聚变堆中第一壁材料钨的紧束缚理论研究

为研究辐照时处于电子激发态下第一壁材料钨(W)的结构演化规律和热力学性质,采用紧束缚方法对聚变堆中W的物理性质进行理论研究。结果表明,体系在高能粒子辐照下诱导的电子激发导致了体系中被辐照的区域自发出现微孔、晶格急剧膨胀、熔点下降等现象。具体地,在中等电子温度(～5 000 K)以下,W的晶格膨胀主要由晶格温度驱动,但在电子温度较高时电子温度导致被辐照区域的晶格膨胀效应不可被忽略。特别是当电子温度很高(10 000 K)时,即便晶格温度不高,电子温度也会导致很大程度晶格膨胀。这对认识聚变堆中第一壁材料W在服役过程中的物理状态十分重要。     

聚变堆第一壁TiC涂层材料研究

本文介绍了第一壁ＴｉＣ涂层材料的化学气相沉积（ＣＶＤ）工艺；研究了涂层工艺条件对涂层微观结构、沉积速率和基体对涂层生长的影响；给出了涂层厚度与涂层工艺条件之间的经验关系式。讨论了ＴｉＣ／石墨、ＴｉＣ／ＭＯ、ＴｉＣ／３１６ＬＳＳ涂层材料的电子束热冲击损伤机理和热疲劳损伤机理，并对ＴｉＣ／石墨、ＴｉＣ／Ｍｏ、ＴｉＣ／３１６ＬＳＳ用做现行Ｔｏｋａｍａｋ第一壁材料的可行性进行了分析。     

聚变堆第一壁TiC涂层材料研究

介绍了TiC涂层的化学气相沉积工艺,TiC涂层材料的电子束热冲击实验和热疲劳试验。在温度为1100℃,CH_4流量为0.36L/min,H_2流量为1.16L/min的工艺条件下,得到了致密的TiC涂层,且沉积速率达0.7μm/min,并给出了涂层厚度与工艺参数之间的经验关系式。在高功率密度(最大值达226MW/m~2,作用0.6s)电子束热冲击下,TiC涂层从基体(石墨、钼、316L不锈钢)脱落,且316 L不锈钢基体被熔化、蒸发。在900℃到-246℃之间的热循环实验下,TiC/316L不锈钢表现出极差的抗疲劳特性,仅在2次热循环之后,就有大量TiC涂层从316L不锈钢基体脱落;虽然TiC/石墨的涂层中有大量网状裂纹形成,但是,在200次热循环之后,TiC涂层与基体仍结合很好;TiC/钼有很好的抗疲劳特性,在200次热循环之后,材料仍没有任何损伤。     

聚变堆第一壁材料的活化特性研究

聚变堆结构材料的活化以及由此产生的环境、辐射安全和放射性废物处置问题是堆的工程可行性关键问题之一,尤其是第一壁材料。本文研究了五种第一壁材料的活化特性,给出了这些材料的放射性、衰变热、BHP值以及WDR、RMR指标的计算结果;同时给出了满足10CFR61规范的各材料的杂质控制指标。本文的结果为聚变堆第一壁材料的选择和研制提供了依据。     

聚变反应堆壁材料钨和钼的表面离子束效应

利用扫描电子显微镜 (SEM )及氘的定量深度分布测量 ,系统地研究了在氘离子轰击下金属钨和钼的损伤情况 ,特别是钨表面气泡的形成及机制 ,以及氘在表面层的滞留量和气泡形成机制之间的关系。D+离子能量为 10 0eV— 1keV ,轰击剂量为 1× 10 19— 1× 10 2 1D+/cm2 。轰击过程中靶表面温度分别控制在室温、6 0 0℃和 80 0℃。     

聚变堆第一壁TiC涂层材料研究(英文)

介绍了TiC涂层的化学气相沉积工艺,TiC涂层材料的电子束热冲击实验和热疲劳试验。在温度为1100℃,CH_4流量为0.36L/min,H_2流量为1.16L/min的工艺条件下,得到了致密的TiC涂层,且沉积速率达0.7/μm/min,并给出了涂层厚度与工艺参数之间的经验关系式。在高功率密度(最大值达226MW/m~2,作用0.6s)电子束热冲击下,TiC涂层从基体(石墨、钼、316L不锈钢)脱落,且316L不锈钢基体被熔化、蒸发。在900℃到-246℃之间的热循环实验下,TiC/316L不锈钢表现出极差的抗疲劳特性,仅在2次热循环之后,就有大量TiC涂层从316L不锈钢基体脱落;虽然TiC/石墨的涂层中有大量网状裂纹形成,但是,在200次热循环之后,TiC涂层与基体仍结合很好;TiC/钼有很好的抗疲劳特性,在200次热循环之后,材料仍没有任何损伤。     

聚变驱动次临界堆第一壁材料辐照损伤的初步研究

介绍了中子对材料的辐照损伤原理及化合物原子平均离位(DPA)截面计算方法;使用辐照损伤计算程序SPECTER计算了聚变驱动次临界堆(FDS-I)第一壁材料CLAM钢的辐照损伤参数,并将CLAM钢的辐照损伤计算结果与相同条件下316SS、SiC等聚变堆结构材料的计算结果进行了比较.     

