CLAM钢中氕氘的渗透与去除

低活化铁素体/马氏体钢（RAFM钢）是聚变堆产氚包层的优选结构材料。氢同位素在结构材料中的扩散渗透特性关系到产氚回收率、燃料循环及运行安全。本工作对国内研发RAFM钢之一的CLAM钢进行了气体驱动的氘渗透实验,得到573～873 K温度范围内氘的宏观溶解度S（mol/(m³•Pa^0.5)）为0.264exp(-22 447/RT),扩散系数D（m²/s）为1.38×10^-7exp(-17 271/RT),渗透率Φ（mol/(m•s•Pa^0.5)）为3.64×10^-8exp(-39 718/RT)。还进行了氕氘气体混合物的渗透实验,确认了渗透同位素效应;探索了钢中溶解氘的真空热释放去除。     

氚在RAFM钢中的渗透

采用气相渗透方法，开展了国产低活化铁素体/马氏体钢（RAFM钢?）之一的CLAM钢的氚渗透实验，研究了影响渗透的关键因素，建立了可靠的实验方法。在573~823?K温度范围内，得出氚的渗透率F_T为2.57×10-8exp(-38639/RT)，氚溶解度S_T为2.2×10-1exp(-38639/RT)，扩散系数D_T?为1.17×10-7exp(-22011/RT)。另外，氘氚混合渗透时存在明显的正同位素效应，在实验温度范围内，推导得出的氘氚渗透分离系数α_DT为1.42，氕氚渗透分离系数α_HT为3.76。      

氧化物弥散强化低活化合金的微观组织及力学性能

为了强化低活化合金(CLF-1)的高温性能,将采用Ar气超声雾化方法制备的CLF-1粉末与纳米Y₂O₃粉末混合后,经高能球磨和热等静压处理,获得氧化物弥散强化（ODS）CLF-1样品。对样品进行不同制度的热处理,并进行了微观组织分析和力学性能测试。分析结果表明,经过正火和回火处理,ODS CLF-1组织为回火马氏体,当正火温度为1 100 ℃时晶粒尺寸最为均匀。回火温度对显微组织影响不明显,但回火温度升高,维氏硬度下降。热处理后样品中观察到明显的弥散分布的Y₂O₃颗粒和位错塞积,证实了弥散强化的作用。Y₂O₃颗粒尺寸不均匀,100 nm左右的大颗粒倾向于沿晶界分布,而较小的颗粒则在晶内分布。ODS CLF-1样品具有良好的高温拉伸性能,600 ℃时抗拉强度为370 MPa,延伸率为18.5%。屈服强度和抗拉强度随热处理温度的升高而降低。     

中国低活化马氏体钢CLAM研究进展

低活化铁素体/马氏体钢(RAFM钢)被普遍认为是未来聚变示范堆和聚变动力堆的首选结构材料。国际上给予了高度重视,许多国家都在研发其特有的RAFM钢。中科院等离子体物理研究所在与国内外多家单位的合作下发展了中国低活化马氏体钢———CLAM。本文总结了CLAM钢研制发展的主要进展,包括其成分优化设计、冶炼加工制备工艺、物理性能、机械性能、辐照性能及与液态LiPb的相容性等测试与研究以及各种焊接工艺研究等,并对今后的发展方向进行了展望。     

注氘低活化马氏体钢在电子辐照下的缺陷行为

低活化铁素体/马氏体(RAFM)钢被视为国际热核聚变反应堆以及聚变反应堆的第1壁候选结构材料之一,很多国家均在研究不同的RAFM钢,中国低活化马氏体(CLAM)钢的研究亦正在进行。核聚变会产生氢、氦、氘及氚,这些气体元素与辐照缺陷结合在一起,对材料的辐照性能会产生较大影响。本文对注氘后不同温度下的辐照后微观结构进行研究。试验利用日本北海道大学的JEOL-1300高压电子显微镜研究注氘CLAM钢从室温到873K在1250keV电子辐照下的微观结构变化。研究结果表明,在电子辐照下,注氘产生的缺陷团会出现消失和长大两种现象,意味着间隙型与空位型位错环在注氘过程中同时产生。并研究了注氘产生的空洞。     

