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Journal of Radioanalytical and Nuclear Chemistry
Authors: Bangfa Ni, Caijing Xiao, Donghui Huang, Hongchao Sun, Guiying Zhang, Cunxiong Liu, Pingsheng Wang, Haiqing Zhang, and Weizhi Tian

Abstract  

China Advance Research Reactor (CARR) at China Institute of Atomic Energy (CIAE), with a non-perturbed maximum thermal neutron flux of 1 × 1015 cm−2 s−1 at the center of active area, is one of the most powerful research reactors in the world. Three neutron channels have been allocated for conventional neutron activation analysis (NAA), thermal neutron prompt gamma activation analysis (PGAA) and cold neutron PGAA, respectively. Two irradiation tube systems are installed in the conventional NAA channel. One of them is for short irradiation with the rabbit size of diameter (Φ)19 × 40 mm, the other one is for long irradiation with the rabbit size of Φ39 × 70 mm. The medium temperature is about 45 °C and the thermal neutron flux is about 3 × 1014 cm−2 s−1 at sample positions. The flux gradient is expected to be very small according to the designed neutron flux distribution. Pneumatic systems are used for samples transfer. The speed of rabbits is designed to be about 20 m/s, and it takes 3 s to travel from irradiation position to detector. Three sets of gamma counting systems and one delayed neutron counting system are being equipped for routine analysis. They are designed for running continuously and automatically. And all the functions can be operated at laboratory or office through remote controlled computer. Software has been made domestically for spectrum peak search, concentration calculation with relative method and k0 method with interference corrections and some other functions for the convenience of users.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Ebihara, Y. Chung, H. Dung, J. Moon, B. Ni, T. Otoshi, Y. Oura, F. Santos, F. Sasajima, Sutisna, B. Wee, W. Wimolwattanapun, and A. Wood

Abstract  

Air particulate matter (APM) samples (PM2.5 and PM10–2.5) were collected at 13 sampling points in 8 Asian countries and their chemical compositions were determined by using neutron activation analysis (NAA) with the k 0-standardization method in addition to conventional comparative method of NAA. Analytical data showed that mass concentration and elemental composition of the APM collected are variable in terms of time and space, and are related to the characteristics of the sampling sites concerned. NAA was proved to be highly effective for the regional characterization of APM in chemical composition.

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Abstract  

The International Atomic Energy Agency (IAEA) has many projects and activities supporting the utilization of nuclear research reactors for neutron activation analysis (NAA). Globally the number of operating nuclear research reactors has been in decline since about 1975. This contrasts with the situation in developing countries where the numbers show a modest increase over the same period. This paper reviews the current status of NAA as seen from the particular perspective of IAEA programs involving studies of biological and environmental specimens. Some of the areas in which NAA is maintaining its role as a competitive technique are briefly reviewed.

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Abstract  

In order to provide a tailored solution for the correction of the 235U interference in k0-NAA, fission k0-factors for the analytically relevant radionuclides/gamma-lines (versus gold as the comparator), are experimentally determined in four channels of the Gent THETIS reactor. A comparison is made with former data from the literature. The new evaluated results are to be implemented in the forthcoming upgrade of the DSMKayzero software package for k0-NAA.

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Abstract  

A new method has been developed aimed at determining traces of lanthanides in the materials of biological origin by NAA. The chemical procedure that involves both, selective and quantitative pre-irradiation isolation of the elements of interest and post-irradiation separation of lanthanides into two groups has been employed. The method is based on classical column ion-exchange and extraction chromatography. In the pre-irradiation step all the accompanying elements are eliminated and the quantitatively isolated lanthanides fraction is free from highly activating macro components, as well as from other trace elements, including uranium, which is the source of spectral and nuclear interferences. After neutron irradiation, the lanthanide fraction is divided into two sub-fractions, taking advantage of the different anion-exchange affinities of individual lanthanide complexes with EDTA towards strongly basic anion-exchanger. This provides the favorable gamma-ray spectrometric measurement conditions enabling reliable determination of 13 elements.

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Abstract  

A neutron spectrum-independent compound nuclear constant, Iko, is proposed for fission interference corrections in reactor NAA by parametric method. Ik0 values for eight major fission interference cases, belonging to three different types, have been determined in six irradiation positions (with th/ e 13,7–134) of three research reactors in our Institute. The general agreement among experimental Ik0 's from different irradiation positions and between experimental and calculated Ik0 values for the same interference case verifies the validity of the method. Calculated Ik0 values for all the possible fission interferences are tabulated. Interferences from238U(n,) and232Th(n,) reactions and reactor fast neutron induced238U(n, f) and232Th(n, f) reactions are discussed.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: Jihao Zhu, Songlin Feng, Dongyu Fan, Xiangqian Feng, Qing Xu, Huishan Quan, Yueming Shen, Zhenxi Zhuo, and Wenjiang Zhang

Abstract  

Chemical composition is an important information of studying the provenance character of ancient pottery and porcelain. The ancient celadon samples produced in Later Tang (850–907 A.D.) to Former Southern Song (1127–1279 A.D.) have been analyzed with NAA. Its provenance characteristic was compared with that of Hongzhou Kiln of Jiangxi Province and Yaozhou Kiln of Shanxi Province in this paper. The experimental data were studied with statistic methods. The results indicated that the chemical compositions of ancient porcelain body samples made in three kilns were different. The difference is able to be identified. The porcelain body materials of both Silongkou Yue Kiln and Hongzhou Kiln were similar. The samples of Yaozhou kiln in north of China existed obvious difference.

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Abstract  

The content of chromium in the DNA, RNA and protein fractions separated from chromium-rich and normal brewer's yeast was determined by neutron activation analysis (NAA). Our results show that the extracted relative amounts and concentrations of DNA, RNA and proteins have no significant difference for two types of yeast, but the chromium content in DNA, RNA and proteins fractions extracted from the chromium-rich yeast are substantially higher than those from the normal. In addition, the concentration of chromium in DNA is much higher than that in RNA and proteins. It is evident that the inorganic chromium compounds can enter the yeast cell during the yeast cultivation in the chromium-containing culture medium and are converted into organic chromium species, which are combined with DNA, RNA and proteins.

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Abstract  

A new universal radiochemical separation scheme for selective and quantitative isolation of molybdenum and neptunium (formed from uranium), from neutron irradiated biological materials has been elaborated. The procedure is based on ion exchange and extraction chromatography with final fixation of molybdenum on a column with -benzoinoxime supported on Bio-Beads SM2 and neptunium on Dowex 1-X8 [No 3 ]. The separated elements are quantified using gamma-spectrometric measurements. The new NAA method is able to overcome problems associated with high contents of phosphorous in some samples and assures detection limits better than 3 ppb for both elements. The validity of the proposed scheme has been demonstrated by the analysis of several CRM's.

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Abstract  

Volcanic gases in the temperature range from 269° to 635° were sampled by means of a filter combination, consisting of two activated charcoal filters, a cooler and a condensate trap. Samples of the steam plume were taken additionally to quantify the depletion of the elements after condensation and dilution by the atmosphere. The elements F, Cl, Br, I, As, Sb, Se, Te and Hg were determined by instrumental and radiochemical NAA. The data obtained are compared to literature values and the total amount released is estimated. The concentrations in the condensate are compared to the amounts on the filters, enabling the identification of some of the compounds present in the gases. Objects of the investigation were Stromboli and Vulcano in Southern Italy.

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