Evaluación de la cohesión de betunes modificados con polvo de neumáticos

This article reports on a study of crumb rubber-mediated improvement in bitumen cohesion, analyzed with the UCL method. UCL, a procedure developed to characterize bituminous binders, evaluates the cohesion obtained by adding a certain amount of bitumen or bituminous mastic to a standard mix aggregate. This method was chosen because it can be used to assess bitumen containing crumb rubber added by either the wet or the dry mix process. In the dry mix process crumb rubber is combined with the mix as if it were a fine aggregate; i.e., crumb rubber and binder are blended during mix manufacture, laying and compaction. In the wet mix process, the binder is blended with the crumb rubber prior to mixing with the aggregate; i.e., when added to the mix, it has already been modified. The effect of digesting this dry mixed material prior to use was also analyzed in the present study. A comparison of the dry (with and without digestion) and wet mix processes showed the latter to be more effective, particularly when the crumb rubber was blended with the binder via microscopic dispersion.El objetivo de este artículo es estudiar la influencia del polvo de neumático en la mejora de la cohesión proporcionada por la adición del polvo de neumático al betún mediante el método UCL. El método UCL es un procedimiento desarrollado para caracterizar ligantes bituminosos, basado en la evaluación de la cohesión dada por una cantidad determinada de un betún o un mástico bituminoso a unos áridos de granulometría establecida (mezcla patrón). Se ha empleado este método porque permite valorar al mismo tiempo los dos procedimientos de incorporación del polvo de neumático al betún: vía seca y vía húmeda.El procedimiento seco se lleva a cabo añadiendo el polvo de neumático a la mezcla como si fuera un filler, de modo que el polvo de neumático y el ligante se mezclan durante la fabricación, extendido y compactación de la mezcla. En el procedimiento húmedo, hay una mezcla previa del ligante con el polvo de neumático, por lo que aquél seaña de a la mezcla cuando ya ha sido modificado. También se ha estudiado la influencia de los tiempos de digestión. Se comparan los dos procedimientos, seco con y sin digestión, y húmedo. El segundo presenta una clara ventaja,especialmente cuando los ligantes son fabricados con dispersión microscópica

Implementation of the Control Rod Movement Option by means of Control Variables in RELAP5/PARCS v2.7 Coupled Code (NUREG/IA-0402)

The objective of this work is to introduce an improvement in best estimate coupled neutronicthermalhydraulic 3D codes simulations, by adding a model for the control rod movement in the coupled code RELAP5/PARCS v2.7, by means of control variables, with the aim of being able to dynamically analyze asymmetric transient accidents, as the reactivity insertion accidents (RIA) in a nuclear reactor, reproducing all the reactors control systems. The modification developed in this work permits the automatic movement of the control rods, activated by the RELAP5 code control system, and also they can depend on signals related to the reactor reactivity, like pressure, fuel temperature or moderator temperature, etc., improving the realism of the calculation and increasing the simulation capabilities. This report was prepared by the Nuclear Engineering Group belonging to the Institute for Industrial, Radiophysical and Environmental Safety (ISIRYM) at the Universitat Politècnica de València (UPV), which collaborates in the simulation area with the Spanish company Centrales Nucleares Almaraz-Trillo (CNAT). The Asociación Española de la Industria Eléctrica (UNESA, Electric Industry Association of Spain), equivalent to the American EPRI sponsored this work.Miró Herrero, R.; Ana Ibáñez, P.; Barrachina Celda, TM.; Martínez-Murillo, J.; Pereira, C.; Verdú Martín, GJ. (2014). Implementation of the Control Rod Movement Option by means of Control Variables in RELAP5/PARCS v2.7 Coupled Code (NUREG/IA-0402). United States Nuclear Regulatory Commission. http://hdl.handle.net/10251/58958

REA 3D-dynamic analysis in Almaraz NPP with RELAP5/PARCS v2.7 and SIMTAB cross-sections tables