1.61 dpa/300℃中子辐照后CLAM钢的硬化和脆化行为

较低温度(350℃)下,反应堆结构材料的中子辐照硬化与脆化行为一直是其核工程应用中关注的热点问题之一。低活化铁素体/马氏体钢(RAFM)是国际热核聚变堆实验包层模块(ITER-TBM)首选结构材料,其在寿期内受到的中子辐照累积剂量不超过3 dpa,服役温度300~500℃。为推进具有我国自主知识产权的中国低活化钢-CLAM钢在ITER中国实验包层模块(ITER-CN-TBM)中的应用,本文通过开展1.61 dpa/300℃中子辐照前后CLAM钢拉伸性能和冲击性能测试以及与国际同类低活化钢相近辐照条件下的性能数据进行对比分析,研究了中子辐照后CLAM钢的硬化和脆化行为。结果表明,CLAM钢辐照后在室温测试时的抗拉强度和屈服强度分别为692 MPa和596 MPa,相比辐照前分别增加了29 MPa和56 MPa,表现出一定程度的辐照硬化。辐照后的韧脆转变温度DBTT相比辐照前增加了56℃,出现辐照脆化现象。与国际同类低活化钢在相近辐照条件下的测试结果对比分析,表明CLAM钢具有相对优异的抗中子辐照能力。     

低活化马氏体钢在ITER水环境中的腐蚀性能研究

低活化马氏体钢作为聚变堆候选的结构材料,其腐蚀性能影响冷却回路辐射场的分布。本文选取CLAM、CNS-1和SCRAM-9 3种钢材,并用T91与3种钢材进行对比,分析4种材料的性能。整个实验回路温度维持在150 ℃,溶氧量小于0.01 mg/kg,pH值为7（20 ℃）,电导率小于1 μS/cm,压力为1 MPa,水的流速设为6 m/s。实验后,所有样品均采用失重分析法、XRD、EDS及SEM分析。结果显示,随着时间的增加,材料的失重量增加,腐蚀速率减少。4种材料的失重量均遵循幂函数规律,T91钢的耐腐蚀性较另3种钢好,而3种材料中CLAM的抗腐蚀性能相对更好;样品表面氧化层变得越来越致密且非常薄。氧化层腐蚀产物主要是Fe₂O₃和Fe₃O₄。     

D+注入Li4SiO4的表面化学状态及其热解吸行为

锂陶瓷氚增殖剂的氢同位素行为是聚变堆固态产氚包层关心的重要课题。本文将3 keV D⁺注入Li₄SiO₄,采用X射线光电子能谱在线分析注氘前后材料表面的化学状态,同时采用热解吸谱（TDS）实验技术,研究注氘后Li₄SiO₄中氢同位素的热解吸行为。实验结果表明：D⁺注入会改变Li₄SiO₄表面的化学环境,产生多种辐照缺陷和化学键合状态;氘滞留量和热解行为受注氘时样品的温度影响较大,可在一定程度上预测产氚包层中氚的滞留行为。     

聚变驱动次临界堆双冷嬗变包层结构设计与分析

给出聚变驱动次临界堆液态金属LiPb/He气双冷嬗变包层参考结构概念,采用了低活化铁素体/马氏体RAFM钢(如CLAM)作为结构材料、简单液态金属流道、两个独立氦气冷却系统以及燃料球/颗粒等设计方案。重点分析了嬗变包层第一壁、重金属区与裂变产物嬗变区的结构设计特点。     

