Zohreh Gholamzadeh; Rohollah Adeli; Mahdi Keivani
Abstract
Routine gamma dosimetry of spent fuels in nuclear power stations is mandatory to manage their storage in dry or wet spent fuel storages. Mostly the spent fuel gamma dose rate measurements out of the spent fuel pool is impossible because of the high exposures of the operators. Therefore, ...
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Routine gamma dosimetry of spent fuels in nuclear power stations is mandatory to manage their storage in dry or wet spent fuel storages. Mostly the spent fuel gamma dose rate measurements out of the spent fuel pool is impossible because of the high exposures of the operators. Therefore, determination of a conversion factor as precise as possible is important that could be applied to convert the measured gamma dose rate inside the water shield to the air values. Simulation methods are powerfully applied to investigate the conversion factor variation trends due to different burnup, cooling time and irradiation history of the spent fuels. The present work uses MCNPX Monte Carlo-based code to determine the trend. The obtained results of this computational study showed that the conversion factor would not have any dependency to the cooling times, burnup values and irradiation history if the detector is placed at special positions in air or water environments. Comparison of the simulation and experimental data showed an acceptable conformity, so that the experimental verified the simulation data trend
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.
Zohreh Gholamzadeh; Mohadeseh Gholshanian; Seyed Mohammad Mirvakili
Abstract
Today thorium based fuels are being investigated as an alternative fuel technology. However, the majority of thorium fuel research studies are limited to reactor physics investigations, which leaves a gap for dose evaluation and shielding concerns of such spent fuels. The present work investigates thorium ...
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Today thorium based fuels are being investigated as an alternative fuel technology. However, the majority of thorium fuel research studies are limited to reactor physics investigations, which leaves a gap for dose evaluation and shielding concerns of such spent fuels. The present work investigates thorium oxide fuel assemblies in Tehran research reactor. The fuel gamma dose rates are calculated at different burnups and cooling times. A comparison between the reactor routine fuel and the thorium oxide fuel is conducted to reveal the thorium-based fuel application shielding challenges. The obtained results showed that inverse to U3O8-Al routine fuel the spent ThO2 gamma dose rates are completely dependent to the burnup values. In addition, for transporting the spent ThO2 fuel with the routine transport casks there is needed to be waited for the higher cooling times than U3O8-Al transportation time or construction of thicker transport casks is needed for transportation of the thorium-based spent fuels at shorter times.
