含硼轻材料屏蔽14.1 MeV中子的实验研究

在零功率堆中子衰变常数(α常数)瞬态测量实验时,必须进行本底中子的屏蔽。利用理论计算和实验测定的方法,得到含B4C聚乙烯对D-T中子的屏蔽效果,并在此基础上,设计了探测屏蔽系统用于α常数的瞬态测量实验。测量结果与系统设计值相符,测量数据的信噪比与理论计算结果相吻合。     

含硼聚乙烯对D-T中子的屏蔽研究

利用理论计算和实验测定的方法,得知了含B4C聚乙烯对D-T中子的屏蔽效果,并在此基础上设计了探测屏蔽系统用于零功率堆中子衰变常数(俗称α常数)的瞬态测量实验．实验的信噪比、测量结果等与系统设计值及理论计算结果相符。     

系统安全分析程序TSACO的开发与验证

选择用于评估高温气冷堆系统安全分析程序瞬态分析能力的HE-FUS3实验装置为对象,利用自主开发的系统热工水力瞬态分析程序TSACO对其进行建模,并对稳态工况和失流事故进行模拟分析。计算结果表明,稳态工况下系统重要部件温度的TSACO程序计算值与HE-FUS3实验值符合较好,失流事故中系统流量和测试段出口温度的计算值与实验值均符合良好,证明了TSACO程序应用于系统瞬态热工安全分析的可靠性。     

西安脉冲反应堆在非脉冲瞬态工况下的动态特性研究

西安脉冲堆仪表与控制系统正在进行数字化改造,需要一套动态特性分析程序提供非脉冲瞬态工况下实时变化的功率和燃料温度等参数。本文在以往铀氢锆脉冲堆经典分析程序的基础上,对堆芯物理模型进行了优化和补充,建立了西安脉冲堆动态特性分析模型,开发了可用于非脉冲瞬态工况分析的西安脉冲反应堆动态特性分析程序（XPRDCA）,开展了堆上实验,将程序的计算结果与堆上实验结果进行了对比,并研究了燃料温度反应性系数和气隙传热系数对动态特性的影响。结果表明,程序计算结果和堆上实验结果符合较好,采用优化后模型的动态特性分析程序计算速度显著提升。该程序可以用于数字化仪表与控制系统的设计和调试。      

基于FR-Sdaso的法国凤凰堆寿期末自然循环实验分析

系统分析程序是开展反应堆安全分析的重要工具之一,也可用于开展系统瞬态实验过程的分析。法国凤凰堆（Phenix）在停运之前开展的自然循环实验是钠冷快堆领域非常重要的系统瞬态实验,为研究钠冷快堆的瞬态特点提供了很好的参考。为分析此实验过程,利用自主研发的系统分析程序FR-Sdaso对凤凰堆进行建模,对其自然循环实验开展计算分析,并将主要参数的计算值与实验值进行了对比分析。结果表明,FR-Sdaso可较好地模拟此实验的瞬态过程,可用于开展钠冷快堆此类瞬态的安全分析。     

基于FR-Sdaso的法国凤凰堆寿期末自然循环实验分析

系统分析程序是开展反应堆安全分析的重要工具之一,也可用于开展系统瞬态实验过程的分析。法国凤凰堆(Phenix)在停运之前开展的自然循环实验是钠冷快堆领域非常重要的系统瞬态实验,为研究钠冷快堆的瞬态特点提供了很好的参考。为分析此实验过程,利用自主研发的系统分析程序FR-Sdaso对凤凰堆进行建模,对其自然循环实验开展计算分析,并将主要参数的计算值与实验值进行了对比分析。结果表明,FR-Sdaso可较好地模拟此实验的瞬态过程,可用于开展钠冷快堆此类瞬态的安全分析。     

西安脉冲堆计算值和实测结果分析

介绍了西安脉冲堆堆芯布置、计算模型和程序以及计算值与实验测量结果分析。西安脉冲堆在满功率（2MW）下连续运行了72小时，证明西安脉冲堆整个系统和设备是良好的、安全可靠的。根据西安脉冲堆计算值与测量值的比较，证明计算程序可靠，具有较高精度。西安脉冲堆理论计算值与实验测量值符合较好，完全满足工程设计要求，实验测量结果达到了设计指标的要求。     

高能脉冲电子束诱变筛选丙酮丁醇梭菌及发酵研究

实验以丙酮丁醇梭菌(Clostridium acetobutylicum)CICC8012为出发菌株,采用高能脉冲电子束(High energy pulsed electron,HEPE)对丙酮丁醇梭菌进行辐照诱变,通过含丁醇的固体培养基对诱变菌株进行胁迫,诱使丙酮丁醇梭菌的丁醇耐受性提高.经过多次诱变和筛选,最终获得...     