聚变堆第一壁涂层材料TiC和TiN的残余应力研究

采用Ｘ衍射法测定了聚变堆第一壁涂层材料ＴｉＣ和ＴｉＮ薄膜的残余应力．对涂层材料不同的制备方法（化学气相沉积ＣＶＤ和物理气相沉积ＰＶＤ）、基体材料（Ｍｏ、石墨和３１６ＬＳＳ）、涂层厚度及沉积温度对残余应力的影响进行了研究．结果表明，ＣＶＤ与ＰＶＤ制备的涂层的残余应力均为压应力，且ＣＶＤ较ＰＶＤ产生的残余应力要低，Ｔｉ／Ｍｏ（ＣＶＤ）随涂层厚度（１４μｍ～６０μｍ）的增加，残余应力增加．ＰＶＤ涂层的残余应力主要为本征应力，高达数ＧＰａ．其值随沉积温度（２００℃～６５０℃）的升高而降低．对残余应力产生的原因作了初步讨论     

聚变堆第一壁用纳米结构ODS钢的发展与前瞻

第一壁结构材料必须满足聚变堆极其严酷的工作环境要求,这是制约聚变堆发展的技术瓶颈之一。近年来发展起来的纳米结构氧化物弥散强化钢的特征性微观结构赋予了该材料优异的抗辐照性能,被视为第一壁结构材料的发展方向。本文简述了国内外第一壁材料的研究与发展概况。     

国际热核实验堆的建造与聚变堆材料研究

当前国际热核实验堆(ITER)的建造对推动聚变材料研究起着关键作用.本文介绍ITER建造对聚变材料研究带来的深刻影响及聚变材料研究本身将产生的变化,旨在让关心聚变材料研究的人们对聚变材料研究的进程、紧迫性和艰巨性有一初步认识.     

Impact of Material Configuration Behind First Wall on Helium Formation in In-Vessel Components of Fusion Reactor

The results of neutron transport calculations of the He formation based on the JENDL gas-production cross section file are discussed for some metals and alloys, namely ²⁷A1, Ti, ⁵¹V, Cr, ⁵⁵Mn, Fe, Ni, Zr, Mo, austenitic stainless steel (Ti modified 316 SS: PCA), Ni-base alloy (Inconel 625), ferritic steel (Fe-11Cr-1Mo: HT-9), Ti-base alloy (Ti-6A1-4V) and V-base alloy (V-5Cr-5Ti). Impacts of the two shields having the steel-rich and the H₂O-rich compositions and the two blankets having the Li₂O/Be-base and the liquid Li/Be-base compositions on the He formation rate in the above-mentioned metals and alloys are discussed. The relation between the He formation rate and the fast neutron flux (14.1 MeV>E>0.1 MeV) is investigated. The decrease of He formation at any distance Δ from the first wall more than Δ_as, the distance where the shape of neutron spectrum reaches its asymptotic form, is modelled by the simple formula based on the exponential dependence, as those reported so far for the fast neutron flux and the displacement damage rate.     

纳米流体对聚变堆材料流动腐蚀的实验研究

设计了旋转叶片式纳米流体腐蚀实验装置,以ITER堆内部件水冷设计方案为参考条件,开展了两种质量分数(0.01%和1%)氧化铝纳米流体对聚变堆结构材料RAFM钢、316L(N)钢及管道热沉材料CuCrZr合金等样品服役条件下的腐蚀实验。样品的SEM、EDS、XPS分析结果表明:两种质量分数的纳米流体对RAFM钢、316L(N)钢的腐蚀轻微,与纳米流体呈现良好的相容性;CuCrZr合金表面生成一层氧化膜,表面腐蚀形貌呈现出点坑及裂纹;腐蚀时间、纳米流体流速及纳米颗粒含量对腐蚀程度和表面形貌影响显著;CuCrZr合金表面发生了吸氧腐蚀与冲刷腐蚀,两者的耦合效应加速了腐蚀进程。     

聚变堆实验包层模块第一壁温度场及热结构分析

铍相对于众多聚变反应堆的第一壁护甲材料,有着许多优点,这些优点使它和钨及碳基材料一起被选作国际热核聚变实验堆（ITER）第一壁的候选防护材料。对中国氦冷固态增殖剂实验包层模块（CHHCSBTBM）第一壁进行多场耦合模拟分析结果表明,使用表面热负荷模拟分析时,未考虑中子负载情况下,模拟分析结果与其它结果有较大出入,故使用表面热负荷模拟分析时必须考虑中子负载情况。而对第一壁热结构分析表明,铍保护板的应力超过了其许用应力,可以寻找其它铍合金或第一壁护甲材料以满足第一壁护甲材料热结构应力要求。     

