides from Concrete During and After Thermal Treatment
متن کامل
Mobile Asbestos Decontamination by Microwave Hybrid Heating
Within the European project "New Safe and Cost Effective Techniques Against Asbestos Risks" different methods for decontamination of asbestos in asbestos containing wastes, abbreviated as ACW from building industry were investigated. A mobile asbestos decontamination unit was developed, aiming at the complete disintegration of asbestos fibres on-site. The process is based on a chemo-thermal tre...
متن کاملA comparative study of infrared and microwave heating for microbial decontamination of paprika powder
There is currently a need in developing new decontamination technologies for spices due to limitations of existing technologies, mainly regarding their effects on spices' sensory quality. In the search of new decontamination solutions, it is of interest to compare different technologies, to provide the industry with knowledge for taking decisions concerning appropriate decontamination technolog...
متن کاملUsing starch powder for the decontamination of I-131 in isolation rooms
Introduction: Various iodine isotopes are undergoing radioactive decay except Iodine-127 (I-127. Iodine I-131 is unsealed radioactive material used in nuclear medicine for both diagnostic and therapeutic procedures in Royal Hospital since 2006. In radiotoxic classification, I-131 is in group 2 element. I-131 is highly reactive element due to its volatilization nature. Currently...
متن کامل