Fabrication of high density thoria-urania fuel pellets

The fabrication of high density homogeneous mixed oxide fuel for the thorium cycle provides technological problems when large amounts of the second component in the mixture have to be used. Based on a laboratory scale experiment, the key process parameters have been elaborated. They are: comminution of the starting powders by dry ball milling and intimate mixing. Sintered densities of ~97% TD have been reached over the entire range of thoria-urania compositions.     

Measurement of the stopping powers of He and H ions near their maximum values by backscattering from a multilayer target

Rutherford backscattering at two different angles on a multilayer target is used to measure the stopping powers of light ions in matter. This method has the advantage that no spectrum width determination is needed so that any error related to this procedure is avoided. Moreover it is almost insensitive to most of the sources of errors suffered by transmission stopping power measurements. This new method has been used to measure the stopping powers of magnesium for helium ions (³He and ⁴He) from 100 to 350 keV with an accuracy better than 10%.     

Fabrication and characterization of tungsten and graphite based PFC for divertor target elements of ITER like tokamak application

The development of the fabrication technology of macro-brush configuration of tungsten (W) and carbon (graphite and CFC) plasma facing components (PFCs) for ITER like tokamak application is presented. The fabrication of qualified joint of PFC is a requirement for fusion tokamak. Vacuum brazing method has been employed for joining of W/CuCrZr and C/CuCrZr. Oxygen free high conductivity (OFHC) copper casting on W tiles was performed followed by machining, polishing and ultrasonic cleaning of the samples prior to vacuum brazing. The W/CuCrZr and graphite/CuCrZr based test mockups were vacuum brazed using silver free alloys. The mechanical shear and tensile strengths were evaluated for the W/CuCrZr and graphite/CuCrZr brazed joint samples. The micro-structural examination of the joints showed smooth interface. The details of fabrication and characterization procedure for macro-brush tungsten and carbon based PFC test mockups are presented.     

Estimation of plasma density perturbation from dusty plasma injection by laser irradiation on tungsten target in DiPS

To investigate the interaction of dusty plasma with magnetized plasmas at divertor plasma simulator, radial profiles of plasma density(ne) and electron temperature were measured in terms of plasma discharge currents and magnetic flux intensity by using a fast scanning probes system with triple tips. Dusty plasma with dusts(a generation rate of 3 μg s~(-1) and a size of 1–10 μm)was produced via interactions between a high-power laser beam and a full tungsten target. As ne increases, the scale of the effects of dusty plasma injection on magnetized plasmas was decreased. Also, the duration of transient fluctuation was reduced. For numerical estimation of plasma density perturbation due to dusty plasma injection, the result was ~10% at a core region of the magnetized plasma with n_e of(2–5)×10~(11) cm~(-3) at steady state condition.     

Effect of the number of graded layers on the microstructure and properties of SiC/C functionally graded materials

SiC/C bulk functionally graded materials (FGMs) with different numbers of graded layers (N) for fusion technology were designed and fabricated successfully by a power stacking method and hot-pressing process under the pressure of 30 MPa at 2000 °C. Results showed that the number of graded layers (N) had marked effect on the microstructure and properties of the as-received SiC/C FGMs. SEM examinations indicated that interfaces between the adjacent layers faded out gradually and became more linearly continuous gradient with increasing number of graded layers, which led to marked improvement in the bend strength and thermal shock resistance of the samples. Water quenching tests with a temperature difference of 500 °C showed that SiC/C FGMs with N > 8 had the best thermal shock resistance for the materials studies, and no cracks occurred after 90 quench cycles.     

离子束辅助沉积TiCN多层膜的研究

利用离子束辅助沉积设备,通过特殊的工艺在45号钢和硅片上生长出具有不同结构的复合多层TiCN膜。通过冷场发射扫描电镜,观察到膜层呈多层晶态和非晶态的复合结构;检测到划痕仪划过的划痕十分平滑,显示出晶态和非晶态膜层与基底具有良好的结合力;用显微硬度计检测膜层的表面硬度,发现不同结构和不同成份的组合对硬度影响很大;在摩擦磨损试验机上进行干摩擦试验,结果表明膜层具有较低的摩擦系数。     

电子束在多层材料中的背散射效应

研究基于简单解析表达式的电子背散射系数与入射电子能量、介质厚度和能损的关系及其对电子束辐射加工的影响，考虑到入射电子在多层介质之间反复的穿透和背散射，编制了ＥＤ４１０程序，计算了不同补底材料和不同入射电子能量下能量沉积的深度分布和剂量因子，利用补底要 背散射抬高接近补底界面处的剂量，较大地改善了辐射加工的均匀性。     

Fabrication and improvement of the density of Li2TiO3 pebbles by the optimization of a sol-gel method

Li₂TiO₃ is regarded as a promising candidate breeder in solid blanket concepts. Pebble configuration has been a preferred option due to its potential advantages in blanket design. Li₂TiO₃ pebbles were successfully fabricated by a water-based sol-gel method previously. However, the sintered density of the pebbles was very low (less than 70% theoretical density). The process parameters were optimized and the sintered density of the pebbles was improved significantly in this work. Li₂TiO₃ pebbles with density as high as 85% were obtained at a relatively lower sintering temperature (1100 °C) and shorter sintering time (4 h). The experimental results showed that the viscosity of the sol was influential to the sphericity of the gel-spheres and thus the sintered pebbles. The variety of lithium source, the pH value of the solution and the sintering conditions demonstrated significant influences on the microstructure and density of the sintered Li₂TiO₃ pebbles.     

