辐射损伤潜径迹的纳米尺度观测研究

综述了近年来用扫描隧道显微镜 (STM )和扫描力显微镜 (SFM)在原子水平上观测辐射损伤潜径迹的研究及进展。详述了辐射损伤潜径迹的形貌、损伤范围、损伤数密度、损伤几率等 ,对损伤潜径迹直径与能损的关系、损伤过程及各种可能的损伤机制进行了分析和讨论。     

放射性食管疾病的临床观察

采用临床病例分析方法探讨了胸部肿瘤放射治疗时引起的放射性食管损伤的临床特点、诊断和治疗措施。根据损伤反应出现的时间早晚,临床上将放射性食管损伤分为急性放射性食管损伤和慢性放射性食管损伤。急性放射性食管损伤在临床上最为多见,主要表现为吞咽困难、吞咽疼痛、胸骨后烧灼感。28例肺癌病人放射治疗后,急性放射性食管损伤发生率为18％,均为3级以下急性损伤,     

中子对Si及GaAs半导体材料位移损伤的数值计算

概述了中子对半导体材料的位移损伤函数及损伤能力的表征,并选用ASTM标准的E722—94给出的Si及GaAs位移损伤函数,用MCNP粒子输运程序计算了Maxwell裂变谱源、Gaussian聚变谱源对Si及GaAs半导体材料的位移损伤以及相对于1MeV单能中子源的损伤等效系数等。     

中子位移损伤监测技术研究

利用硅双极晶体管直流增益倒数与中子注量具有线性关系的特点,将其作为位移损伤监测器以获取不同中子辐射场的损伤特性。采用两种不同的数据分析方法,分别得到了两种位移损伤监测器阵列的相对损伤常数。研究结果为在现有的实验条件和测试手段基础上选择位移损伤监测器和分析监测结果奠定了基础。     

荷电离子轰击靶材料损伤潜径迹的原子水平观测研究

叙述了用扫描隧道显微镜和原子力显微镜观测研究荷电离子轰击靶材料的损伤潜径迹的状况和进展，观测研究了Ａｕ离子和Ｈ＾＋轰击高定向石墨的ＳＴＭ。给出了损伤形貌、损伤范围、表面损伤数密度和离子注入剂量的关系，并对损伤过程进行了分析和讨论。     

剂量率在严重事故下乏燃料损伤评价系统中的应用

本文介绍了一种利用剂量率监测值评价严重事故时乏燃料损伤程度的方法。分别计算不同富集度、燃耗的乏燃料100%包壳损伤的剂量率作为数据库,根据停堆时间、事故的发生时间与实际监测值来评估乏池中燃料的损伤份额,实现了对乏池中不同类型燃料的损伤程度的差异化评估。本文方法已应用于秦山二期的乏燃料损伤评价系统中。     

核电厂大范围损伤管理导则研究现状

火灾、地震、水淹、极端天气条件等超设计基准外部事件可能造成核电厂大范围损伤,不仅使得电厂的系统与设备大面积失效,还导致正常的应急体系无法运转。目前,国内外都在开展应对核电厂大范围损伤的研究,以完善核电厂的纵深防御体系,降低大范围损伤事故产生的后果。本文调研了国内外核电厂大范围损伤的研究现状,分析了美国核电厂的大范围损伤管理导则、灵活多样的处理策略及台湾地区核电厂的断然处置措施,并对国内大范围损伤管理导则的研究与开发提出了一些思路与建议。     

辐射免疫损伤与防护

近年来,随着分子生物学和分子免疫学新技术的发展和引入,免疫系统辐射损伤效应研究得到了较快发展。本文从辐射免疫损伤效应方面,介绍了免疫系统和淋巴细胞损伤特点,辐射对免疫器官和外周血淋巴细胞的影响,辐射所致细胞凋亡及剂量;从分子机理方面,介绍了辐射对细胞因子免疫调节功能的影响,辐射免疫损伤效应中信号转导机制,辐射对凋亡调控基因的影响;从辐射免疫损伤防护方面,介绍了细胞因子、生长因子和基因转染的应用研究。同时,探讨了辐射免疫损伤效应和机理研究方面需要解决的问题,提出了进一步寻找有效的辐射免疫损伤防护措施的切入点。     

