Examinando por Autor "Bonales, L. J."

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Radiolytic degradation of sulphonated BTP and acetohydroxamic acid under EURO-GANEX process conditions
(Elsevier BV, 2021-06-05) Sánchez García, I.; Bonales, L. J.; Galán, H.; Perlado, J. M.; Cobos, J.; European Commission (EC)
In this work, we present a study which tackles the stability of molecules involved in EURO-GANEX aqueous phase, the acetohydroxamic acid (AHA) and the sulphonated BTP (SO3-Ph-BTP), taking into account factors such as the known AHA hydrolysis, acidity of the media, and the radiolysis of AHA and SO3-Ph-BTP. To better understand the system, the radiolysis of AHA and SO3-Ph-BTP in HNO3 has been studied first separately, at low doses (up to 50 kGy) compared with those expected for the recycled organic phase. The concentration after exposure to gamma radiation of AHA and its hydrolysis products, as well as of SO3-Ph-BTP, was measured for the first time by using Quantitative Raman Spectroscopy (QRS), showing that this technique can be used as a reliable tool for assessing the stability of these systems. In addition, the proton concentration and extraction efficiency of each assay were monitored and assessed. Our study extends the knowledge about the resistance to radiation of extractants involved in the EURO-GANEX aqueous phase, showing greater robustness when both molecules are irradiated together, and contributes not only to design reliable simulation strategies of the long-term EURO-GANEX process performance, but also to develop analysing tools for further processes implementations.
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Raman spectroscopy coupled to principal component analysis for studying UO2 nuclear fuels with different grain sizes due to the chromia addition
(Elsevier BV, 2021-01-08) Milena Pérez, A.; Bonales, L. J.; Rodríguez Villagra, N.; Fernández Carretero, Sergio; Baonza, V. G.; Cobos, J.; Agencia Estatal de Investigación (AEI); European Research Council (ERC); Milena Pérez, A. [0000-0002-4413-6693]; Baonza, V. G. [0000-0001-9994-0980]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Current necessities of nuclear power plants have led to increase burn-up of the fuel during operation. In this context, some undesirable processes, such as a higher release of gaseous fission products, may occur. New UO2-based fuels are being developed by adding doping agents. Chromia (Cr2O3) has proved to considerably enhance grain growth during sintering, and thus promote the retention of these fission products. The study of these Cr-doped UO2 fuels at in situ conditions would allow testing the real performance of the fuel in operating conditions. The existence of Raman portable instruments makes this scenario feasible. But first, the measurement protocols need to be developed. Therefore, in this paper, we explore the use of Raman spectroscopy as an approach for the analysis of the effect of Cr2O3 addition in a set of UO2single bondCr2O3 sintered pellets. The validity of Raman is demonstrated by using Principal Component Analysis (PCA). Three Principal Components describe 98.8% of the total variance of the data, and they are related to the main Raman modes of the samples. In addition, SEM images have shown the presence of bigger precipitates of Cr2O3 not only when the solubility limit of Cr3+ is exceeded, but also when it is not reached. By XRD, the well-known Vegard behavior is observed, and a solubility limit of Cr3+dissolved into the UO2 matrix is found to be (748±16) ppm for the particular sintering conditions used.