Wafaa Rashed

Bio: Wafaa Rashed is an academic researcher. The author has contributed to research in topics: Effective dose (radiation) & Absorbed dose. The author has an hindex of 3, co-authored 3 publications receiving 53 citations.

Concentration of u-238, u-235, ra-226, th-232 and k- 40 for some granite samples in eastern desert of egypt.

Abstract: The distribution of natural radionuclide γ-ray activities and their respective annual effective dose rates, produced by 40 K, 238 U, 226 Ra, 235 U and 232 Th, were determined for granite samples collected along the road of Idfu - Marsa Alam in eastern desert of Egypt. This subject is important in environmental radiological protection, since granites are widely used as building material. The variation in concentration of radionuclides for thirty granite samples was determined. A HPGe spectrometer was used for quantification of gamma emitting radionuclides in the sediments. All sediments contained radionuclides from the uranium and thorium series as well as 40 K. 238 U concentrations in the samples ranged (from 12.03±0.88 to 19.34±1.41 Bq.kg - 1 ), 235 U (from 1.16±0.11 to 4.83±0.44, Bq.kg -1 ), 226 Ra (from 9.69±0.82 to 18.97±1.33 Bq.kg -1 ), 228 Ra ranged (from 10.24±0.70 to 17.35±1.29) 232 Th range (from 9.99±0.67 to l7.65±1.23 Bq.kg -1 ) and 40 K (from 298.58±21.74 to 955.78±69.58 Bq.kg -1 ). Radium-equivalent activities (Raeq) in addition to the internal hazard index (Hin) have also been determined. Granite samples Raeq varies between 49.05 and 113.39 Bq.kg -1 . The total absorbed dose rates in air calculated from the concentrations of the three radionuclides ranged from 24.24 to 58.05 nGy.h -1 and the external annual effective dose rate of the areas were determined to be between 0.12 and 0.28 mSv.y -1 . The results can be considered as base values for distribution of natural radionuclides in the region and will be used as reference information to assess any changes in the radioactive background level due to geological processes.

Radioactivity Levels and Soil-to-Plant Transfer Factor of Natural Radionuclides from Protectorate Area in Aswan, Egypt

Abstract: The aim of this study is to determine the transfer factor soil-to-plant and to assess the concentration level of natural and artificial radionuclide (238U, 226Ra, 228Ra, 232Th, 40K and 137Cs) in samples from Saluga and Ghazal Protectorate area in Aswan, Egypt, by using High Pure Germanium detector (HPGe) Environmental Radioactivity Measurements Labrotary in faculty of science Qena. Reported values for natural radionuclides ranged from 8.81 ± 0.64 to 28.88 ± 2.10, from 6.98 ± 0.51 to 26.01 ± 1.89, from 12.29 ± 0.89 to 33.32 ± 2.43, from 12.53 ± 0.91 to 32.81 ± 2.39 and from 383.90 ± 27.95 to 711.98 ± 51.83 Bq.kg-1 for 238U, 226Ra, 228Ra, 232Th and 40K, respectively. 137Cs activity concentration was found to be in the range from 0.36 ± 0.03 to 9.73 ± 0.71 Bq.kg-1 and was calculated through transfer factor TF reported in this article.

Measurements of Naturally Occurring Radioactive Materials for some Granite Rocks samples in the Eastern Desert Egypt.

Abstract: The distribution of natural radionuclide γ-ray activities and their respective annual effective dose rates, produced by 238 U, 226 Ra, 228 Ra, 235 U, 232 Th and 40 K were determined for igneous rock samples collected along the road between Idfu and Marsa Alam in eastern desert of Egypt. This subject is important in environmental radiological protection, since igneous rocks are widely used as building material. The variation in concentration of radionuclides for thirty igneous rock samples was determined. A HPGe spectrometer was used for quantification of gamma emitting radionuclides in the samples. All igneous rocks contained radionuclides from the uranium and thorium series as well as 40 K. 238 U concentrations in samples ranged from 12.03±0.88 to 19.34±1.41 Bq.kg -1 , 235 U from 1.16±0.11 to 4.83±0.44, Bq.kg -1 , 226 Ra from 9.69±0.82 to 18.97±1.33 Bq.kg -1 , 228 Ra ranged from 10.24±0.70 to 17.35±1.29, 232 Th range from 9.99±0.67 to l7.65±1.23 Bq.kg -1 and 40 K from 298.58±21.74 to 955.78±69.58 Bq.kg -1 .

Natural Radioactivity Assessment and Radiation Hazards of Pegmatite as a Building Material, Hafafit Area, Southeastern Desert, Egypt

Abstract: Sixty-seven sites of Hafafit pegmatite from the Southeastern Desert of Egypt were investigated radiometrically in the field using an in situ γ-ray spectrometer to determine eU, eTh, and K contents. The obtained results ranged from 0.4 to 6 ppm for eU with a mean value of 2.5 ppm, from 0.2 to 32 ppm for eTh with a mean value of 6.7 ppm, and from 0.7% to 5.4% for K with a mean value of 3.3%. Consequently, the radiological effects from these rocks were estimates by determination of the environmental parameters: gamma activity concentration index Iγ, external hazard index Hex, internal hazard index Hin, external absorbed dose rates in outdoor, and external absorbed dose rates in indoor air. The results obtained in this study showed that values U, Th, and K lie in the range of the acceptable world values. In addition, the calculated radiation hazard parameters (Iγ, Hex, and Hin) have values lower than the world values, while the calculated external absorbed dose rates (Dair) have values higher than the world and Egyptian permissible levels.

Natural radioactivity in granite stones used as building materials in Iran.

Abstract: Due to increasing concern about environmental radiological protection, specific radioactivity concentrations of (226)Ra, (232)Th and (40)K in different types of commonly used granite stone samples collected from the Tehran city of Iran have been determined by means of a high-resolution HPGe gamma-spectroscopy system. The activity concentrations of (232)Th, (226)Ra and (40)K in the selected granite samples ranged from 18 to 178, 6 to 160 and 556 to 1539 Bq kg(-1), respectively. The radium equivalent activities (Ra(eq)) are lower than the limit of 370 Bq kg(-1) set by NEA-OECD [Nuclear Energy Agency. Exposure to radiation from natural radioactivity in building materials. Report by NEA Group of Experts. OECD (1979)], except in two samples. The internal hazard indexes have been found well below the acceptable limit in most of the samples. Five samples of investigated commercial granite stones do not satisfy the safety criterion illustrated by UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation. Exposure from natural sources of radiation. Report to the General Assembly (1993). Applying dose criteria recently recommended by the EC [European Commission Report on Radiological Protection Principles Concerning the Natural Radioactivity of Building Materials. Radiation Protection 112 (1999)] for superficial materials, all investigated samples meet the exemption dose limit of 0.3 mSv y(-1).

Measurement of natural radioactivity and radiation hazard assessment in the soil samples of Ramanagara and Tumkur districts, Karnataka, India

Abstract: The activity concentration of primordial radionuclides, 226Ra, 232Th and 40K in soil samples of Ramanagara and Tumkur districts were determined by gamma spectrometry using HPGe detector. The average activity concentrations of 226Ra, 232Th and 40K were found to be 33.78 ± 1.99, 77.44 ± 2.37 and 791.58 ± 5.78 Bq Kg−1 respectively. The measured activity concentrations of these radionuclides were compared with world average activity concentration of soil. The radiological hazard indices of the natural radioactivity have been calculated and compared with the internationally approved values. The concentration of these radionuclides with different size and depth of the soil samples was studied.