DEVELOPMENT OF ACTINIDE-HYDRIDE FUEL

氢化物燃料已经用于研究反应堆（例如，TRIGA反应堆）多年来。近年来，有人提出了利用锕系元素进行核废料嬗变的方法。确立这一设想的最重要的研发项目之一是开发能够安全辐照到高燃耗的锕系元素靶。在这项研究中，使用U-Th-Zr-H型靶材，因为氢化物的氢化学势接近Np和Am的氢化学势。用Sieverts装置成功地制备了无大裂纹的U-Th-Zr-H芯块。扫描电子显微镜（SEM）和X射线衍射（XRD）分析表明，氢化物靶由锕系金属相、锕系氢化物相和Zr氢化物相组成。锕系元素靶的热导率数据是设计氢化物燃料棒所必需的。用激光闪光法测量了U-Th-Zr-H系靶材的热扩散率。根据测得的热扩散率、密度的文献数据和比热的关系计算了热导率。导热系数的设计相关性已被开发为温度和氢含量的函数。

Hydride fuels have been used in research reactors (e.g., TRIGA reactors) for many years. Recently, the transmutation method of nuclear wastes using actinide hydrides has been proposed. One of the most important R＆D items to establish the idea is the development of actinide-hydrides target, which can be safely irradiated up to high burnups. In this study, the U-Th-Zr-H type target material was used, since the hydrogen chemical potential of the hydride is close to that of Np and Am hydrides. The U-Th-Zr-H pellet have been successfully fabricated without large crack by means of a Sieverts apparatus. The scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses show that the hydride targets consist of actinide metal phase, actinide hydride phase and Zr hydride phase. Thermal conductivity data of actinide-hydrides targets are necessary for the design of the hydride fuel pin. The thermal diffusivity measurements of the U-Th-Zr-H type target material have been performed by means of a laser-flash method. The thermal conductivity was calculated from the relation of the measured thermal diffusivity, the literature data of the density, and the specific heat. The design correlation of the thermal conductivity has been developed as a function of temperature and hydrogen content.