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Abstract  

Emanation Thermal Analysis (ETA), based on the measurement of the release of radon from previously labelled samples, has been used for 'in-situ’ characterisation of the morphology changes of intercalated montmorillonitic clay. The thermal behaviour of hydroxyaluminium intercalated montmorillonite was monitored in course of the preparation of alumina pillared montmorillonite, making possible to determine optimal temperature for the isothermal treatment of the intermediate product. Moreover, the thermal stability of alumina pillared montmorillonite porous structure was determined from the ETA data. A good agreement of ETA data and surface area, XRD patterns. DTA, and TG resulted was found.

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Abstract  

Emanation thermal analysis was used to characterize the thermal behaviour of alumina coatings as deposited on EUROFER 97 steel surface by filtered vacuum arc technique. Temperature ranges of the healing of cracks and structure irregularities observed by SEM were determined from the ETA results. Transport properties of the alumina coatings were assessed from the ETA results by the evaluation of radon diffusion parameters in the temperature range from 50 to 300°C. Healing microstructure irregularities of the alumina coatings can be expected in the range 300–700°C as indicated by the decrease of the radon release rate. From the ETA results it followed that the onset of healing the cracks observed by the SEM on the surface of one alumina coating sample can be expected at 430°C.

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Abstract  

A modified radiometric method for the determination of plutonium in irradiated nuclear fuel is described. The analysis consists of total plutonium alpha-activity, activity ratio238Pu:(239Pu+240Pu) and burnup determination. The error of plutonium determination is practically identical with that of a classical radiometric method. The method suggested is suitable for large sample series of the same type of irradiated nuclear fuel.

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Abstract  

The paper describes a method for the determination of uranium content in enriched U–Al alloys. The mass-spectrometric isotope dilution method was proposed and verified for the determination of uranium in these materials. A solution of natural uranylnitrate, prepared by dissolution of standard reference material NBS-U-960, was used as a spike. Uranium was separated from aluminium in the form of chloro complexes by sorption on anion exchange resin Dowex 1-X8 from 9M HCl. The error of determination lies in an interval 0.03–0.07% rel. for uranium contents 18.2–22.8 wt%.

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Determination of the balance of the nuclear reactor fuel burn-out process by gamma-spectrometry of fission products III

Determination of the burn-up on the basis of the activity quotients106Ru/137Cs and134Cs/137Cs

Journal of Radioanalytical and Nuclear Chemistry
Authors:
V. Bulovič
,
J. Krtil
,
F. Sus
,
Z. Maksimovic
, and
E. Klosova

Abstract  

The possibility for the determination of heavy water reactor fuel burn-up on the basis of gamma-spectrometric measurements of the activity quotients106Ru/137Cs and134Cs/137Cs has been experimentally investigated. The investigation has been carried out on the non-enriched uranium metal fuel of the Czechoslovak Nuclear Power Plant Al. A spectrometer with germanium detector has been used for spectrum analysis of the irradiated fuel gamm-radiation. Burn-up has been determined (1) by the applied here procedure, and (2) from the results of mass-spectrometric determination of the isotopic composition and content of U, Pu and Nd. Two groups of the values obtained have been compared and the influence of the errors of the measured activity quotients on the established deviations has been evaluated.

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Abstract  

Individual steps of the neodynium method for burn up determination are discussed. The main attention is paid to neodymium separation from fission products, mass-spectrometric measurement of its isotopic composition, and to the calculation of the burn up results from the measured data. The conclusions were verified on burn up analysis for the irradiated fuel from heavy and light water reactors.

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Abstract  

The concentration and isotopic composition of uranium were determined in a solution of burnt WWER reactor fuel. The isotopic composition was determined by mass spectrometry, whereas for determining the concentration of uranium various methods were used. The interlaboratory mean square errors of the determination of uranium concentration by isotopic dilution analysis and by chemical methods were 0.37 and 1 rel.%, respectively, the content being 2.06 mg U/g fuel solution. The mean uranium concentrations obrained by both methods differ from each other by 1.04 rel.%.

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Abstract  

Determination of the isotopic composition and concentration of uranium, plutonium and neodymium by mass-spectrometric isotope dilution is described. Isotopes233U,242Pu and150Nd were used as spikes. Isotopic composition was measured with a Varian-TH 5 mass spectrometer. Optimum amounts loaded onto the filament were 2–5 μg U, ∼0.1 μg Pu and <0.1 μg Nd. The accuracy and reproducibility of the isotopic ratio and concentration measurements were evaluated.

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Abstract  

Determination of106Ru,134Cs,137Cs and144Ce in samples of irradiated fuel from the Czechoslovak atomic power station Al is described. The determination is based on gamma-spectrum analysis. The analysis was performed using a Ge(Li) semiconductor detector; for the determination of the isotope mentioned the lines in the energy interval from 400 to 1300 keV were used. The analyses of both dissolved and non-dissolved samples of the fuel were performed. The results of the determinations and their comparison are given in detail.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
M. Földesová
,
P. Lukáč
,
P. Dillinger
,
E. Klosová
,
Z. Málek
,
E. Večerníková
, and
V. Balek

Abstract  

Zeolites from Nižný Hrabovec (Slovak Republic) were, modified with solutions of NaOH. The changes of zeolites in the temperature range 20–1200 °C were studied by thermal analysis (DTA, TG, ETA), X-ray analysis and REM analysis. Thermal analysis showed that the process of dehydration started between temperatures 20 and 600 °C, over this temperature the dealumination and structural changes have taken place. X-ray analysis and REM analysis showed the structural changes of natural zeolites and gradual loss of cristallinity of the chemically modified zeolites.

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