الفهرس | Only 14 pages are availabe for public view |
Abstract I’ Radiation received by human is of either natural or artificial origin. Before the discovery of artificial production of radiation, natural sources were the only sources of exposure. Today, natural sources still contribute almost 80 percent of the collective radiation exposure ofthe world’s population, so they contribute more significantly than does artificial radiation to collective exposure dose. By living andlor working either in” the open or inside buildings, human beings are exposed to radiation from sources outside their bodies. The radiation is mainly from cosmic rays and radionuclides in the ground and walls buildings. Also, by ingesting food and water, and inhaling air. In the present study natural radioactivity in soil, fertilizer, foodstuffs, ground water and crude oil has been determined using gamma spectrometry. In order to achieve this work, the thesis is composed of seven chapters. Chapter one is an introduction and previous studies in the field of measurements of environmental radiation in soil, foodstuffs, fertilizer, groundwater and crude oil. The chapter also contains the aim of the present work. Chapter two represents a theoretical background concerning radioactivity from natural and man made sources. Also, the chapter deals with radioactivity in soil, foodstuffs, fertilizer, groundwater, and crude oil and dose assessment. Chapter three contains methods of sample collection and prepar?-tio~. It includes detailed description of experimental work, detection of radioactivity and calibration of the detector (HPGe). Chapter four includes the results and discussion of obtained results for soil and fertilizer and its comparison with pervious data. The main results are given in the following: The average concentrations of 226Ra, 232Th, 40K and 137 Cs in soil samples were 16.43, 18.3,268.18,3.25 Bq kg” respectively. The dose rate conversion factors (DRCFs) were calculated in this work to deduce the gamma ray absorbed dose rate at 1 meter above ground surface in stead of using the published values. The obtained values ofthese factors are compared with other published values and were found to be in good agreement. |