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  • Author or Editor: F. Bou-Rabee x
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Abstract  

The activity concentrations of natural radionuclides in building materials applied in the State of Kuwait were measured in order to asses the radiological hazard from that source. The samples of raw materials: soil, sand, gypsum and cement as well as different kinds of concrete or bricks were analyzed by -ray spectrometry with a HPGe detector. The radium equivalent activity concentrations in the samples varied between 4.2 to 283 Bq kg–1. This value is generally significantly lower than the value of 370 Bq kg–1 which corresponds to an annual external radiation dose inside dwellings equal to 1.5 mSv. The hazard from external -radiation of building materials has been found to be comparable to that from external -fields of primordial radionuclides in the surface soil of Kuwait.

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Abstract  

A chemical procedure for transferring deposited solid matter from a cellulose filter into the liquid scintillation cocktail has been described. The influence of chemical and color quenching on alpha and beta detection efficiency, as well as on misclassification of beta and alpha pulses was corrected by an external standard method. Under the chosen pulse shape discrimination level (PSD), the alpha and beta detection efficiencies were above 85% and spillovers of alpha and beta pulses were below 10% and 2% respectively. Determination limits for samples containing up to 200 mg of mineral matter were 0.015 mBq m–3 for alpha, 0.055 mBq.m–3 for210Pb and 0.055 mBq.m–3 for beta activity (counting time 12000 s and volume of filtered air 1000 m3). The method has been applied for routine monitoring of210Pb as well as for gross alpha and beta activities of longer-living radionuclides (T1/2.>11 hrs) in suspended air matter.

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Abstract  

A method in which222Rn is extracted from 0.5 1 water samples to 20 ml toluene is described. 10 ml toluene solution with extracted222Rn is directly added to a glass scintillation vial containing 10 ml of liquid naphthalene based scintillation cocktail. Apart from diluting by toluene, the final counting solution still has excellent properties in terms of: / separation by pulse shape analysis, detection efficiency and background in the -region. The detection limit of222Rn for 0.5 1 water samples was 1.5 mBq l–1 (for 12,000 s count time). The concentration of222Rn in different environmental samples such as rain, tap and mineral waters as well as deep well waters were determined.

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Summary  

The activity concentration of natural radionuclides and 137Cs in the bottom sediments cores from Kuwait Bay have been determined by γ-ray spectrometry. Particular attention was devoted to the exact determination of two uranium isotopes: 235U and 238U in order to find any presence of depleted uranium dispersed during the 1991 Gulf War. The calculated 238U/235U activity ratios for all the surface (15 cm) as well as the core profile (up to 70 cm in depth) samples were within the limit of one standard deviation close to the value of 21.5 for natural uranium. Simultaneous instrumental determination of the unsupported 210Pb and 226Ra in a few sediment core profiles was used for quantification of sediment accumulation rates. The calculated sedimentation rates (for the constant atmospheric 210Pb flux rate - CRS model) ranged from 0.2 to 0.6 cm . y-1 and were close to the data calculated by the Weibull distribution of 137Cs in undisturbed sediment cores.

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