TY - JOUR
T1 - Possible origin of the gamma-ray discrepancy in the summation calculations of fission product decay heat
AU - Yoshida, Tadashi
AU - Tachibana, Takahiro
AU - Storrer, François
AU - Oyamatsu, Kazuhiro
AU - Katakura, Jun Ichi
PY - 1999/2
Y1 - 1999/2
N2 - 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.
AB - 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.
KW - After-heat
KW - Beta decay
KW - Beta-strength function
KW - Branching ratios
KW - Decay heat
KW - Fission products
KW - Fission yield
KW - Gross theory
KW - Loss of coolant
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U2 - 10.1080/18811248.1999.9726191
DO - 10.1080/18811248.1999.9726191
M3 - Article
AN - SCOPUS:0033075308
VL - 36
SP - 135
EP - 142
JO - Journal of Nuclear Science and Technology
JF - Journal of Nuclear Science and Technology
SN - 0022-3131
IS - 2
ER -