反应堆冷中子源的调试运行

冷中子源装置利用14.5 K的低温氦气作为制冷剂。通过制冷系统的不停运转,将冷源氢系统内的氢液化。液态的氢充满着整个堆内部件系统的慢化剂室,使得其周围的热中子与液氢慢化剂进行能量交换,变为冷中子,再通过中子导管将冷中子输送到散射大厅各台谱仪上。冷源装置所有子系统调试运行的成功是获得冷中子的基础。在冷源调试中,氦制冷系统调试运行最为繁琐。着重介绍氦制冷系统在调试过程中遇到的问题及解决措施。     

中国先进研究堆冷中子源氘系统充氢调试

正中国先进研究堆(CARR)冷中子源装置采用单相液氘作为冷中子慢化剂,液氘慢化剂通过堆内装置热虹吸回路封闭式自然循环和氦气夹层内低温氦气(约19 K)的冷却维持在液态状态。CARR冷中子源氘系统充氢调试的主要目的是采用氢替代氘进行首次氢装载、运行考验和氢卸载试验,验证氢装载/卸载操作程序;通过氦气制冷系统中氘气体分析仪测量氦气中的氢含量以进一步检查冷包及热虹吸回路的密封性。在充氢之前不开堆情况下启动冷源系统备用模式(SO)运行,采用含有200ppm氘气的混合氦     

CARR冷中子源物理方案研究

冷中子源是中国先进研究堆(CARR)作为应用平台开展中子散射实验的重要系统。本文建立了可开展冷中子源装置氢系统物理方案研究的计算程序和方法。对影响核发热和冷中子增益的多种因素进行了计算和优化选择,确定了氢系统物理方案。分析结果表明:符合CARR冷中子源自身特点且在国际上具有创新意义的月牙形冷包结构,在核发热量较小的条件下获得了较好的冷中子增益。     

中国先进研究堆冷中子源堆内安装

正中国先进研究堆(CARR)冷中子源堆内部分由真空容器及堆内组件组成,包括热虹吸系统、主法兰和与冷中子源堆外系统的连接管线部分,称为冷源堆内装置。CARR冷中子源堆内装置安装在重水箱内,冷包及热虹吸回路装置安装在真空容器内,氘系统管线、氦制冷系统管线、真空管线在堆水池内需要安装固定并与冷包及热虹吸回路装置连接。冷包处在堆芯活性区中心标高位置。CARR冷中子源堆内安装具体流程如图1所示。冷中子源堆内安装具有难度大、精度高、技术     

用于凝聚态物理研究的中子散射技术

本文目的是介绍中子技术在凝聚态物理研究中的应用。主要介绍中子散射的基本原理、实验方法及冷中子源、超冷中子源、中子导管和中子单色器。     

中国先进研究堆冷中子源系统充氘综合调试

正中国先进研究堆(CARR)冷中子源装置采用单相液氘作为冷中子慢化剂,液氘慢化剂通过堆内装置热交换器热虹吸回路封闭式自然循环和氦气夹层内低温氦气(约19K)的冷却维持在液态。CARR冷中子源系统充氘调试主要目的为:1)实现首次氘装载、冷中子源冷态运行考验及带核综合试验,验证冷中子源系统满足合同规定的技术要求,能够安全稳定地运行;2)测量冷中子源热负荷、冷中子源运行模式运行参数验证以及冷中子     

CARR冷中子源系统可行性研究

建立冷中子源装置,开展中子散射实验研究是CARR堆的重点应用之一。由冷中子源装置获得的冷中子,其良好的波动特性,可为生物学、凝聚态物理学和生命科学等领域提供极为有用的研究工具,给出明显优于其他研究手段的研究结果。     

中国先进研究堆冷中子源设备冷却水回路系统验收试验

正中国先进研究堆(CARR)冷中子源系统中设备冷却水回路系统为确保堆外氦制冷回路正常运行的保障系统,它是重要回路之一。冷中子源系统中氦制冷回路系统运行时,系统内压缩机和冷箱中的透平膨胀机因发热而需要冷却,其冷却源来自设备冷却水系统,以维持其机体在合适的温度范围内。设备冷却水回路系统验收试验包括:系统回路水压力试验;回路装置密封性试验;回路系统不带负荷运转试验;回路系统带负荷运转试验。系统回路水压力试验针对全冷却回路,包括压缩机、冷箱供水管路、换热器、冷却泵以及相关阀门仪表和接口,采用水为介质,打压方案为通过排水     

中国先进研究堆冷中子源核发热和冷中子增益研究

为准确计算和研究中国先进研究堆（CARR）冷中子源装置氢系统的核发热和冷中子增益，建立了一整套计算方法。对参考堆的验证计算证明了该方法的正确性和有效性。对影响CARR冷中子源核发热和冷中子增益的各种因素（如慢化剂、冷包材料、冷包形状等）进行了计算和优化选择。结果表明：在核发热量较小的条件下获得了较好的冷中子增益。     

冷中子源中氢系统的纵深防御设计

反应堆冷中子源装置的安全性包括核安全、辐射安全和氢安全,其中氢安全是最复杂的一方面.冷中子源氢系统一般采取纵深防御的安全设计方法,即通过多重屏障的技术措施尽可能杜绝氢和空气(氧气)直接接触的可能性.本文详细描述了一座建设中的反应堆冷中子源氢系统的纵深防御安全设计特点,这种安全设计可以确保冷中子源的氢安全性.     

