Extraction of uranium in caustic sludge from the production of nuclear fuel components by countercurrent dissolution and acid curing

Journal of Radioanalytical and Nuclear Chemistry - The uraniferous caustic sludge (UCS) produced in the production of uranium fuel components was hardly to leach directly, due to its very low-grade...     

Determination of uranium and plutonium in VVER spent fuel solutions using differential spectrophotometry

The method of differential spectrophotometry with the use of Arsenazo III for uranium determination with masking Zr and Pu by 1,2-diaminecyclohexanetetraacetic acid in acetate buffer and carboxyarsenazo for determination of plutonium without its separation from uranium is applied for analysis of the spent fuel of VVER type reactors.     

A new method for alkaline dissolution of uranium metal foil

In order to develop a production process of ⁹⁹Mo by fission of low-enriched uranium, the first purification step, which consists of dissolution of a uranium metal foil target, was studied. It was found that alkaline NaClO gave good results, reaching the dissolution of up to 300 m of uranium foil. The different conditions for the dissolution were studied and the optimum ones were found. The influence of NaClO and NaOH concentration, temperature, dissolving solution volume per unit of surface and dissolution time were investigated. During this step, a gas, identified as H₂, was generated, and a precipitate characterized as Na₂U₂O₇ was observed. A stoichiometric reaction for this uranium dissolution is proposed.     

Determination of oxygen to uranium ratio in irradiated uranium dioxide by controlled potential coulometry

This work reports the determination of oxygen to uranium (O/U) ratio in irradiated UO_2+x fuel pellet of burnup of ca. 34 GWd/t by controlled potential coulometry. The method is based on the dissolution of the nuclear fuel in strong phosphoric acid (SPA) at 180–190 °C under an inert atmosphere. After dissolution, 8% sulphuric acid is added in order to obtain a 20% SPA in 8% sulphuric acid. A controlled potential coulometric determination of uranium(VI) is carried out at ?0.60V vs. ferri-ferrocyanide. The uranium(IV) contained in an aliquot of the fuel solution is oxidised to uranium(VI) with cerium(IV) sulphate, and the total uranium content is then determined by coulometry. Optimum experimental conditions have been established using simulated irradiated fuel solution containing various fission products which include cerium, tellurium, palladium, ruthenium, molybdenum and zirconium. Interference of the fission products and the possible removal of their interferences by preelectrolysis at +0.5 V vs. saturated calomel electrode (SCE) have been investigated. The accuracy of the coulometric method is confimed by polarographic measurement using several unirradiated UO_2+x fuel of known stoichiometry.     

Determination of isotopic composition and concentration of uranium,plutonium and neodymium by mass-spectrometric isotope dilution in the irradiated fuel of the Czechoslovak atomic power station A-1

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.     

Chlorination of uranium metal to uranium trichloride using ammonium chloride

Journal of Radioanalytical and Nuclear Chemistry - Given that the most feasible option for fabricating chloride-based molten salt fuel for molten-salt reactors (MSRs) is to use uranium/transuranic...     

Assay of uranium in scrap and waste produced at natural uranium metal production and fuel fabrication plants

The paper describes the results and observations on the analyses of uranium in calcium fluoride slag, silica cake and fused salt cake obtained in uranium metal and fuel plants. The analysis is done by (1) non-destructive assay by passive gamma ray counting, (2) chemical analysis, and (3) solid state nuclear track detector (SSNTD) technique. The details of the development of NDA method to suit the requirements of the sample are given. The difficulties encountered in chemical assay are described. SSNTD method has been applied to such materials for the estimation of the uranium for the first time. A simple scheme for the recovery of uranium and the salt mixture from the fused salt cake is also described.     

Determination of uranium isotopes in irradiated thorium dioxide by alpha spectrometry using WinALPHA for deconvolution of complex spectra

Isotopic composition of uranium obtained from irradiated thorium dioxide was determined using alpha spectrometry by employing WinALPHA for the deconvolution of the alpha spectra recorded using electrodeposited sources. The results obtained were found to agree within 1% with those determined by thermal ionization mass spectrometry. The deconvolution methodology is important since it is possible to account for the in-growth of ²²⁸Th, which interferes in the determination of ²³²U by alpha spectrometry. The present methodology has the potential to determine isotopic composition of uranium in the irradiated thorium based nuclear fuels, employing alpha spectrometry.     

