Martin Lemes - Academia.edu (original) (raw)
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Instituto Tecnológico y de Estudios Superiores de Monterrey (ITESM)
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Papers by Martin Lemes
Entre los distintos tipos de accidentes que pueden ocurrir en un reactor nuclear refrigerado por ... more Entre los distintos tipos de accidentes que pueden ocurrir en un reactor nuclear refrigerado por agua, el denominado LOCA (Loss Of Coolant Accident) es uno de los mas severos. Bajo estas condiciones el sistema registra una fuerte caida de presion y/o una disminucion marcada en la velocidad de circulacion del refrigerante, por lo que el calor acumulado en las barras combustibles debe ser disipado en condiciones de refrigeracion defectuosas, lo que puede ocasionar un gran aumento de la temperatura. En estas condiciones, debido a la disociacion del vapor de agua producto de la rapida oxidacion de las vainas, se produce un incremento considerable del contenido de hidrogeno en el material, que puede ocasionar danos severos durante un rapido enfriamiento. Por otro lado, ese hidrogeno puede ser liberado a la atmosfera al variar las condiciones de operacion del nucleo con el consiguiente peligro de provocar danos severos en el recinto de contencion de los elementos combustibles. En este tra...
Journal of Nuclear Materials, 2015
In the present work the behavior of fuel pellets for LWR power reactors in the high burnup range ... more In the present work the behavior of fuel pellets for LWR power reactors in the high burnup range (average burnup higher than about 45 MWd/kgU) is analyzed. For extended irradiation periods, a considerable Pu concentration is reached in the pellet periphery (rim zone), that contributes to local burnup. Gradually, a new microstructure develops in that ring, characterized by small grains and large pores as compared with those of the original material. In this
Annals of Nuclear Energy, 2014
In this paper we summarize all the models included in the latest version of the DIONISIO code rel... more In this paper we summarize all the models included in the latest version of the DIONISIO code related to the high burnup scenario. Due to the extension of nuclear fuels permanence under irradiation, physical and chemical modifications are developed in the fuel material, especially in the external corona of the pellet. The codes devoted to simulation of the rod behaviour under irradiation need to introduce modifications and new models in order to describe those phenomena and be capable to predict the behaviour in all the range of a general pressurized water reactor. A complex group of subroutines has been included in the code in order to predict the radial distribution of power density, burnup, concentration of diverse nuclides and porosity within the pellet. The behaviour of gadolinium as burnable poison also is modelled into the code. The results of some of the simulations performed with DIONISIO are presented to show the good agreement with the data selected for the FUMEX I/II/III exercises, compiled in the NEA data bank.
Journal of Nuclear Engineering and Radiation Science, 2019
DIONISIO is a computer code designed to simulate the behavior of one nuclear fuel rod during its ... more DIONISIO is a computer code designed to simulate the behavior of one nuclear fuel rod during its permanence within the reactor. Starting from the power history and the external conditions to which the rod is subjected, the code predicts all the meaningful variables of the system. Its application range has been recently extended to include accidental conditions, in particular the so-called loss of coolant accidents (LOCA). In order to make realistic predictions, the conditions in the rod environment have been taken into account since they represent the boundary conditions with which the differential equations describing the fuel phenomena are solved. Without going into the details of the thermal-hydraulic modeling, which is the task of the specific codes, a simplified description of the conditions in the cooling channel during a LOCA event has been developed and incorporated as a subroutine of DIONISIO. This has led to an improvement of the fuel behavior simulation, which is evidence...
Entre los distintos tipos de accidentes que pueden ocurrir en un reactor nuclear refrigerado por ... more Entre los distintos tipos de accidentes que pueden ocurrir en un reactor nuclear refrigerado por agua, el denominado LOCA (Loss Of Coolant Accident) es uno de los mas severos. Bajo estas condiciones el sistema registra una fuerte caida de presion y/o una disminucion marcada en la velocidad de circulacion del refrigerante, por lo que el calor acumulado en las barras combustibles debe ser disipado en condiciones de refrigeracion defectuosas, lo que puede ocasionar un gran aumento de la temperatura. En estas condiciones, debido a la disociacion del vapor de agua producto de la rapida oxidacion de las vainas, se produce un incremento considerable del contenido de hidrogeno en el material, que puede ocasionar danos severos durante un rapido enfriamiento. Por otro lado, ese hidrogeno puede ser liberado a la atmosfera al variar las condiciones de operacion del nucleo con el consiguiente peligro de provocar danos severos en el recinto de contencion de los elementos combustibles. En este tra...
Journal of Nuclear Materials, 2015
In the present work the behavior of fuel pellets for LWR power reactors in the high burnup range ... more In the present work the behavior of fuel pellets for LWR power reactors in the high burnup range (average burnup higher than about 45 MWd/kgU) is analyzed. For extended irradiation periods, a considerable Pu concentration is reached in the pellet periphery (rim zone), that contributes to local burnup. Gradually, a new microstructure develops in that ring, characterized by small grains and large pores as compared with those of the original material. In this
Annals of Nuclear Energy, 2014
In this paper we summarize all the models included in the latest version of the DIONISIO code rel... more In this paper we summarize all the models included in the latest version of the DIONISIO code related to the high burnup scenario. Due to the extension of nuclear fuels permanence under irradiation, physical and chemical modifications are developed in the fuel material, especially in the external corona of the pellet. The codes devoted to simulation of the rod behaviour under irradiation need to introduce modifications and new models in order to describe those phenomena and be capable to predict the behaviour in all the range of a general pressurized water reactor. A complex group of subroutines has been included in the code in order to predict the radial distribution of power density, burnup, concentration of diverse nuclides and porosity within the pellet. The behaviour of gadolinium as burnable poison also is modelled into the code. The results of some of the simulations performed with DIONISIO are presented to show the good agreement with the data selected for the FUMEX I/II/III exercises, compiled in the NEA data bank.
Journal of Nuclear Engineering and Radiation Science, 2019
DIONISIO is a computer code designed to simulate the behavior of one nuclear fuel rod during its ... more DIONISIO is a computer code designed to simulate the behavior of one nuclear fuel rod during its permanence within the reactor. Starting from the power history and the external conditions to which the rod is subjected, the code predicts all the meaningful variables of the system. Its application range has been recently extended to include accidental conditions, in particular the so-called loss of coolant accidents (LOCA). In order to make realistic predictions, the conditions in the rod environment have been taken into account since they represent the boundary conditions with which the differential equations describing the fuel phenomena are solved. Without going into the details of the thermal-hydraulic modeling, which is the task of the specific codes, a simplified description of the conditions in the cooling channel during a LOCA event has been developed and incorporated as a subroutine of DIONISIO. This has led to an improvement of the fuel behavior simulation, which is evidence...