Molten salt reactors,being the only reactor type among Generation Ⅳ advanced nuclear reactors that utilize liquid fuels,offer inherent safety,high-temperature,and low-pressure operation,as well as the capability for ...Molten salt reactors,being the only reactor type among Generation Ⅳ advanced nuclear reactors that utilize liquid fuels,offer inherent safety,high-temperature,and low-pressure operation,as well as the capability for online fuel reprocessing.However,the fuel-salt flow results in the decay of delayed neutron precursors(DNPs)outside the core,causing fluctuations in the effective delayed neutron fraction and consequently impacting the reactor reactivity.Particularly in accident scenarios—such as a combined pump shutdown and the inability to rapidly scram the reactor—the sole reliance on negative temperature feedback may cause a significant increase in core temperature,posing a threat to reactor safety.To address these problems,this paper introduces an innovative design for a passive fluid-driven suspended control rod(SCR)to dynamically compensate for reactivity fluctuations caused by DNPs flowing with the fuel.The control rod operates passively by leveraging the combined effects of gravity,buoyancy,and fluid dynamic forces,thereby eliminating the need for an external drive mechanism and enabling direct integration within the active region of the core.Using a 150 MWt thorium-based molten salt reactor as the reference design,we develop a mathematical model to systematically analyze the effects of key parameters—including the geometric dimensions and density of the SCR—on its performance.We examine its motion characteristics under different core flow conditions and assess its feasibility for the dynamic compensation of reactivity changes caused by fuel flow.The results of this study demonstrate that the SCR can effectively counteract reactivity fluctuations induced by fuel flow within molten salt reactors.A sensitivity analysis reveals 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.This underscores the critical need to optimize this parameter.Moreover,by judiciously selecting the SCR’s length,number of deployed units,and the placement we can achieve the necessary reactivity control while maintaining a favorable balance between neutron economy and heat transfer performance.Ultimately,this paper provides an innovative solution for the passive reactivity control in molten salt reactors,offering significant potential for practical engineering applications.展开更多
钍基熔盐堆(TMSR)核能系统项目是中科院未来10年先导研究专项之一,其研究目标是研发第四代裂变反应堆核能系统,计划至2020年之前建成2MW钍基熔盐实验堆,形成支撑未来TMSR核能系统发展的若干技术研发能力,并解决钍铀燃料循环和钍基熔盐...钍基熔盐堆(TMSR)核能系统项目是中科院未来10年先导研究专项之一,其研究目标是研发第四代裂变反应堆核能系统,计划至2020年之前建成2MW钍基熔盐实验堆,形成支撑未来TMSR核能系统发展的若干技术研发能力,并解决钍铀燃料循环和钍基熔盐堆相关重大技术挑战,研制出工业示范级钍基熔盐堆,实现钍资源的有效使用和核能的综合利用。钍基核燃料具有232Th/233U转换效率高、在热中子堆中也能增殖、产生较少的高毒性放射性核素、有利于防核扩散等优点,但也面临燃料制备困难、232U衰变子核的强γ辐射给乏燃料处理和燃料再加工带来的困难、钍铀转换反应链中间核233Pa会吸收堆内中子从而影响233U产量。核燃料利用的工作模式有开环模式、改进的开环模式和闭环模式。熔盐堆是第四代反应堆的6个候选堆型之一,非常适合用作钍铀燃料循环,熔盐堆加上干法在线分离技术有可能实现完全的钍铀燃料闭式循环。本世纪初提出的氟盐冷却高温堆(Fluoride salt-cooled High temperature Reactors,FHRs),用氟化熔盐作为冷却剂,采用TRISO燃料颗粒作为核燃料,其中球床型氟盐冷却高温堆可以在改进的开环模式实现钍铀燃料循环。熔盐堆良好的高温特性使其成为核能非电应用主要候选者之一,反应堆产生的高温热可直接用于页岩油开采和高温制氢等工业领域。展开更多
作为四代堆6种候选堆型中唯一的液态燃料反应堆,熔盐堆对未来核能和钍资源利用具有重要意义,特别是熔盐快堆(Molten Salt Fast Reactor,MSFR)还具有较大的增殖比和较好的温度负反馈。由于启动新的熔盐快堆需要较高的燃料装载量,若能改善...作为四代堆6种候选堆型中唯一的液态燃料反应堆,熔盐堆对未来核能和钍资源利用具有重要意义,特别是熔盐快堆(Molten Salt Fast Reactor,MSFR)还具有较大的增殖比和较好的温度负反馈。由于启动新的熔盐快堆需要较高的燃料装载量,若能改善MSFR的增殖性能,则有利于提高233U产量并缩短燃料倍增时间。首先应用SCALE6.1针对MSFR的径向增殖盐、新增轴向增殖盐和新增石墨反射层这三方面分析了初始增殖比,同时从核素吸收率角度说明增殖比变化的原因和MSFR的设计不足并对其进行了优化;然后应用基于SCALE6.1开发的熔盐堆在线处理模块(Molten Salt Reactor Reprocessing Sequence,MSR-RS)进行燃耗分析。结果表明,新增轴向增殖盐可以进一步提高增殖性能;新增石墨反射层可以节省增殖盐装载量。改进后的堆型运行时增殖比可以维持在1.1以上,233U年产量提高至133 kg,倍增时间缩短至36 a,并且堆芯在整个运行寿期都能保持足够的温度负反馈。展开更多
