中性子の後方散乱を利用した非破壊計測（第１報，システムの実現と有効性の検証）

　石油タンクや配管などのような，密封容器中の堆積物量や容器内面の付着物量の検査は容器の破壊により行われることが多い．これを非破壊で行う場合．大がかりな装置が必要となり，簡単には検査できない．そこで本研究では，堆積物量や付着物量の計測を非破壊で行うことを目的に，中性子測定システムを構築する．本システムは，中性子を放出する線源として放射性同位元素を用い，計測対象である容器に中性子を照射する．これにより中性子と容器内容物との相互作用で生じる後方散乱を放射線検出器で検知する．この後方散乱と内容物量との間には相関関係があり，これを利用し内容物量を計測する．本報告では，構築した中性子測定システムの概要を説明する．後方散乱と内容物量との相関関係を調べるために実施した，内容物の質的・量的な変化．および遮蔽物の厚さを変化させた実験の結果を示す．

The contents in the sealed container，such as an oil tank, and a tube, accumulate and also stick inside. A container is destroyed generally, when these are inspected. The large-scale device is necessary to inspect without destroying a sealed container and we can not check them so easy. Then, in this research, the neutron measurement system is constructed, for the purpose of that measures the volume of deposits and adhesion inside a sealed container, without destroying it. In this system, the radioisotope is adoped as the source that radiate neutron. And a neutron is irradiated to the container that is an object of measurement. The back scatter that happens by the interaction between a neutron and contents of container is found with the radiation detector. There is correlation between back scatter and volume of contents, and volume of contents are measured by utilizing this. In this report, we explain the outline of the neutron measurement system that is constructed by the author. To check the correlation between back scatter and volume of contents, we carried out the experiment that changed the quality and volume of a contents. Similarly we carry out the experiment that changed the thickness of a shelter. Some results are presented in the form of parametric graphs and tables.