奥氏体321不锈钢在550 ℃静态铅铋共晶合金中的腐蚀行为

奥氏体321不锈钢常用作核反应堆冷却剂主管道结构材料,铅铋共晶合金是第四代核能系统（Gen Ⅳ）铅冷快堆冷却剂的主要候选材料。为研究321不锈钢与高温液态铅铋共晶合金的相容性,对321不锈钢在550 ℃液态铅铋共晶合金中的200、400、600 h腐蚀现象进行了研究。对不同腐蚀时间后腐蚀试样的表面和截面分别进行了XRD和SEM、EDS检测。结果发现：在321不锈钢试样表面产生了一种随腐蚀时间增加先生长后脱落的含O、Ti、Pb元素的化合物（Ti₂O和Pb₂O₃）;在321不锈钢基体与铅铋共晶合金交界处会产生一层随腐蚀时间增加不断增厚的扩散层;321不锈钢在铅铋共晶合金中发生溶解腐蚀,在Fe、Cr元素不断向铅铋共晶合金中溶解时,伴随着Pb、Bi元素向基体中的渗透。     

铁素体/马氏体钢和奥氏体不锈钢的液态铅铋腐蚀行为与机理

液态铅铋共晶合金[liquid lead-bismuth eutectic,LBE,Pb44.5Bi55.5,%(质量分数)]具有优异的热工水力和中子学性能,是第四代液态金属冷却快堆最重要的冷却工质之一。但是,液态铅铋冷却快堆的主要候选材料包括铁素体/马氏体钢(如T91)和奥氏体不锈钢(如316L和15-15Ti)存在液态金属腐蚀问题,一定程度上阻碍了液态铅铋快堆工程化应用进度。本文综述了液态铅铋腐蚀的基本机制以及铁素体/马氏体钢和奥氏体不锈钢的液态铅铋腐蚀行为,总结了抑制液态铅铋腐蚀的主要方法,并展望了未来研究方向。     

液态铅铋回路设计研制与材料腐蚀实验初步研究

铅铋合金共晶体是加速器驱动次临界系统(ADS)重要的散裂靶材料和冷却剂候选材料,也是先进快中子堆的重要冷却剂材料,液态铅铋回路是开展液态铅铋合金相关技术研究的必备实验平台。FDS团队正在设计研制KYLIN系列铅铋实验回路,本文基于中国首座热对流铅铋回路KYLIN-Ⅰ开展了马氏体钢T92、CLAM和奥氏体钢316L在480℃下,流速为0.14 m/s的饱和氧浓度铅铋中的腐蚀实验研究。初步实验结果显示,三种实验材料均发生氧化腐蚀。     

水化学对燃料元件包壳腐蚀行为的影响

燃料元件包壳的水侧腐和吸氢是当前进一步提高燃耗的主要限制因素，由于一回路水中加入Ｈ３ＢＯ３和ＬｉＯＨ，使包壳的腐蚀问题变得更为复杂。本文综述了ＬｉＯＨ及ＬｉＯＨ－Ｈ３ＢＯ３对锆合金水侧腐蚀的影响，以及研究这种影响机理的现状。     

T91钢在氧浓度为0.01ppm静态铅铋合金中的界面腐蚀特征

开展了铅基反应堆候选结构材料T91钢在500℃、0.01ppm氧浓度、静态铅铋共晶合金(LBE)中的腐蚀行为研究,腐蚀时间依次为500、1 000、2 000h。采用SEM观察腐蚀界面组织形貌,并结合EDX分析界面产物成分及元素扩散行为。结果显示:T91钢发生了氧化腐蚀,表面生成了具有3层结构的氧化膜。最外层为疏松且有LBE渗透的Fe3O4层,中间层为致密且具有保护性的(Fe,Cr)3O4层,最内层为富含铬元素的内氧化层(IOZ)。随着腐蚀时间的增加,Fe3O4层和(Fe,Cr)3O4层的厚度先快速增加,在1 000h时分别达到6.5μm和7.4μm;随着腐蚀时间进一步增加,Fe3O4层的厚度略有减小而(Fe,Cr)3O4层的厚度略有增加,而IOZ的厚度却一直近似以线性规律缓慢增加。     

铅铋合金环境中高强AlCrFeNi多主元合金的腐蚀行为

传统结构材料限制了铅铋核能系统性能的进一步提高,为给铅铋反应堆提供高性能结构材料,针对高强Al₁₇Cr₁₀Fe₃₇Ni₃₆多主元合金开展了高温静态铅铋合金环境相容性研究。研究表明,在500~600℃的铅铋饱和氧环境下,合金形成致密的Fe-Cr-Al-O氧化膜与疏松的氧化铁双层氧化膜结构,双层氧化膜厚度仅有1.5 μm,氧化膜生长速率极低;Fe-Cr-Al-O氧化膜在高温铅铋环境具有极佳的致密性、结构与组织稳定性,显著保护了液态铅铋向基体溶解。相比于传统的铁素体/马氏体钢（F/M钢）、奥氏体不锈钢,Al₁₇Cr₁₀Fe₃₇Ni₃₆多主元合金在高温铅铋环境中应用具有明显的优势。     