球形压头半径对离子辐照后RAFM钢硬度及力学性能提取的影响

纳米压痕仪中压头形状直接决定压头载荷-深度曲线，进而影响宏观力学性能的提取，但压头半径对辐照后材料硬度及力学性能提取的影响依然缺乏深入的研究。本文研究了不同半径球形压头(0.3、1.0和10.0μm)对辐照后低活化铁素体/马氏体(RAFM)钢硬度和力学性能提取的影响。不管压头半径如何改变，所有辐照样品均出现反尺寸效应，纳米压痕仪接触面积测量误差是导致该现象产生的主要原因。此外，离子辐照后所有样品均出现辐照硬化，但随着辐照剂量的增加，硬化现象逐渐减弱，直至出现辐照软化。相同载荷与辐照剂量条件下，低活化铁素体/马氏体钢硬度随压头半径的增加而逐渐降低。不管辐照剂量如何改变，随着压头半径的增加，提取出的弹性模量逐渐增加而屈服强度逐渐减小。相同压头半径时，弹性模量和屈服强度随辐照剂量的增加均呈现先增加后减小的趋势。对比未辐照样品，压头半径增加至10.0μm时，所提取出的屈服强度和弹性模量更接近于拉伸实验所获得的数值。以上结果表明：球形压头可用于提取离子辐照后低活化铁素体/马氏体的宏观力学性能，并且半径越大预测结果越接近拉伸实验所获得的数值。     

氚在RAFM钢表面的吸附研究

采用气相吸附法研究了室温下RAFM钢表面对氚的吸附与释放行为,并使用316L钢、1Cr18Ni9Ti钢进行了对照实验。结果表明,RAFM钢表面的氚吸附与释放性质与316L钢、1Cr18Ni9Ti钢的非常相似,相同表面状态的样品,在相同实验条件下的吸附氚量相差不超过50%。可推测,未经深度除水处理的RAFM钢暴露于氚后,表面会形成富氚层,浓度远高于基体溶解氚,厚度不大于10 μm。表面氚的形态以化学吸附和物理吸附的氚化水为主,约占90%以上。室温下RAFM钢表面吸附的氚在干燥气氛中的释放非常缓慢,但遇水会因氚-水间的同位素交换而加速释放。     

Hydrogen permeation of Hastelloy XR for high-temperature gas-cooled reactors

Hydrogen permeation of Hastelloy XR, which was developed for high-temperature gas-cooled reactors, has been investigated with a simulated gas to the reactor environment, 80% H₂ + 15% CO + 5% CO₂. In this gas environment, Hastelloy XR formed chromium oxide and manganese-spinel oxide on the surface and showed a good quality to prevent hydrogen permeation. The prevention behavior can be interpreted in terms of a hydrogen diffusion model in a uniform oxide layer, and dependences of permeation rate on time and temperature are explained by variation of oxide thickness. The pressure dependence of the permeation rate for the oxidized alloy as well as bare metals obeyed Sieverts' law. The environmental effects on hydrogen permeation are also discussed on the basis of correlation between the characteristics of the surface layer and the permeation behaviors.     

PdY合金管束的氢渗透性能

PdY合金膜因其具有良好的透氢性能与机械性能,有望应用于聚变堆氢同位素纯化工艺。基于PdY合金膜的服役参数及氚安全要求,有必要研究在低氢压下PdY合金膜的氢同位素渗透特性,为后续设计氢同位素纯化组件提供数据支撑。本工作基于直管外压式PdY扩散器,研究了低氢压(<50 kPa)、工作温度为350～450℃条件下,厚度为80μm的PdY合金薄膜管的氢渗透速率与膜两侧压力、工作温度的关系。结果表明,低氢压下,PdY合金膜的氢渗透规律符合■,且压力指数n等于0.9,渗透速率控制机制主要表现为表面过程控速;提高工作温度使得合金膜的渗透通量增大,且温度对扩散过程的影响更大,使渗透过程更加趋于表面控速。此外,计算了该工作温度范围下的渗透系数,并通过阿伦尼乌斯公式推导求得渗透活化能约为24.54 kJ/mol,渗透常数Φ₀为5.86×10^-6 mol/(m·s·kPa^0.9)。低氢压下,该厚度膜的渗透系数可由5.86×10^-6e~(-24.54/(RT)) mol/(m·s·kPa^0.9...     

