燃料棒电子束环焊缝试样腐蚀后产生蓝色氧化膜环的机理

燃料棒电子束焊接试样腐蚀后,在近环焊缝区会出现蓝色氧化膜环现象。研究了蓝色环氧化膜的 微观结构和形貌,测量了表面膜厚度和成分。用常规腐蚀法、加速腐蚀法和离子注入法研究了蓝色氧化 膜环处的抗腐蚀性能。试验表明:近环焊缝区已形成蓝色环后并不影响该处锆合金在继续腐蚀时的抗 腐蚀性能,也不影响燃料棒整体的抗腐蚀性能。根据实验结果提出了蓝色氧化膜环的产生机理和消除措施,并在大规模生产中得到了验证。     

反应堆压力容器密封面材料非正常工况下的腐蚀性能研究

针对压力容器密封面材料在核工程应用中发生的腐蚀问题,研究了反应堆压力容器密封面材料非正常工况下的腐蚀性能.利用静态高压釜研究308L不锈钢在不同Clˉ浓度条件下的腐蚀行为,采用金相显微镜和扫描电镜( SEM)对样品进行观察和分析.结果表明,在270℃、5.5 MPa条件下,Clˉ浓度低于1 mg/L时308L不锈钢没有发生点腐蚀、缝隙腐蚀和应力腐蚀;随着Clˉ浓度提高,308L不锈钢对点腐蚀、缝隙腐蚀和应力腐蚀的敏感性显著增加.     

核级不锈钢堆焊材料腐蚀性能研究

采用GB43 3 4 7 84和法国RCC MMC1 3 1 0对国产两种堆焊材料进行了点腐蚀、晶间腐蚀试验 ,在模拟压水堆核电站介质 (温度 3 45℃ ,80 0mg/LB ,2mg/LLi)条件下 ,研究了堆焊材料的应力腐蚀和均匀腐蚀性能。试验结果表明 :在高温含B水中 ,U型试样试验 5 0 0 0h后无应力腐蚀破裂 ,静态月平均腐蚀速率小于 2mg/dm2 。两种堆焊材料均具有优良的耐腐蚀性。     

不锈钢堆焊层在Cl-溶液中的腐蚀性能研究

采用浸泡腐蚀试验方法,研究了不锈钢堆焊层材料在Cl^-溶液中的腐蚀情况,并通过金相显微镜、扫描电子显微镜、能谱分析观察表面形貌。研究表明,室温条件下堆焊层材料未发生任何腐蚀。在高温条件下,Cl^-的存在诱导了点腐蚀的发生,且随着Cl^-浓度的增加,点腐蚀加剧;较高浓度的Cl^-可导致缝隙内金属元素Cr的流失,缝隙腐蚀加深;应力腐蚀裂纹有沿晶开裂的特征,应力腐蚀敏感性随Cl^-浓度的增加有提高的趋势。     

基于声发射技术的蒸汽发生器传热管点腐蚀研究

蒸汽发生器传热管的腐蚀是影响核动力装置安全运行的重要问题之一,传热管的腐蚀以点腐蚀的危害最为常见。利用声发射仪器,对蒸汽发生器传热管进行腐蚀实验时的信号进行采集和分析,并对腐蚀点进行了准确定位。实验结果表明,传热管的点腐蚀经历3个阶段:发展期、平稳期和迅速发展期。声发射技术能比其它任何无损检测方法更早地发现传热管腐蚀损伤,可对蒸汽发生器的安全和运行情况进行在线实时监测,具有重要的意义。     

注锌水化学对Zr-Sn-Nb合金腐蚀性能影响

采用高压釜腐蚀试验研究Zr-Sn-Nb合金在模拟压水堆一回路注锌水化学环境中的腐蚀行为,对Zr-Sn-Nb合金在无锌和加锌水化学环境中的腐蚀增重、氧化膜形貌等现象进行分析。结果表明:Zr-Sn-Nb合金在无锌和加锌水化学环境中腐蚀150 d时腐蚀增重曲线发生转折,加锌对Zr-Sn-Nb合金腐蚀增重量、腐蚀动力学规律、氧化膜形貌、氧化膜物相、氧化膜厚度、氢化物分布和吸氢浓度无明显影响。      

304NG不锈钢均匀腐蚀性能研究

用MARS循环腐蚀回路对304NG不锈钢进行了1500h的循环水腐蚀考验,对均匀腐蚀速率进行了定量评估。试验结果表明:在模拟核反应堆一回路循环水条件下,304NG控氮不锈钢板材、锻件的均匀腐蚀速率为1.40mg/(dm2ˇ30d)和1.91mg/dm2(dm2ˇ30d),0Cr18Ni10Ti不锈钢板材、锻件的均匀腐蚀速率为4.44mg/(dm2ˇ30d)和4.65mg/(dm2ˇ30d),304NG控氮不锈钢的均匀腐蚀速率低于0Cr18Ni10Ti不锈钢。     

