Abstract

Zirconium silicide (Zr₃Si₂) is a heavy reflector material particularly effective for application to a Gas-cooled Fast Reactor (GFR) such as the General Atomics Energy Multiplier Module (EM²) and Fast Modular Reactor (FMR). In this work, the manufacturability of a high-density Zr₃Si₂ compound, in the Zr₃Si₂ phase, was investigated using hot-pressing and spark-plasma-sintering methods. The microstructure, composition, and thermal properties of the resulting hot-pressed material were measured, resulting in a 96% relative density and a 96% phase pure material. The thermal properties were consistent with those necessary for use under GFR operating conditions. The structural and dimensional stability of the material was also measured before and after neutron irradiation up to 10¹⁷ n/cm² in the research reactor, resulting in an average linear dimensional change of <0.12%. The preliminary irradiation tests also confirmed the micromechanical stability of the Zr₃Si₂ phase, with no evidence of microcracking after irradiation. The results of the irradiation tests verify the fabrication method of Zr₃Si₂ for nuclear applications, but further irradiation tests under high-temperature and high-irradiation conditions will be required to qualify the material for GFR applications.

摘要

硅化锆 (Zr ₃ Si ₂ ) 是一种重反射材料，特别适用于气冷快堆 (GFR)，例如通用原子能倍增器模块 (EM ² ) 和快速模块化反应堆 (FMR)。在这项工作中，高密度 Zr ₃ Si ₂化合物的可制造性，在 Zr ₃ Si ₂相，使用热压和火花等离子体烧结方法进行研究。测量所得热压材料的微观结构、成分和热性能，得到 96% 的相对密度和 96% 的相纯材料。热性能与在 GFR 操作条件下使用所需的热性能一致。在研究反应堆中，在高达 10 ¹⁷  n/cm ^{2 的}中子辐照之前和之后，还测量了材料的结构和尺寸稳定性，导致平均线性尺寸变化 <0.12%。初步辐照试验也证实了 Zr ₃ Si ₂相，辐照后没有微裂纹的迹象。辐照测试的结果验证了用于核应用的 Zr ₃ Si ₂的制造方法，但需要在高温和高辐照条件下进行进一步的辐照测试，才能使材料符合 GFR 应用的要求。