Nondestructive burnup evaluation and gamma spectroscopy analysis of spent fuel elements in the ITU TRIGA Mark II research reactor

This study presents a comprehensive burnup analysis of all fuel elements in the ITU TRIGA Mark II research reactor core using non-destructive assay (NDA) techniques based on gamma spectroscopy. Two distinct fuel inspection systems were employed to measure the gamma activity, with¹³⁷Cs used as the primary burnup indicator due to its strong correlation with fuel depletion. The results show a clear burnup pattern, with higher values in the inner core rings that gradually decreases toward the outer rings. This asymmetric burnup distribution underscores the need for reactor core reconfiguration, for which an optimized layout is proposed. Additionally, gamma spectroscopic analysis of fuel element F30 was conducted at cooling times of 10, 130, and 755 days. The results also suggest that¹⁴⁰La is a promising candidate for future burnup studies, which will be pursued in subsequent research.