Difference between revisions of "Default isomeric branching ratios"

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(Calculating branching ratios from energy-dependent data)
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* [[Branching ratio example|Serpent input file and post-processing script]]
 
* [[Branching ratio example|Serpent input file and post-processing script]]
 
* [http://virtual.vtt.fi/virtual/montecarlo/misc/sss_jeff31a.bra Energy-dependent branching data from JEFF-3.1 activation file]
 
* [http://virtual.vtt.fi/virtual/montecarlo/misc/sss_jeff31a.bra Energy-dependent branching data from JEFF-3.1 activation file]
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[[Category:Input]]

Latest revision as of 15:53, 29 November 2017

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:

  1. Use of default constant ratios (see table below)
  2. Use of user-defined constant ratios (see the set isobra option)
  3. 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: