ABSTRACT
Two of the important radionuclides which are entered to environment and human diet are radium-226 [[226]Ra] and cesium-137 [[137]Cs]. It is clear that the methods for preparation of foods such as peeling, washing, cooking or frying can affect the dose which is received by human due the to consumption of foodstuffs. An experiment has been performed at the environmental monitoring section of NRPD, aiming to measure the transfer of [226]Ra and [137]Cs from the tea leaves to drinking part of tea. Tea samples were pulverized to obtain a homogenous matrix which was weighed and placed in 1000 cm[3] Marinelli beaker. After making tea, the liquid tea and tea-discard were analyzed separately. Measurement of [226]Ra and [137]Cs was performed by gamma spectrometry system using a high purity germanium [HPGe] detector with 40 % relative efficiency. The detector was shielded by 10 cm lead an all sides with cadmium -copper as liners. It was found that the activity concentration transferred from tea leaves to drinking tea for [137]Cs and [226]Ra are less than 2% and 17% respectively. On the basis of these measurements it seems that no significant levels of radioactivity of [226]Ra and [137]Cs can be found in drinking part of tea. The low concentration of the mentioned radionuclides in drinking tea is mostly due to tea dust and can be removed by its washing before preparing tea
ABSTRACT
Natural uranium exists in earth crust and seawater. The concentration of uranium might increase by human manipulation or geological changes. The aim of this study was to verify susceptibility of laser flourimetry method to determine the uranium concentration in Caspian Sea and Persian Gulf water. Laser flourimetric method was used to determine the uranium concentration in several samples prepared from Caspian Sea and Persian Gulf water. Biological and chemical substances were eliminated in samples for better evaluation of the method. As the concentration of natural uranium in samples increases, the response of instrument [uranium analyzer] increases accordingly. The standard deviation also increased slightly and gradually. Results indicate that the laser flourimetry method show a reliable and accurate response with uranium concentration up to 100 micro g/L in samples after removal of biological and organic substances