分类： 物理学 >> 核物理学 提交时间： 2025-04-16
摘要： The 2019 edition of the International Reactor Physics Evaluation Project (IRPhEP) Handbook incorporated the Molten Salt Reactor Experiment (MSRE) benchmark, providing keff (effective multiplication factor) values derived from first criticality experiments and control rod worth calculations for multiple nuclear data libraries including ENDF/B-VII.1. This benchmark constitutes the first comprehensive reference case for molten salt reactor physics, having been extensively utilized to assess the consistency and accuracy of Monte Carlo codes and nuclear data libraries in molten salt reactor modeling. Since 2011, the Thorium Molten Salt Reactor (TMSR) nuclear energy system has been under development at the Shanghai Institute of Applied Physics, Chinese Academy of Sciences to facilitate thorium resource utilization. In support of this initiative, the China Nuclear Data Center developed specialized CENDL-TMSR-V1 libraries tailored for thorium-uranium fuel cycles. Nevertheless, the verification status of Chinese nuclear libraries CENDL-3.2 and CENDL-TMSR-V1 in molten salt reactor applications remains unexplored. In this work, a high-fidelity MSRE model was developed using OpenMC, with comparative analyses conducted across four evaluated nuclear data libraries: ENDF/B-VII.1, ENDF/B-VIII.0, CENDL-3.2, and CENDL-TMSR-V1. A systematic evaluation of neutronic parameters was performed, encompassing reactivity coefficients, control rod differential worth, zero-power flux distribution, and 500-day burn-up calculations. Key findings reveal that: The relative deviations in keff between all libraries and IRPhEP benchmark values remain below 300 pcm (0.3% Δk/k). The maximum relative discrepancy in power distribution predictions between CENDL-series libraries and ENDF/B-VII.1 is <2%. The keff deviations during burn-up calculations are maintained within 0.2%/. This study validates the applicability of CENDL-series libraries for molten salt reactor neutronic simulations.
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.
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： 2025-05-15
Li, Mr. Qi-Ming
Fu, Dr. Yao
Tian, Dr. Jian
Zhou, Dr. Chong
Zou, Dr. Yang 邹杨
fu, Prof. yuan 傅远
Hou, Dr. Jie 后接
Yu, Prof. Xiaohan
Xu, Prof. Hongjie
摘要： This study experimentally investigated the heat transfer performance of a novel shell-and-tube fluoride Salt to Salt Heat Exchanger (SSHX) featuring baffles with integrated drainage ports, designed to mitigate salt freeze blockage risks during shutdown in Molten Salt Reactors (MSRs). Experiments were conducted in a Scaled Simulation Fluoride Salt-cooled Reactor (SF0) test facility. A new empirical correlation for tube-side heat transfer was proposed as Nu=0.0246Re0.8Pr0.267 (valid for Re=9000~15000 and Pr=8~12), demonstrating excellent agreement with experimental data within a maximum deviation of 5%. Comparative analysis revealed the modified Dittus-Boelter equation is still a suitable choice for predicting fluoride salt convective heat transfer behavior in tubular geometries, outperforming the Gnielinski and Sieder-Tate models, which overpredicted data by 17-25%. For shell-side heat transfer, applying a 31% enhancement factor (ε=1.31) to the Kern correlation aligns predictions with experimental results within an error range of -6.0% to 7.0%. These findings address a critical engineering challenge in SSHXs while preserving thermal efficiency, offering essential experimental data and valuable insights for the design of fluoride SSHXs in MSRs.
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