Determination of boron in glass by neutron transmission method

Neutron transmission method has been used for the determination of boron in borosilicate glasses. The method is sensitive and rapid to control the spatial homogeneities of glass-product in the melting furnace.Dedicated to Academician J. Csikai on his 60th birthday.This work was supported by the National Foundation for Research (Contact No. 259).     

Determination of boron in glass by the nuclear track technique

Summary Determination of Boron in Glass by the Nuclear Track Technique The nuclear track technique using the¹⁰B(n)⁷Li reaction, has been applied to determine boron in concentration ranges (1.59 to 7.75%) ordinarily considered high for nuclear determinations. Factors limiting the overall precision of the method and restricting the linear dependence of track density on boron concentration are examined. Boron alpha track densities are used to construct planar profiles of boron distribution within the surface region of bulk glass and CVD films. Calibration curves for quantitative lateral profiling of surfaces are constructed and show the selective corrosion of borosilicate glass surface resulting in boron depletion.     

Determination of radium isotopes in soil samples by alpha-spectrometry

A sensitive and accurate method for determination of radium isotopes in soil samples by α-spectrometry has been developed ²²⁵Ra, which is in equilibrium with its mother ²²⁹Th, was used as a yield tracer. Radium in soil samples was fused together with Na₂CO₃ and Na₂O₂ at 600 °C, leached with HNO₃, HCl and HF, preconcentrated by coprecipitation with BaSO₄, separated from uranium, thorium and iron using a Microthene-TOPO chromatographic column, isolated from barium in a cation-exchange resin column using 0.05M 1,2-cyclohexylene-dinitrilo-tetraacetic acid monohydrate as an eluant, electrodeposited on a stainless steel disc, and counted by α-spectrometry. The detection limit of the method is 0.43 Bq·kg⁻¹ for ²²⁶Ra, ²²⁸Ra and ²²⁴Ra if 0.50 g of soil sample are analyzed. The method was checked with two certified reference materials supplied by the IAEA, and reliable results were obtained Fourteen soil samples collected from the refractory industry in Italy were also analyzed. The mean radiochemical yields for radium were 85.7±4.3%, and the obtained radium concentrations in the soil samples were in the range of 8.08–3878 Bq·kg⁻¹ for ²²⁶Ra, of 1.60–678 Bq·kg⁻¹ for ²²⁸Ra and 1.25–550 Bq·kg⁻¹ for ²²⁴Ra, with ²²⁸Ra/²²⁶Ra and ²²⁴Ra/²²⁶Ra ratios ranged from 0.159–0.821 and from 0.142 to 0.525, respectively.     

Determination of uranium isotopes in environmental samples by alpha-spectrometry

A new and accurate method for the determination of uranium isotopes (²³⁸U, ²³⁴U and ²³⁵U) in environmental samples by alpha-spectrometry has been developed. Uranium is preconcentrated from filtered water samples by coprecipitation with iron(III) hydroxide at pH 9-10 using an ammonia solution and the precipitate is dissolved in HNO₃ and mineralized with H₂O₂ and HF; uranium in biological samples is ashed at 600 °C, leached with Na₂CO₃ solution and mineralised with HNO₃, HF and H₂O₂; uranium in soil samples is fused with Na₂CO₃ and Na₂O₂ at 600 °C and leached with HCl, HNO₃ and HF. The mineralized or leaching solution in 2M HNO₃ is passed through a Microthene-TOPO (tri-octyl-phosphine oxide) column; after washing, uranium is directly eluted into a cell with ammonium oxalate solution, electrodeposited on a stainless steel disk and measured by alpha-spectrometry. The lower limits of detection of the method is 0.37 Bq^.kg^-1 (soil) and 0.22 mBq^.l^-1 (water) for ²³⁸U and ²³⁴U and 0.038 Bq^.kg^-1 (soil) and 0.022 mBq^.l^-1 (water) for ²³⁵U if 0.5 g of soil and 1 litre of water are analyzed. Five reference materials supplied by the IAEA have been analyzed and reliable results are obtained. Sample analyses show that, the ²³⁸U, ²³⁴U and ²³⁵U concentrations are in the ranges of 0.30-103, 0.49-135 and 0.02-4.82 mBq^.l^-1 in waters, of 1.01-7.14, 0.85-7.69 and 0.04-0.32 Bq^.kg^-1 in mosses and lichens, and of 25.6-53.1, 26.4-53.8 and 1.18-2.48 Bq^.kg^-1 in sediments. The average uranium yields for waters, mosses, lichens and sediments are 74.5±9.0%, 80.5±8.3%, 77.8±4.9% and 89.4±9.7%, respectively.     