[EN] The Rod Ejection Accident (REA) belongs to the Reactivity-Initiated Accidents (RIA) category of accidents and it is part of the licensing basis accident analyses required for pressurized water reactors (PWR). The REA at Hot Zero Power (HZP) is characterized by a single rod ejection from a core position with a very low power level. The evolution consists basically of a continuous reactivity insertion. The main feature limiting the consequences of the accident in a PWR is the Doppler Effect. To check the performance of the coupled code RELAP5/PARCS v2.7 a REA in Almaraz NPP is simulated. These analyses will allow knowing more accurately the PWR real plant phenomenology in the RIA most limiting conditions.This work has been partially supported by the Spanish Ministerio de Educación y Ciencia under project PHB2007-0067-PC and by the Brazilian Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) under project CAPES/DGU 159/08. This work has also been partially supported by the Spanish Ministerio de Educación y Ciencia under project ENE2008-02669, the Generalitat Valenciana under project ACOMP/2009/058, and the Universitat Politècnica de València under project PAID-05-09-4285. The authors wish to acknowledge the technical and financial support of the Almaraz-Trillo AIE for this work.Barrachina Celda, TM.; Garcia-Fenoll, M.; Ánchel Añó, FC.; Miró Herrero, R.; Verdú Martín, GJ.; Pereira, C.; Da Silva, C.... (2011). REA 3D-dynamic analysis in Almaraz NPP with RELAP5/PARCS v2.7 and SIMTAB cross-sections tables. Progress in Nuclear Energy. 53(8):1167-1180. https://doi.org/10.1016/j.pnucene.2011.07.012S1167118053

Modelización del estado estacionario de las condiciones de flujo de un reactor TRIGA mediante el código de dinámica de fluidos computacional ANSYS CFX

[ES] El uso de los códigos de Dinámica de Fluidos Computacional (CFD) 3D para predecir el flujo estacionario y transitorio en los reactores nucleares está creciendo rápidamente y constituye una nueva tendencia en su estudio. En este trabajo se presenta un modelo de un reactor de entrenamiento TRIGA (Training Research Isotopes General Atomic) tipo IPR-R1 desarrollado con el código de CFD ANSYS-CFX. El reactor nuclear TRIGA IPR-R1 está ubicado en el Centro de Desarrollo de Tecnología Nuclear (CDTN/CNEN) de Brasil y consiste en un reactor de investigación de 250 kW, moderado y refrigerado con agua ligera, con reflectores de grafito y de piscina abierta. En el trabajo se muestra el desarrollo del modelo de CFD y se muestran los resultados de la simulación en estado estacionario operando a 50 kW de potencia.Martínez Lianes, M.; Miró Herrero, R.; Verdú Martín, GJ.; Pereira, C.; Chiva Vicent, S.; Mesquita, AZ. (2011). Modelización del estado estacionario de las condiciones de flujo de un reactor TRIGA mediante el código de dinámica de fluidos computacional ANSYS CFX. Grupo Senda. http://hdl.handle.net/10251/49301

Prospective multicenter study of carbapenemase-producing Enterobacteriaceae from 83 hospitals in Spain reveals high in vitro susceptibility to colistin and meropenem

The aim of this study was to determine the impact of carbapenemase-producing Enterobacteriaceae (CPE) in Spain in 2013 by describing the prevalence, dissemination, and geographic distribution of CPE clones, and their population structure and antibi- otic susceptibility. From February 2013 to May 2013, 83 hospitals (about 40,000 hospital beds) prospectively collected nondupli- cate Enterobacteriaceae using the screening cutoff recommended by EUCAST. Carbapenemase characterization was performed by phenotypic methods and confirmed by PCR and sequencing. Multilocus sequencing types (MLST) were determined for Kleb- siella pneumoniae and Escherichia coli. A total of 702 Enterobacteriaceae isolates met the inclusion criteria; 379 (54%) were CPE. OXA-48 (71.5%) and VIM-1 (25.3%) were the most frequent carbapenemases, and K. pneumoniae (74.4%), Enterobacter cloacae (10.3%), and E. coli (8.4%) were the species most affected. Susceptibility to colistin, amikacin, and meropenem was 95.5%, 81.3%, and 74.7%, respectively. The most prevalent sequence types (STs) were ST11 and ST405 for K. pneumoniae and ST131 for E. coli. Forty-five (54.1%) of the hospitals had at least one CPE case. For K. pneumoniae, ST11/OXA-48, ST15/OXA-48, ST405/ OXA-48, and ST11/VIM-1 were detected in two or more Spanish provinces. ST11 isolates carried four carbapenemases (VIM-1, OXA-48, KPC-2, and OXA-245), but ST405 isolates carried OXA-48 only. A wide interregional spread of CPE in Spain was ob- served, mainly due to a few successful clones of OXA-48-producing K. pneumoniae (e.g., ST11 and ST405). The dissemination of OXA-48-producing E. coli is a new finding of public health concern. According to the susceptibilities determined in vitro, most of the CPE (94.5%) had three or more options for antibiotic treatment