Development of the bremsstrahlung counting method for in-situ measurements of tritium absorbed into materials.

研究和开发降低燃料循环中氚库存的技术对于建立热核聚变反应堆是必不可少的。为此，有必要发展原位无损测量材料中氚溶出量和深度分布的技术。从这一观点出发，本文研究了(I)氚的深度分布与韧致辐射x射线谱之间的关联，以及(Ii)用计算机模拟来分析韧致辐射x射线谱。首先，开发了一个模拟程序，通过计算机模拟的方法，从韧致辐射X射线能谱分析中评估材料中的氚深度分布。为了验证程序的有效性，以氚均匀标记的有机聚合物材料为模型材料，测量了韧致辐射X射线能谱，并与计算机模拟得到的能谱进行了比较。作为…此外，模拟得到的光谱与测量结果吻合得很好，对于主要由碳等低Z元素组成的丙烯酸树脂，证实了从表面到约1 mm深度存在的氚是可能测量到的。这些结果表明，所开发的模拟程序对于分析含氚材料发出的韧致辐射x射线谱是有价值的。在这些实验之后，考察了本方法对具有不均匀氚深度分布的金属材料如Pd、Zr和ZrNi的适用性。在这些材料中，观察到了特征x射线谱和韧致辐射x射线谱，因此，上述模拟程序被改进为分析由两种x射线谱组成的复合谱。结果表明，改进后的程序完全适用于复杂光谱的再现。因此，本方法对于多组分组成的金属材料的氚深度分布的原位无损测量是非常有用的。较少

Research and development of techniques to lower tritium inventory in a fuel cycle is indispensable for the establishment of a thermonuclear fusion reactor. For this purpose, it is necessary to develop the techniques to measure in-situ and nondestructively the amount and the depth profile of tritium dissolved into materials. From this viewpoint, (i) correlation between a depth profile of tritium and a bremsstrahlung x-ray spectrum and (ii) analysis of a bremsstrahlung x-ray spectrum with a computer simulation have been examined in the present study. First of all, a simulation program has been developed to evaluate the tritium depth profiles in materials from analyses of a bremsstrahlung x-ray spectrum by means of a computer simulation. To examine validity of the developed program, a bremsstrahlung x-ray spectrum was measured using an organic polymer material labeled uniformly with tritium as a model material, and it was compared with the spectrum obtained by a computer simulation. As a … More result, it was seen that the spectrum obtained from the simulation agreed quite well with that observed by measurements, and for acrylic resin mainly consisting of low-Z elements such as carbon, it was confirmed that it is possible to measure tritium which exist in the depth from the surface to about 1mm. From those results, it was revealed that the developed simulation program is valuable for the analyses of a bremsstrahlung x-ray spectrum emitted from the materials containing tritium. After these experiments, applicability of the present method to the metallic materials such as Pd, Zr and ZrNi having a non-uniform depth profile of tritium was examined. In these materials a characteristic x-ray spectrum was observed along with a bremsstrahlung x-ray spectrum, and the simulation program mentioned above, therefore, was improved to analyze a complex spectrum consisting of two kinds of x-ray spectrum. It was seen that the improved program is thoroughly applicable to reproduction of the complex spectra. Accordingly, it was concluded that the present method is quite useful for in-situ and nondestructive measurements of a tritium depth profile for metallic materials constituted of multi-components. Less