Desarrollo e inclusión de modelos para nuevos materiales destinados a combustibles de tecnología avanzada en el Código DIONISIO
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Comisión Nacional de Energía Atómica; Argentina. Gerencia de Área Académica. Gerencia Instituto de Tecnología "Jorge Sabato"
Universidad Nacional San Martin. Instituto de Tecnología "Jorge Sabato"; Argentina
Universidad Nacional San Martin. Instituto de Tecnología "Jorge Sabato"; Argentina
Resumen
La sección Códigos y Modelos de la Gerencia Ciclo del Combustible Nuclear ha venido desarrollando un código de combustible denominado DIONISIO, cuya finalidad es la simulación del comportamiento de una barra combustible típica de un reactor nuclear de potencia. El código, actualmente, cuenta con más de 70 modelos interconectados que atienden a la mayor parte de los fenómenos que ocurren bajo irradiación en condiciones normales de operación del reactor. Algunos de los fenómenos que predice el código son el comportamiento térmico y mecánico, la liberación de gases de fisión, el hinchado o swelling y la densificación de las pastillas, las condiciones termohidráulicas del canal que rodea a la barra, el crecimiento de capa de óxido, entre otros. Asi mismo, el código cuenta con un módulo para simular el comportamiento de los combustibles tipo placa, diseño que se emplea comúnmente en reactores de investigación. Los materiales ATF son parte de los futuros reactores nucleares, aquellos de los denominados de Generación III+ y Generación IV, que buscan, además de aumentar la eficiencia energética, promover la sustentabilidad de la energía nuclear, mejorando siempre la seguridad de la misma. En este sentido surge una de las primeras definiciones de materiales ATF, aquellos que aumentan el rango de seguridad de los reactores que los utilizan, sea porque sus propiedades permiten trabajar en condiciones menos demandantes, sea porque dado un hipotético accidente, estos materiales proveen de mejores respuestas ante solicitación extrema. Debido a este escenario futuro, desarrollar una librería de materiales ATF para un código combustible como DIONISIO es un paso necesario y fundamental desde el punto de vista tecnológico, ya que aunque la Argentina no posea desarrollos de combustibles ATF actualmente, es de esperar que en un futuro los tenga, si es que desea mantenerse como una de las pocas naciones que producen tecnología nuclear del planeta.
The Codes and Models Section of the Nuclear Fuels Management has been developing a fuel code called DIONISIO, whose purpose is to simulate the behavior of a typical fuel rod of a nuclear power reactor. The code currently has more than 70 interconnected models that address most of the phenomena that occur under irradiation under normal reactor operating conditions. Some of the phenomena that the code predicts are the thermal and mechanical behavior, the release of fission gases, the swelling and densification of the tablets, the thermohydraulic conditions of the channel surrounding the rod, the growth of the oxide layer, among others. Likewise, the code has a module to simulate the behavior of plate-type fuels, a design that is commonly used in research reactors. The development of this complex module involved, first, the separate development and evaluation of models to describe the different physical processes and, subsequently, their incorporation into the code as new particular subroutines, respecting the architecture, mode of execution and versatility of the rest of the code. The new accident module allows analyzing and quantifies the behavior of the coolant fluid, whether in single or double phase, evaluating at every momento the system pressure, the coolant flow and the vapor fraction in the different axial positions of the channel. It is noted that, in an accident context, the rapid variation experienced by the conditions to which the fuel rod is subjected gives rise to greater complexity in the calculation, since certain simplifying assumptions that are used in normal operating conditions must be abandoned. Due to this future scenario, developing an ATF materials library for a fuel code like DIONISIO is a necessary and fundamental step from a technological point of view, since although Argentina does not currently have ATF fuel developments, it is expected that in a next future will have them, if the focus is to remain be one of the few nations that produce nuclear technology on the planet.
The Codes and Models Section of the Nuclear Fuels Management has been developing a fuel code called DIONISIO, whose purpose is to simulate the behavior of a typical fuel rod of a nuclear power reactor. The code currently has more than 70 interconnected models that address most of the phenomena that occur under irradiation under normal reactor operating conditions. Some of the phenomena that the code predicts are the thermal and mechanical behavior, the release of fission gases, the swelling and densification of the tablets, the thermohydraulic conditions of the channel surrounding the rod, the growth of the oxide layer, among others. Likewise, the code has a module to simulate the behavior of plate-type fuels, a design that is commonly used in research reactors. The development of this complex module involved, first, the separate development and evaluation of models to describe the different physical processes and, subsequently, their incorporation into the code as new particular subroutines, respecting the architecture, mode of execution and versatility of the rest of the code. The new accident module allows analyzing and quantifies the behavior of the coolant fluid, whether in single or double phase, evaluating at every momento the system pressure, the coolant flow and the vapor fraction in the different axial positions of the channel. It is noted that, in an accident context, the rapid variation experienced by the conditions to which the fuel rod is subjected gives rise to greater complexity in the calculation, since certain simplifying assumptions that are used in normal operating conditions must be abandoned. Due to this future scenario, developing an ATF materials library for a fuel code like DIONISIO is a necessary and fundamental step from a technological point of view, since although Argentina does not currently have ATF fuel developments, it is expected that in a next future will have them, if the focus is to remain be one of the few nations that produce nuclear technology on the planet.