Fundamentals of 3-D Neutron Kinetics and Current Status

This lecture includes the following topics: 1) A summary of the cell and lattice calculations used to generate the neutron reaction data for neutron kinetics, including the spectral and burn up calculations of LWR cells and fuel assembly lattices, and the main nodal kinetics parameters: mean neutron generation time and delayed neutron fraction; 2) the features of the advanced nodal methods for 3-D LWR core physics, including the treatment of partially inserted control rods, fuel assembly grids, fuel burn up and xenon and samarium transients, and ex core detector responses, that are essential for core surveillance, axial offset control and operating transient analysis; 3) the advanced nodal methods for 3-D LWR core neutron kinetics (best estimate safety analysis, real time simulation); and 4) example applications to 3-D neutron kinetics problems in transient analysis of PWR cores, including model, benchmark and operational transients without, or with simple, thermal-hydraulics feedback

Basis for Coupled 3-D Neutronics-Thermal-Hydraulics

The purpose of this seminar is first to discuss the basis of the coupling between 3-D Neutron- Kinetics and Thermal-Hydraulics codes, including the control and 3-D variables to interchange, the transform of the 3-D NK and TH core nodalizations, and the schemes for temporal coupling and time-step control. As representative examples of the NK-TH core coupling, we discuss first the integration of a 3-D NK nodal code with a TH subchannel code, for detailed transient core analysis; and second the coupling of 3-D NK nodal codes with TH system codes, for general transient and safety analysis. In chapter 2, we analyze several prototype model transients in PWR, where large 3-D core asymmetries are found and the NK-TH coupling is quite significant, including loss-of-flow and symmetric and asymmetric core cooling, considering the effects on the responses of the excore detectors. In chapter 3, we discuss the analysis of an increase-of-flow transient actually occurred in an operating PWR and the comparison with the measured data. In chapter 4, we summarize the phenomena and results of the calculations of the NEA/NSC Benchmark on the main steam line break (MSLB) transient in a PWR. Finally, we will discuss the state-of-the-art issues in LWR coupled NK-TH 3-D transient analysis and ongoing and planned computational developments

Development of an Analytic Nodal Diffusion Solver in Multigroups for 3D Reactor Cores with Rectangular or Hexagonal Assemblies.

More accurate modelling of physical phenomena involved in present and future nuclear reactors requires a multi-scale and multi-physics approach. This challenge can be accomplished by the coupling of best-estimate core-physics, thermal-hydraulics and multi-physics solvers. In order to make viable that coupling, the current trends in reactor simulations are along the development of a new generation of tools based on user-friendly, modular, easily linkable, faster and more accurate codes to be integrated in common platforms. These premises are in the origin of the NURESIM Integrated Project within the 6th European Framework Program, which is envisaged to provide the initial step towards a Common European Standard Software Platform for nuclear reactors simulations. In the frame of this project and to reach the above-mentioned goals, a 3-D multigroup nodal solver for neutron diffusion calculations called ANDES (Analytic Nodal Diffusion Equation Solver) has been developed and tested in-depth in this Thesis. ANDES solves the steady-state and time-dependent neutron diffusion equation in threedimensions and any number of energy groups, utilizing the Analytic Coarse-Mesh Finite-Difference (ACMFD) scheme to yield the nodal coupling equations. It can be applied to both Cartesian and triangular-Z geometries, so that simulations of LWR as well as VVER, HTR and fast reactors can be performed. The solver has been implemented in a fully encapsulated way, enabling it as a module to be readily integrated in other codes and platforms. In fact, it can be used either as a stand-alone nodal code or as a solver to accelerate the convergence of whole core pin-by-pin code systems. Verification of performance has shown that ANDES is a code with high order definition for whole core realistic nodal simulations. In this paper, the methodology developed and involved in ANDES is presented

América y España: los dos viajes oficiales de la infanta Eulalia de Borbón (1893) y la infanta Isabel de Borbón (1910) que hicieron el vínculo.