Influences of physical properties of two-phase mixture on voidfraction in an annular vessel

To keep the void fraction of two-phase hydrogen in the moderator cell of the cold neutron source (CNS) of China Advanced Research Reactor (CARR) to a specified range, an annular vessel with the same size as the actual moderator cell was used as test section. Deionized water and alcohol, sucrose, and sodium chloride solutions with different concentrations were used as working fluid to find out influences of physical properties, such as density, viscosity and surface tension, of the two-phase mixture on void fraction. The tests proved that the ratio of surface tension to density of liquid phase has great influence on void fraction: the larger the ratio, the smaller the void fraction. Since the ratio of surface tension to density of Freon 113 is lower than that of liquid hydrogen, Freon 113 can be used as a working fluid to study the void fraction in the two-phase hydrogen thermosiphon loop in the CNS of CARR and the results will be conservative.     

Thermo-siphon mock-up test for the cold neutron source of HANARO

Due to the national demand for a cold neutron beam utilization, a cold neutron research facility project has been carried out since July 2003 to install a cold neutron source (CNS) in HANARO. The CNS adopts a two-phase thermo-siphon of liquid hydrogen as a working fluid to remove a heat load. The CNS consists of an in-pool assembly (IPA) and other components including a hydrogen buffer tank. The liquid level in the moderator cell is measured by a gamma-ray densitometer under a normal cold operation, and the cool down time to fill the required liquid hydrogen into the moderator cell is numerically simulated and compared with the experimental data from a thermo-siphon mock-up test. The self-regulating characteristic of the two-phase thermo-siphon loop is also confirmed by a comparison of a model simulation’s results, which use a thermodynamic model, with the experiment’s results. From these results, the HANARO-CNS is found to maintain the required conditions for a stable cold neutron production against a heat load variation along with the reactor’s power. Furthermore, the thermodynamic behavior in the IPA is observed to determine whether or not the integrity of the IPA is maintained under an abnormal condition of the helium refrigeration system.     

CARR冷中子源氢系统冷却方式及自稳特性研究

为了解决CARR高核功率、低富集度下冷包壁面的高热流密度及冷中子源装置的开堆-开源和开堆-停源工况等难题,提出了带助冷的两相热虹吸自然循环冷却方式;建立了冷包内氮气、各层冷包材料和液氢之间的换热简化模型,编制了计算程序,并分析了指定条件下的换热量;从理论上推导和建立了该冷却方式的自稳特性方程,并进行了自稳定性分析。结果表明,该种冷却方式不仅解决高热流密度和开堆停源等热工难题,还证明了该冷却方式具有一定的自稳特性。     

Mockup tests for developing the CARR-CNS with a two-phase thermo-siphon loop

The cold neutron source (CNS) is a facility to increase cold neutrons by scattering thermal neutrons in liquid hydrogen or deuterium around 20 K. For extracting a stable cold neutron flux from the CNS, the liquid quantity in the moderator cell should be maintained stably against disturbance of nuclear heating. The China Institute of Atomic Energy (CIAE) is now constructing the China Advanced Research Reactor (CARR: 60 MW). and designing the CARR-CNS with a two-phase thermo-siphon loop consisting of a condenser, two moderator transfer tubes and an annular cylindrical moderator cell. The mock-up tests were carried out using a full-scale loop with Freon-113,for validating the self-regulating characteristics of the loop, the void fraction less than 20% in the liquid hydrogen of the moderator cell, and the requirements for establishing the condition under which the inner shell has only vapor. The density ratio of liquid to vapor and the volumetric evaporation rate due to heat load are kept the same as those innormal operation of the CARR-CNS. The results show that the loop has the self-regulating characteristics and the inner shell contains only vapor, while the outer shell liquid. The local void fraction in the liquid increases with increasing of the loop pressure.     

