Nondestructive burnup verification by gamma-ray spectroscopy of LEU silicide fuel plates irradiated in the RSG GAS multipurpose reactor

摘要

Nondestructive burnup verification by gamma-ray spectroscopy of two LEU silicide fuel plates, irradiated in the Indonesian RSG GAS multipurpose reactor, has been successfully conducted. The two fuel plates, one from the central part and another from the outer part, were extracted from the in-house manufactured, experimental silicide fuel assembly which had a declared burnup level of approximately 50% loss of U-235. As a burnup indicator, the Cs-134/Cs-137 activity ratio was selected and measured to obtain the axial distribution of relative burnup, its average values, burnup peak values and peak locations for each fuel plate, as well as the burnup difference between central and outer plates. A detail depletion analysis using SRAC2006 code system and JENDL-3.3 based library was conducted to obtain the Cs-134/Cs-137 activity ratio based on the irradiation history of the fuel element. An excellent agreement between the calculated and measured values of the activity ratio was confirmed.