Durante cinco siglos de historia común entre América y España, solo tres personas de la familia real española pisaron realmente América, y las tres fueron infantas: Carlota Joaquina de Borbón (1775-1830), y las hermanas Isabel de Borbón (1851-1931) y Eulalia de Borbón (1864-1958), hijas de Isabel II. Estas dos últimas realizaron sendos viajes oficiales, en representación de la Corona española, de gran resonancia en sus vidas personales, la historia de la Casa real y el vínculo común entre América y España. El primero fue el viaje oficial de la Infanta Eulalia, en 1893, con motivo del IV Centenario del Descubrimiento de América, que le llevó en un largo periplo a visitar Puerto Rico, Cuba y Estados Unidos, donde fue recibida por el presidente Cleveland y visitó la Exposición Universal Colombina en nombre del rey España -Alfonso XIII- y la reina regente María Cristina. Por lo que en el viaje vio, la infanta Eulalia vaticinó la inminente guerra y la pérdida de la isla de Cuba en 1898. El segundo fue el viaje oficial de la Infanta Isabel de Borbón, alias La Chata, a Buenos Aires, en 1910, para conmemorar el Centenario de la Independencia de Argentina, en representación de su sobrino el rey Alfonso XIII. El comprometido viaje se inició con amenazas de boicot a su presencia, y terminó con un memorable éxito diplomático y personal de la infanta, que fue de gran beneficio para la imagen de la Corona española y para la renovación de vínculos afectivos entre América y Españapost-print359 K

Relación entre la condición física cardiovascular y la distribución de grasa en niños y adolescentes

Fundamentos: El objetivo de este estudio es determinar la relación entre el grado de condición física cardiovascular y la acumulación y distribución de masa grasa en niños y niñas de 7 a 17 años. Material y métodos: La muestra se compone de 1.625 niños y 1.244 niñas, a los que se determinó la potencia aeróbica máxima mediante el test de carrera de la Course Navette. Previamente, se realizó una evaluación antropométrica con el fin de poder establecer la cantidad total de masa grasa subcutánea acumulada (suma de 6 pliegues corporales), así como la cantidad de masa grasa subcutánea acumulada en la región del tronco (suma de 3 pliegues del tronco). Se formaron 2 grupos en función de la condición física cardiovascular. Los sujetos que obtuvieron menores valores de VO2 máx (dos últimos quintiles) formaron parte del grupo de baja condición física cardiovascular, mientras que aquellos cuyos valores de VO2 máx se encontraron entre los dos quintiles superiores formaron parte del grupo de alta condición física cardiovascular. Resultados: Una vez ajustados por las diferencias de edad, talla y masa corporal, los resultados de este estudio demuestran que tanto en niños como en niñas un grado superior de condición física cardiovascular se asocia con cantidades significativamente menores de grasa subcutánea no sólo en el cuerpo entero, sino particularmente en la zona del tronco. Conclusiones: En los niños y niñas con una mejor condición física cardiovascular se observa una composición corporal más saludable y un menor riesgo de accidente cardiovascular. Es importante incorporar el grado de condición física en la valoración del riesgo de salud en las poblaciones estudiadas

Análisis de la transmutación de Actínidos Minoritarios en un reactor rápido de sodio con modelo de carga homogéneo mediante el código MCNPX-CINDER

El reactor rápido refrigerado por sodio (SFR) constituye uno de los conceptos más prometedores de los seis considerados en la Generación IV de reactores nucleares, encontrándose actualmente en fase de investigación. En este marco surge el proyecto europeo CP ESFR (Collaborative Project for an European Sodium Fast Reactor) cuya finalidad es analizar los diversos desafíos y oportunidades que el desarrollo de este tipo de reactores plantea, ya sea en términos de seguridad, tecnología de sodio, capacidades transmutadoras, etc

La vigilancia en España 3 años después de la entrada en vigor de la Ley General de Salud Pública

