الفهرس 
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Abstract
Regarding to the great benefits from the studies of natural radioactivity and to continue the program of measuring natural radioactivity in different environmental media started in the Environmental Radioactivity Measurements Laboratory (ERML), Faculty of Science, South Valley University, Qena, Egypt since 1990, measurement of natural radioactivity and studying the effect of grain sizes on the natural radioactivity and radon exhalation rate of phosphate, soil, and building materials (sand, granite, marble and limestone) from Aswan and Qena governorates, Egypt were considered in this thesis.
This work is mainly concerned with many issues.
The first concern is to investigate the activity concentrations such as 40K, as well as radionuclides from the 226Ra and 232Th series in different samples using gamma spectroscopy.
The second concern is to investigate the effect of grain size on the activity concentrations in different samples.
The third concern is to estimate the radiation hazard health, by calculating the annual effective doses for human, and effect of grain size on the radiation hazard health, and comparing between the obtained results and the other published data.
The fourth concern is to investigate the effect of grain size on the activity concentrations and exhalation rate of 222Rn in phosphate, soil and building materials, using the ionization chamber ”Alpha GUARD”.
Finally, investigation the physical properties that affect on radon exhalation rate (thickness, area, temperature).
The measurements described in this study were performed using Low-level gamma ray spectrometer. It consists of ″3x3″ NaI (Tl). The system was calibrated for energy using standard point sources (60Co, 137Cs), and calibrated for efficiency using standard solution QCYB41. Every sample was placed in face to face geometry over the detector for 10 to 24 hour for (226Ra, 232Th and 40K) concentrations measurements. Prior to sampling counting, background were normally taken every week under the same condition of sample measurement, and using the ionization chamber Alpha GUARD PQ2000PRO along with the additional special equipment AquaKIT was used for determining 222Rn concentration in all samples.
The average concentrations (Bq/kg) of 226Ra,232Th and 40K for all investigated samples are summarized in the following table:
Type of sample
Activity concentration (Bq/kg)
226Ra
232Th
40K
Phosphate
6427.39±276
801.4±49
5749.71±495
Soil
139.88±6
162.84±10
1578.38±136
Sand
55.36±2
30.41±2
725.71±62
Granite
268.61±12
566.96±39
6367.98±548
Marble
70.08±3
28.93±2
242.91±21
Limestone
44.43±2
7.71±0.48
311.16±27
from the obtained results, the higher values were 6427.39±276 and 801.4±49 (Bq/kg) for 226Ra and 232Th found in phosphate sample