Determination of thorium isotopes in gas lantern mantles by alpha-spectrometry

A procedure for the determination of the three main isotopes of thorium in gas lantern mantles by alpha-spectrometry has been developed. The samples examined were dissolved in concentrated nitric acid and thorium was precipitated as hydroxide. Thorium was then dissolved in hydrochloric acid to be extracted into a TOPO solution, back-extracted with sulfuric acid, electrodeposited onto a steel disc and finally counted alpha-spectrometrically. The radiochemical recovery for thorium was 94% with a counting efficiency of 37%.     

Determination of plutonium in the presence of uranium by alpha-spectrometry

The plutonium determination by alpha-particle spectrometry with semiconductor detectors in the presence of uranium has been described. It has been found that plutonium as well as uranium can be electrodeposited quantitatively on nickel or stainless steel discs from solutions in isopropanol. The time of deposition does not exceed 35–40 min. The determination of plutonium is possible within the uranium to plutonium weight ratio of 4000 with the accuracy better than 2%.     

Determination of boron concentration in borosilicate glass,boron carbide and graphite samples by conventional wet-chemical and nuclear analytical methods

Boron is an important element in nuclear technology. A comparative study was carried out for the determination of boron in borosilicate glass, boron carbide and graphite samples by wet-chemical and nuclear analytical methods. Wet chemical methods namely titrimetry, Inductively Coupled Plasma Mass Spectrometry and ICP Optical Emission Spectrometry and nuclear analytical methods namely Particle Induced Gamma-Ray Emission and Nuclear Reaction Analysis were used. Boron concentrations were in trace (mg kg^?1) level in graphite and percentage level in borosilicate glass and boron carbide.     

Determination of radium isotopes in mineral and environmental water samples by alpha-spectrometry

Summary A method for the determination of low-level radium isotopes in mineral and environmental water samples by alpha-spectrometry has been developed. Radium-225, which is in equilibrium with its mother ²²⁹Th, was used as a yield tracer. Radium were preconcentrated from water samples by coprecipitation with BaSO₄and iron (III) hydroxide at pH 8-9 using ammonia solution, then isolated from uranium, thorium and iron using a Microthene-TOPO chromatography column at 8M HCl, separated from barium in a cation-exchange resin column using 0.05M 1,2-cyclohexylenedinitrilotetraacetic acid monohydrate at pH 8.5 as an eluant, and finally electrodeposited on a stainless steel disc in a medium of 0.17M (NH₄)₂C₂O₄at pH 2.6 and current density of 400 mA^. cm^-2, and counted bya-spectrometry. Optimum experimental conditions for radium separation, purification and electrodeposition have been studied and discussed in the paper. The lower limits of detection of the method are 0.11 mBq^. l^-1for ²²⁶Ra, ²²⁸Ra and ²²⁴Ra, respectively, if 2 l of water are analyzed. The method has been checked with a certified reference material IAEA-Soil-6 supplied by the International Atomic Energy Agency and reliable results were obtained. Eighteen water samples collected in Italy have been analyzed with the method, the mean radiochemical yields for radium were 86.2±6.5%. The obtained radium concentrations were in the range of 0.50-60.8 mBq^. l^-1for ²²⁶Ra, of 0.10-25.7 mBq^. l^-1for ²²⁸Ra, and of￡LLD-7.97 mBq^. l^-1for ²²⁴Ra. The ²²⁸Ra/²²⁶Ra and ²²⁴Ra/²²⁶Ra ratios were in the range of 0.189-4.45 and￡LLD-0.941, respectively.     