流体物性对冷中子源冷包截面含气率的影响模化研究

采用差压法测出了冷中子源模拟冷包中环形通道内不同层面的平均含气率,发现液相的表面张力与密度的比值是决定截面含气率的主要物性因素;此比值越大,含气率越低。氟利昂113的表面张力与密度的比值比液氢的相应值低。故可以选用氟利昂113作为模拟工质对中国先进研究堆冷中子源中气液两相氢循环的含气率进行模拟研究,且试验结果将偏于保守。     

South Africa's opportunity to maximise the role of nuclear power in a global hydrogen economy

Global concern for increased energy demand, increased cost of natural gas and petroleum, energy security and environmental degradation are leading to heightened interest in using nuclear energy and hydrogen to leverage existing hydrocarbon reserves. The wasteful use of hydrocarbons can be minimised by using nuclear as a source of energy and water as a source of hydrogen. Virtually all hydrogen today is produced from fossil fuels, which give rise to CO₂ emissions. Hydrogen can be cleanly produced from water (without CO₂ pollution) by using nuclear energy to generate the required electricity and/or process heat to split the water molecule. Once the clean hydrogen has been produced, it can be used as feedstock to fuel cell technologies, or in the nearer term as feedstock to a coal-to-liquids process to produce cleaner synthetic liquid fuels. Clean liquid fuels from coal - using hydrogen generated from nuclear energy - is an intermediate step for using hydrogen to reduce pollution in the transport sector; simultaneously addressing energy security concerns. Several promising water-splitting technologies have been identified. Thermo-chemical water-splitting and high-temperature steam electrolysis technologies require process temperatures in the range of 850 °C and higher for the efficient production of hydrogen. The pebble bed modular reactor (PBMR), under development in South Africa, is ideally suited to generate both high-temperature process heat and electricity for the production of hydrogen. This paper will discuss South Africa's opportunity to maximise the use of its nuclear technology and national resources in a global hydrogen economy.     

一种降低CARR堆冷中子源氢系统中子慢化室内含气率的方法

CARR核功率达60MW;其慢化室中液氢产气量大,含气率高,对于系统的慢化能力、反应堆的安全等都有重大影响。为了降低慢化室与内筒间环形通道中的截面含气率,本文采取在慢化室内筒顶端开孔的措施,以导出慢化室内筒下部金属及液氢核发热产生的氢气。通过对一系列小直径短管的流量与压力关系的测量,获得了小直径短管的流量与压力关联式,并以此关联式为依据,得到了最佳开孔数与最佳直径。论证了此方法在核功率变化时的自我调节性与稳定性。     

An equilibrium and kinetic study of the liquid sodium-hydrogen reaction and its relevance to sodium-water leak detection in LMFBR systems

A detailed study of the thermodynamic and kinetic properties of the liquid sodium-hydrogen system has been made. The technique employed was to measure the rate of absorption to equilibrium of successive hydrogen additions by a vigorously stirred excess of liquid sodium (< 10 ppm dissolved oxygen) in an isothermal, constant volume, stainless steel (316) reaction vessel in the temperature range 610–677 K. The results have been used to estimate the variation of hydrogen pressure with time for a given, steady, water leak rate into the argon gas blanket above the liquid sodium level in a secondary heat exchanger of an LMFBR, and also to calculate solution rates of hydrogen bubbles (formed from a sodiumwater reaction under the liquid sodium surface) as a function of initial bubble radius.     

Water and hydrogen in heavy liquid metal coolant technology

Lead and lead-bismuth are currently considered as coolants in some reactor and accelerator driven system designs. Processes related to water steam and hydrogen supply to the primary circuit are very important for the coolant technology. The similar physical and chemical processes occur, for instance, in case of steam leaks to the coolant caused by failure of steam generator (SG). In this paper are designs of heat and mass exchangers, in which water or other liquid and gaseous media are in direct contact with heated lead-containing coolant. These heat and mass exchangers can be used for evaporation of liquids, as well as for hydrogen production technologies.     

Numerical investigation of liquid metal magnetohydrodynamic flow in multilayer flow channel inserts

In the high temperature liquid metal blanket of fusion-based hydrogen production reactor (named FDS-III), there is a remarkable feature that the multilayer flow channel inserts (MFCI) as function component are put into the breeding zone. The low thermal conductivity of MFCI can prevent the internal PbLi's heat conduct to the outside. So the outlet temperature can achieve high temperature around 1000 °C for high efficient production of hydrogen. However, the flow of liquid metal meandering through the MFCI will cause complex magnetohydrodynamic (MHD) effect under the strong fusion magnetic field. Liquid metal MHD effect is a key issue which should be concerned in high temperature breeder blanket (HTL). In this work, a numerical study was carried out to investigate the MHD effect of liquid metal PbLi in the MFCI. The MHD flows with typical modified geometry of the HTL MFCI were considered. The characteristics of flow and induced current fields were analyzed, and the pressure drop was evaluated. It also can be seen that the conductivity of the MFCI will have great impact on liquid metal flow's current and velocity distributions.