Inconel-690合金在核电厂水质环境中的均匀腐蚀性能研究

模拟核电厂水质环境,采用动水腐蚀回路研究3种蒸汽发生器传热管商用690材料的均匀腐蚀性能以及氧化膜的特性,并分别采用国家标准和美国标准对材料均匀腐蚀速率和腐蚀产物释放速率进行评价。结果表明:690合金管在核电厂水质环境中具有极低的腐蚀速率和腐蚀产物释放速率,日本住友管的腐蚀性能略优于宝钢管。     

海水泵泵轴腐蚀原因分析及对策

通过浸泡试验和电化学试验对泵轴材料3Cr13的耐蚀性进行了研究。结果表明,3Cr13、镀铬层在海水中不耐局部腐蚀;且3Cr13的自腐蚀电位比其他海水泵部件低,易受电偶腐蚀。综合分析认为导致4号海水泵泵轴腐蚀的根本原因在于泵轴材料3Cr13在海水中不耐局部腐蚀,并在装配间隙、电偶效应等条件的驱动以及泥沙的磨损作用下,发生缝隙腐蚀、电偶腐蚀和磨损腐蚀,加速了泵轴基体的腐蚀进程,从而导致泵轴因腐蚀而失效。建议改进密封和选用耐蚀性更好的替换材料。     

某些加工因素对改性800合金碱性应力腐蚀破裂敏感性的影响

通过显微组织检验、拉伸试验、应力分析、C形环应力腐蚀试验、俄歇电子能谱(AES)分析、腐蚀形貌观察,研究了某些加工因素(冷加工和热处理)对国产改性800合金(800M)在沸腾的50%NaOH+0.3%SiO2+0.3%Na2S2O3溶液中的应力腐蚀破裂(SCC)敏感性的影响.冷加工拉伸25%的800M合金管的晶粒变形拉长,屈服强度和抗拉强度增大而延伸率降低,管的残余应力增加,SCC敏感性增加.对冷变形800M合金管热处理,随温度的升高,晶粒逐渐等轴化并变大,延伸率增大,屈服强度、抗拉强度和残余拉应力和SCC敏感性降低.AES分析表明,800M合金在沸腾碱液中恒电位极化后的表面膜是富Ni 而贫Fe 、Cr的.C形环试样碱性SCC裂纹在点蚀坑起源萌生,裂纹沿晶界扩展.     

P11钢在湿蒸汽中流动加速腐蚀性能的模拟与实验研究

在核电厂中，二回路碳钢管道的流动加速腐蚀（FAC）对安全生产造成很大影响。根据工程经验和实验室数据，采用Cr含量超过0.1%的碳钢管道可大幅减轻或避免FAC。Cr含量大于1%的SA335-P11钢以其较好的性价比而多被推荐用于核电站蒸汽管道。为了确认P11钢表面氧化膜在高流速湿蒸汽作用下的稳定性，本文采用小型管状试样进行了FAC实验，得到了试样的减重规律和内表面的腐蚀形貌。实验结果表明，试样入口部分形成了明显的FAC形貌，表面氧化膜破坏严重，而在试样的中部，FAC不明显。CFD模拟结果表明，试样入口处局部流速较平均流速高约24%，表面剪切力大，与实验结果一致。     

在高功率毫米波暴露下大鼠和小鼠的致伤和致死实验观察

使用高功率8mm波源，实验观察了在平均功率密度P0≈3．5W／cm^2，不同暴露时间、不同暴露部位条件下，对小鼠和大鼠的致伤和致死情况。实验发现，高功率8mm波暴露下大鼠和小鼠的致伤特点类似于不同程度的烧伤，而眼睛、耳朵等器官易受永久性的损伤。致死实验发现，体重10～200g的大、小鼠由高功率毫米波致死时吸收的能量W与体重m有着较好的线性相关性。     

Evaluation of corrosion behaviors for reactor pressure vessels/primary containment vessels in Fukushima Daiichi units 1–3 nuclear power plant

Fukushima Daiichi nuclear power plants (1F) were damaged by unprecedented severe accident in the Great East Japan Earthquake on 11 March 2011, and seawater has been injected as an emergency countermeasure for the core cooling. Although, the RPV and PCV were not supposed to be exposed to diluted seawater, they have been exposed to diluted seawater environment or high-moisture environment. Therefore, seawater corrosion has become an important issue. Immersion corrosion tests were performed for low-alloy steel of RPV material and carbon steel of PCV material in 1F cooling-water-simulated environment. As a result, the mass loss by corrosion was reduced with the decreasing temperature and chloride ion concentration. Moreover, the effects of nitrogen deaeration and Na₂WO₄ addition on corrosion protection were remarkable among the selected corrosion countermeasures. In addition, the integrity assessments of RPV and PCV were performed considering the reduction of plate thickness based on corrosion test data and the load condition based on earthquake response analysis results. It had been confirmed that primary stresses for RPV and PCV equipment satisfied with the allowable values until at least 15 years after the accident.     