脉冲反应堆脉冲运行瞬态的子通道分析

为获得脉冲运行瞬态的堆芯温度场变化情况,本文开发了适用于低温、常压工况的脉冲反应堆瞬态热工分析子通道程序PRC-STAC。利用TRIGA MARKⅡ反应堆的瞬态参数对程序进行了验证,验证结果表明,二者符合较好。利用PRC-STAC程序计算了西安脉冲堆燃料元件和堆芯冷却剂的瞬态热工参数,并讨论了脉冲运行对燃料元件的安全影响。     

钠冷快堆直流式蒸汽发生器固定网格与滑移网格模型对比分析

根据钠冷快堆核电厂直流式蒸汽发生器(OTSG)的热工水力特性,基于固定网格模型和滑移网格模型编制了OTSG瞬态分析程序OTAC。对美国能源技术工程中心(ETEC)的OTSG停闭实验进行了模拟,并将计算值与实验值作了对比分析。结果发现,两种模型的计算值与实验值吻合较好,其中固定网格模型只有在网格数目足够多时才能避免计算结果的突跳,而滑移网格模型可在较少网格数目下取得很好的计算效果,提高了数值稳定性,避免了计算结果的不连续。     

The AC losses measurement and analysis of superconducting NbTi CICC for HT-TU superconducting Tokamak

Superconducting TF and PF coils have been measured in SULTAN test facility. Segregated copper strands are included in four NbTi CICC and this is a technical innovation. Two AC losses measurement methods, calorimetric and electromagnetic methods, have been used in the experiments, and a broad frequency range (from 0.05 Hz to 6 Hz) is covered in sample test. The purpose of this experiment was to investigate AC losses of TF and PF CICC conductor including segregated copper and to check the design of PF and TF CICC coated with different resistive barriers (Pb-30Sn-2Sb and Ni plating on NbTi strands).     

Stability and design criterion for cable-in-conduit-conductors with a broad transition to normal state

Stability criterion in cable-in-conduit conductors (CICC) is often associated with heat removal rate higher than heat generated in the normal zone, which requires low current density in the strands. We show that this criterion is not a mandatory requirement for serviceability of CICC and that CICC may work reliably at higher current densities. In conditions of limited and well defined perturbations, sufficient stability is provided not by a large amount of copper and high transient heat transfer, but by a smooth transition to the normal state and easy current redistribution. A strand parameter space in terms of I_c and N-value meeting CICC requirements for stability, limited heat generation, and minimum temperature margin is proposed and discussed. The theory predictions are compared with known experimental data on CICC.     

CICC Joint Development and Test for the Test Facility

The superconducting joint of the NbTi Cable-in -conduit Conductor (CICC) has been developed and tested on the magnet test facility at Institute of Plasma Physics, Chinese Academy of Sciences. The CICC is composed of (2NbTi+lCu)x3x3x(6+ltube) strands each with 0.85 mm in diameter, which has been developed for a central solenoid model coil. The effective length of the joint is about 500 mm. There have been two common fabrication modes, one of them is to integrate the 2 CICC terminals with the copper substrate via lead-soldering, and the other is to mechanically compress the above two parts into an integrated unit. In the current range from 2 kA to 10 kA the joint resistance changes slightly. Up to now, 11 TF magnets, a central solenoid model coil, a central solenoid prototype coil, and a large PF model coil of PF large coil have been completed via the latter joint in the test facility.     

Manufacture of ITER feeder sample conductors

The ITER feeders are the components that connect the ITER magnet systems located inside the main cryostat to the cryogenics, power-supply and control system interfaces outside the cryostat. The feeder busbars rely on the Cable-In-Conduit Conductor (CICC) design concept as all the conductors for the ITER magnet systems. There are two types of busbars for the feeder systems. One is the Main Busbar (MB) for the TF, CS and PF feeders, and the other is the Corrector Busbar (CB) for the CC feeders. The busbar cable is wound from multiple stage sub-cables made with Cu and superconducting strands. The superconducting material is NbTi for the busbar strands of all feeder systems. All Feeder conductors are provided by China. The R&D programs are needed to acquire knowledge on the behavior of such conductors.Since the conductors are new, some full size copper dummy conductors have been produced for the testing of the cabling parameters, definition of automatic TIG welding of seamless jacket section, elaboration of cable insertion and compaction. Then, two short qualification conductor samples (MB and CB) are prepared in ASIPP, and NbTi advanced strands are produced by Western Superconductor Technology (WST).The details of manufacturing procedures for Feeder conductor samples will be described in this paper.     

