分类： 物理学 >> 核物理学 提交时间： 2025-07-04
摘要： A first attempt to simulate the charge exchange process of C2+ to C-, in which C2+ with low energy through an exchange medium, using the Monte Carlo Software Geant4 has been accomplished. The yields of Cq (q=-2, -1, 0 and +1) from injected C2+ with different energies into different exchange medium are measured by setting up the physical model in the simulation program. The effect of different energies (range from 60 to 300keV), different exchange medium (isobutene and methane), different density distribution of exchange medium in charge exchange cell on the charge exchange efficiency have been studied. The comparison of the present results with the experimental results shows the feasibility of this method. Moreover, the present results demonstrate that low-density diffuse regions on either side of the high-density central region in the charge exchange cell has a significant contribution to improving the charge exchange efficiency. The charge exchange efficiency in organic non-metallic gases of isobutene is higher than in methane, particularly, an efficiency close to 2% of C2+ to C- conversion can be achieved in methane.
分类： 物理学 >> 核物理学 提交时间： 2025-02-20
Yu, Mr. Changqing
Zhu, Dr. Guifeng
Jia, Dr. Shuyang
Zou, Dr. Yang 邹杨
Yan, Dr. Rui
Guo, Dr. Jian
Liu, Dr. Yafen
Zhou, Dr. Bo
Zhao, Dr. Xuechao
摘要： Knowing the precise relationship between fuel loading and reactivity helps guide the smooth progress of reactor criticality extrapolation and online refueling in molten salt reactors (MSRs). This study aims to explore and explain the linear relationship between reactivity and the reciprocal of uranium concentration in thermal spectrum MSRs. By applying the neutron balance theory, we analyzed the absorption of neutrons by various nuclides under several single lattice models with varying fuel concentrations. Our findings reveal a simple linear correlation between reactivity and the reciprocal of uranium concentration, which is successfully explained from the perspective of nuclear reaction cross-sections that adhere to the 1/v law in a thermal neutron spectrum. Furthermore, we identified the single-group neutron absorption cross-sections of structural materials and carrier salts exhibit an approximate linear relationship with the single-group fission cross-section of 235U, and the reciprocal of the fission cross-section of 235U exhibits an approximate linear relationship with uranium concentration. This linear relationship will deviate as the volume fraction of molten salt continues to increase since more neutrons will be captured in the resonance energy spectrum. But it remains valid within a 25% volume fraction of molten salt, and still demonstrates its broad applicability in the physical design and operation of thermal molten salt reactors.
分类： 物理学 >> 核物理学 提交时间： 2024-12-17
Yu, Mr. Changqing
Zhu, Dr. Guifeng
Jia, Dr. Shuyang
Zou, Dr. Yang 邹杨
Yan, Dr. Rui
Guo, Dr. Jian
Liu, Dr. Yafen
Zhou, Dr. Bo
Zhao, Dr. Xuechao
摘要： Knowing the precise relationship between fuel loading and reactivity helps guide the smooth progress of reactor criticality extrapolation and online refueling in molten salt reactors (MSRs). This study aims to explore and explain the linear relationship between reactivity and the reciprocal of uranium concentration in thermal spectrum MSRs. By applying the neutron balance theory, we analyzed neutron absorption by various nuclides under several single lattice models with varying fuel concentrations. Our findings reveal a simple linear correlation between reactivity and the reciprocal of uranium concentration, which is successfully explained from the perspective of nuclear reaction cross-sections that adhere to the 1/v law in a thermal neutron spectrum. Furthermore, we identified the single-group neutron absorption cross-sections of structural materials and carrier salts exhibit an approximate linear relationship with the single-group fission cross-section of 235U, and the reciprocal of the fission cross-section of 235U exhibits an approximate linear relationship with uranium concentration. This linear relationship will deviate as the volume fraction of molten salt continues to increase since more neutron will be captured in the resonance energy spectrum. But it remains valid within a 25% volume fraction of molten salt, and still demonstrates its broad applicability in the physical design and operation of thermal molten salt reactors.