Properties of hydride-forming metals and of multilayer hydrogen permeation barriers

Interference microscopy and scanning electron microscopy have been used to measure mechanical effects of tritium decay and ³He accumulation in thin film tritides of Sc, Ti, Y, Ho, and Er, all of which exhibit thickness increase of 2–4% y^?1, followed by the development of bubbles and craters and the occurrence of significant mechanical film failure. Scandium and erbium deuterotritide films have been subjected to 20 keV N₂⁺ ion bombardment in an ion microprobe mass analyzer to produce sputter ion species characteristic not only of the original film (e.g., M⁺, MO⁺, MD⁺, MT⁺) but also of compounds formed during the sputtering operation (e.g., ScN⁺). Hydrogen isotope permeation has been measured for the homogeneous metals Cu, Ceramvar and Mo, for a Ceramvar-copper-Ceramvar laminate, and for tin-coated Rodar. Measured permeation rates through the laminate are significantly less than those predicted from the permeabilities of its individual constituents. Permeation rates of deuterium through Mo exhibit a somewhat lower activation energy than has been reported in the literature.     

Legendre expansion of neutron flux over entire multilayer slab geometry

The monoenergetic integral transport equation for a multilayer slab geometry has been solved by Legendre expansion method. The method utilizes an expansion of the neutron flux over entire multilayer slab geometry in Legendre polynomials of the position co-ordinate (Single Expansion Method—SEM). This formulation is an extension of Carlvik's (1968) method for a homogeneous slab. Earlier (Raghav, 1984) the expansion of the neutron flux was done in each layer in Legendre polynomials of the position co-ordinate (Multi Expansion Method—MEM). The aim in this paper is to compare both the approaches of SEM and MEM. A few multilayer slab systems with vacuum boundary conditions have been selected for this purpose and K_eff, the effective multiplication factor of the system, has been compared.SEM requires the evaluation of the integrals where the limits are not −1 to +1 (as they are in MEM and where analytical expressions can be derived), in these cases we have derived recurrence relations (which are described in the Appendix) to evaluate such integrals.     

氯化球团料密度测量方法的研究

测量氯化球团料密度的γ射线透射法能用于热中子透射计的密度修正。讨论了测量原理、γ源的选择、锂玻璃探头对γ射线的响应并测定了氯化球团料的γ射线质量衰减系数。测定密度的相对误差约为2％。     

Fabrication and properties of lithium hydride

Lithium hydride is a crystalline material that is a relatively stable compound. Uses include neutron shielding or moderating because of a high hydrogen density and the employment of the ⁶Li isotope. Fabrication by powder techniques can supply compacts of near theoretical density. The material is chemically reactive and must be protected from atmospheric moisture.     

低密度氘代对二乙烯基苯泡沫的研制

通过魏梯希-霍恩(Wittig-Horneew)反应合成了氘代对二乙烯基苯,并利用红外、核磁共振和质谱对其结构及氘代率进行了表征。同时利用高内相乳液法(HIPE)制备了低密度全氘代对二乙烯基苯泡沫。泡沫氘代率、形貌结构和力学性能表征结果表明,材料氘代率为95%,密度为25 mg/cm3时平均孔径为6μm,弹性模量为2.58 MPa。     

Fabrication of zirconia-based targets for transmutation

The fabrication of homogeneous (Am,Y,Zr)O_2−x pellets and heterogeneous pellets, containing (Am,Y,Zr)O_2−x spheres dispersed in an inert matrix, by dust-free processes has been investigated. Due to the high activity of americium, the preparatory fabrication tests and process development are being carried out using cerium analogue element. The sol gel route is used to produce highly porous Y_0.15Zr_0.85O_2−x spheres, which are then infiltrated with a cerium nitrate solution to give (Ce,Y,Zr)O_2−x. The goal (28 wt% Ce) can be achieved. Homogeneous targets with densities up to 94 %TD have been obtained.     

纳米孔径重离子微孔膜的制备

应用中国原子能科学研究院HI 13串列加速器产生的重离子32S和79Br轰击聚对苯二甲酸乙二醇酯（PET）薄膜,再对薄膜进行化学蚀刻处理使由重离子辐照损伤产生的潜径迹形成微孔,制备出孔径为100～900nm的重离子微孔膜。为增加径迹蚀刻速率与体蚀刻速率之比,化学蚀刻前采用紫外光辐照薄膜。蚀刻过程中采用电导蚀刻法监测膜孔径生长过程。对32S和79Br辐照制备的重离子微孔膜进行了比较,79Br离子辐照制备的微孔膜与32S离子辐照制备的微孔膜相比,孔型圆整,锥角更小;在制备纳米微孔膜方面79Br离子优于32S离子。     

CdZnTe核辐射探测器的制备

本文简要介绍了采用国产碲锌镉(CdZnTe)单晶材料制备的CdznTe核辐射探测器工艺及测试结果.对α带电粒子Thc-c/(6.04MeV、8.78MeV)FWHM=2.O%、241 Am(5.486MeV)FWHM=2.3%,137Cs低能7(662keV)FWHM=9.7%和207Bi(1048.1keV、975.6keV)内转换电子所测定的能谱.     

氢化海绵钛粉末制备

介绍了氢化海绵钛粉末制备的工艺流程,即海绵钛块经过渗氢,得到的氢化海绵钛块在高纯氩气保护的手套箱中用鄂式破碎机破成小于10mm的颗粒,再用高速破碎机破碎成粉末,用自行研制的机械筛分机对粉末进行筛分,并对粉末的粒度和杂质氧、氮含量进行分析,最后得到合格的粉末,其氢-钛原子比达到1.8～2.1,粉末粒度在74μm以下占98.9%,氧、氮含量分别低于2500μg/g、150μg/g,年生产能力达到3t.