高注量辐照条件下RPV钢退火及再辐照损伤的正电子湮没研究

Radiation embrittlement of reactor vessel steels (RPV) is one of the important degradation phenomena in the continued long-life safe operation of light water reactors. This project is to study on irradiation, post-irradiation annealing and re-irradiation damages in pure Fe, low Cu model steels and China’s domestic RPV steels using positron annihilation spectroscopy, a powerful tool to detect vacancy-type defects and defect’s chemical environment, in combination with atom probe tomography（APT）, transmission electron microscopy (TEM) and nanoindentation. Main research contents are: （1）To study the formation of vacancy-type defects，the evolution of Cu-rich precipitates or Mn-Ni rich precipitates of high irradiated samples after proton and heavy ion irradiations. （2）To analyze the recovery of vacancy-type defects，dissolution of Cu-rich precipitates or Mn-Ni rich precipitates of high irradiated samples after the post-irradiation annealing. (3) To mainly investigate the microstructural and defect’s changes after re-irradiation, to compare the differences of the matrix damages, Cu precipitate and other elements such as Mn, Ni, Si synergetic effect of hardening and embrittlement after the initial irradiation and re-irradiation，and to further setup the correlation between microstructural parameters and hardness. This work is very helpful to understand the microscopic mechanisms of irradiation-induced hardening and embrittlement in RPV steels and to provide important benchmark data about nuclear power plant life

反应堆压力容器（RPV）钢的辐照脆化一直是国内外研究者关注的重大问题之一。本项目选择纯Fe、低Cu模拟钢及国产RPV钢为研究对象，采用带电粒子辐照模拟中子辐照；利用正电子湮没谱学对原子尺度缺陷和缺陷的化学环境特别敏感特长，配合APT、TEM及纳米压痕等方法研究样品辐照、退火及再辐照后的微结构与性能变化。主要研究内容为：(1) 探讨高注量质子和重离子辐照条件下，基体缺陷的形成及演化规律，富Mn-Ni团簇等LBP相的析出过程；(2) 研究国产钢不同退火条件下基体缺陷的回复，富Cu原子等团簇的溶解规律；(3)重点研究退火样品再辐照微结构和缺陷的变化, 比较研究RPV材料初始辐照和再辐照的异同，建立微结构参数与力学性能的关系。本项目研究将加深了解RPV钢初始辐照及再辐照损伤机理，为我国在役核电站RPV辐照损伤评估技术及机组延寿提供科学理论依据和实验数据。

反应堆压力容器（Reactor pressure vessel，简称RPV）作为核电站一回路中“不可更换的”关键性部件，在长时间的运行过程中会遭受到高温、高压和中子辐照的影响导致材料的硬化和脆化。本项目结合慢正电子束多普勒展宽、TEM、三维原子探针层析（3D-APT）和纳米压痕技术，深入、系统研究了高注量质子和重离子辐照条件下，国产RPV钢（A508-3钢,Cu含量0.01wt.%）缺陷的形成及演化规律，富Cu 原子团簇或Mn-Ni相的析出过程。重点研究了国产A508-3钢及低Cu模拟钢(Fe-Cu合金，Cu含量分别为0.05wt.%，0.1wt.%)高注量质子辐照下退火及再辐照过程的微结构和缺陷的变化，Cu 从基体中析出的行为，以及 Mn、Ni、Si 等其它元素对硬化和脆化的协同作用。研究表明高注量辐照的国产A508-3钢经退火处理后其内部缺陷基本回复，即使其韧性恢复，并且再辐照行为与初始辐照类似，因此，热退火消除辐照缺陷方法可以作为我国核电站（如秦山1 号机组、大亚湾1、2 号机组）延寿的一种重要方法。研究成果有助于了解高注量条件下RPV钢辐照脆化机理，为更准确地对在役核电站RPV 材料进行辐照损伤评估提供了技术支持。四年内，在Journal of Nuclear Materials, Radiation Physics and Chemistry 等刊物发表论文18 篇，出版专著2本，获批专利5项。