CALCULATION OF GAMMA-RAY SPECTRUM OF AGGREGATE FISSION PRODUCT NUCLIDES AND FITTING OF THE GAMMA-RAY SPECTRUMDepartment of Fuel Safety Research Tokai Research Establishment Japan Atomic Energy Research Institute Tokai-mura, Naka-gun, Ibaraki-ken, 319-11, Japan Gamma-ray spectrum data of fission product nuclides has been compiled as a data library. The data library contains the theoretically estimated spectra for application to the nuclides with no and/or deficient measured spectra. The gamma-ray energy spectra from aggregate fission product nuclides calculated by using the library showed a rather good agreement with measured ones for a wide range of cooling time after a fission burst of important fissile nuclides. By using the results, the gamma-ray spectra were converted into coarse energy group structure. The time dependence of the energy release of the each energy group was expressed as a sum of exponentials. The fitted results and their errors will be described. KEYWORDS: Gamma Ray Spectrum, Fission Product Nuclides, Exponential Fit |