聚变驱动次临界堆第一壁材料辐照损伤的初步研究

介绍了中子对材料的辐照损伤原理及化合物原子平均离位(DPA)截面计算方法;使用辐照损伤计算程序SPECTER计算了聚变驱动次临界堆(FDS-I)第一壁材料CLAM钢的辐照损伤参数,并将CLAM钢的辐照损伤计算结果与相同条件下316SS、SiC等聚变堆结构材料的计算结果进行了比较.     

硬化材料平面应变Ⅰ型裂纹尖端塑性损伤场

用损伤力学和断裂力学相结合的方法，研究了硬化材料平面应变Ⅰ型裂纹尖端的塑性损伤场，首先引入了一个新的能同时反映变形和三轴应力约束对破坏影响的一般韧性损伤模型，然后用非耦合算法，求得了Ⅰ型裂纹损伤区的形状和大小，给出了裂尖损伤分布的解析表达式，并以Ｃ－Ｍｎ钢和ＤＥ３６钢为例做了具体分析，获得了一些有意义的结果。     

Contribution to the theory of radiation effects on some properties of graphite

A substantial change occurs in several of the properties of graphite subjected to in-pile irradiation. These changes are the result of damage to the crystal lattice structure of the graphite. The present article presents a calculation of the change in lattice constant and internal energy of a unit volume of a crystal of graphite containing Frenkel defect-type imperfections. The results of the calculation are compared with experimental data.In conclusion, the author would like to avail himself of this opportunity to express his profound gratitude to A. I. Leipunskii for his kind attention to the progress of the work and the numerous useful comments advanced in discussions of the results.     

Ion beam induced damage in CaF2

The change in lattice parameter and the induced damage are studied in single crystal CaF₂ bombarded by a 15 MeV Cl ion beam. The lattice parameter change (strain) and the damage for increasing ion beam dose (5 × 10¹²/cm² to 7 × 10¹⁵/cm²) is observed via X-ray rocking curve analysis using a double-crystal diffractometer and X-ray reflection topography. The ion beam energy (range = ～ 4.5 μm in CaF₂) is such that both the electronic region and the nuclear cascade region of energy loss show up in the diffraction signal. By kinematical X-ray diffraction theory analysis, the progress of strain/damage depth profile with increasing beam dose is shown explicitly. The increase in strain is nonlinear with beam dose for the dose range studied. For increasing beam dose, the strain level in the electronic energy loss region is fixed, while that in the nuclear collision loss region increases effectively until that region becomes completely amorphous.     

沟槽型X射线两次衍射单色器研究

为获得高能量分辨率、高准直的同步辐射光,应用X射线衍射动力学原理,并依据上海光源小角散射线站光学参数,设计并加工了两次衍射的单晶硅(111)面沟槽型单色器。测量了两反射面平行度、斜切角及摇摆曲线,并对摇摆曲线的测量值进行了误差分析。理论模拟与实验数据对比分析显示:有效减小晶体加工过程中的残余应力导致的晶格畸变、改善晶体形貌、调整斜切角与增加衍射级次可降低晶体的衍射角宽,进而提高出射光的准直性和能量分辨率。经计算,在同步辐射光能量为10keV条件下,单晶硅(111)面沟槽型单色器的本征能量分辨率为1.452×10~(-4)。     

Derivation of enhanced potentials for uranium dioxide and the calculation of lattice and intrinsic defect properties

