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Abstract  

Accurate nuclide identification depends on the ability to determine if specific peaks are present in the spectrum. Several current handheld nuclide identifiers and portal monitors use a variant of a peak quality value for this. The peak quality is usually calculated as the peak area divided by the uncertainty of the peak area and when this quotient is above a threshold value, the peak is said to be present. Other works [Terracol et al. In: 2004 IEEE Nuclear Science Symposium Conference Record, Rome, Italy, 2004, Ryder In: Scanning Electron Microscopy/1977 V. 1, Proceedings of the Workshop on Analytical Electron Microscopy, Chicago, 1977] have developed a formalism to calculate the peak uncertainty for interfering peaks based on the detector resolution, background, individual peak areas, and peak separation. The threshold on peak uncertainty determines the minimum activity that will be identified or detected. Care must be used in the selection of the threshold in order to comply with the false positive and false negative requirements of the detection system regime, or “concept of operations”. The performance standards for the handheld identifiers and portal monitors specify the nuclides required to be identified. From this list and other commonly expected nuclides, the energies of the expected gamma rays can be tallied, yielding a table of the separations of adjacent peaks possible in the collected spectrum. Using the formalism, the peak quality value can be determined as a function of the detector resolution, peak area and background for the energy separations in the table determined above. Results are shown for the cases of HEU and plutonium with the masking nuclides of NORM, 133Ba, or 57Co for both germanium and sodium iodide detectors. Typical resolutions, efficiencies and counting times were used.

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Abstract  

Use of hydrogen peroxide as a masking agent for uranium during the EDTA titration of yttrium in an yttrium-uranium mixture containing large amounts of uranium has been investigated. High acetate ion concentration was necessary to keep the peroxy complex of uranium in solution during the titration. It has been observed that upto 500 mg of uranium could be tolerated in the determination of yttrium with 0.5 ml of 30% hydrogen peroxide in {lM acetate medium. The precision and accuracy of the method based on 16 determinations of yttrium at 6–16 mg level in presence of 300 mg uranium has been found to be ±0.2%.

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Abstract  

The distribution of a radioactively labelled substance was measured in two different solvent extraction systems in the presence of substoichiometric amounts of different masking reagents. The theory of the errors involved in the method is elaborated, recommendations are given for the choice of the conditions of the determination, e.g. which combination of extractant and masking reagent is preferable, which of the two elements should be labelled, what is the optimum concentration of the masking reagent and what values of distribution ratios are desirable.

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Abstract  

The extraction of group IB, IIB and IIA-VA elements with 1-phenyl-3-methyl-4-trifluoroacetyl-pyrazolone-5 in chloroform has been investigated as a function of pH. The stripping of metal ions into solutions of KCN, HClO4 and appropriate pH buffers has been studied. The masking effects of cyanide, citrate, iodide, thiosulphate and thiourea on the extraction have been examined. Selective group and individual separations have been proposed on the basis of pH control, masking effects and back-extraction.

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Abstract  

The method of differential spectrophotometry with the use of Arsenazo III for uranium determination with masking Zr and Pu by 1,2-diaminecyclohexanetetraacetic acid in acetate buffer and carboxyarsenazo for determination of plutonium without its separation from uranium is applied for analysis of the spent fuel of VVER type reactors.

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Abstract  

The separation of Zn−Cd, Ag−Hg, Cd−Ag and Pb−Bi−Po by extraction chromatography in the system dithizone-carbon tetrachloride is reported. It is shown that it is possible to calculate optimum conditions for the separation of the metals from the extraction constants of the metal chelates and the stability constants of the metal complexes with masking agents.

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Abstract  

The extraction behaviour is reported of zinc(II), cadmium(II) and mercury(II) complexes of thiocarbohydrazide in benzene, chloroform, carbon tetrachloride, di-isopropyl ether, ethyl acetate, amyl acetate, and amyl alcohol. The separation of the three elements has been achieved by the use of various masking agents, as well as by making use of the effect ofpH on their extractability.

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Abstract  

The extraction-chromatographic behaviour of zinc on a column with dithizone as chelating agent has been investigated in the absence and presence of oxalic acid as masking agent. From the results the extraction constant and the stability constants of zinc oxalate complexes have been determined. These values are in good agreement with the published data so that it seems possible to predict the extraction-chromatographic separation of various metals from known extraction and stability constants.

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Abstract  

A selective liquid scintillation method is proposed for the determination of uranium in geological samples by -counting. This method permits the determination of uranium in presence of other radionuclides. The extraction of uranium with HDEHP into the scintillator is conducted in the presence of DTPA in the aqueous phase. The optimum conditions provide quantitative extraction of uranium while masking the other -emitters.

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Abstract  

The liquid-liquid extraction behaviour of mercury(II) as bromide, iodide and thiocyanate has been investigated in different oxygenated and non-oxygenated solvents. The effects of the molarity of acids, their sodium or potassium salts, the concentration of Hg(II) ions, the temperature and masking anions have been studied. The possibilities of separation of Hg(II) from Zn(II), Cd(II) Tl(I), Tl(II) and Au(III) in these extractions are discussed.

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