Default isomeric branching ratios
Branching ratios to isomeric states are used in burnup calculation for the production of long-lived meta-stable nuclides, such as 241mAm or 148mPm. The data is not available in ACE format cross section libraries and must therefore be obtained elsewhere. Serpent provides three options for defining the branching ratios:
- Use of default constant ratios (see table below)
- Use of user-defined constant ratios (see the set isobra option)
- Use of energy-dependent ratios read from ENDF format files (see the set bralib option)
User-defined constant ratios override the default values, energy-dependent data overrides constant ratios.
Default data
The default constant branching ratios from update 2.1.27 on are listed below. The values are calculated from energy-dependent branching ratios in the JEFF-3.1 activation file in PWR flux spectrum. The last two columns refer to ground-state and isomeric-state fractions, respectively.
Nuclide | ZAI | MT | Frac. (g) | Frac. (m) |
---|---|---|---|---|
Na-23 | 110230 | 102 | 0.23200 | 0.76800 |
Cl-37 | 170370 | 102 | 0.88090 | 0.11910 |
Sc-45 | 210450 | 102 | 0.55600 | 0.44400 |
Co-59 | 270590 | 102 | 0.44400 | 0.55600 |
Ge-72 | 320720 | 102 | 0.50120 | 0.49880 |
Ge-74 | 320740 | 102 | 0.66600 | 0.33400 |
Ge-76 | 320760 | 102 | 0.40050 | 0.59950 |
Se-76 | 340760 | 102 | 0.74090 | 0.25910 |
Se-78 | 340780 | 102 | 0.11780 | 0.88220 |
Se-80 | 340800 | 102 | 0.84540 | 0.15460 |
Se-82 | 340820 | 102 | 0.14020 | 0.85980 |
Br-79 | 350790 | 102 | 0.76870 | 0.23130 |
Br-81 | 350810 | 102 | 0.09140 | 0.90860 |
Kr-78 | 360780 | 102 | 0.97040 | 0.02960 |
Kr-80 | 360800 | 102 | 0.60310 | 0.39690 |
Kr-82 | 360820 | 102 | 0.33300 | 0.66700 |
Kr-84 | 360840 | 102 | 0.18390 | 0.81610 |
Rb-85 | 370850 | 102 | 0.87910 | 0.12090 |
Sr-84 | 380840 | 102 | 0.25300 | 0.74700 |
Sr-86 | 380860 | 102 | 0.19880 | 0.80120 |
Y-89 | 390890 | 102 | 0.99790 | 0.00210 |
Y-90 | 390900 | 102 | 0.74960 | 0.25040 |
Nb-93 | 410930 | 102 | 0.31010 | 0.68990 |
Nb-94 | 410940 | 102 | 0.96100 | 0.03900 |
Mo-92 | 420920 | 102 | 0.99780 | 0.00220 |
Rh-103 | 451030 | 102 | 0.92400 | 0.07600 |
Rh-105 | 451050 | 102 | 0.90400 | 0.09600 |
Pd-106 | 461060 | 102 | 0.95270 | 0.04730 |
Pd-108 | 461080 | 102 | 0.97790 | 0.02210 |
Pd-110 | 461100 | 102 | 0.85000 | 0.15000 |
Ag-107 | 471070 | 102 | 0.98980 | 0.01020 |
Ag-109 | 471090 | 102 | 0.95400 | 0.04600 |
Cd-110 | 481100 | 102 | 0.99450 | 0.00550 |
Cd-112 | 481120 | 102 | 0.86850 | 0.13150 |
Cd-114 | 481140 | 102 | 0.88120 | 0.11880 |
Cd-116 | 481160 | 102 | 0.66600 | 0.33400 |
In-113 | 491130 | 102 | 0.41910 | 0.58090 |
Sn-112 | 501120 | 102 | 0.72530 | 0.27470 |
Sn-116 | 501160 | 102 | 0.95680 | 0.04320 |
Sn-118 | 501180 | 102 | 0.97940 | 0.02060 |
Sn-120 | 501200 | 102 | 0.98750 | 0.01250 |
Sn-122 | 501220 | 102 | 0.01120 | 0.98880 |
Sn-124 | 501240 | 102 | 0.03750 | 0.96250 |
Sn-126 | 501260 | 102 | 0.30180 | 0.69820 |
Sb-121 | 511210 | 102 | 0.93690 | 0.06310 |
Te-120 | 521200 | 102 | 0.88710 | 0.11290 |
Te-122 | 521220 | 102 | 0.64480 | 0.35520 |
Te-124 | 521240 | 102 | 0.99120 | 0.00880 |
Te-126 | 521260 | 102 | 0.86890 | 0.13110 |
