PHOTOACTIVATION OF NUCLEAR ISOMERS FOR ASSAYING IRRADIATED REACTOR FUEL
Institute of Isotopes of the Hungarian Academy of Sciences
H-1525 Budapest, POB 77, Hungary
Indium samples were activated by (γ,γ') method along the central longitudinal axis of spent fuel assemblies seven weeks after their discharge from the core of a pressurized water reactor type WWER-440 in Paks, Hungary. Measuring 115Inm isomeric activities excited by gamma radiation of fission products (140Ba-140La) allowed scanning fuel assemblies axially by this method enabling reactor power distribution to be determined. A comparison was made between the results of the WWER-440 cassette mockup measurement and those of the fuel assembly measurements. The method -in addition to the computerized burnup calculations- can be useful for reactor operational and safeguards purposes.