复合防氚材料阻氚性能的测定

本文介绍借助以水捕集渗透氚的方法测定复合防氚材料阻氚性能的原理、实验装置和结果。实验结果表明,不同的复合防氚材料相对于74~#氯丁像胶的氚气渗透率约为1/(29)—1/(16),说明这些材料的阻氚性能普遍优于氯丁橡胶。     

Al_2O_3(SiO_x)/PVC复合材料的研制和防氚性能测试

本文介绍了三种无机/有机防氚复合材料,即SiOx/PVC复合材料、Al2O3/PVC复合材料、Al2O3/SiOx/PVC复合材料的制备,并与普通PVC材料进行了防氚效果测试比较。结果显示,在1atm,氚气浓度为7.48×108Bq/L的情况下,三种复合材料对氚的渗透率分别为2.88×104Bq/(cm2·h)、2.09×104Bq/(cm2·h)、0.64×104Bq(/cm2·h),较普通PVC材料氚渗透率7.18×104Bq(/cm2·h)明显降低;三种复合材料氚渗透达到稳态的延迟时间分别为18.8、20.1、63.7h,明显大于普通PVC的2.1h。说明相对于普通PVC材料,三种复合材料对氚的渗透率低、延迟时间长、有较好的阻氚性能。其中Al2O3/SiOx/PVC复合材料的性能最好,明显优于氯丁橡胶。     

氚气在弹性复合材料中的溶解、扩散和渗透性能的测量

本文根据氚气具有很强渗透性能及其在不同材料中渗透性能的差异,用正比计数测量技术对氚气在各种材料中的渗透性能进行测量、比较,从中选出最佳复合形式,提供生产制造防氚手套。     

医用一次性防护服材料辐照灭菌后效应研究

为研究辐照后效应对防护服材料的影响,采用辐照方法对医用一次性防护服材料进行灭菌处理,对比辐照前、后医用一次性防护服材料的外观形貌、力学性能和液体阻隔性能的变化。结果表明,通过电子扫描显微镜观察发现,辐照并未对熔喷纤维和热熔压纹的形貌造成影响,辐照后效应对材料的抗合成血液渗透、抗水渗透和过滤效率并未造成明显影响,过滤效率仍高达99.8%;力学性能受辐照影响较大,断裂强力和断裂伸长率均显著降低。材料的关键性能指标在辐照灭菌处理后虽有下降,但满足国标GB/T 19082-2009要求,本结果可为辐照加工服务企业和防护服生产企业生产高质量的医疗防护材料提供参考。     

B4C-Al中子吸收材料拉伸性能及断裂机理

为评价粉末冶金法制备的B₄C-Al中子吸收材料的力学性能,采用静态拉伸的试验方法研究板材的室温及高温拉伸性能,并运用扫描电镜进行断口形貌观察,对复合材料的断裂机理进行讨论。研究表明：室温下,B₄C质量分数为30%的B₄C-Al复合板材的屈服强度为200 MPa,抗拉强度为250 MPa,断后伸长率为2.5%;在实验范围内,随着温度的升高,材料的抗拉强度和屈服强度下降,并趋于一致,材料的断后伸长率增加并达到最大值。复合材料的断裂宏观表现为脆性断裂,断裂是由基体内微孔隙成核、聚集和基体与增强相的界面脱粘断裂的共同作用造成的。     

硼酸盐晶须增强聚乙烯复合材料及其热中子屏蔽性能研究

以硼酸镁(Mg2B2O5)和硼酸铝(Al4B2O9)晶须作为中子吸收体与高密度聚乙烯(HDPE)复合,制备了硼酸盐晶须/HDPE复合材料。讨论了影响材料力学性能及屏蔽性能的因素,并与常用的碳化硼(B4C)屏蔽材料进行了对比。实验结果表明:3种复合材料对热中子的屏蔽效果为B4CMg2B2O5Al4B2O9,复合材料对热中子的屏蔽率均随吸收体含量和材料厚度的增加而增大,当硼酸镁晶须/HDPE复合材料的厚度为15.76mm时,材料对热中子的屏蔽率可达86.58%。晶须/HDPE复合材料的拉伸强度随晶须含量的增加而增大,当硼酸镁晶须的含量为9.1%时,复合材料的拉伸强度可达24.39 MPa,和碳化硼/HDPE复合材料相比,硼酸盐晶须更能增强HDPE基屏蔽材料的力学性能。     

