Phys. Sect. logo

WIMS Library Update Project

NDS logo
Back
Bottom

Fission products lumped into the pseudo fission product
No. Nuclide No. Nuclide No. Nuclide No. Nuclide
1 32-Ge- 72 21 38-Sr- 88 41 48-Cd-114 61 54-Xe-132
2 32-Ge- 73 22 39-Y 89 42 48-Cd-116 62 56-Ba-134
3 32-Ge- 74 23 40-Zr- 90 43 49-In-113 63 56-Ba-135
4 32-Ge- 76 24 40-Zr- 91 44 50-Sn-115 64 56-Ba-136
5 33-As- 75 25 40-Zr- 92 45 50-Sn-117 65 56-Ba-137
6 34-Se- 76 26 40-Zr- 93 46 50-Sn-118 66 56-Ba-138
7 34-Se- 77 27 40-Zr- 94 47 50-Sn-119 67 58-Ce-140
8 34-Se- 78 28 40-Zr- 96 48 50-Sn-126 68 58-Ce-142
9 34-Se- 80 29 41-Nb- 94 49 51-Sb-121 69 59-Pr-141
10 34-Se- 82 30 42-Mo- 96 50 51-Sb-123 70 60-Nd-142
11 35-Br- 79 31 42-Mo- 97 51 52-Te-122 71 60-Nd-144
12 35-Br- 81 32 44-Ru- 99 52 52-Te-123 72 60-Nd-146
13 36-Kr- 80 33 44-Ru-100 53 52-Te-124 73 60-Nd-148
14 36-Kr- 82 34 44-Ru-102 54 52-Te-125 74 60-Nd-150
15 36-Kr- 84 35 44-Ru-104 55 52-Te-126 75 62-Sm-154
16 36-Kr- 86 36 46-Pd-104 56 52-Te-128 76 64-Gd-152
17 37-Rb- 85 37 46-Pd-106 57 52-Te-130 77 64-Gd-160
18 37-Rb- 87 38 46-Pd-110 58 53-I 129 78 65-Tb-159
19 38-Sb- 86 39 48-Cd-111 59 54-Xe-128 79 65-Tb-160
20 38-Sb- 87 40 48-Cd-112 60 54-Xe-130 80 -
 

Lumped fission product processing and averaging
The cross section data for all pseudo fission product components were processed into multigroup constants with the NJOY code. The processing was carried out at 700 K assuming infinite dilution. The free gas model was selected for the thermal scattering matrix. The flux calculator option was applied up to the higher possible energy within the WIMS-D resonance range. The WLUP averaging spectrum was used to produce the multi-group cross section data.

The cross sections of the pseudo fission product were calculated by weighted averaging of the constituent nuclides. In the frame of WLUP the cumulative yields were used as weights to obtain the pseudo fission product for a fissile nuclide, eventually corrected for the precursors where necessary to avoid double counting.

The yields depend on the parent fissile nuclide. The differences between the cross sections of the pseudo fission product from different fissile isotopes were found rather small than the originally anticipated ones. Therefore it was decided to define a single pseudo fission product for all fissile nuclides by taking the average of the pseudo fission product cross sections of U-235, U-238 and Pu-239 in the ratio of 54%, 8% and 38% respectively.
Back
Top