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氚溶解在材料中的量和深度分布的技术。从这个观点出发，本研究考察了(i)氚的深度剖面与轫致辐射x射线谱之间的相关性，以及（ii）利用计算机模拟对轫致辐射x射线谱进行分析。首先，开发了一个模拟程序，利用计算机模拟的方法，从轫致辐射x射线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，以均匀标记有氚的有机高分子材料为模型材料，测量了轫致辐射x射线光谱，并与计算机模拟得到的光谱进行了比较。结果表明，模拟得到的光谱与实测结果吻合较好，对于碳等低z元素为主的丙烯酸树脂，可以测量到从表面到1mm左右深度的氚。结果表明，所开发的模拟程序可用于分析含氚材料的轫致辐射x射线谱。通过这些实验，验证了该方法在Pd、Zr和ZrNi等具有非均匀氚深度分布的金属材料中的适用性。在这些材料中观察到特征x射线光谱和轫致辐射x射线光谱，因此对上述模拟程序进行了改进，以分析由两种x射线光谱组成的复杂光谱。结果表明，改进后的程序完全适用于复光谱的再现。结果表明，该方法可用于多组分金属材料氚深度剖面的原位无损测量。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