医院中子照射器分析室剂量场研究

医院中子照射器建成后,对分析室内及其屏蔽门外的γ剂量率和中子剂量当量率进行了测量,测量结果显示：分析室内局部γ剂量率与设计值相差较大,分析室屏蔽门外γ剂量率超过原设计监督区限值7.5 μSv/h,因此需对分析室内部及其屏蔽门进行屏蔽改造。根据蒙特卡罗程序模拟计算结果及实际使用情况给出最终屏蔽方案,即在分析室束流孔道所在墙面加装厚度为16 cm的铅屏蔽材料屏蔽γ射线,对四周墙面及屏蔽门内侧加装厚度为1 cm的含锂聚乙烯板屏蔽散射中子。改造后分析室剂量最高点γ剂量率下降277倍,中子剂量当量率下降5.8倍,屏蔽门外γ剂量率下降近90倍。     

辐照交联对膨胀阻燃剂/乙烯-辛烯共聚物复合材料力学性能及阻燃绝缘性能的影响

采用机械共混法向乙烯-辛烯共聚物中添加不同含量的膨胀阻燃剂(聚磷酸铵、季戊四醇、三聚氰胺),然后采用电子束辐照,制备出交联型膨胀阻燃复合材料。通过极限氧指数、热失重、燃烧性能等参数表征电子束辐照交联对其阻燃性能的影响。结果表明,辐照交联后,复合材料的氧指数提高1~2;对力学性能而言,断裂伸长率随着吸收剂量的增加呈现下降趋势,拉伸强度则呈现上升趋势;对热释放的影响,复合材料的燃烧过程缩短,释热、释烟更为集中,在200 kGy吸收剂量下辐射交联后,总热释放量由94.8 MJ/m~2下降至79.1 MJ/m~2,总烟释放量由1 122.9 m~2/m~2下降至928.4 m~2/m~2,燃烧过程缩短约25%,CO释放率由0.062 2kg/kg下降至0.043 9 kg/kg,CO_2生成率由1.44 kg/kg上升至1.51 kg/kg;对绝缘性能而言,随着吸收剂量的增加,材料的体积电阻率变化幅度很小,提示辐照对材料的绝缘性能影响很小。     

金属样品残余氚测量方法

为定量评价氚在结构材料和老龄贮氢材料内部的滞留量,用化学蚀刻法测定不锈钢内部氚浓度大小、分布情况及同位素交换后老龄贮氚铀床的氚滞留量。结果表明,贮氚13年的不锈钢样品中氚主要存在于样品内表面由表及里的120μm范围内,样品蚀刻深度110.6μm范围内,不锈钢的平均氚滞留量～9.37×10-4mmol/g,贮氚铀粉平均氚滞留量～4.16×10-5mmol/g。该方法对测量金属中微量氚有较高灵敏度,可检测金属中残余氚的滞留量。     

Isotope exchange reaction between tritiated water and hydrogen on SiC

SiC has been considered as a primary candidate material for a first wall component in future fusion reactor because it has been claimed that SiC has excellent high-temperature properties, good chemical stability and low activation. However, the behavior of tritium on SiC has not been discussed yet. In this study, tritium trapping capacity on the surface of SiC was experimentally obtained at the temperature range of 25-800 °C in consideration of tritium trapping to the experimental system. The capacity, which was independent of the water vapor pressure in the gas phase and the temperature, was determined as about 10⁶ Bq/cm². The isotope exchange reaction rate between tritiated water in a gas phase and hydrogen on the surface was quantified at the temperature of 25, 500 and 700 °C in consideration of the behavior of tritium trapping at change of experimental condition by the numerical curve fitting method applying the serial reactor model. The reaction rate was observed to be constant as 3.48 × 10⁻⁵ m/s. Additionally tritium release behavior from the surface of SiC in water vapor atmosphere was predicted and compared with that for graphite and stainless steel.     

氦-3回路中氚的辐射安全分析

氚安全是确保燃料元件堆内功率瞬态试验的关键因素之一。本文首先分析了氚的来源和危害,提出了氦-3回路氚的防护和去污措施,然后讨论了氚在正常运行和事故时释放到包容箱和工艺间的量和处理措施,最后评价了氦-3系统发生不同安全措施失效的事故情况下工作人员的氚内照射剂量。结果表明:系统正常运行时工作人员所受最大剂量为1.27 μSv/d,除了氚安全措施全部同时失效且HT短时间全部被氧化成HTO的极限事故以外,在一般事故情况下氚对工作人员产生的最大剂量小于10 mSv。     

The properties of N-doped diamond-like carbon films prepared by helicon wave plasma chemical vapor deposition