Entropy generation minimization (EGM) to optimize mass flow rate in dual channel cable-in-conduit conductors (CICCs) used for fusion grade magnets

Dual channel cable-in-conduit conductors (CICCs) used in tokamaks such as International Thermonuclear Experimental Reactor (ITER) consist of annular channel packed with superconducting strands and a clear central channel separated by a spiral from the annular channel. Supercritical helium (SHe) operating at 4.5 K and 0.5 MPa is used for forced convective cooling of CICC. Pressure drop is inevitable in the process of forced convective cooling, leading to the development of velocity gradients and temperature gradients. These velocity gradients and thermal gradients result in entropy generation in CICCs.The present work aims at estimating volumetric rate of entropy generation (EG) in dual channel CICC. Subsequently, entropy generation minimization (EGM) technique is used to find optimum mass flow rate at which volumetric rate of EG is minimum. Pumping power and heat transfer corresponding to minimum rate of EG are also calculated. Computational fluid dynamics (CFD) is used as a tool to estimate EG as the analytical solution for turbulent forced convective flows requires inaccurate simplifications. A three dimensional model of dual channel CICC is developed in GAMBIT-2.1 and solved using a compatible solver FLUENT-6.3.26. The annular region of CICC is assumed to be porous and the central channel is assumed as clear region for EG analysis using CFD. The pressure gradients and heat transfer coefficient estimated from the simulations are validated against relevant experimental results available in the literature. The effect of mass flow rate on volumetric rate of EG in turbulent forced convective flow is studied using CFD.     

Characterization of superconducting wires and cables by X-ray micro-tomography

Due to their mechanical strength and ability to withstand the large electromagnetic force applied to the superconductors in large magnets during excitation, the Cable-in-Conduit-Conductor (CICC) type superconductors will be employed in the next stage of fusion magnets. Here, we discuss the recent results on the application of a non-invasive method for the characterization of CCIC by X-ray micro-tomography (μXCT). The experiments have been carried out on a high resolution X-ray tomograph in INFLPR (http://tomography.inflpr.ro). An open type nanofocus X-ray source with maximum high voltage of 225 kVp at 15–30 W maximum power and multiple targets of W on different windows materials (Be, Al, Cu or diamond) is the main component. X-rays are detected by means of amorphous silicon flat panel sensor in the cone-beam configuration and high-energy efficient line sensor based on individual scintillators in the fan-beam scanning configuration. The quality of tomographic images (≈40 μm space resolution) allowed the majority of strands of analyzed CICC samples to be fully reconstructed along the investigated segment (up to 300 mm long). Our method provides: (i) local and global void fractions (over a 300 mm length of the sample), (ii) void homogeneity factor as the ratio between void space surface and perimeter and (iii) twist pitch angle of individual strands and its distribution in 3D. It can be used to investigate superconducting CICC during their manufacture, installation or after service inspection, for purposes of QA, characterization or development.     

Thermal analysis of toroidal field coil in EAST at 3.7 K

The thermal performance of toroidal field (TF) coil is studied at 3.7 K in Experimental Advanced Superconducting Tokamak device (EAST) to obtain the higher stability for the higher plasma parameters operation. It is a good way to lower the operating temperature of TF coil to acquire the higher stability margin. This paper describes the structure and cooling process design of TF coil and case firstly. Based on the thermal load in the case, the thermal performance of the TF coil is performed at the plasma disruption state. The helium temperature in the cable-in-conduit conductor (CICC) and case is evaluated during the 1.5 MA plasma disruptions. Then, the experimental results of TF coil which has been cooled at 3.7 K and discharged in 10 kA are shown including the thermal loss evaluation. Finally, the thermal stability performance of TF coil is analyzed according to the 3.7 K experimental results and the stability prediction is performed at 1.5 MA plasma current operations.     

Simulation and test of quench in CICC: The SMES experience

This paper summarizes the work done as part of the U.S. SMES program to simulate quench evolution on the 200 kA CICC developed by the Bechtel Team. As a large-scale CICC with a central tube, this work has led to a number of results applicable to other conductors sharing similarities with the SMES-CICC. The paper presents the evolution in computational models, since 1987 to date, and describes QUIPS, a test intended to validate these computer models. The paper concludes with observations on the directions in the field as perceived by the author.     

Calculation of AC Losses of CICC for Superconducting Outsert Coils in a Hybrid Magnet

This paper is devoted to predict AC loss of Cable in Conduit Conductor (CICC) which is of importance in the design of conductors. The consideration for the conductor’s design and main parameters for the magnets are introduced. In order to attain a good accuracy in the calculation of AC losses, the field distribution within superconducting outsert should be considered. Calculation of the AC losses, including hysteresis losses and coupling losses, is conducted. An emphasis is put on the hysteresis loss during the ramp up of the current to the operational current (15.3 kA) and the coupling loss of the conductor in a power-down condition for insert. The results are obtained to be 74.9kJ and 950J for 40 T hybrid magnets, respectively. Based on the calculation, a brief analysis of losses effect on the conductor design and the operation of magnet is given for the purpose that the capacity of the cryogenertor can be evaluated and the stability regime can be improved in our future work on the hybrid magnets.     

Current Sharing Temperature Test and Simulation with GANDALF Code for ITER PF2 Conductor Sample

Cable-in-conduit conductor （CICC） conductor sample of the PF2 coil for ITER was tested in the SULTAN facility. According to the test results, the CICC conductor...