铅铋快堆堆芯包壳多场耦合腐蚀行为的数值模拟研究

铅铋快堆中液态铅铋（LBE）腐蚀结构材料是制约铅铋快堆发展的关键难题之一,液态铅铋流动过程中对结构材料的侵蚀作用不可忽视。为开展高温液态铅铋环境下堆芯燃料包壳动态腐蚀特性研究,本文针对包壳管候选材料T91钢建立氧化、还原、侵蚀耦合腐蚀模型,结合计算流体力学（CFD）方法,对燃料包壳表面腐蚀现象进行模拟研究,并对影响腐蚀的关键因素进行分析。研究结果表明：一定铅铋流速下,燃料组件内沿液态铅铋流动方向,包壳表面温度越高,尖晶石层平衡厚度越厚,包壳厚度损失速率越高,运行800 h后,燃料组件仅剩出口处残留磁铁矿层;随着燃料组件入口液态铅铋流速的增加,包壳厚度损失速率越高;当入口流速为2 m/s,氧化层稳定情况下,中心棒的包壳厚度损失速率为0.044 98 mm/a;当燃料组件包壳表面氧浓度大于发生氧化反应的最低值时,包壳厚度损失速率随包壳表面温度升高而增加;当包壳表面氧浓度小于发生氧化反应的最低值时,包壳会直接被液态铅铋溶解,溶解速率高达上千mm/a。     

U-Zr合金燃料与铅、铋及其合金静态相容性研究

U-Zr合金燃料与液态铅、铋及其合金静态相容性是铅铋冷却反应堆燃料论证及设计的重要依据。试验选取600oC,保温1 000 h范围内,开展了U-Zr合金燃料与铅、铋及其合金静态相容性的研究。采用扫描电镜(Scanning Electronic Microscopy,SEM)及X射线衍射(X-ray Diffraction,XRD)分析了U-Zr合金燃料与铅铋等合金的界面反应情况,试验结果表明:U-Zr合金样品在铅铋合金的长时间(1 000 h)作用下,产生了不同程度的侵蚀现象,侵蚀程度可达到mm级。纯铋、纯铅、铅铋、铅锡、铅铋锡等均对U-Zr芯块有一定程度的侵蚀,其侵蚀程度排序约为BiPb-BiPb-Bi-SnPb≈Pb-Sn。U-Zr芯块的腐蚀机理为溶解和共晶形成金属间化合物的综合过程,U和Pb、Bi分别能够形成金属间化合物UPb_3和UBi_2。U-Zr芯块的侵蚀程度取决于U和Zr在冷却剂成分中的固溶度和共晶反应速率。     

A Review on the Potential Use of Austenitic Stainless Steels in Nuclear Fusion Reactors

Various engineering materials; austenitic stainless steels, ferritic/martensitic steels, vanadium alloys, refractory metals and composites have been suggested as candidate structural materials for nuclear fusion reactors. Among these structural materials, austenitic steels have an advantage of extensive technological database and lower cost compared to other non-ferrous candidates. Furthermore, they have also advantages of very good mechanical properties and fission operation experience. Moreover, modified austenitic stainless (Ni and Mo free) have relatively low residual radioactivity. Nevertheless, they can’t withstand high neutron wall load which is required to get high power density in fusion reactors. On the other hand, a protective flowing liquid wall between plasma and solid first wall in these reactors can eliminate this restriction. This study presents an overview of austenitic stainless steels considered to be used in fusion reactors.     

Development of a method to lower recontamination after chemical decontamination by depositing Pt nano particles: (I) Consideration of the suppression mechanism using a quantum dynamics calculation

The Pt coating (Pt-C) process has been developed to lower the recontamination by radioactive elements after chemical decontamination of piping surfaces. In this process, a layer of fine Pt nano particles is formed in an aqueous solution on the base metal of the piping following the chemical decontamination. In this study, we confirmed that the suppression effect by the Pt-C toward ⁶⁰Co deposition on type 316 stainless steel using a ⁶⁰Co deposition test under hydrogen water chemistry. Furthermore, we investigated the suppression mechanism of deposition of radioactive elements by a quantum molecular simulation. The deposition amounts of ⁶⁰Co which were incorporated in oxides after 1000 h with and without the Pt-C process were about 90 and 10.2 Bq/cm², respectively. The amount of ⁶⁰Co deposition with Pt-C is about 10% that of non-coated specimens. The ⁶⁰Co incorporation for the Pt-C specimen was suppressed by decreasing the formation of oxides. We considered this phenomenon using a quantum dynamics calculation and concluded that the Fe–O bonds in oxides were weakened by the effect of Pt and hydrogen radicals which were produced in the reaction between H₂ and Pt, and then oxides were dissolved into the water.     

