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Abstract  

The thermal neutron moderation analysis facility at the Institute of Experimental Physics, Debrecen, Hungary has been used to determine the weight percent of total hydrogen content in Nigerian palm oil. The facility utilizes the fast neutron moderation technique in which the intensity of reflected thermalized neutrons is proportional to the hydrogen content of the sample exposed to fast neutrons. Using a 100 cm3 sample the total hydrogen content in the oven-dry palm oil sample was found to be 12.0±0.1% within a measuring time of 5 minutes. The method is fast and can be used in plant quality control where the hydrogen content must be determined within specific limits.

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Abstract  

The determination of the hydrogen concentrations in coal and metal samples were investigated by using the PGAA system at the HANARO Research Reactor, KAERI. The calibration curve of the hydrogen concentration was obtained from a standard sample and the effects of the interference peaks near the gamma-energy region of hydrogen were investigated. The background in the hydrogen peak of a prompt gamma-ray spectrum was measured for the sample chamber and shielding materials of an atmospheric state. The combined uncertainties estimated for the analysis procedure were in the range of 4–5%. Two kinds of certified reference materials, NIST SRM 1632c (Coal), NIST SRM 173c (Titaniumbase Alloy) and NIST SRM 2453 (Titanium Alloy) were used to verify the accuracy and precision of the measurement. The relative error was in the range of 3–6% and the relative standard deviation were less than 4%.

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Abstract  

The hydrogen isotope radiolytic yields, G(H2), G(HD) and G(D2) were determined in H2O/D2O mixtures under chemical conditions close to a LOCA in a PHWR like Atucha I Nuclear Station, that is 2·10–3 MH3BO3 and p(H+D)=8.5±0.2. The total hydrogen radiolytic yield G(H2+HD+D2) as a function of the deuterium atom fraction goes through a flat maximum at about 0.58. This result in dicates that the 4% flammability limit for hydrogen in the reactor's containment with be reached sooner than what is expected assuming a linear combination of pure H2 and D2 radiolytic yields. Hydrogen radiolytic production in 10–3 M KBr in H2O/D2O mixtures gives the same results as in the boric solutions suggesting a bimolecular B(OH) 4 +OH reaction. Identical isotope concentration factors were calculated for both solutions.

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Abstract  

We have developed an absolute, quantitative procedure to determine the hydrogen content and to describe its concentration profile in the near-surface region of solids. The experimental technique used is the Elastic Recoil Detection Analysis of protons induced by helium-4 beam bombardment in the energy range 1.8 MeV. The deconvolution of the recoil spectra is obtained by means of a computer program which simulates all the physical processes of4He/1H interaction. The hydrogen content is calculated using a new recoil cross section expression. The analyses are performed in silicon crystals implanted with hydrogen at 10 keV. The implantation dose is evaluated with an accuracy of 10% and the hydrogen depth profile is given with an accuracy of ±10 nm around 200 nm.

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Abstract  

Hydrogen isotope exchange reaction rate in tritium and methane mixed gas, as induced by tritium decay and beta radiation, has been experimentally measured. Initially T2 gas was filled to 40 kPa and 20 kPa of CH4 gas was added. The mixed gas spectrum was analyzed periodically by laser Raman spectrometry. The first order HT and H2 formation rates and T2 and CH4 decay rates by hydrogen isotope exchange reaction were observed between 2.9·10–3 h–1 and 4.8·10–3 h–1. Although the estimated hydrogen isotope exchange reaction rate was 1/20–1/10 slower than the rate of H2+T2 mixed gases, it was nearly equivalent to the ion formation rate by tritium beta radiation. This suggested that isotopic hydrogen radicals formed via ionization would disappear in the presence of methane.

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Abstract  

Prompt gamma-ray analysis was applied to determine hydrogen in geological samples. In order to obtain accurate values, blank values were estimated and subtracted. Samples were dried to constant weight in an oven. Helium gas was introduced into the sample box to purge the air containing moisture during the measurement. Hydrogen contents in some geochemical standard samples were determined and highly reproducible values were obtained.

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Abstract  

The overall tritium separation factor between molecular hydrogen and liquid pyrrole and pyrrolidine has been measured between 280 and 325 K. The data are comparable with values of α measured for similar exchange reactions involving ammonia and methylamine. There is a visible correlation of the isotope effect with the energy of hydrogen bond formed by NH groups of liquid ammonia, methylamine, pyrrole and pyrrolidine.

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Abstract  

An improved method based on the moderation of intermediate neutrons for the measurement of hydrogen in small samples is described. With the aid of boron and cadmium filters, a space shielded from slow neutrons is set up close to an isotopic neutron source shrouded by water moderator. A BF3 proportional counter enclosed with a sample cell is placed in this space. The neutron count rate of the counter increases when a hydrogen-containing material is introduced into the cell, due to the moderation of intermediate neutrons passing through the filters. With a 1.3 μg252Cf neutron source, the lower limit of hydrogen detection for 200 ml samples in 10 min count time is 0.01 wt.%. This method is suitable for measuring the H2O content of heavy water.

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Abstract  

Hydrogen sulphate, nitrate and perchlorate salts of diphenylamine have been prepared and characterized by elemental, spectral and gravimetric analyses. Thermal decomposition of these salts has been evaluated by TG (static air) and DSC (inert atmosphere). The proton transfer reaction plays a major role during thermolysis of these salts. The diphenylammonium hydrogen sulphate under thermal and microwave irradiation forms 4-(phenylamino) benzenesulphonic acid by sulphonation process, whereas nitrate and perchlorate salts do not form corresponding nitro and perchloro derivatives, rather they ignite and explode, respectively, to form gaseous products along with a residual carbon .

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Journal of Thermal Analysis and Calorimetry
Authors: Laetitia Laversenne, Christelle Goutaudier, Rodica Chiriac, Catherine Sigala, and Bernard Bonnetot

Abstract  

The hydrogen storage capabilities of alkaline borohydrides through a hydrolyzing process were determined by taking into consideration the hydration of the end products. Comparison of LiBH4, NaBH4 and KBH4 showed their storage capacities to be dependent on the composition of the metaborate formed. This composition is ruled by the hydrolysis conditions, especially the temperature reached during the reaction and the stability of the hydrates. The borohydride with the highest hydrogen content in the solid state, LiBH4, could be less efficient than KBH4 if the hydrolysis is performed at 120°C.

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