Authors:A. Sanchez-Ocampo, H. Lopez-Gonzalez, and M. Jimenez-Reyes
The behavior of uranyl ion and tervalent Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu in the solvent extraction system: M–HCl–H2O–TBP has been studied together with chromatographic elution of the first nine of these rare earth elements using DOWEX 50Wx8 resin. >99.5% of the rare earth elements, with a single exception, remained in the aqueous phase of the solvent extraction system where the initial concentration of hydrochloric acid was between 4 and 6 M. Under these conditions uranyl ions were readily extracted by TBP. The rare earth elements were quantitatively eluted from the chromatographic column using 6M hydrochloric acid solution and the uranyl ions in a 0.75M sulfuric acid solution.
Authors:E. Quintero-Ponce, H. López-González, and L. Cervantes-Naranjo
The aim of this work was to determine the contamination of I-131 in milk samples by low background -spectrometry and low background -counting techniques in the vicinity of the Nuclear Center in Salazar, Mexico. The low background -spectrometry was done directly. The determination by low background -counting consisted of a radiochemical separation of I-131 by ion exchange from the milk samples followed by measurement in a low background -counting system. The results indicated that there was no contamination of I-131 in the samples.
Authors:H. López-González, E. Quintero-Ponce, and L. Cervantes-Naranjo
The conditions to measure the gross alpha and gross beta radioactivity in water samples from the surrounding of the Nuclear
Center (Instituto Nacional Investigaciones Nucleares, (ININ), and Collection, Treatment and Storage Center for Low Level Radioactive
Waste (Maquixco) in the State of Mexico were established. The samples were collected from 1987 to 1996. The gross alpha and
gross beta radioactivity in the samples were determined by a gas-flow proportional counter. The results indicated that the
gross alpha and gross beta radioactive contamination in water samples were below the maximum contaminant level (MCL).
Authors:H. López-González, M. Jiménez-Reyes, M. Solache-Ríos, and A. Rojas-Hernández
Solubility product (Lu(OH)3(s)⇆Lu3++3OH−) and first hydrolysis (Lu3++H2O⇆Lu(OH)2++H+) constants were determined for an initial lutetium concentration range from 3.72·10−5 mol·dm−3 to 2.09·10−3 mol·dm−3. Measurements were made in 2 mol·dm−3 NaClO4 ionic strength, under CO2-free conditions and temperature was controlled at 303 K. Solubility diagrams (pLuaq vs. pCH) were determined by means of a radiochemical method using 177Lu. The pCH for the beginning of precipitation and solubility product constant were determined from these diagrams and both the first
hydrolysis and solubility product constants were calculated by fitting the diagrams to the solubility equation. The pCH values of precipitation increases inversely to [Lu3+]initial and the values for the first hydrolysis and solubility product constants were log10β*Lu,H = −7.92±0.07 and log10K*sp,Lu(OH)3 = −23.37±0.14. Individual solubility values for pCH range between the beginning of precipitation and 8.5 were SLu3+ = 3.5·10−7 mol·dm−3, SLu(OH)2+ = 6.2·10−7 mol·dm−3, and then total solubility was 9.7·10−7 mol·dm−3.
Authors:M. Azahra, J. López-Peñalver, M. Camacho-García, C. González-Gómez, T. El Bardouni, and H. Boukhal
Aerosols samples in near-surface air of Granada (Spain) were collected on a weekly basis. The seasonal 210Pb and 7Be concentrations were determined during the five-year period, from October 1993 to September 1997. The elements, despite their different origin and their different distribution throughout the atmosphere, present the same seasonal variation. There was a tendency for a maximum during the summer season and a minimum during fall and/or winter. In this work, the concentration of 7Be and 210Pb and meteorological data have been used in order to determine the periods of the potential radioactive pollution. This study, also, shows that the deposition of 7Be occurs primarily by precipitation except during the investigation periods where precipitation was scarce and irregular.
Authors:J. Ramírez-García, M. Jiménez-Reyes, M. Solache-Ríos, E. Fernández-Ramírez, H. López-González, and A. Rojas-Hernández
The solubility of europium at 0.02M, 0.1M and 0.7M NaClO4 ionic strength solutions was determined by a radiometric method and pEus-pCH diagrams were obtained. Hydrolysis constants were also determined at the same ionic strengths by pH titration and the values found were log *
1 = -7.68±0.11, -8.07±0.10 and -8.20±0.11. The log Ksp values were -23.5±0.2, -22.7±0.2 and -21.9±0.2 for 0.02M, 0.1M and 0.7M NaClO4 ionic strengths, respectively, at 303 K under CO2-free conditions and the extrapolated value at zero ionic strength was log Ksp0 = -24.15. The working pCH ranges for the calculation of the hydrolysis constants were selected from the pEus-pCH diagrams in the region where precipitation of europium oxide or hydroxide was less than 20%. Europium removal from aqueous solutions with zeolites was explored.
Authors:O. Diaz, A. M. G. Figueiredo, C. A. Nogueira, N. Lopez, H. Gonzalez, M. V. Manso, M. Saiki, and M. B. A. Vasconcellos
The nonideality of the epithermal neutron flux distribution at a reactor site parameter (α) and the thermal-to-epithermal neutron ratio (ƒ) were determined in three typical irradiation positions of the IEA-R1 reactor of IPEN-CNEN/SP, Sao Paulo, Brazil, using the “Cd-ratio for multimonitor” and “bare bi-isotopic monitor” methods, respectively. This characterization is to be used in the k0-method of NAA, recently introduced at the IPEN.