Fission Product Gases from Uranium Dioxide Irradiated with Thermal Neutron

Uranium dioxide was irradiated with thermal neutrons in the Hitachi training reactor. Fission product isotopic rare gases, Kr and Xe, were determined by isotope dilution method with mass spectrometer. Details of the procedure are described. Mass spectra of the isotopic rare gas fission products are shown and it has been found that the ratio of the detected amount of each isotope agreed well with the ratio of their fission yields.