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  • Author or Editor: P. Kalsi x
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Abstract  

A narrow span (E o ±0.1 V) controlled potential coulometric method has been developed for the determination of neptunium in 1M H2SO4 with a RSD of 0.2%. The main advantage of this method over the existing coulometric methods is that it can tolerate up to a 5-fold excess of plutonium. The method involves carrying out the electrolysis to about 97% and calculating by an iterative computation the formal electrode potential in situ, which is used to calculate the total amount present in the sample. The method consists in oxidation of all the neptunium to Np (VI) by Ce(IV), destruction of excess Ce(IV) and reduction of Np(VI) to Np(V) by NaNO2, destruction of excess nitrite by sulfamic acid followed by coulometric titration of Np(V) to Np(VI).

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Abstract  

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.

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Abstract  

Nuclear analytical techniques namely fission track technique using solid state nuclear track detector (SSNTD) and instrumental neutron activation analysis (INAA) have been standardized and applied for quantification of low uranium concentrations in liquid samples such as feed, elute and brine and solid sorbent samples respectively. The quantification of uranium is required for its recovery study from seawater, which is one of the potential sources of uranium. The uranium concentration of a liquid sample obtained by SSNTD method was compared with the other well established conventional techniques like ICP-MS, ICP-AES, adsorptive stripping voltametry and alpha spectrometry. INAA was applied for uranium concentration determination in the radiation grafted polyamidoxime sorbent samples.

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The thermal dehydration and decomposition of copper(II) phthalate monohydrate was studied by isothermal and non-isothermal methods. The decomposition process consisted of three steps: two steps of dehydration and the third of decomposition. The kinetics of isothermal dehydration reactions follow (i) a unimolecular law up to the formation of copper(II) phthalate hemihydrate, and (ii) a phase boundary model giving anhydrous copper(II) phthalate, while the kinetics of isothermal decomposition reaction comply with the Erofeev-Avrami equation, [−ln(1−α)]1/n =Kt+C. The energies of activation for the formation of the decomposition products were calculated. The decomposition products were characterized by elemental analysis, photomicrographic observations, infrared and reflectance spectra and X-ray powder diffraction data.

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Abstract  

The estimation of low level alpha activity is difficult in waste samples containing large concentration of salts and beta–gamma activity. In the present study, the feasibility of gross alpha-activity measurement for simulated high level waste (SHLW) in solution medium by alpha-track registration technique has been attempted. The results showed that it is possible to use this technique for gross alpha-activity estimation of ~200 Bq/mL in solution medium with a precision and accuracy of ~30%. The importance of measuring 200 Bq/mL alpha activity in SHLW solutions is that this value corresponds to about 4,000 Bq/g activity in the solid medium which is the safe disposable limit. The advantage of this method over other methods is that it is not sensitive to beta–gamma emitters and salts and is very simple and inexpensive.

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Abstract  

A simple technique based on the measurement of the ratio of alpha-decay constant to neutron induced fission cross section for pure actinides using solid state nuclear track detectors (SSNTDs) is developed for the identification of the actinides in trace levels in pure solutions. The alpha-decay constant to fission cross section ratios for depleted U,238Pu and240Pu have been measured for the epicadmium neutron induced fission of these actinides. The measured values are (6.19±0.34)·106, (6.95±0.26)·1012, (2.12±0.95)·109 and (2.18±1.58)·1011 sec−1·cm−2, respectively. These ratios can be used for the trace level identification of pure actinides.

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Abstract  

A cotrolled potential coulometric method has been developed in 1M HClO4 for the determination of uranium using an electrolysis cell and coulometer. A noteworthy feature of this method is its applicability even in the presence of large excess of calcium, barium and lead, situations where the commonly used coulometric method in 0.5M H2SO4 medium and the well known potentiometric method in H3PO4 medium are not applicable, Results of the determination of uranium in a number of aliquots of synthetic solutions of (U,Ca), (U, Ba) and (U, Pb) showed a precision of the order of 0.2% and the experimental values of uranium content agreed with the expected values within the precision limits. Similar results were obtained with samples of synthetic mixtures of U3O6 and CaF2 powder containing 1–5% U and 95–99% Ca. The method was then successfully used to determine the U-conten of some typical samples of CaF2 slag (containing 1–5% U) generated during the calciothermic reduction of UF4 to U-metal at conversion plants.

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Abstract  

An iterative computational method for the determination of metal ions in aqueous solutions which form reversible couples such as Fe(II)/Fe(III), Pu(III)/Pu(IV) etc. by controlled potential coulometry has been developed. The method involves carrying out the electrolysis to about 95–97% and calculating the total amount present in the sample by an iterative computational method. The method utilizes the direct application of the Nernst equation. The important criterion to be met is that the coulogram of the couple should strictly obey the Nernst equation. The validity of the method has been checked by analyzing about 50 samples of a standard iron solution. Results of analysis of mixtures of Pu and Fe by the iterative technique show that the interference of Fe can almost entirely be eliminated. However, analysis of Pu samples by this procedure gives results about 2–3% lower than the expected value. A careful examination of the experimental coulograms of Pu in lM HClO4 indicates a slight deviation from the theoretical coulogram, where as those of Fe match exactly.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
C. Agarwal
,
A. Goswami
,
P. Kalsi
,
S. Singh
,
A. Mhatre
, and
A. Ramaswami

Abstract  

Cumulative yields of 27 fission products have been determined in 229Th(n,f) by recoil catcher technique followed by gamma-ray spectrometry. Absolute fission yields were arrived at from the fission rate measured by track etch counting method. Mass yields were obtained from the cumulative yields using the charge distribution parameters reported in the literature. The values agree well with the reported values obtained both by physical and radiochemical methods. The resulting asymmetric mass distribution shows strong fluctuation in the yields in the light and heavy wings with a periodicity of five mass units.

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