Thermodynamic optimization of the AF-BeF_(2)(A=K,Rb,and Cs),KF-CsF,and RbF-CsF systems was performed within the framework of phase diagrams calculation.The model parameters were optimized based on experimental data an...Thermodynamic optimization of the AF-BeF_(2)(A=K,Rb,and Cs),KF-CsF,and RbF-CsF systems was performed within the framework of phase diagrams calculation.The model parameters were optimized based on experimental data and theoretically calculated values.The results show that the thermodynamically calculated values for the AF-BeF_(2)(A=K,Rb,and Cs),KF-CsF,and RbF-CsF systems agree well with the experimental data.Next,a set of reliable and self-consistent thermodynamic databases was built,and the liquidus projections and invariant points of the sub-ternary systems of the KF-RbF-CsF-BeF_(2)system were calculated.Furthermore,the melting temperature with the corresponding composition was predicted using the phase diagrams calculation technique,and the radial distribution functions,coordination numbers,angular distribution functions,and diffusion coefficients of the quaternary KF-RbF-CsF-BeF_(2)system were calculated using ab initio molecular dynamics.The results show that the quaternary KF-RbF-CsF-BeF_(2)system with the proportion 3.50-28.92-21.78-45.80 mol%or 1.80-35.42-52.40-10.38 mol%is one of the most promising candidate coolants for molten salt reactors in terms of thermodynamics and kinetics.This work provides direct guidelines for the screening and optimization of molten salts in the nuclear energy field.展开更多
基金supported by Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2020261)Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA02010000)the Young Potential Program of Shanghai Institute of Applied Physics,Chinese Academy of Sciences(No.SINAP-YXJH-202412).
文摘Molten salt reactors,being the only reactor type among Generation Ⅳ advanced nuclear reactors that utilize liquid fuels,offer inherent safety,high-temperature,and low-pressure operation,as well as the capability for online fuel reprocessing.However,the fuel-salt flow results in the decay of delayed neutron precursors(DNPs)outside the core,causing fluctuations in the effective delayed neutron fraction and consequently impacting the reactor reactivity.Particularly in accident scenarios—such as a combined pump shutdown and the inability to rapidly scram the reactor—the sole reliance on negative temperature feedback may cause a significant increase in core temperature,posing a threat to reactor safety.To address these problems,this paper introduces an innovative design for a passive fluid-driven suspended control rod(SCR)to dynamically compensate for reactivity fluctuations caused by DNPs flowing with the fuel.The control rod operates passively by leveraging the combined effects of gravity,buoyancy,and fluid dynamic forces,thereby eliminating the need for an external drive mechanism and enabling direct integration within the active region of the core.Using a 150 MWt thorium-based molten salt reactor as the reference design,we develop a mathematical model to systematically analyze the effects of key parameters—including the geometric dimensions and density of the SCR—on its performance.We examine its motion characteristics under different core flow conditions and assess its feasibility for the dynamic compensation of reactivity changes caused by fuel flow.The results of this study demonstrate that the SCR can effectively counteract reactivity fluctuations induced by fuel flow within molten salt reactors.A sensitivity analysis reveals 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.This underscores the critical need to optimize this parameter.Moreover,by judiciously selecting the SCR’s length,number of deployed units,and the placement we can achieve the necessary reactivity control while maintaining a favorable balance between neutron economy and heat transfer performance.Ultimately,this paper provides an innovative solution for the passive reactivity control in molten salt reactors,offering significant potential for practical engineering applications.
