Abstract
Gamma decay heat released from fission products (FPs) has been measured for fast-neutron fissions of 235U, 239Pu and 233U using the radiation spectrometry method. The sample irradiations were for 10 and 100s in the fast neutron source reactor "YAYOI" of the University of Tokyo. Spectral data for γ-ray were obtained at post-irradiation time intervals ranging 11-25, 950s using a NaI (Tl) scintillation detector. The data were processed to the form of γ-ray energy release rates per fission for each set of time-interval parameters. The standard representation of the decay heat following fission pulse (in cooling times ranging 19-24, 000s) was provided from the γ-ray energy release rates. The uncertainties (1σ) of the decay heat data were about 5% for 235U and 239Pu, and about 7% for 233U.
The data obtained from the present experiments are compared with three summation calculations using JNDC, TASAKA and ENDF/B-IV decay data libraries, and with other experimental results. The summation calculation results using the JNDC FP decay data library are in better agreement with the present data than the other calculations.
