ADS散裂靶结构材料设计与性能研究

Accelerator driven systems (ADS) coupled with a subcritical core loaded with nuclear fuel is believed to be one of the most promising technologies for nuclear waste transmutation, which allows the safe use of fuels with small decayed neutron fractions. With these ADS, finding proper structural materials used for spallation target, that produces high-energies neutrons coming into the reactor core under the sustained injection of the accelerated particles, still remains urgent and immediate challenging, due to ultra-severe irradiation, high-temperature and extreme lead-bismuth eutectic (LBE) corrosion as well as heavy thermal-strained environments. In this ongoing project, the first task is, based on well-known heat-resistant T91 and corrosion-resistant, irradiation-resistant EP823 steels and utilizing alloying design skills and a surface nano-crystallization technology, to develop the corresponding structural materials for spallation target with improved properties, substantially obeying the requirements of various technologies below 550℃ for ADS. The second task is to design and characterize a new type of nano-intermetallic-phase coherent strengthening ferrite steel with an aim of improved high-temperature resistance up to as high as 700 ℃ used for ADS. In order to achieve these goals, we will investigate in details the target materials by adopting various advanced experimental techniques with combination of the-state-of-art computational simulations. In the experimental aspects, we will utilize homogenized smelting and solidification, special heat treatment, and real LBE corrosion environment and also including thermal mechanical simulation of welded joint to obtain a series of crucial data on the microstructural evolutions, mechanical properties and LBE corrosion resistance and their alloying-microstructural-mechanical-corrosion interplay at different conditions (i.e., temperature, strain and LBE corrosion as well as wielding joint). In the theoretical simulations, we will employ first-principles calculations and Monte-Carlo simulations (also EA-MC package) to clarify alloying principles, to understand the coherent strengthening and precipitate-formation mechanisms of nano intermetallic-phase in ferrite matrix, and to systematically simulate the microstructural and defect evolutions under severe neutron irradiations. This project will lay the foundation for the reasonable choice of the target materials and related counterparts of ADS of diverse technological significance. Its successful performance will definitely guide and enhance the constructions of so-called principal, experimental and demonstrating reactors of ADS in China.

加速器驱动次临界系统（ADS）是国际公认的最有前景的嬗变技术之一。而其中的散裂靶结构材料是亟待解决的问题。本研究拟在T91和EP823合金的基础上，通过调整成分并结合表面纳米化技术，使散裂靶结构材料满足ADS系统中550℃以下服役的技术要求；发展新型纳米级共格金属间化合物强化的铁素体结构材料，并阐明金属间化合物的析出强化机理，将使用温度提高至700℃。研究散裂靶结构材料的均质化制备技术、热处理工艺、微观组织、力学性能及与Pb-Bi合金的相容性；采用热力物理模拟手段研究焊接接头组织状态对材料相关性能的影响机制；通过第一原理结合蒙特-卡罗计算模拟，揭示材料合金化准则、纳米共格金属间化合物强化机制和辐照条件下相关材料组织和缺陷演化规律，预测材料抗辐射性能。本研究能够为ADS系统散裂靶结构材料的合理选择和相关部件的优化设计提供理论依据，对加快ADS系统原型堆、实验堆和示范堆的建设具有推动作用。

加速器驱动次临界系统（ADS）是国际上公认的最有前景的嬗变技术之一。其中的散裂靶结构材料是亟待解决的问题。本项目掌握了低氧、低硫散裂靶结构材料均质化冶炼技术，获得O、S含量20ppm和低夹杂物水平的超纯净熔炼技术。在EP823和低活化F/M钢9Cr2WVTa基础上，通过成分设计、热处理工艺调控组织等，制备出综合力学性能较好的高Si 9Cr系钢及9C-AlSi钢，并发展了第三组元效应和9-12%Cr F/M钢在LBE环境中的氧化机制。利用表面纳米化技术和旋锻加工工艺细化晶粒，阐明了晶粒细化对提高9Cr F/M钢抗高温氧化性能的作用机理。通过表面纳米化和离子注入技术在马氏体钢表面生成纳米团簇，对理解ODS钢中Y-Ti-O纳米团簇的形成机制具有重要意义。设计了金属间化合物强化的Fe-Cr-Zr铁素体钢，探索制备耐更高温度的低活化钢。系统开展了堆结构材料焊接性和焊接接头组织性能及耐Pb腐蚀性能研究，研究发现对F/M钢，碳含量应该控制在0.14-0.17%，配套焊材中的碳含量应该控制在0.10-0.14%，可实现焊接接头与母材的等强韧匹配。探索了不同Si、C含量下焊接热影响区Pb-Bi相容性，并提出了氧化模型。通过第一性原理结合蒙特卡罗计算模拟，发现氢围绕辐照产生的空位形核生长的一般化物理机理和缺陷演化机理，为进一步大规模辐照损伤计算积累基础数据。以上的研究结果为ADS结构材料的合理选择和相关部件的优化设计提供理论依据。