Omid Safarzadeh; Farahnaz Saadatian-Derakhshandeh
Abstract
The effective β-fraction has a key role in the dynamic response of the reactor. This study aims to assess the suitability and accuracy of the detailed models of DRAGON5 and DONJON5 code for estimation of the effective fraction of delayed neutron for the VVER-1000 reactor core. DRAGON5 is adopted ...
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The effective β-fraction has a key role in the dynamic response of the reactor. This study aims to assess the suitability and accuracy of the detailed models of DRAGON5 and DONJON5 code for estimation of the effective fraction of delayed neutron for the VVER-1000 reactor core. DRAGON5 is adopted to homogenize and condense lattice physics constants of fuel assemblies during fuel burnup, followed by DONJON5, which is used to calculate forward and adjoint flux profiles on the reactor core geometry. A thermal-hydraulic subroutine is developed for VVER-1000 reactor hollow fuel pellets to embody the reactivity feedback raised by changing the reactor power profile. The effective β-fraction is evaluated for each fissile and fertile isotopes in terms of fuel burnup. The results of the coupling scheme are evaluated using the KASKAD code package of Bushehr NPP-I (BNPP-I). The results indicate that the use of SHI and SYBILT modules of DRAGON5 are essential to achieve reasonably precise resolution.
Zohreh Gholamzadeh; Atieh JozVaziri
Abstract
Thorium is more abundant in nature than uranium. The fertile thorium fuel can breed to fissile U-233 by absorbing a neutron. The produced fissile has good neutronic performance in both thermal and fast neutron spectra. Many types of thorium-based fuels were applied ...
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Thorium is more abundant in nature than uranium. The fertile thorium fuel can breed to fissile U-233 by absorbing a neutron. The produced fissile has good neutronic performance in both thermal and fast neutron spectra. Many types of thorium-based fuels were applied in different nuclear reactors. Also natural thorium oxide is used as seed/blanket configuration that the ThO2 rods are used in the outer sections of any fuel assembly. The present study aims to investigate the ThO2 fuel rod loading in 3000 MW VVER-1000 power reactor. MCNPX and ORIGEN codes were used to evaluate its effects on the core neutronic. In addition, the gamma emission rates of ThO2 spent fuel than the UO2 routine fuel of VVER-1000 was investigated. The obtained results of the computational study showed the ThO2 fuel rod loading in some VVER-1000 fuel assemblies would not end to a breeding behavior of the reactor core even after one-year burnup at 3000 MW power. However, the enriched uranium fuel loading reduction may make a motivation for thorium fuel application in the power reactor.
