「ふげん」発電所の主要構造材元素組成分析

摘要

廃止措置で解体が始まっている「ふげん」の多種多様な構造材を採取し，その元素組成を，GDMS，ICP-AES，ICP-MSおよび化学分析を使い分析した。この結果，主要構造材に関して次のようなことがわかった。（1）「ふげん」建屋，施設および設備から広範囲に多数の構造材を採取して，分析した結果，解体時に放射化評価に利用できる「ふげん」の建設期（1970年代）の元素組成のデータを得た。%Elemental data for construction materials used in nuclear power plants are necessary for the prediction of radioactivity induced by neutron irradiation. To evaluate radioactivity in retired Japanese nuclear power plants, it is preferable to use elemental data of the structural materials actually used in each plant. However, since there is no such domestic database, NUREG elemental data are commonly used for this type of evalua­tion. It is, therefore, required to establish a domestic elemental database of the structural materials actually used in power plants. In order to obtain elemental data, more than 130 specimens were collected from the structural materials of the Fugen Nuclear Power Plant, which was constructed in the 1970s and whose operation was stopped in 2003. Seventy-six compositional elements in the specimens were analyzed using appropriate chemical analyses and measurement techniques, such as glow discharge mass spectroscopy and inductively coupled plasma mass spectroscopy. These obtained data were compared with NUREG elemen­tal data and other standard or reference data. As a result, it was determined that the concentrations of major elements were not so different from NUREG elemental data and other standard or reference data. On the other hand, a slight difference was seen among the concentrations and their standard deviation in the analyt­ical data of impurities, such as cobalt. These data are expected to become a reference in the establishment of domestic standard data, and they are also expected to be applied to the evaluation of irradiation-induced radioactivity in the structural materials of reactors that are subject to decommissioning in the future.