Study on the Radiation Induced Reactions in Aqueous Solutions

在一开始，我们挑选了以下四个目标。第一个是对浓水溶液中的辐射诱导反应的澄清。这与核技术中的辐射效应密切相关，例如乏燃料的后处理。通过在不同酸性溶液中的测量，发现辐射的直接作用变得很重要。这可用于与阴离子相对应的自由基的形成。事实上，我们首次在浓的CIO_3水溶液中发现了CIO_3自由基。二是美国国家放射科学研究院HIMAC的离子束脉冲辐解系统的建设和应用，这是世界上唯一的离子束脉冲辐解装置。这为我们研究离子束诱导的LET效应，为辐射生物学和放射治疗等辐射科学提供了基础知识。通过测定清除量与浓度的依赖关系，讨论了水分解产物的空间分布。第三部分是基于杂散动力学扩散模型的水溶液辐射诱发反应计算机计算程序的开发。编制了计算程序，并进行了分析。最后一项是研制高时间分辨的皮秒甚至亚皮秒分辨率的脉冲辐解装置，用于研究辐射诱导反应的主要过程，但目标仍然很远。经过三年的努力，前三个主题已经令人满意地进行了，结果的细节已总结在一份报告中。

At the beginning, we picked up the following four targets. The first one is the clarification of radiation induced reactions in concentrated aqueous solutions. This is closely related to theradiation effects in nuclear technology, such as reprocessing of the spent fuels. From the measurements in different kinds of acid solutions, it was found that direct action of radiation becomes important. This can be used for the radical formation corresponding to anions. In fact, we found CIO_3 radical for the first time in concentrated CIO_3 aqueous solution. The second is the construction and application of ion beam pulse radiolysis system at HIMAC,National Institute of Radiological Sciences, which is the only one ion beam pulse radiolysis facility in the world. This provides us to study the LET effect induced with ion beams to obtain the basic knowledge for radiation science such as radiation biology and radiation therapy. From the measurement of the concentration dependence of scavenging yields, the spatial distribution of the water decomposition products have been discussed. The third one is the development of computer calculation code for radiation induced reactions in aqueous solutions based on spur kinetic diffusion model. The calculation code has been prepared and has been employed for the analysis. The last subject is the development of highly time resolved pulse radiolysis equipment with pico, even sub-pico second resolution for the study on the primary processes in radiation induced reactions but the goal is still far. After three years efforts, the first three subjects have been carried out with satisfaction and the details of the results has been summarized in a report.