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Abstract  

The sorption capacities of hydrous SiO2 and ZrO2 for the Zn(ammine) ion have been observed to increase on irradiation with γ-rays, by ca. 4.1 and 3.8%, respectively. The rates of sorption increase differently in the irradiated exchangers, depending upon their characteristic natures; e. g. when the external concentration of the Zn(ammine) solution is 0.2M, the increase in the F value due to irradiation is more striking in the case of SiO2 than for ZrO2. On the other hand, at a lower external concentration of the Zn(ammine) solution (0.01M), the increase in the F value, particularly during the first five minutes, is more significant for ZrO2.

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Abstract  

The analysis of mineral contents in space foods is needed to obtain an information on a comprehensive elemental composition as well as the investigation on the effects of human nutrition and health based on the dietary intake of mineral elements. Recently, six items of new Korean space foods (KSFs) such as kimchi, bibimbap, bulgogi, a ramen, a mulberry beverage and a fruit punch which was developed by the KAERI, and the contents of more than 15 elements in the samples were examined by using instrumental neutron activation analysis (INAA). Five biological certified reference materials, NIST SRM were used for analytical quality control. The results were compared with those of common Korean foods reported, and these results will be applied toward the identification of irradiated foods.

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Radiation-induced effects on alternative fuels

IV. γ-Ray irradiation of asphaltenes from coal

Journal of Radioanalytical and Nuclear Chemistry
Authors: F. Lanças and D. Pereira

Abstract  

Asphaltenes obtained from high-ash coal by precipitation with n-hexane were -ray irradiated at different doses up to 320 kGy. After irradiation the vials were opened and submitted to chemical analysis using chromatography (PLC, GPC, GC), spectroscopic (MMR IR) and additional methods (elemental analysis, VPO). Based upon the class distribution obtained through preparative liquid chromatography (PLC-8) and the chemical analysis, a mechanism is proposed to explain the -ray effects on the irradiation of asphaltenes.

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Abstract  

Variation of tritium concentration was examined for 100 days in the course of degradation of fresh pine needles, which were left on a pine forest floor. No difference was observed on free water tritium (FWT) and organically bound tritium (OBT) concentrations of sterilized samples by gamma-ray irradiation or fumigation and control samples, attributable to incomplete sterilization. The OBT concentrations did not increase within the experimental period as the level of humus collected from the forest floor. The results suggest that a longer degradation time, more than 100 days, is necessary to elevate OBT up to the level, which is observed in the general environment.

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Abstract  

A method for the determination of sulphur in fly ash by instrumental proton activation analysis using the34S/p,n/34mCl reaction was developed. The 2128.5 keV and 3305.0 keV -rays of34mCl /t=32.0 min/ were measured on a Ge/Li/ -spectrometer, shielded with a lead absorber to attenuate low energy -rays. Irradiation and measuring conditions were optimized. The detection limit for instrumental analysis is 0.3 to 1 mg g–1 and the standard deviation is cca. 4% for a typical sample.

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Abstract  

Chemical separation yield of actinide elements from soil samples containing high amounts of organic matters was often low as compared to that for samples containing low organic matters. We compared chemical yield of uranium and plutonium from organic-rich Japanese soil and humic acid samples which were subjected to three different pretreatment procedures ((1) pulverization only, (2) dry-ashing at 510 °C after pulverization, and (3) 680 kGy gamma-ray irradiation after pulverization) prior to acid digestion. Separation of U and Pu was performed by U-TEVA resin and AG1-X8 anion exchange resin, respectively. For organic samples, pretreatment procedures governed the yield of actinide elements significantly. Chemical separation yield of U was low (6±1%) for Aldrich humic acid sample after dry-ashing at 510 °C. For such samples, gamma-ray irradiation improved the yield of U to 35±22%. Recovery of Pu was lower for some organic soil samples which were dry-ashed at 510 °C (27±2%) as compared to those which were not dry-ashed (62±10%).

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Abstract  

The molecular aggregation of acrylic and methacrylic acid esters containing long-fluorocarbon chains: 2-(perfluoroalkyl)ethyl acrylate (FFnEA) and 2-(perfluoroalkyl)ethyl methacrylate (FFnEMA) (F(CF2)nCH2CH2OCOC(X)=CH2, where X=H, CH3 and n=6, 8, 10) was investigated by differential scanning calorimetry (DSC) and temperature controlled X-ray powder diffraction measurement. These compounds exhibited some characteristic polymorphic behaviors depending on the length of fluorocarbon chain and the -position methyl group. The solid-state polymerization by -ray irradiation was studied for these compounds in the various crystal forms. In the solid-state polymerization, highest polymerizability was observed in the crystal form that exists in the highest temperature region for each compound.

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Abstract  

Coordination number of network-former (NWF) and formation of nonbridging oxygen (NBO) at the site neighboring to NWF can be estimated from Mössbauer measurements, since small amounts of Fe3+ and Sn4+ substitute NWF in several oxide glasses. Gamma-ray or thermal neutron irradiation of oxide glasses causes electron or charge transfer from oxygen to the Mössbauer ions, and the probability depends on the fraction of NBO. On the contrary, -ray irradiation of phosphate glasses results in oxidation of Fe2+ to Fe3+ since iron plays a role of network modifier (NWM) at interstitial sites. Debye temperature D obtained from low-temperature Mössbauer measurements reflects the site occupation of Mössbauer ions in glasses. A linear relationship between glass transition temperature (T g) and quadrupole splitting () of Fe3+,T g rule, is also effective for determining the site occupation of Mössbauer ions.

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Abstract  

The extracting abilities for thorium, uranium and some fission products by five sulfoxides are given. The results show that di(2-ethylhexyl) sulfoxide (DEHSO) is not only completely miscible with kerosene, but also superior to tri-n-butyl phosphate in some properties. The extraction behavior of uranium, thorium and some fission products such as zirconium, niobium and ruthenium from aqueous nitric acid with DEHSO in kerosene has been studied over a wide range of conditions. DEHSO extracted uranium and fission products better than TBP under all conditions and is similar to TBP in extraction of thorium. A study of extraction mechanism indicates that U and Th are extracted as disolvates, whereas HNO3 is extracted as monosolvate. Extraction of the two actinides decreases with increasing temperature, indicating the extraction to be exothermic. Preliminary studies show that -ray irradiated DEHSO extracts Zr and Nb to a smaller extent than irradiated TBP in the range of 104–107 rad.

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Abstract  

Samples of a new, naphthenic based electrical-grade insulating mineral oil (type AV-58), were irradiated with -rays from a60Co source. Doses of up to 640 kGy were used in order to investigate the chemical effects promoted by -rays in the oils. After irradiation the samples were fractionated by preparative liquid chromatography into eight compound classes, which were then analyzed by high resolution gas chromatography. By comparing the profile of each class with the equivalent fractions of the same oil without irradiation, it could be concluded that no appreciable changes were found within the dose range investigated. This result indicates that -ray irradiation of contaminants, such as PCB's, in these oils could be conducted without matrix interference.

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