An efficient method for detecting damaged FAs; burnup and PPF estimations by gamma spectroscopy

The purpose of this study is to provide a quick and efficient experimental method to identify and find damaged fuel assemblies (FAs) among all assemblies of the core. This method is based on gamma spectroscopy by measuring the activity ratio of the desired fission fragments that leaked into the coolant. Using the 134Cs/137Cs activity ratio, and considering the history factor for each FA, we determine the fuel burnup. Furthermore, from the 133I × 135I /133Xe activity ratio, the power peaking factor can be determined. This spectroscopy is carried out for the Tehran Research Reactor to find its failed FA positions. Then, the spectrum at different cooling times has been studied. Specifically, from the 134Cs/137Cs (0.1212 ± 0.003) activity ratio and the fuel history factor (2.1023), the fuel burnup of damaged fuel is anticipated to be 33.9%, and the result of the computational codes is found to be 33.1%; these two results are consistent with each other. The results of both experiment and code analysis show the relatively reasonable estimation of this method in finding the location of damaged FAs.