Possible origin of the gamma-ray discrepancy in the summation calculations of fission product decay heat

Tadashi Yoshida*, Takahiro Tachibana, François Storrer, Kazuhiro Oyamatsu, Jun Ichi Katakura

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


In order to identify the origin of the ubiquitous and long-standing discrepancy seen in the γ-ray component of the FP decay heat in the cooling time range 300-3,000 s, a comprehensive analysis of the differences between the summation calculations and the experiments has been carried out. There may be some missing of the β-strength in the high energy region of the FPs in the mass region A=100-110. Especially, 102Tc, 104Tc, 105Tc and 108Rh are potentially responsible for the γ-ray discrepancy seen in the three major fissioning nuclides, 235U, 238U and 239Pu, systematically. The β-strength functions are theoretically calculated in order to validate this possibility. It is proved that the chance for finding the additional β-strength required to solve the discrepancy is not so large but still exists, and the exact β-feed from Tc to the highly excited levels in Rb should be identified experimentally. Finally, the impact of the β-ray discrepancy on the reactor-core decay heat is evaluated quantitatively for the first time. It may introduce 0.5-1% underestimation of the total FP decay heat from 1 to 2,000 s after reactor shutdown, and the underestimation may reach 3% at the maximum when the γ-ray component of the decay heat is separately taken into consideration.

Original languageEnglish
Pages (from-to)135-142
Number of pages8
JournalJournal of Nuclear Science and Technology
Issue number2
Publication statusPublished - 1999 Feb


  • After-heat
  • Beta decay
  • Beta-strength function
  • Branching ratios
  • Decay heat
  • Fission products
  • Fission yield
  • Gross theory
  • Loss of coolant

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering


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