In this paper, N-doped diamond-like carbon(DLC) films were deposited on silicon substrates by using helicon wave plasma chemical vapor deposition(HWP-CVD) with the Ar/CH_4/N_2 mixed gas. The surface morphology, structural and mechanical properties of the N-doped DLC films were investigated in detail by scanning electron microscopy(SEM), x-ray photoelectron spectroscopy(XPS), Raman spectra, and atomic force microscopy(AFM). It can be observed from SEM images that surface morphology of the films become compact and uniform due to the incorporation of N. The maximum of the deposition rate of the films is 143 nm min~(-1), which is related to the high plasma density. The results of XPS show that the N incorporates in the films and the C-C sp~3 bond content increases firstly up to the maximum(20%) at 10 sccm of N_2 flow rate, and then decreases with further increase in the N_2 flow rate. The maximum Young's modulus of the films is obtained by the doping of N and reaches 80 GPa at 10 sccm of N_2 flow rate, which is measured by AFM in the scanning probe microscope mode. Meanwhile, friction characteristic of the N-doped DLC films reaches a minimum value of 0.010.     

Long-term corona behaviour and performance enhancing mechanism of SiC/epoxy nanocomposite in SF6 gas environment

Surface coating technology is an effective way to solve the interface insulation problem of DC GIS/GIL basin insulators, but the performance of the coating will change greatly, and the insulation strength will be completely lost, after long-term use in the extreme conditions of corona erosion. In this research, the multi-needle-plate electrode platform was constructed to explore the long-term use performance of Si C-doped nanocomposite exposed to corona discharge in SF6gas. Samples with a high S...     

中国氦冷固态增殖剂实验包层模块材料研究进展

在未来核聚变反应堆中,为补充氚的消耗,需要在核聚变堆的包层中进行氚的在线增殖,以维持核聚变反应的持续进行。为验证这一关键技术,在国际热核聚变实验堆（ITER）上开展了ITER TBM计划（实验包层项目）。作为ITER计划成员方之一,中方以中国氦冷固态增殖剂实验包层模块（HCCB TBM）概念参与ITER TBM计划。HCCB TBM现今进入初步设计阶段,而材料的制备技术和性能数据是支撑其结构设计、安全分析和服役工况评估的基础。本文综述和分析了HCCB TBM结构材料低活化铁素体/马氏体钢（RAFM钢）与功能材料氚增殖剂和中子倍增剂的研究现状,并对这些材料下一步的研究方向进行了展望。     

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。     

Tritium diffusion through oxide surface films on niobium

Diffusion of tritium in niobium has been investigated using recoil implantation with particular emphasis on the role of surface oxide films. In conformity with previously reported data, bulk diffusion in niobium is found to be extremely rapid and surface oxide films significantly retard the release rate of tritium. The observed tritium release data indicate diffusion through cracks or defects in the oxide film below 500°C and transport through an intact film at temperatures higher than 500°C. The release rates are described in terms of a mathematical model with the necessary model parameters determined from experimental data. The oxide films could be removed with a reducing hydrogen atmosphere, thereby resulting in classical bulk diffusion controlled release above 700°C. Below 700°C the oxide layers were stable in hydrogen, presumably because of a moderately high oxygen potential resulting from minute amounts of moisture in the sample chamber.     

Tritium management in the first-wall materials of A-DC and TAURO blankets

The tritium management in the first wall of two European breeding blanket options, A-DC and TAURO, has been simulated numerically to analyse the influence of the material selected: ODS-RAFM steel for the Advanced Dual-Coolant (A-DC) and SiC_f/SiC composite for TAURO options. The SRIM code has been used to simulate triton implantation and define the tritium source in each kind of material as a function of the depth. The TMAP4 code was used to analyse the posterior transitory gas transport process within the material, while taking into account the tritium transport properties of each material and the temperature variation through material thickness and operating time. Both the transient evolution and the final steady-state tritium transport behaviour have been characterised. The tritium transient flux to the coolant, the recycling flux and the absorbed tritium transient inventories have been simulated. Main conclusions have been drawn about the tritium performance of each first wall.     

氚在真空贮存容器材料中的吸附和渗透行为

研究了贮存氚靶约4 a和20 a的两个316 L不锈钢真空贮存容器(以下简称贮存容器)及其垫片材料对氚的吸附行为,并对氚在贮存容器材料中的渗透速率进行了测量和分析。结果表明,贮存容器外表面氚污染为几十Bq/cm2,不锈钢与陶瓷中吸附的氚活度均为106Bq/g;热解吸至1 273 K过程中,材料中99%的氚释放出来;在解吸出的氚中,陶瓷中的HTO比例高于不锈钢;贮存温度对氚靶贮存容器的渗氚速率有较大影响,夏季约为冬季的4倍。上述结果提示,氚在贮存容器材料内表面吸附后,一部分会向晶格扩散并滞留下来;另一部分则透过材料向外环境渗透,其中温度是影响氚向外环境渗透的主要因素之一。