ResumenEn 2014, el Grupo de Trabajo de Vigilancia Epidemiológica de la Sociedad Española de Epidemiología llevó a cabo un estudio descriptivo con el fin de evaluar el desarrollo de la Ley General de Salud Pública, promulgada en España en 2011. Se remitió una encuesta a las 19 comunidades y ciudades autónomas para evaluar la existencia de sistemas de información y otros aspectos de los distintos apartados de vigilancia incluidos en la ley. Todas disponían de un sistema de información para enfermedades transmisibles y en seis para condicionantes sociales; 18 vigilaban al menos una enfermedad crónica y 14 alguno de sus determinantes. El 100% analizaba sistemáticamente la información procedente de la vigilancia de las enfermedades transmisibles. Hay margen de mejora para la vigilancia de la salud pública en España. La acción debe ir dirigida a los principales problemas de salud.AbstractIn 2014, the Epidemiological Surveillance Working Group of the Sociedad Española de Epidemiología (Spanish Society of Epidemiology), carried out a descriptive study in order to evaluate the level of development of the Spanish Public Health Law since its enactment in 2011. A survey collecting data on the existence of information systems and other aspects pertaining to each surveillance section included in the law was sent to all 19 autonomous communities and cities. All regional authorities reported the presence of an information system for communicable diseases, and six also reported an information system for social factors. 18 reported that at least one chronic disease was subject to surveillance and 14 confirmed surveillance of some of its determinants. They all systematically analysed the data derived from the communicable diseases. There is room for improvement in Public Health surveillance in Spain, and action should be aimed at the main health problems

Transient analysis in the 3D nodal kinetics and thermal-hydraulics ANDES/COBRA coupled system

Neutron kinetics has been implemented in the 3D nodal solver ANDES, which has been coupled to the core thermal-hydraulics (TH) code COBRA-III for core transient analysis. The purpose of this work is, first, to discuss and test the ability of the kinetics solver ANDES to model transients; and second, by means of a systematic analysis, including alternate kinetics schemes, time step size, nodal size, neutron energy groups and spectrum, to serve as a basis for the development of more accurate and efficient neutronics/thermal-hydraulics tools for general transient simulations. The PWR MOX/UO2 transient benchmark provided by the OECD/NEA and US NRC was selected for these goals. The obtained ANDES/COBRA-III results were consistent with other solutions to the benchmark; the differences in the TH feedback led to slight differences in the core power evolution, whereas very good agreements were found in the other requested parameters. The performed systematic analysis highlighted the optimum kinetics iterative scheme, and showed that neutronics spatial discretization effects have stronger influence than time discretization effects, in the semi-implicit scheme adopted, on the numerical solution. On the other hand, the number of energy groups has an important influence on the transient evolution, whereas the assumption of using the prompt neutron spectrum for delayed neutrons is acceptable as it leads to small relative errors

The analytic nodal diffusion solver ANDES in multigroups for 3D rectangular geometry: Development and performance analysis

In this work we address the development and implementation of the analytic coarse-mesh finite-difference (ACMFD) method in a nodal neutron diffusion solver called ANDES. The first version of the solver is implemented in any number of neutron energy groups, and in 3D Cartesian geometries; thus it mainly addresses PWR and BWR core simulations. The details about the generalization to multigroups and 3D, as well as the implementation of the method are given. The transverse integration procedure is the scheme chosen to extend the ACMFD formulation to multidimensional problems. The role of the transverse leakage treatment in the accuracy of the nodal solutions is analyzed in detail: the involved assumptions, the limitations of the method in terms of nodal width, the alternative approaches to implement the transverse leakage terms in nodal methods – implicit or explicit _, and the error assessment due to transverse integration. A new approach for solving the control rod ‘‘cusping” problem, based on the direct application of the ACMFD method, is also developed and implemented in ANDES. The solver architecture turns ANDES into an user-friendly, modular and easily linkable tool, as required to be integrated into common software platforms for multi-scale and multi-physics simulations. ANDES can be used either as a stand-alone nodal code or as a solver to accelerate the convergence of whole core pin-by-pin code systems. The verification and performance of the solver are demonstrated using both proof-of-principle test cases and well-referenced international benchmarks