Te-128 | 521280 | 102 | 0.92450 | 0.07550 |
Te-130 | 521300 | 102 | 0.85590 | 0.14410 |
Te-132 | 521320 | 102 | 0.85170 | 0.14830 |
I-129 | 531290 | 102 | 0.41300 | 0.58700 |
I-131 | 531310 | 102 | 0.98390 | 0.01610 |
Xe-124 | 541240 | 102 | 0.83000 | 0.17000 |
Xe-126 | 541260 | 102 | 0.86910 | 0.13090 |
Xe-128 | 541280 | 102 | 0.89230 | 0.10770 |
Xe-130 | 541300 | 102 | 0.91640 | 0.08360 |
Xe-132 | 541320 | 102 | 0.88670 | 0.11330 |
Xe-133 | 541330 | 102 | 0.96000 | 0.04000 |
Xe-134 | 541340 | 102 | 0.98530 | 0.01470 |
Cs-133 | 551330 | 102 | 0.90700 | 0.09300 |
Cs-134 | 551340 | 102 | 0.99600 | 0.00400 |
Cs-135 | 551350 | 102 | 0.98400 | 0.01600 |
Cs-137 | 551370 | 102 | 0.90210 | 0.09790 |
Ba-130 | 561300 | 102 | 0.88710 | 0.11290 |
Ba-132 | 561320 | 102 | 0.91750 | 0.08250 |
Ba-134 | 561340 | 102 | 0.92630 | 0.07370 |
Ba-135 | 561350 | 102 | 0.99780 | 0.00220 |
Ba-136 | 561360 | 102 | 0.97310 | 0.02690 |
Ce-136 | 581360 | 102 | 0.86620 | 0.13380 |
Ce-138 | 581380 | 102 | 0.97870 | 0.02130 |
Pr-141 | 591410 | 102 | 0.65190 | 0.34810 |
Pr-143 | 591430 | 102 | 0.31000 | 0.69000 |
Pm-147 | 611470 | 102 | 0.53300 | 0.46700 |
Eu-153 | 631530 | 102 | 0.98400 | 0.01600 |
Dy-164 | 661640 | 102 | 0.37000 | 0.63000 |
Ho-165 | 671650 | 102 | 0.94900 | 0.05100 |
Er-166 | 681660 | 102 | 0.25030 | 0.74970 |
Lu-175 | 711750 | 102 | 0.33310 | 0.66690 |
Lu-176 | 711760 | 102 | 0.99900 | 0.00100 |
Hf-179 | 721790 | 102 | 0.99100 | 0.00900 |
W-182 | 741820 | 102 | 0.86990 | 0.13010 |
W-184 | 741840 | 102 | 0.99830 | 0.00170 |
Re-185 | 751850 | 102 | 0.99900 | 0.00100 |
Re-187 | 751870 | 102 | 0.97290 | 0.02710 |
Au-197 | 791970 | 102 | 0.99900 | 0.00100 |
Hg-196 | 801960 | 102 | 0.96600 | 0.03400 |
Hg-198 | 801980 | 102 | 0.99180 | 0.00820 |
Pb-206 | 822060 | 102 | 0.97830 | 0.02170 |
Bi-209 | 832090 | 102 | 0.67910 | 0.32090 |
Pa-233 | 912330 | 102 | 0.48710 | 0.51290 |
U-234 | 922340 | 102 | 0.50000 | 0.50000 |
Np-235 | 932350 | 102 | 0.40000 | 0.60000 |
Np-239 | 932390 | 102 | 0.35730 | 0.64270 |
Pu-236 | 942360 | 102 | 0.50010 | 0.49990 |
Am-241 | 952410 | 102 | 0.91900 | 0.08100 |
Am-243 | 952430 | 102 | 0.06260 | 0.93740 |
Bk-247 | 972470 | 102 | 0.40000 | 0.60000 |
Es-253 | 992530 | 102 | 0.03200 | 0.96800 |
Es-255 | 992550 | 102 | 0.98400 | 0.01600 |
Calculating branching ratios from energy-dependent data
Calculating branching ratios from energy-dependent data is relatively easy using standard detectors. For example, the capture fractions of 241Am to ground and metastable state of 242Am can be obtained with detector input:
% --- Detector material: mat Am241 1.0 95241.09c 1.0 % --- Detector: (reaction rates using spectrum in material "fuel") det 1 dm fuel dr 102 Am241 dr 102g Am241 dr 102m Am241
Branching ratios to ground and metastable states can then be obtained by dividing the results in the 2nd and 3rd detector bin with the result of the first bin. The ground state fraction can then be used as the input for the set isobra card.
For a complete example, see:
- Serpent input file and post-processing script
- Energy-dependent branching data from JEFF-3.1 activation file: File:JEFF-3.1 activation file.tgz.