IOSR Journal of Applied Physics (IOSR-JAP) e-ISSN: 2278-4861.Volume 11, Issue 6 Ser. I (Nov. – Dec. 2019), PP 20-32 www.iosrjournals.org DOI: 10.9790/4861-1106012032 www.iosrjournals.org 20 | Page Radioactivity and Radiological Hazard Effects for Granitic Gneisses at Wadi Abu Rushied Area, South Eastern Desert, Egypt. T. El Sayed. Mohamed 2 , E. S. Abd El-Halim 1 , M. A. M. Mahmoud 2 , S. F. Hassan 2 , A. Sroor 1 , S. El-Bahi 1 . (1). Physics Department, Faculty of Women for art, science and education, Ain Shams University, Egypt. (2). Nuclear Materials Authority, Cairo, Egypt. Abstract: A three main types of measurements were performed in order to get a complete assignment for radioactivity impacts for the studied area,i) A ground gamma-ray spectrometric survey has been performed using a portable gamma-ray spectrometer model Rs-230., The gamma-ray spectrometric maps acquired indicate various concentrations of radioactivity over the studied area, which reflects a contrasting radioelement contents for the exposed rock. ii) The activity concentrations of naturally occurring radionuclides in the area under investigation, were determined using high pure germanium detector (HPGe) with a specially designed shield, in order to assess the radiological health hazards.Absorbed dose rate (D), radium equivalent (Ra eq ), external hazard index (H ex ), annual effective dose equivalent (AEDE), representative level index (I γ ), excess lifetime cancer risks (ELCR) and annual gonadal dose equivalent (AGDE) are calculated.The results were compared with the international recommended values, higher values for both activity concentrations and radiation indices were measured for the studied samples. iii) The activity ratios in the selected samples are calculated to clues for what happened in the studied rock. Groundwater circulation and Weathering, lead to different physico-chemical conditions affecting 238 U and 234 U will result in their fractionation and, thus, the respective activity ratios will therefore be greater or less than unity. Key words: Granitic Gneisses/ Natural radioactivity/ Activity ratios/ Annual gonadal dose equivalent/ Excess life cancer risk. --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 01-11-2019 Date of Acceptance: 16-11-2019 --------------------------------------------------------------------------------------------------------------------------------------- I. Introduction Abu Rushied area is located in the South Eastern Desert of Egypt (about 45 km southwest of Marsa Alam), between latitudes 24° 37ʹ 43"–24° 38ʹ 26" N and longitudes 34° 46ʹ 00" – 34°46ʹ 35" E. The main rocks in the studied area are the granitic gneisses, surrounded mafic-ultramafic rocks and granites. Uranium minerals, iron oxides, zincite, clay minerals, fluorite and manganese oxides are present as thin films along fractures planes in the studied area [1]. It is also dissected by the two main shear zones trended N-S and E-W direction. These shear zones are occupied by a mineralized and highly altered lamprophyre dyke [2]. Many alteration halos are observed, such as argillization, hematitization, silicification, greisenization, sericitization and fluoritization [1]. These types of alteration are associated with a wide variability in radioactivity with or without U- mineralization plays an important role in localizing uranium (U) and thorium (Th) mineralization. In this case a significant component of the background radiation exposure to human beings are generating, depends on their contributing compositions values of total dose [3]. Natural radionuclides 238 U, 235 U and 232 Th may become incorporated in igneous materials when they are originally formed from the molten state [4]. Since these radionuclides are not uniformly distributed, the knowledge of their distribution in soil and rocks plays a vital role in radiation protection and measurement [5]. The terrestrial background radiation levels are related to the types of rock from which the soils originate. Levels of higher radiation are associated with igneous rocks as granite and lower levels with mafic-ultramafic and sedimentary rocks. [6]. II. Geologic setting The studied rock is named as granitic gneiss,which occurs in the field down thrusted the ophiolitic mélange and foliated in ENE-WSW direction, it is occupying the core of that granitic pluton and cross cut by two shear zones. The studied area (500x1000 m) is characterized by low to moderate topography and highly tectonized rocks. (Fig. 1)show a grade 100 x 100m representing the collected sample.