Determination of alpha-emitting uranium isotopes in soft tissues by solvent extraction and alpha-spectrometry

A radiochemical procedure has been developed for the determination of alpha-emitting isotopes of uranium ((238)U, (235)U and (234)U) in soft tissues. Known amounts of sample are spiked with (232)U internal tracer and wet-ashed. Uranium is co-precipitated with iron hydroxide as carrier, and extracted into 20% trilaurylamine solution in xylene after dissolution of the precipitate in 10M hydrochloric acid. The uranium, after stripping into an aqueous phase, is electro-deposited onto a platinum disc and counted by alpha-spectrometry. The radiochemical recovery ranges from 60 to 85% for bovine liver samples. The average radiochemical recoveries for human tissues vary from 53 to 78%.     

Determination of isotopic thorium in biological samples by combined alpha-spectrometry and neutron activation analysis

The determination of isotopic thorium by alpha-spectrometric methods is a routine practice for bioassay and environmental measurement programs. Alpha-spectrometry has excellent detection limits (by mass) for all isotopes of thorium except²³²Th due to its extremely long half-life. This paper reports a pre-concentration neutron activation analysis (PCNAA) method for²³²Th that may be performed following alpha-spectrometry if a suitable source preparation material is utilized. Human tissues and other samples were spiked with²²⁹Th and the thorium was isolated from the sample using ion exchange chromatography. The thorium was then electrodeposited from a sulfate-based medium onto a vanadium planchet, counted by alpha-spectrometry, and then analyzed for²³²Th by neutron activation analysis. The radiochemical yield was determined from the alpha-spectrometric method. Detection limits for²³²Th by this PCNAA method are approximately 50 times lower than achieved by alphaspectrometry.     

微波消解-分光光度法测定大豆中的硼量

研究了分光光度法测定大豆中的硼时样品的微波消解方法。建立了合理的分析步骤。进行了微波消解条件的选择及方法的精密度、准确度试验。试验结果表明:消解完全仅需20 min,相对标准偏差均小于7.6%,其方法的加标回收率为92%~105%。     

Natural radioactivity in bioassay by alpha-spectrometry measurements

Personnel of nuclear facilities are checked regularly for internal contamination by bioassay measurements. Although these persons are generally not involved in any incident, natural radioactivity from U, Th and Ra can be found in their urine or faeces. Uranium total activity in urine has been found with a range of 0.051 to 3.0 mBq/24 h and in faeces from 14.5 to 380 mBq/d. ²³⁴U/²³⁸U ratio for urine is 1.48 but this ratio varies from 0.47 to 19. By comparison, the ²³⁴U/²³⁸U ratio found in urine from workers in volved with natural uranium or 4.5% enriched uranium is 1.0 and around 4.0 respectively. ²³⁰Th, ²²⁸Th and sometimes ²³²Th have also been detected. The total thorium activity varies from 0.137 to 5.6 mBq/24 h in urine and from 9 to 183 mBq/d in faeces. ²²⁸Th has generally been found in excess of ²³²Th. All these measurements were performed by alpha-spectrometry. The few ²²⁶Ra results have been measured using the Lucas or emanation method.     

Determination of boron and nitrogen in boron nitride

Improved techniques are described for the determination of boron and nitrogen in pure boron nitride. Controlled fusion of boron nitride with sodium carbonate in a muffle furnace is followed by a potentiometric titration of the boric acid. A special quartz vessel is described for the determination of nitrogen. The boron nitride is fused with sodium hydroxide and the resulting ammonia is swept into a receiver and titrated with standard hydrochloric acid. Boron and nitrogen values with their standard deviation are given for a typical pure boron nitride.     

Determination of 222Rn in Iranian mineral waters using liquid scintillation alpha-spectrometry

Liquid scintillation counting (LSC) method has been used for the measurement of ²²²Rn in mineral water samples under a pilot project for the first surveillance in Iran. Low level background LSC counter Quantulus and pulse-shape analysis method have been employed. The concentration of ²²²Rn found in mineral waters of the studied areas ranges from about 1 to 75 Bq/l. The best lower limit of detection obtained with the applied technique was 0.069 Bq/l for a counting time in the range of 236–296 minutes.     

