Technique of Dynamical Observation of Atomic Scale Structural Change and Initial Stage of Neutron Radiaton Damage

对中子辐照只作了简要的描述：参照RTNS-II聚变中子辐照的结果，JMTR裂变反应堆的受控辐照取得了稳定的进展。特别强调的是，通过在名古屋大学高压电子显微镜实验室建立辐射危害控制区，首次成功地对中子辐照样品进行了电子辐照。根据碰撞级联产生的极小点缺陷团簇在电子辐照下的行为，可靠地识别了它们的性质。研究了不同材料中中子辐照缺陷的退火行为，以了解级联团簇的形成机制和中子辐照过程中温度变化的影响。高能电子辐照下各种缺陷行为的动力学观察揭示了以下几点。(1)发现小间隙团簇的一维易运动是中子辐照诱导位错结构的晶体取向依赖的原因。(2)通过观察和分析小的点缺陷簇的生长和收缩，推导出点缺陷反应的随机波动，使我们了解到由碰撞级联形成的胚发育成间隙簇的成功概率非常小。(3)采用局域电子辐照实验检测间隙原子的一维运动；(4)采用间歇电子辐照技术测量间隙原子的基本缺陷参数。

Only the brief description is made on neutron irradiation : a steady progress has been made with controlled irradiation with the fission reactor JMTR,referred to the results of fusion neutron irradiaton with RTNS-II.Specially emphasized is the first success of the electron irradiation of neutron irradiated samples, by establishing radiation harzard control area in the High Voltage Electron Microscopy Laboratory of Nagoya University. The nature of very small point defect clusters produced by collision cascades was identified reliably from their behavior under electron irradiation. Annealing behavior of neutron irradiation induced defects in various materials was pursued to understand both the formation mechanism of the clusters from cascades and the effect of temperature variation during eutron irradiaton.The other dynamical observation of various defect behavior under high energy electron irradiation disclose the followings. (1) One dimensional easy motion of small interstitial clusters was found to be responsible for the crystallographic orientation dependence of neutron-irradiation-induced dislocation structures. (2) Stochastic fluctuation of point defect reactions deduced from the observation and analysis of the growth and shrinkage of small point defect clusters made us to understand the very small success probability of the growth of interstitial clusers from the embryo made by collision cascades. (3) One dimensional motion of interstital atoms was detected by localized electron irradiation experiment, and (4) fundamental defect parameters were measured by the development of intermittent electron irradiation technique.