  The application of a high purity germanium (HPGe) gamma spectrometer in
determining the fuel element burnup in a future reactor is studied. The HPGe
detector is exposed by a Co60 source with varying irradiation rate from 10 kcps
to 150 kcps to simulate the input counting rate in real reactor environment. A
Cs137 and a Eu152 source are positioned at given distances to generate certain
event rate in the detector with the former being proposed as a labeling nuclide
to measure the burnup of fuel element. It is shown that both the energy
resolution slightly increasing with the irradiation rate and the passthrough
rate at high irradiation level match the requirement of the real application.
The influence of the background is studied in different parameter sets used in
the particularly developed procedure of the background subtraction. It is
demonstrated that with the typical input irradiation rate and Cs137 intensity
relevant to deep burnup situation, the precision of the Cs137 counting rate in
the current experiment is consistently below 2.8%, indicating a promising
feasibility of utilizing an HPGe detector in the burnup measurement in future
bed-like reactor.