分类： 物理学 >> 核物理学 提交时间： 2025-05-14
Cao, Mr. Jintong
Zhu, Dr. Guifeng
Yu, Mr. Changqing
Liu, Dr. Yafen
Zou, Dr. Yang 邹杨
Yan, Dr. Rui
Xu, Prof. Hongjie
摘要： Molten salt reactors, being the only reactor type among Generation IV advanced nuclear reactors to utilize liquid fuel, offer inherent safety, high-temperature and low-pressure operation, as well as the capability for online fuel reprocessing. However, fuel salt flow results in the decay of delayed neutron precursors (DNPs) outside the core, leading to fluctuations in the effective delayed neutron fraction and consequently impacting reactor reactivity. Particularly under accident scenarios—such as combined pump shutdown and inability to rapidly scram the reactor—the reliance solely on negative temperature feedback may cause a substantial increase in core temperature, posing a threat to reactor safety. To address these issues, this paper introduces an innovative design for a passive fluid-driven Suspended Control Rod (SCR) aimed at dynamically compensating for reactivity fluctuations caused by DNPs flowing with fuel flow. The control rod operates passively by leveraging the combined effects of gravity, buoyancy, and fluid dynamic forces, thereby eliminating the need for any external drive mechanism and allowing direct integration within the core’s active region. Using a 150 MWth thorium-based molten salt reactor as the reference design, a mathematical model was developed to systematically analyze the effects of key parameters—including the SCR's geometric dimensions and density—on its performance, examine its motion characteristics under different core flow conditions, and assess its feasibility for dynamic compensation of reactivity changes caused by fuel flow. The study’s results demonstrate that the SCR can effectively counteract the reactivity fluctuations induced by fuel flow within molten salt reactors. Sensitivity analysis revealed that the SCR’s average density exerts a profound impact on its start-up flow threshold, channel flow rate, resistance to fuel density fluctuations, and response characteristics, underscoring the critical need to optimize this parameter. Moreover, by judiciously selecting the SCR’s length, number of deployed units, and placement, one can achieve the necessary reactivity control while also maintaining a favorable balance between neutron economy and heat transfer performance. Ultimately, this study provides an innovative solution for passive reactivity control in molten salt reactors, offering substantial potential for practical engineering applications.
分类： 物理学 >> 核物理学 提交时间： 2025-03-31
Cao, Mr. Jintong
Zhu, Dr. Guifeng
Yu, Mr. Changqing
Liu, Dr. Yafen
Zou, Dr. Yang 邹杨
Yan, Dr. Rui
Xu, Prof. Hongjie
摘要： Molten salt reactors, being the only reactor type among Generation IV advanced nuclear reactors to utilize liquid fuel, offer inherent safety, high-temperature and low-pressure operation, as well as the capability for online fuel reprocessing. However, fuel salt flow results in the decay of delayed neutron precursors (DNPs) outside the core, leading to fluctuations in the effective delayed neutron fraction and consequently impacting reactor reactivity. Particularly under accident scenarios—such as combined pump shutdown and inability to rapidly scram the reactor—the reliance solely on negative temperature feedback may cause a substantial increase in core temperature, posing a threat to reactor safety. To address these issues, this paper introduces an innovative design for a passive fluid-driven Suspended Control Rod (SCR) aimed at dynamically compensating for reactivity fluctuations caused by DNPs flowing with fuel flow. The control rod operates passively by leveraging the combined effects of gravity, buoyancy, and fluid dynamic forces, thereby eliminating the need for any external drive mechanism and allowing direct integration within the core’s active region. Using a 150 MWth thorium-based molten salt reactor as the reference design, a mathematical model was developed to systematically analyze the effects of key parameters—including the SCR's geometric dimensions and density—on its performance, examine its motion characteristics under different core flow conditions, and assess its feasibility for dynamic compensation of reactivity changes caused by fuel flow. The study’s results demonstrate that the SCR can effectively counteract the reactivity fluctuations induced by fuel flow within molten salt reactors. Sensitivity analysis revealed that the SCR’s average density exerts a profound impact on its start-up flow threshold, channel flow rate, resistance to fuel density fluctuations, and response characteristics, underscoring the critical need to optimize this parameter. Moreover, by judiciously selecting the SCR’s length, number of deployed units, and placement, one can achieve the necessary reactivity control while also maintaining a favorable balance between neutron economy and heat transfer performance. Ultimately, this study provides an innovative solution for passive reactivity control in molten salt reactors, offering substantial potential for practical engineering applications.
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