On the determination of radium by alpha-spectrometry

In order to determine radium in environmental samples by -spectrometry, the way in which some changes in the chromatographic conditions can affect the purification of the element on cation exchange columns from hydrochloric solutions have been studied. Some modifications have also been introduced in the method of electrodeposition of radium from an ammonium oxalate electrolyte.     

Determination of (236)U and transuranium elements in depleted uranium ammunition by alpha-spectrometry and ICP-MS

It is well known that ammunition containing depleted uranium (DU) was used by NATO during the Balkan conflict. To evaluate the origin of DU (the enrichment of natural uranium or the reprocessing of spent nuclear fuel) it is necessary to directly detect the presence of activation products ((236)U, (239)Pu, (240)Pu, (241)Am, and (237)Np) in the ammunition. In this work the analysis of actinides by alpha-spectrometry was compared with that by inductively coupled plasma mass spectrometry (ICP-MS) after selective separation of ultratraces of transuranium elements from the uranium matrix. (242)Pu and (243)Am were added to calculate the chemical yield. Plutonium was separated from uranium by extraction chromatography, using tri- n-octylamine (TNOA), with a decontamination factor higher than 10(6); after elution plutonium was determined by ICP-MS ((239)Pu and (240)Pu) and alpha-spectrometry ((239+240)Pu) after electroplating. The concentration of Pu in two DU penetrator samples was 7 x 10(-12) g g(-1) and 2 x 10(-11) g g(-1). The (240)Pu/(239)Pu isotope ratio in one penetrator sample (0.12+/-0.04) was significantly lower than the (240)Pu/(239)Pu ratios found in two soil samples from Kosovo (0.35+/-0.10 and 0.27+/-0.07). (241)Am was separated by extraction chromatography, using di(2-ethylhexyl)phosphoric acid (HDEHP), with a decontamination factor as high as 10(7). The concentration of (241)Am in the penetrator samples was 2.7 x 10(-14) g g(-1) and <9.4 x 10(-15) g g(-1). In addition (237)Np was detected at ultratrace levels. In general, ICP-MS and alpha-spectrometry results were in good agreement.The presence of anthropogenic radionuclides ((236)U, (239)Pu,(240)Pu, (241)Am, and (237)Np) in the penetrators indicates that at least part of the uranium originated from the reprocessing of nuclear fuel. Because the concentrations of radionuclides are very low, their radiotoxicological effect is negligible.     

Determination of boron in marine carbonates by prompt gamma-ray analysis

Boron in carbonate reference samples was measured by neutron-induced prompt gamma-ray analysis (PGA) using cold and thermal neutron guide beams of the JRR-3M reactor. In order to determine B contents in marine carbonates, the Doppler-broadened -ray peak of 478 keV was used together with the correction of interference from Na-peak of 472 keV. We determined B in coral samples within 3% of analytical precision. The data obtained by the present method are mostly consistent with reported values. Here, we report PGA of B in marine carbonates.     

Determination of boron in nickel-base alloys by the dianthrimide method

The dianthrimide method for the determination of boron in iron and low-alloy steels may be applied to nickel-base materials. The sample is dissolved, without any loss of boron, by hydrochloric and sulphuric acids and the resulting boric acid determined spectrophotometrically with dianthrimide. Background corrections are necessary to compensate for the absorbance from ions such as nickel and iron.     

Determination of lithium by boron spiking and proton irradiation

A major matrix effect that hampers nuclear analysis with charged particles is found in the range differences which charged particles experience in samples and comparators. The determination of lithium in ores was attempted by the previous determination of the ranges of protons therein. This was achieved by the homogeneous spiking of the ores with pure boron compounds of known composition and therefore known calculated ranges. Pure lithium compounds, also with known calculated ranges, were used as lithium standards. Determinations were carried out by proton-induced prompt photon spectrometry on nuclides of lithium and boron. Results obtained for standard reference ores, SRM 181 and-183, were in good agreement with the specificfied values.