Previously reported forms of the cation-anion Buckingham potential provide a significantly greater contribution than the repulsive Coulombic component at short-range thus predicting an unphysical attraction between the pair of ions. A detailed reappraisal of the computer modelling of uranium dioxide (UO₂) employing atomistic simulation techniques is presented. An improved set of interatomic potentials is derived in order to describe the lattice correctly under conditions subsequent to radiation damage with the creation of Frenkel pair defects.Novel methodology is employed in the derivation of potentials ensuring applicability over the entire region of interest. The cation-anion potential is obtained via a combination of empirical fitting to crystal structural data and parametric fitting to additional physical properties. These potentials are subsequently verified and validated by calculation of additional bulk lattice properties, whose values agree favourably with those measured experimentally.Atomistic computer simulation techniques are then used to investigate the defect properties of UO₂. The theoretical techniques are based upon efficient energy minimization procedures and Mott-Littleton methodology for accurate defect modelling and employed to calculate intrinsic defect formation energies and enable predictions of the expected type of intrinsic disorder to be made.     

Calcul du profil d'endommagement par une source isotrope de fragments de fission: Application aux gaines d'acier inoxydable du combustible UO2

The damage distribution produced by an isotropie fission fragments source in contact with a metallic target has been investigated. More precisely, the density of energy transferred by such a source to the target lattice has been computed as a function of the depth in the target. The basis of these calculations is Lindhard's theory which gives for each fission fragment emitted by the source the energy lost in atomic collisions. The results can be applied to the fission fragments damage produced by the fuel of a nuclear reactor in the clad which contains it.     

Effect of radiation damage on the erosion of graphite by atomic hydrogen

The reactivity of graphite with atomic hydrogen is strongly enhanced after irradiation with 2 MeV ⁴He⁺ at doses of about 10¹⁷?10¹⁸ cm^?2. The observed effect is explained in terms of crystal lattice stress induced by the radiation damage in the irradiated area.     

Determination of the electronic energy loss of light ions in a silicon lattice by using the transmission ion channeling method

Charged particle activation analysis (CPAA) is able to analyze light elements such as carbon and oxygen at trace levels in semiconductor materials. This technique requires the knowledge of the stopping powers of these materials for channeled ions. The electronic energy loss for ions entering the crystal lattice in a random direction is well established. The electronic energy losses for protons, deuterons, ³He⁺ and ⁴He⁺ ions entering a 3.6 μm thick silicon single crystal along the 1 0 0 direction were measured by using the transmission of particles technique. Data obtained were compared with those obtained by other authors using theoretical and experimental methods.     

Radiation damage in beryllium oxide single crystals

Radiation damage in single crystal BeO has been studied using ⁶⁰Co gamma, 2 MeV electron, and epithermal neutron irradiations. The temperature of irradiation and the accumulated dose were kept within the range in which the change in the $\text{a}$ lattice parameter has been found to predominate. The observed changes produced by ⁶⁰Co irradiation are attributed to ionization of crystal impurities. Both electron and neutron irradiation produce optical absorption bands at about 5.25 and 6.5 eV. The energy at which the band peak occurs varies slightly with the conditions of irradiation and from sample to sample. No e.p.r. resonance could be correlated with either band. Neither F⁺ nor V^? centers were observed. The data from the annealing of these two bands indicate that they arise from different but related defects and that they are not due to simple point defects.     

Ion beam studies of H and He in metals

The use of ion beams to study hydrogen and helium in metals is demonstrated. The ³He (d,p)⁴He nuclear reaction previously has been used together with ion channeling to determine the lattice locations of ion-implanted D and ³He in tungsten. Preliminary results applying these techniques to helium bubble and blister formation in tungsten are also presented and show that changes attributed to helium bubble formation are observed in tungsten at a He fluence as low as 6 × 10¹⁶ He/cm². The retention of ion-implanted deuterium in W, Au, and Pd surfaces is shown to be greatly enhanced by prior He ion-induced lattice damage. The amount of the damage trapping is also found to depend on whether the metal is in single crystal or polycrystalline form.     

高能磷离子注入硅晶格的损伤初探

对高能磷离子注入硅、低剂量迭加注入硅，高能低能双注入硅中引起的晶格损伤、二次缺陷及退火效应进行了初步探讨。