Determination of uranium after its selective extraction as phenylacetate

The method described is based on the extraction of uranium with a chloroform solution of phenylacetic acid from slightly acidic solution containing nitrilotriacetic acid, which masks all interfering metals. After stripping into very dilute hydrochloric acid, uranium is reduced with ascorbic acid and determined complexometrically. The method permits reliable determination of uranium in the presence of all quadri-, ter- and bivalent metals investigated, molybdenum(VI), tungsten(VI), and vanadium(V).     

Determination of uranium and thorium concentration in some Egyptian rock samples

Uranium (U) and thorium (Th) isotopes and their several radioactive descendants found in soil, rock, water, plants, air, etc., contribute to the natural radiation exposure of the population. Phosphate rocks are really rich natural sources of uranium and thorium among the other minerals forming the earth's crust. U and Th concentrations in some Egyptian phosphate samples were determined using a nuclear track registration methodology and -ray spectroscopy. The resulting latent tracks from all -decaying isotopes in both U and Th series were recorded in plastic detectors. A uniquely sensitive polycarbonate CR-39 nuclear detector was used. Results showed that the U and Th concentration in the samples studied range from about 4.0 up to 35.0 ppm and from 11.0 to 124.0 ppm, respectively. Results are discussed within the frame work of track formation methodology in plastic and -ray spectroscopic analysis.     

Determination of low uranium concentration in carbonate-bicarbonate solutions by X-ray fluorescence

A method has been developed for the direct determination of uranium in carbonate solutions by X-ray fluorescence. Uranium, in the concentration range 0.2–50 ppm, is first absorbed as the carbonate complex on an anion exchange resin and then determined by X-ray fluorescence. A sensitivity corresponding to 20 ppb in 250 ml solution and a precision of ±6.5% was obtained. The sensitivity was 100-fold greater than that obtained by the direct determination in solution by X-ray fluorescence.     

锆存在时铀中杂质元素的化学分离-ICP-AES法

采用磷酸三丁酯（TBP）－氢化煤油萃取油、过氧化氢掩蔽钛、磷酸氢二铵沉淀锆的方法，用ICP－AES法同时测定了锆存在在时铀中的铁、锰、铜、硅、铝、镍和钛7种杂质元素的含量。当测定范围在100μg/g-1000μg/g时，相对标准偏差＜9．0％，回收率为96％－109％。     

Determination of uranium concentration in domestic water samples by fission track method

The sensitive and simple fission track detection technique using a dry method with Melinex-0 plastic track detector has been applied for the determination of uranium concentration in samples of domestic water supply plants collected from different states of India, namely West Bengal, Uttar Pradesh, Rajasthan, Punjab and Delhi. Our analyses show that uranium concentration of water samples collected from different types of domestic water supply plants vary from 0.6±0.02 to 19.2±0.6 g/l. The present investigations may be useful from the point of view of radiation hygiene.     

Determination of uranium concentration in water by liquid anion exchange-delayed neutron analysis

Dissolved uranium is selectively removed from 11 of filtered, acidified water using a liquid anion exchange resin (Amberlite LA-1) dissolved in 10 ml of purified kerosene. The organic phase is then analyzed by a standard delayed neutron counting technique. Yields of removed uranium are consistently greater than 90 percent over a measured concentration range of 1.0 to 100 ppb uranium. The absolute detection limit based on 11 of water is 0.06 ppb. Elemental interferences are minimal and the results compare favorably with fluorometric analyses of natural waters.     

The determination of caesium 137 in irradiated uranium and irradiated thorium using anion-exchange paper and the ring oven technique

Summary By use of a strongly basic anion-exchange resin paper in the hydroxide or carbonate forms, caesium 137 can be separated from irradiated uranium solutions on a ring oven. A ring oven separation of caesium 137 from irradiated thorium can also be achieved by using an oxalate-hydroxide form resin paper. In each case the caesium 137 is washed to the ring zone with water and determined by-ray spectrometry. The coefficient of variation of the methods is less than 2 per cent.

