Radiological status in sea-sediments and sand near an oil shale power plant in North-Western Greece

Journal of Radioanalytical and Nuclear Chemistry - Oil and oil products belong to the naturally occurring radioactive materials-ΝΟRΜs. In the present study, the radiological status...     

Radiological characterization of drinking waters in Central Italy

Due to the importance of water in human life, its quality must be strictly controlled; for this purpose, simple and reliable analytical methods must be available. In this study, a monitoring of radioactivity content was performed in tap waters collected in a region of Central Italy to check the compliance with recent European and Italian regulations. Gross alpha and beta activities, ²³⁸U, ²³⁴U, ²²⁶Ra, ²²²Rn, and ³H concentrations were measured. Gross alpha and beta activities were determined by standard ISO 9696 and ISO 9697; for ²²⁶Ra, ²²²Rn and ³H determination, liquid scintillation was used. ²³⁸U and ²³⁴U concentrations were determined by alpha spectrometry after separation from the matrix by extraction chromatography and electroplating. The results revealed that the tritium concentration was always lower than 6.75 Bq l^− 1. The concentrations (mBq l^− 1) of ²²⁶Ra, ²²²Rn, ²³⁸U, and ²³⁴U ranged from < 1.70 to 15.31, from 0.69 to 20.3, from 0.65 to 48.77, and from 0.78 to 51.50, respectively.²³⁴U/²³⁸U ratios were higher than 1 in most cases. The results obtained revealed that, in most samples, gross alpha and gross beta were lower than the parameter value indicated in the international regulations. An attempt was also made to find a correlation between these results and the chemical parameters of waters.     

Radiological chronometry of uranium metal samples

Radiological chronometry is an important tool in nuclear forensics that uses several methods to determine the length of time that has elapsed since a material was last purified. One of the chronometers used in determining the age of metallic uranium involves measuring the fractional ingrowth of ²³⁰Th from its parent ²³⁴U with the assumption that the uranium metal contained no impurities, especially thorium, when it was purified. The affects of different etching procedures were evaluated for the removal of surface oxidation with three different types of uranium metal samples to determine whether the etching procedure affects the radiological age. The sample treated with a rigorous etching procedure had exhibited the most reliable radiological age while less rigorous etching yields a radiological age from 15 years to hundreds of years older than the known age. Any excess thorium on the surface of a uranium metal sample presents a bias in age determination and the sample will appear older than the true age. Although this research demonstrates the need for rigorous surface etching, a bias in the radiological age could have arisen if the uranium in the metal was heterogeneously distributed.     

Radiological inventory of irradiated graphite samples

In France, graphite is present as reflector, moderator or structural element in 9 gas cooled reactors which are now in the decommissioning phase The storage, whose characteristics have to be determined, dedicated to irradiated graphite is planned in France for 2010. Consequently, the radiological inventory of the graphite has to be done Measurement campaigns already organized on different graphite samples showed discrepancies for the computed “calculation/measurement” ratio and the necessity to acquire more experimental results was stressed. The ability to realize an experimental radiological inventory, with particular attention to ³H, ¹⁴C, ³⁶Cl, and ⁶³Ni, was studied. A new mineralization was developed based on an acid attack (iodic + sulfuric acid). This process causes a high gaseous emission and cannot be applied to analyses of volatile elements such as ¹⁴C, ³H, and ³⁶Cl. The routine pyrolysis protocol used to measure these elements in other matrices was specially adapted to the graphite samples. After these mineralizations, radiochemical steps were conducted in order to separate the different requested radionuclides. The mean yield of the complete separation process was evaluated for each of them and the detection limits were determined.     

Radiological characterization of low-and intermediate-level radioactive wastes

An analytical procedure for the determination of activation products ²³⁸Pu, ²⁴¹Pu, ²³⁹Pu/²⁴⁰Pu, ²⁴¹Am, ²³⁷Np, and a fission product ⁹⁰Sr in radioactive wastes is presented. Samples were decomposed using Fenton’s reaction. The separation was performed by anion-exchange chromatography, extraction chromatography, using TRU and Srresin, and precipitation techniques, followed by α-spectrometry and LSC counting. Tracer solutions and pure ion exchange resins were used to prepare artificial samples and trace nuclides during the analytical procedure. Some real samples of spent ion-exchange resins originating from our TRIGA Mark II research reactor were analyzed.     

1999 Calendar of Events

Plasmas and Polymers -     

1999 Calendar of Events

Plasmas and Polymers -     

Radiological characterization of spent control rod assemblies

Three different spent control rods were obtained for direct-assay measurements and empirical sampling and analysis. They were: 1) a BWR cruciform control rod, 2) a PWR rod-cluster control assembly, and 3) a burnable poison-rod assembly. The dominant activity of the BWR cruciform control rod and the PWR burnable poison-rod assembly is⁶⁰Co, whereas the PWR rod-cluster control assembly is dominated not only by⁶⁰Co, but also by^108mAg and^110mAg, which are found in the Ag–In–Cd alloy of the absorber rods. The radionuclide inventories calculated for the three spent control rods from the empirical sampling data agree very well with data determined from the two direct assay methodologies. The concentration of^108mAg in the rod-cluster control assembly will have to be considered when these types of spent control rods are prepared for waste disposal.     

Radiological characterization and environmental impact in northwestern coast of Egypt

A study of environmental radioactivity along the northwestern coast of Egypt was performed by the Central Laboratory for Environmental Radioactivity Measurements Inter-comparison and Training within the framework of the research project: Radiological Studies/Measurements of Natural and Man-made Radionuclides in the Environment. The present paper contains important conclusions, correlations and interpretations of the environmental measurements. The samples collection and measurements were conducted according to the Egyptian Atomic Energy Authority monitoring plan for locations along the northwestern coast of Egypt and its main tributaries of interest. The specific activities of ²²⁶Ra (²³⁸U series), ²²⁸Ra (²³²Th series), ⁴⁰K and ¹³⁷Cs (Bq/kg dry weight) were measured using gamma-ray spectrometers based on hyper-pure germanium detectors. The absorbed radiation dose rates in air (nGy/h) due to natural radionuclides in shore sediment and radium equivalent activity index (Bq/kg) were calculated. The specific activity ratios of ²²⁸Ra/²²⁶Ra were calculated for evaluation of the geo-chemical behavior of these radionuclides. Samples textures and CaCO₃ and total organic matter contents of sediments were also determined while the pH, major cations and anions such as Na⁺, K⁺, Ca⁺⁺, Mg⁺⁺and Cl^?, SO₄ ^– and HCO₃, respectively were also determined in water samples.     

Radiological assessment of the bauxite residue valorization chain

Journal of Radioanalytical and Nuclear Chemistry - The behavior of radionuclides in the bauxite residue valorization chain has been analyzed, and accumulation ratios have been measured for...