Assessment of contamination distribution of "Monju", 7; Optimization of the elemental composition of "Monju" structural materials to enhance the reliability of radiation evaluation

Kishimoto, Yasufumi*; Kato, Mitsuaki*; Kinoshita, Takuma*; Nanri, Tomohiro ; Mashimo, Ryutaro; Hayashi, Hirokazu 

The third phase of Monju decommissioning involves dismantling equipment within the controlled area. Accurate radiation assessments, avoiding both underestimation and excessive conservatism regarding worker dose and waste radioactivity, are crucial. Elemental composition significantly influences assessment reliability. This report aimed to optimize elemental composition by analyzing 76 elements in preserved structural materials (SUS304, SUS316, Inconel) using glow discharge mass spectrometry. This data established representative elemental compositions, moving away from reliance on limited design values previously used. Applying analysis from actual materials enables more realistic evaluations and is expected to enhance the precision of radiological assessments.