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Zusammenfassung Mit einem stark basischen Anionenaustauschpapier in der Hydroxid- oder Carbonatform kann¹³⁷Cs aus bestrahlten Uranlösungen auf einem Ringofen abgetrennt werden. Mit einem Oxalat-Hydroxid-Harzpapier läßt sich¹³⁷Cs auch von bestrahltem Thorium auf einem Ringofen trennen. In beiden Fällen wird¹³⁷Cs mit Wasser in die Ringzone gespült und durch-Strahlspektrometrie bestimmt. Die Methoden unterliegen Abweichungen von weniger als 2%.

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Résumé Par l'emploi d'un papier échangeur d'anion sous forme hydroxyde ou carbonate, le césium 137 peut être séparé de solutions d'uranium irradié au four annulaire. On peut aussi séparer, au four annulaire, le césium 137 du thorium irradié, avec un papier résineux sous forme hydroxyde-oxalate. Dans chacun cas, le césium 137 est chassé vers la zone annulaire par de l'eau et déterminé par spectrométrie. Les méthodes peuvent fournir une précision meilleure que 2 pour cent.

     

Non-destructive determination of nuclear fuel burn-up by measuring the gamma radiation of fission products in irradiated uranium oxide

The burn-up of²³⁵U was determined in two uranium oxide samples (0.713 and 89.9%²³⁵U in mixture) irradiated simultaneously with a cobalt monitor, from the amounts of⁹⁵Zr,¹⁰³Ru,¹³⁷Cs,¹⁴⁰Ba and¹⁴⁴Ce obtained by measuring the intensities of the corresponding gamma radiations. The samples were irradiated for 23 days, and the fission products were measured after cooling for 100 days, nondestructively, by means of a Ge(Li) spectrometer. The integrated neutron flux was determined by measuring the produced⁶⁰Co in the cobalt monitor. The burn-up in both samples was determined by measuring the intensity of eight gamma energies (0.5–1.6 MeV). The determined values are in good agreement. The standard deviation of the mean value ( ) is 5%. The atom per cent fission of²³⁵U in both samples, calculated according to , differs by 1%. The measured σ _f for²³⁵U is in good agreement with the data reported in the literature.     

Determination of uranium in uranium hexafluoride material

A rapid and precise method has been developed for the determination of uranium in uranium hexafluoride material that contains essentially no non-volatile impurities. Approximately 7 g of uranium hexafluoride is transferred into a tared fluorothene tube, weighed, frozen, and hydrolyzed in 150 ml of ice-cold water in a platinum dish. The solution is evaporated to dryness, and the residue is ignited to urano-uranic oxide and weighed. The precision of a single analysis at the 95% confidence interval is ± 0.06% of the value, with no significant bias     

Determination of uranium in presence of plutonium using differential spectrophotometry

The use of beams of heavy ions such as carbon, neon and argon for radiation therapy has the advantage that they have a very sharp Bragg maximum. When the Bragg peak coincide with the tumour location, it is possible to deposit the bulk of the energy of the ion in the region occupied by the malignancy. However, the concentration of ions and free radicals will be very high in the Bragg peak region which has not received the attention it deserves. So mutual recombination of these species will be very high. It is therefore necessary to assess the extent of these radical-radical recombinations at very high LET values. Spur diffusion model calculations have been made for high energy argon ions using water as a medium. For comparison, calculations have been done for proton tracks. It has been shown that in the Bragg peak region of argon ions even very high concentrations of scavengers have very little effect on radical-radical interactions. The implication is that when LET values are very high, practically all the radicals undegro recombination with each other. In order to explain the observed lethality of high LET radiation, it is suggested that the hydrogen peroxide formed also contribute to the killing of cells. In addition, the decomposition of H₂O₂ will contribute oxygen. This may be one of the reasons why high LET radiation shows strong lethality to hypoxic cells.