[IEEE 2009 1st International Conference on Advancements in Nuclear Instrumentation, Measurement Methods and their Applications (ANIMMA) - Marseille, France (2009.06.7-2009.06.10)] 2009 1st International Conference on Advancements in Nuclear Instrumentation, Measurement Methods and their Applications - Utilization of freshly induced high-energy gamma-ray activity as a measure of fission rates in re-irradiated burnt UO2 fuel