氢氦在钨中的影响的第一性原理研究

采用PBE形式的广义梯度近似(GGA)的第一性原理计算方法研究了氢或氦在钨中产生点缺陷的形成能以及缺陷形成后对钨的弹性的影响;采用同样的方法研究了空位和自间隙原子这两种缺陷。经计算发现:氢氦掺杂在钨的晶体结构中会引起晶体体积的变化,其变化结果跟掺杂的位置有关,在四面体或八面体处的掺杂会使晶体体积增加,替位掺杂会引起晶体体积减小;从形成能来看,氢掺杂在钨中最占优的位置是四面体处,而氦最占优的则是替位掺杂。在几种缺陷中,形成能最小的是氢的四面体掺杂,形成能最大的则是钨的自间隙原子形成;钨中若含有氢或氦的点缺陷,晶体的体弹模量和剪切模量会发生改变,当钨中含有氢替位或自间隙原子时晶体会向塑性改变,含有其他点缺陷时晶体会沿着脆性方向转变。但总体来说带有缺陷的钨仍然具有延展性。值得注意的是,氢或氦在钨中会引起晶体的各向异性,其具体结果与缺陷所处位置相关,只有缺陷属于替位时才不会发生各向异性。本文的研究工作可为第一壁材料的开发提供理论参考。     

Molecular Dynamics Study on the Diffusion Properties of Hydrogen Atoms in Bulk Tungsten

Molecular dynamics simulations were performed to study the diffusion behavior of hydrogen atoms in body-centered cubic(bcc) tungsten(W). The energy distribution of a single hydrogen atom in the (001) plane of tungsten lattice was computed. The values of diffusion barriers agree well with other theoretical and experimental results. The interaction between an H atom and a vacancy was simulated, which shows evidence of strong binding effect. The temperature effect on the diffusion behavior of hydrogen atoms was investigated. The critical temperature for an H atom to diffuse in bulk W with and without vacancies were calculated to be 950 K and 450 K, respectively, which is supported by several experimental results. In addition, the diffusion coefficient of hydrogen atoms in tungsten was evaluated and analyzed.     

Analyses of Passive Plasma Shutdown during Ex-vessel Loss of Coolant Accident in the First Wall/Shield Blanket of Fusion Reactor

An ex-vessel loss of coolant accident (LOCA) in the first wall/shield blanket of a fusion reactor has been analyzed by a hybrid code consisting of plasma dynamics and heat transfer analysis of in-vessel components. We investigated possibility of passive plasma shutdown scenario during the accident in International Thermonuclear Experimental Reactor (ITER). The safety analysis code which we developed can treat impurity concentration from the first wall and the divertor with a transport probability into the main plasma and a time delay given as input. It was found that the plasma is passively shutdown by a density limit disruption due to beryllium release from heated first wall surfaces about 168 seconds after the LOCA, when the transport probability of beryllium from the first wall into the plasma and the time delay were assumed to be 10^?2 and the energy confinement time, respectively. At that time, the surface temperature of the outboard center (plasma facing component (PFC) with beryllium) and the temperature of the coolant tube in the first wall (stainless steel 316) reach about 1,120°C and about 1,080°C, respectively. Although the coolant tube does not melt, the copper heat sink between the PFC and the coolant tube melts before the passive shutdown. The heat sink of copper in the outboard baffle also melts before the passive shutdown, though the PFC surface of tungsten does not melt. Consequently, we have a possibility of passive plasma shutdown before the cooling tubes melt during the ex-LOCA of the first walllshield blanket in ITER, however, further studies are needed on the effects on plasma burn control, impurity release and emission of implanted D-T fuel.     

Study on the RF inductively coupled plasma spheroidization of refractory W and W-Ta alloy powders

Spherical powders with good flowability and high stacking density are mandatory for powder bed additive manufacturing. Nevertheless, the preparation of spherical refractory tungsten and tungsten alloy powders is a formidable task. In this paper, spherical refractory metal powders processed by high-energy stir ball milling and RF inductively coupled plasma were investigated.By utilizing the technical route, pure spherical tungsten powders were prepared successfully, the flowability increased from 10.7 s/50 g to 5.5 s/50 g and apparent density increased from6.916 g cm~(-3) to 11.041 g cm~(-3). Alloying element tantalum can reduce the tendency to microcrack during tungsten laser melting and rapid solidification process. Spherical W-6 Ta(%wt)powders were prepared in this way, homogeneous dispersion of tantalum in a tungsten matrix occurred but a small amount of flake-like shape particles appeared after high-energy stir ball milling. The flake-like shape particles can hardly be spheroidized in subsequent RF inductively coupled plasma process, might result from the unique suspended state of flaky particles under complex electric and magnetic fields as well as plasma-particle heat exchange was different under various turbulence models. As a result, the flake-like shape particles cannot pass through the high-temperature area of thermal plasma torch and cannot be spheroidized properly.