文摘钍基熔盐堆(TMSR)核能系统项目是中科院未来10年先导研究专项之一,其研究目标是研发第四代裂变反应堆核能系统,计划至2020年之前建成2MW钍基熔盐实验堆,形成支撑未来TMSR核能系统发展的若干技术研发能力,并解决钍铀燃料循环和钍基熔盐堆相关重大技术挑战,研制出工业示范级钍基熔盐堆,实现钍资源的有效使用和核能的综合利用。钍基核燃料具有232Th/233U转换效率高、在热中子堆中也能增殖、产生较少的高毒性放射性核素、有利于防核扩散等优点,但也面临燃料制备困难、232U衰变子核的强γ辐射给乏燃料处理和燃料再加工带来的困难、钍铀转换反应链中间核233Pa会吸收堆内中子从而影响233U产量。核燃料利用的工作模式有开环模式、改进的开环模式和闭环模式。熔盐堆是第四代反应堆的6个候选堆型之一,非常适合用作钍铀燃料循环,熔盐堆加上干法在线分离技术有可能实现完全的钍铀燃料闭式循环。本世纪初提出的氟盐冷却高温堆(Fluoride salt-cooled High temperature Reactors,FHRs),用氟化熔盐作为冷却剂,采用TRISO燃料颗粒作为核燃料,其中球床型氟盐冷却高温堆可以在改进的开环模式实现钍铀燃料循环。熔盐堆良好的高温特性使其成为核能非电应用主要候选者之一,反应堆产生的高温热可直接用于页岩油开采和高温制氢等工业领域。
文摘作为四代堆6种候选堆型中唯一的液态燃料反应堆,熔盐堆对未来核能和钍资源利用具有重要意义,特别是熔盐快堆(Molten Salt Fast Reactor,MSFR)还具有较大的增殖比和较好的温度负反馈。由于启动新的熔盐快堆需要较高的燃料装载量,若能改善MSFR的增殖性能,则有利于提高233U产量并缩短燃料倍增时间。首先应用SCALE6.1针对MSFR的径向增殖盐、新增轴向增殖盐和新增石墨反射层这三方面分析了初始增殖比,同时从核素吸收率角度说明增殖比变化的原因和MSFR的设计不足并对其进行了优化;然后应用基于SCALE6.1开发的熔盐堆在线处理模块(Molten Salt Reactor Reprocessing Sequence,MSR-RS)进行燃耗分析。结果表明,新增轴向增殖盐可以进一步提高增殖性能;新增石墨反射层可以节省增殖盐装载量。改进后的堆型运行时增殖比可以维持在1.1以上,233U年产量提高至133 kg,倍增时间缩短至36 a,并且堆芯在整个运行寿期都能保持足够的温度负反馈。
基金supported by the National Natural Science Foundation of China(Nos.12205364 and 12375282)Guangdong Provincial Natural Science Foundation(Nos.2024A1515012570 and 2024A1515010885)the Fundamental Research funds for the Central Universities,Sun Yat sen University。
文摘Thermodynamic optimization of the AF-BeF_(2)(A=K,Rb,and Cs),KF-CsF,and RbF-CsF systems was performed within the framework of phase diagrams calculation.The model parameters were optimized based on experimental data and theoretically calculated values.The results show that the thermodynamically calculated values for the AF-BeF_(2)(A=K,Rb,and Cs),KF-CsF,and RbF-CsF systems agree well with the experimental data.Next,a set of reliable and self-consistent thermodynamic databases was built,and the liquidus projections and invariant points of the sub-ternary systems of the KF-RbF-CsF-BeF_(2)system were calculated.Furthermore,the melting temperature with the corresponding composition was predicted using the phase diagrams calculation technique,and the radial distribution functions,coordination numbers,angular distribution functions,and diffusion coefficients of the quaternary KF-RbF-CsF-BeF_(2)system were calculated using ab initio molecular dynamics.The results show that the quaternary KF-RbF-CsF-BeF_(2)system with the proportion 3.50-28.92-21.78-45.80 mol%or 1.80-35.42-52.40-10.38 mol%is one of the most promising candidate coolants for molten salt reactors in terms of thermodynamics and kinetics.This work provides direct guidelines for the screening and optimization of molten salts in the nuclear energy field.