某游泳池式反应堆全厂断电事故分析

采用RELAP5/MOD3.3程序对某游泳池式反应堆的全厂断电事故工况进行计算,对堆内冷却剂流动逆转过程进行了模拟计算,并对全厂断电事故下堆芯漏流和组件间流动等相关参数对流动逆转的影响进行了深入分析。结果表明,该反应堆在失去全部强迫流动的情况下,能形成足够的自然循环流量,以导出堆芯余热,燃料组件不会发生破损。     

Effect of addition of corrosion inhibitors on corrosion behaviors of PCV material under diluted artificial seawater environment

ABSTRACT

Fukushima Daiichi nuclear power plants (1F) were damaged by unprecedented severe accident in the great east Japan earthquake, and seawater and freshwater had been injected as an emergency countermeasure for the core cooling. Although, the primary containment vessel (PCV) was not supposed to be exposed to diluted seawater, the PCV will be exposed to diluted seawater environment until fuel debris removal is completed. Therefore, it is necessary to establish a countermeasure of corrosion for the PCVs made of carbon steel. In this study, the effect of the addition of corrosion inhibitor, which is one of the corrosion countermeasures, was investigated by two types of corrosion tests. As a result of the immersion corrosion test, it was found that any of the three kinds of corrosion inhibitor could suppress corrosion of carbon steel. In addition, as a result of the inhibitor interim addition test, it was found that corrosion of carbon steel covered with corrosion products could be suppressed by optimizing the additive amount of corrosion inhibitor in the cooling water.     

堆芯氧化腐蚀产物沉积层内两相沸腾传热传质特性

多孔形貌的氧化腐蚀产物沉积层一方面会增大热阻导致传热恶化,另一方面硼吸附会导致堆芯功率分布发生改变,因此,准确预测沉积层内的传热传质特性对反应堆的经济性和安全性有重要意义。本文将多孔介质层内的沸腾传热、毛细流动、溶质输运、化学反应等多物理现象进行耦合,提出了预测沉积层内的传热传质特性的高保真方法。冷却剂在毛细作用下进入多孔介质,并在烟囱表面蒸发。溶质随毛细流扩散进入多孔介质并被浓缩,各溶质间保持化学平衡。上述方法可以合理预测沉积层内的温度、流速、压力和溶质浓度分布,与Haq等相比,相对误差在±0.83%以内。在此基础上,分析了沉积层孔隙率、厚度、烟囱半径、烟囱直径等形貌参数对传热传质的影响规律。     

孔板管道下游与射流冲击的CFD模拟及实验研究

在核电厂中,流动加速腐蚀主要发生在二回路,对生产实践造成很大影响。本次研究运用CFD在250 ℃和273 ℃下对带有孔板的直管以及射流冲击结构进行模拟研究,得出流场及剪切力在管道内和试样表面的分布,找出带孔板管道由于管壁减薄引起的薄弱环节及角度对射流冲击的影响。结果表明,直管孔板中管径比的变化对冲刷后剪切力最大点影响很小。冲刷角度越小,剪切力越大,机械作用越强。     

核电厂凝汽器管束模块内流动及换热特性数值分析

针对国内某核电厂凝汽器钛管变形问题，采用多相流动CFD方法开展凝汽器内部管束模块不同工况下的流动和换热特性分析，采用有限元分析局部钛管受力情况。研究结果表明，凝汽器在冬季临停工况下，空冷区将结冰；机组启动时，在凝汽器内部流场力及重力作用下冰体运动而损伤钛管，造成凝汽器空冷区周边钛管大规模变形。      

Radiation Dosage Due to Neutrons Produced in a Vehicle by Protons in the Trapped Radiation Belt

The rate of production of neutrons by geomagnetically trapped protons incident on a vehicle was measured by a neutron counting system carried into the trapped radiation belt by a pod flow piggy back on an Atlas rocket on December 19, 1961. The flux of neutrons produced by radiation belt protons incident on the pod was determined to be at least 700 neutrons/(cm2 sec); the actual value depends somewhat on the energy spectrum of the neutrons. This flux was estimated to be equivalent to a dose rate in tissue of 0.10 rems/hr. On the basis of proton flux measurements made in the radiation belt by Freden and White, a calculation was made of the tissue dosage which would have been received in the same environment directly from protons. These calculations were made by obtaining a numerical integration of the dE/dx times RBE times flux product over the entire energy spectrum. The total dose calculated amounted to 2.78 rems/ hr. Further calculations were made to estimate the dose rates which would have been received by tissue in the same environment but with varying amounts of shielding around the vehicle. The proton dose is, of course, reduced by the shield but the neutron dose actually increases as the shielding thickness is increased. It is seen that the neutron dose equals the proton dose at .3 rems/hr. when aluminum shielding of 2.6" surrounds the vehicle and it exceeds the proton dose with thicker shielding.     

可逆流体换向装置性能的数学模型及参数计算

针对压冲流体在可逆流体换向装置(RFD)中的流动特性，以能量方程为基础建立数学模型。在RFD性能评价平台上，确定了数学模型方程中的流量系数及压能转换系数。结果表明：流量系数Cd与可逆流体换向装置的入流结构形式有关；当RFD的结构参数恒定时，压能转换系数与无因次参数K呈线性关系。此结果对RFD流体力学模型的建立有推动作用。