Kambiz Valavi; Ali Pazirandeh; Gholamreza Jahanfarnia
Abstract
In the present work, a time-dependent neutron diffusion simulator is developed utilizing the second order of average current nodal expansion method. Generally, nodal methods can accurately simulate the reactor core with coarse meshes as long as the sizes of a fuel assembly. In this case, an adopted iterative ...
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In the present work, a time-dependent neutron diffusion simulator is developed utilizing the second order of average current nodal expansion method. Generally, nodal methods can accurately simulate the reactor core with coarse meshes as long as the sizes of a fuel assembly. In this case, an adopted iterative approach is used for resolving the time-dependent three-dimensional multi-group neutron balance equations coupled with six-group precursor equations. In order to evaluate the implemented methodology, two popular transient problems are used including TWIGL two-dimensional seed-blanket reactor and three-dimensional LMW LWR. For indicating the precision of the method, the numerical results of high (second) order approach also have been compared with the basic methodology i.e. the zeroth order solution. From the comparison of obtained results with references, the suitable and precise simulating of transient schemes can be comprehended using the time-dependent second order average current nodal expansion method. Moreover, the results confirm that the second order solution can treat the coarse mesh dynamic problems with more accuracy relative to the basic approach.
Mohammad Hossein Bahrevar; Gholamreza Jahanfarnia; Ali Pazirandeh; Mohsen Shayesteh
Abstract
In this study, thermal-hydraulic analysis of partial loss of coolant flow accident in supercritical pressure light water reactor (SCWR) with a new geometric design has been investigated. In the new design, the coolant and moderator circuits are separated. This analysis was performed using the development ...
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In this study, thermal-hydraulic analysis of partial loss of coolant flow accident in supercritical pressure light water reactor (SCWR) with a new geometric design has been investigated. In the new design, the coolant and moderator circuits are separated. This analysis was performed using the development of a transient-state thermal-hydraulic code in which the equations of mass, momentum, and energy are solved. The porous Media approach is used to solve these equations. By extracting the results of transition modeling, it is observed that in the new geometric design, by separating the coolant and moderator circuits, the maximum fuel clad temperature is lower than the maximum fuel clad temperature value of the previous designs. As in the new design at the end of the transition, the maximum fuel clad temperature has decreased by about 37% compared to the initial state. The result of the calculations in this study shows that the new design, in which the coolant and moderator circuits are separated, has created more safety in a chosen transition.