液态铅铋合金管内流动传热特性研究

为研究液态铅铋合金的流动传热特性,建立了相应的实验台架,并开展了传热特性试验,获得了1组针对液态铅铋合金的传热关系式。同时使用Fluent程序对圆管内铅铋合金的流动换热进行了模拟计算,以研究不同湍流普朗特数模型和不同湍流模型的选取对计算结果的影响。根据计算结果,探讨了不同湍流普朗特数模型对计算结果的影响,并得到了不同Peclet数下推荐使用的物理模型。     

钼离子注入奥氏体不锈钢引发亚结构的变化

用加速电压为５０ｋＶ、剂量为２×１０１７ｉｏｎｓ／ｃｍ２的钼离子注入经１１５０℃固溶处理的奥氏体不锈钢（１Ｃｒ１８Ｎｉ９Ｔｉ）中,利用透射电子显微镜弱束成像技术研究了被注入材料的横截面样品,发现离子辐照引发被注入材料亚结构变化的深度远大于离子本身的注入深度,其亚结构为多种位错组成的复杂位错组态,这种亚结构会使被注入材料具有相当于加工硬化的效果。探讨了离子注入材料中由辐照引发的加工硬化现象,即所谓的“长程效应”的原因     

Cathodic polarization curves of the oxygen reduction reaction on various structural materials of boiling water reactors in high temperature–high purity water

Cathodic polarization curves of the O₂ reduction reaction were measured by using electrodes made from typical structural materials of boiling water reactors (BWRs) to evaluate the effects of kind of material on the electrochemical corrosion potential (ECP) calculation. To estimate ECPs at any region in the BWRs on the basis of the BWR environmental conditions, anodic and cathodic polarization curves should be obtained in advance under relevant conditions. The concentration of oxidants such as O₂ and H₂O₂ in coolant changes depending on the region in which they exist. As well, reduction reaction rates might differ depending on the kind of materials. In this work, the cathodic polarization curves of type 316L stainless steel (316L SS) and Alloy 182 were measured in high purity water at 553 K with different O₂ concentrations and compared with those of type 304 SS (304 SS). The results showed that the cathodic polarization curves differed depending on the kind of materials at the activation-controlled region. But, the difference in the ECP vs. O₂ concentration relationship was small when the ECPs were calculated by using both anodic and cathodic polarization curves measured on the objective material.     

堆用不锈钢在模拟一回路中腐蚀的穆斯堡尔研究

用透射、内转换电子和内转换Ｘ射线发射三种穆斯堡尔谱学方法,配合Ｘ射线衍射和俄歇电子能谱研究核电站用不锈钢Ｆ３１６Ｔｉ的腐蚀。钝化膜和腐蚀产物的组分及微观结构,提供了研究堆用不锈钢腐蚀的微观结构研究基础。通过腐蚀机理,可以与宏观腐蚀的数据相印证。结果表明,抗蚀不仅与碳含量有关,尤其与热处理过程以及表层团溶状态有关。     

铅铋快堆一回路充排系统可靠性分析

铅铋快堆属于第四代反应堆,其一回路采用液态铅铋合金冷却.铅铋快堆一回路充排系统可以调节反应堆主容器内液态金属液位,该系统充满含有放射性物质的液态金属,其可靠性水平对反应堆运行及安全有重要影响.本文以中国科学院核能安全技术研究所·FDS团队自主设计的铅铋快堆一回路充排系统为研究对象,运用故障树分析方法对该系统进行可靠性分...     

Corrosion Resistance of Fe-Al-Alloy-Coated Ferritic/Martensitic Steel under Bending Stress in High-Temperature Lead-Bismuth Eutectic

The corrosion test was performed for ferritic/martensitic steel HCM12A with and without Fe-Al alloy coating in LBE at temperatures of 550 and 650°C under loading for an immersion time up to 500 h. After the corrosion test at 550°C for 500 h, both of the uncoated and Fe-Al-coated HCM12A showed a good corrosion resistance without the influence of the tensile stress on the LBE corrosion. On the other hand, after the corrosion test at 650°C, the Fe-Al coating layer on the specimen surface exhibited no LBE dissolution corrosion because of the formation of a stable oxide protection film on the coating layer surface, although the coating layer cracked. The LBE penetrated into the cracks and corroded the base metal and the precoating layer. The uncoated HCM12A exhibited the double oxide layers of FeO and Fe- Cr spinel. The FeO was damaged in the bent zone by the stress, and the Fe-Cr spinel layer was not destroyed by the influence of cracking and the tensile stress. The cracking and stress did not have a large influence on the overall oxidation corrosion rate.