INVESTIGATION OF AN EGYPTIAN ALABASTER ORE BY MEASURING ITS NATURAL RADIOACTIVITY AND BY NAA USING K0 STANDARDIZATION AND COMPARATOR METHODS

Passive gamma-ray spectrometry and neutron activation analyses (NAA) were applied in investigating an alabaster ore sample. In the passive measurement 273.4 g of standard monazite sand (with uranium and thorium concentrations of 2860 and 39400mg/kg, respectively) was used in finding the energy dependence on the efficiency of the used HPGe detection system. An alabaster ore sample weighing 172.9g of identical volume and geometry as the monazite sample was used in the passive measurement.The concentration of the radioactive series parent in mg/kg of the sample and dose ratein mSv/hr at 1 meter was calculated. In the long time irradiation NAA, a thermal toepithermal neutron flux ratio of 77.68 and a cadmium ratio of 5.94 for gold were measured by the cadmium difference method using thin gold foils. This was done bylocating 269.1 mg of the alabaster sample wrapped in a thin aluminum foil together with a bare and cadmium covered thin gold foils weighing 5.4 and 6.4 mg respectively,in the same irradiation can. The can was irradiated in one of the vertical wet channels of the ET-RR-1 for 48 h. at power 1.6 MW. In the short irradiation NAA, 373.5 mgalabaster sample and 295.0 mg standard geological sample (JB-1) as a comparator were irradiated separately for 50 sec. by using the pneumatic irradiation rabbit system(PIRS) in the vertical tangential thermal column of the ET-RR-2. The power was 18MW and the thermal neutron flux was of the order of 1011 n / cm2. s.