Tritium diffusivity in crystal grain of Li2TiO3 and tritium release behavior under several purge gas conditions

It has been reported by the present authors that behavior of tritium release from solid breeder grain is consisted of diffusion in grain, tritium transfer at surface layer and surface reactions on grain surface such as adsorption or isotope exchange reactions. Tritium release curves estimated using the tritium release model gave good agreement with observed tritium release curves from Li₄SiO₄, Li₂ZrO₃ or LiAlO₂.

Tritium release behavior from Li₂TiO₃ under humid purge gas, dry purge gas and dry purge gas with hydrogen conditions is discussed in this study, tritium release curves using the release model that we proposed previously give a good agreements with experimental tritium release curves. Tritium effective diffusivity in the crystal grain of Li₂TiO₃ is also estimated in this study using a curve-fitting method applied to the release curves obtained under the humid purge gas condition. It is discussed that change of color of Li₂TiO₃ surface under hydrogen purge gas condition is observed and this phenomenon might affect tritium release behavior from Li₂TiO₃.     

R&D progress of Korean HCSB TBM

Several R&Ds are being performed for Korean helium cooled solid breeder (HCSB) test blanket module (TBM) in the field of hydrogen isotopes permeation characteristics measurement in the helium purge line, joining technologies of structural materials, breeder pebble materials development, and the measurement of pebble bed characteristics. Electron beam welding for reduced activated ferritic–martensitic (RAFM) steel is evaluated to find optimal welding conditions. Also, a hydrogen permeation measurement apparatus is newly installed for the evaluation of the permeation barrier characteristics of stainless steel and RAFM steels. Two fabrication methods of lithium orthosilicate pebbles are investigated using slurry droplet methods. As methods of silicon carbide coating on the graphite pebble, microwave coating and chemical vapor deposition coating are evaluated. Two apparatuses are established to assess the thermo-mechanical properties of graphite and breeder pebble beds. The current status of R&D activities on these areas is introduced and the main progresses are addressed in this paper.     

Hydrogen transport and solubility in 316L and 1.4914 steels for fusion reactor applications

Equations are given which describe the permeation rate, diffusivity and solubility of hydrogen over the range 250–600°C at pressures up to 10⁵Pa for the 316L stainless and modified 1.4914 martensitic candidate steels proposed for the construction of the Next European Torus (NET). For heat-treated 316L steel, the permeation rates measured agreed well with previous work and did not vary significantly from specimen to specimen or from batch to batch.

Measurements of the permeation rate of hydrogen and deuterium through the modified 1.4914 steel, believed to be the first made, show that the martensitic steel is significantly more permeable than the austenitic steel, by an order of magnitude at 250°C and a factor of five at 600°C. This difference could make it necessary to use permeation barriers on critical components made from the martensitic steel in order to reduce the tritium permeation rate to acceptable levels.     

Hydrogen and Deuterium Transport through Type 304 Stainless Steel at Elevated Temperatures

The permeation time-lag method have been used to determine the permeabilities, diffusion coefficients and solubilities of hydrogen and deuterium in type 304 stainless steel of three kinds of surface treated specimens; with oxide film, reduced by H₂ gas and Pd coated. For the specimen with a thin oxide film the permeability increased abruptly at the temperature higher than 1,050 K owing to reduction of the oxide film by H₂ gas introduced. The permeability and diffusion coefficient for hydrogen-reduced specimens agreed with those for Pd-coated specimens showing the data of bulk diffusion limited. The isotope effects for permeability Φ_H/Φ_D, diffusion coefficient D _H/D _D and solubility were about 1.4, 1.2 and 1.1, respectively. From these values θ(=hν/k)=1,530±50K and θ′(=hν/k)=2,740±20K were obtained by the quantum effect of a harmonic approximation.