Theoretical Treatment of the Asymptotic Behavior of Fission Product Decay Heat toward Very Short Cooling-Time

The asymptotic behavior of the FP decay heat has been studied toward the very short cooling-time range down to 0.1s after a fission event. For this purpose we apply the second generation of the gross theory of β-decay and estimate the decay properties of short-lived FP nuclides. In order to reproduce the recent measurements adequately, we introduce a new parameter named the Q00-factor, and optimize it in terms of the calculation of the half-lives and the average β- and γ-ray energy releases per decay (E β- and E γ-values). The favorable value of the Q00-factor is 1.0 for the half-lives and about 0.4 for the E β- and E γ-values. The E β and E γ-values thus calculated for the short-lived nuclides, whose β-decay Q-values are larger than 3–4 MeV, guarantee a good reproduction of asymptotic behavior of the measured decay heat toward the very short cooling-time range. Adoption of the present calculation to data files for the summation calculations is recommended from a practical point of view.

[1]  T. Tachibana,et al.  Semi-gross theory of nuclear β-decay , 1997 .

[2]  N. Cerf,et al.  Single and multi-event canonical r-process: astrophysics and nuclear physics considerations. , 1996 .

[3]  A. H. Wapstra,et al.  The 1995 update to the atomic mass evaluation , 1995 .

[4]  A. H. Wapstra,et al.  The 1993 atomic mass evaluation: (I) Atomic mass table , 1993 .

[5]  Tadashi Yoshida,et al.  Calculation of Beta-Ray Spectra from Individual and Aggregate Fission Products , 1992 .

[6]  O. Tengblad,et al.  Beta and gama spectra of short-lived fission products , 1990 .

[7]  H. Klapdor-kleingrothaus,et al.  Second-generation microscopic predictions of beta-decay half-lives of neutron-rich nuclei , 1990 .

[8]  M. Uno,et al.  Empirical mass formula with proton-neutron interaction , 1988 .

[9]  戴 光曦,et al.  核素图册 = Chart of the nuclides , 1987 .

[10]  T. Tachibana,et al.  Improvement of the Gross Theory of -Decay. II , 1990 .

[11]  Tadashi Yoshida,et al.  Decay Heat Calculations Based on Theoretical Estimation of Average Beta- and Gamma-Energies Released from Short-Lived Fission Products , 1981 .

[12]  R. W. Peelle,et al.  Fission-Product Energy Release for Times Following Thermal-Neutron Fission of Plutonium-239 and Plutonium-241 Between 2 and 14 000 s , 1981 .

[13]  T. A. Love,et al.  Fission-Product Energy Release for Times Following Thermal-Neutron Fission of 235U Between 2 and 14 000 s , 1980 .

[14]  Tadashi Yoshida.  Estimation of Nuclear Decay Heat for Short-Lived Fission Products , 1977 .

[15]  K. Tasaka,et al.  Calculation of the decay power of fission products , 1974 .

[16]  Kohji Takahashi,et al.  Beta-decay half-lives calculated on the gross theory , 1973 .

[17]  Kohji Takahashi.  Gross Theory of First Forbidden β-Decay , 1971 .

[18]  Kohji Takahashi,et al.  Gross Theory of Nuclear β-Decay , 1969 .