10.2.9. Decay Resource Format
The decay resource is a simple text format file that can be processed by COUPLE to create a binary decay-only library that can be used directly by ORIGEN. In general, this is not necessary, as the decay resource distributed with SCALE has already been processed with COUPLE to produce the end7dec ORIGEN decay-only binary library file. Modifying the decay data or the set of nuclides ORIGEN tracks requires modification of the decay resource file. The format is described in Table 10.2.11. Note that as of the SCALE 6.2 release, ORIGEN now uses the SCALE Standard Composition resource for abundance data and the “ABUND” field shown below is ignored by COUPLE when reading the decay resource.
Data name |
Definition |
LIB |
Nuclide sublib (used by COUPLE) |
NUC1 |
Nuclide identifier |
IU |
Units for the half life value (see numref:tab-origen-hl-units) |
HALFL |
Value of the half life in IU units |
FB1 |
Beta decay transition leading to a daughter in the metastable state |
FP |
Positron emission decay fraction or orbital electron capture to the ground state |
FP1 |
Positron emission decay fraction or orbital electron capture to a metastable state |
FA |
Alpha particle emission decay fraction |
FT |
Isomeric transition decay fraction |
LIB1 |
Nuclide type in the library |
FSF |
Spontaneous fission decay fraction |
FBN |
Delayed neutron decay (beta particle and a neutron) fraction |
Q |
Recoverable energy per decay (MeV) |
ABUND |
Natural atom isotopic abundance in percent (no longer used) |
AMPC |
Maximum permissible concentration in air |
WMPC |
Maximum permissible concentration in water |
LIB1 |
Nuclide type in the library (used by COUPLE) |
FG |
Fraction of recoverable decay energy Q associated with gamma rays |
FB |
Beta decay transition leading to a daughter in the ground state |
FBB |
Double beta decay fraction |
FN |
Neutron decay fraction |
FBA |
Beta decay plus an alpha particle emission decay fraction |
The variable LIB (and LIB1)defines the nuclide sublibrary (1/2/3=activation product/actinide/fission product). Variable LIB1 is included for formatting purposes only.
The nuclide identifier is read in variable NUC1 and is subsequently stored in array NUCL. The nuclide identifier is given by
where Z is the atomic number, A is the atomic mass number, and I is the isomeric state, where \(I=0\) designates a ground state, and \(I=1\) is the first metastable state.
The variable HALFL is the physical half-life in units designated by the variable IU, as shown in Table 10.2.12. The definitions of 11 variables representing the different decay mode branching fractions are given in Table 10.2.11. The decay branching fractions are used in constructing the transition matrix.
IU |
Units of half-life |
1 |
seconds |
2 |
minutes |
3 |
hours |
4 |
days |
5 |
years |
6 |
stable |
7 |
103 years |
8 |
106 years |
9 |
109 years |
The variable Q is the total amount of recoverable energy (MeV) per disintegration released by radioactive decay used for decay heat calculations. It does not include the energy of neutrinos emitted during beta decay transitions. The variable FG is the fraction of recoverable energy per disintegration that comes from gamma rays and x-rays. The value of Q is obtained directly from ENDF/B-VII.1 as the sum of the average beta, gamma, and alpha decay energy values. The quantity includes the energy from all electron- related radiations such as \(\beta^-\), \(\beta^+\), Auger electrons, etc., all gamma rays, x-rays, and annihilation radiations, and the average energy of all heavy charged particles and delayed neutrons. The contribution from alpha decay energy includes the energy of the recoil nucleus. A part of the recoverable energy per decay not included in the ENDF/B-VII.1 values is the additional contribution from spontaneous fission. This energy was calculated as the product of the spontaneous fission branching fraction and recoverable energy per fission using a value of 200 MeV per fission and added to the ENDF/B-VII.1 recoverable Q energy. A value of 12.56 MeV gamma energy per fission was used in computing the fraction of recoverable spontaneous fission energy from gamma rays.
External bremsstrahlung radiation is not included in the values of FG since the bremsstrahlung spectrum depends on electron interactions with the medium that contains the decay nuclide. The energy from capture gamma rays accompanying \(\left( \alpha,n \right)\) reactions is also not included since it also depends on the medium. The variable ABUND is the atom percent abundance of naturally occurring isotopes.
An example of the decay resource content for selected fission products is presented as Example 10.2.1.
3 DECAY LIBRARY: fission products (ENDF/B-VII.1)
3 10030 5 1.2320E+01 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 0.0000E+00 0.0000E+00 5.6900E-03 0.0000E+00 6.4100E-09 4.4000E-04
3 0.0000E+00 1.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 20030 6 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 0.0000E+00 0.0000E+00 0.0000E+00 1.3700E-04 1.0000E+00 1.0000E+00
3 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 20040 6 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 0.0000E+00 0.0000E+00 0.0000E+00 1.0000E+02 1.0000E+00 1.0000E+00
3 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 260650 1 8.1000E-01 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 0.0000E+00 0.0000E+00 4.7424E+00 0.0000E+00 1.0000E+00 1.0000E+00
3 3.5861E-01 1.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 270650 1 1.1600E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 0.0000E+00 0.0000E+00 2.7723E+00 0.0000E+00 1.0000E+00 1.0000E+00
3 3.3206E-02 1.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 280650 3 2.5172E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 0.0000E+00 0.0000E+00 1.1863E+00 0.0000E+00 4.6300E-09 1.0300E-04
3 4.7061E-01 1.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 290650 6 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 0.0000E+00 0.0000E+00 0.0000E+00 3.0830E+01 1.0000E+00 1.0000E+00
3 6.0103E-01 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 240660 1 1.0000E-02 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 0.0000E+00 0.0000E+00 8.2733E+00 0.0000E+00 1.0000E+00 1.0000E+00
3 5.0000E-01 1.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 250660 1 6.4000E-02 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 0.0000E+00 1.0880E-01 8.4471E+00 0.0000E+00 1.0000E+00 1.0000E+00
3 4.8945E-01 8.9120E-01 0.0000E+00 0.0000E+00 0.0000E+00
3 260660 1 4.4000E-01 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 0.0000E+00 0.0000E+00 4.2271E+00 0.0000E+00 1.0000E+00 1.0000E+00
3 5.0000E-01 1.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 270660 1 2.0000E-01 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 0.0000E+00 0.0000E+00 5.8904E+00 0.0000E+00 1.0000E+00 1.0000E+00
3 4.1561E-01 1.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 280660 4 2.2750E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 0.0000E+00 0.0000E+00 7.3330E-02 0.0000E+00 9.2600E-10 6.1700E-06
3 0.0000E+00 1.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 290660 2 5.1200E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 0.0000E+00 0.0000E+00 1.1645E+00 0.0000E+00 1.0000E+00 1.0000E+00
3 8.3989E-02 1.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 300660 6 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
3 0.0000E+00 0.0000E+00 0.0000E+00 2.7900E+01 1.0000E+00 1.0000E+00
3 9.8809E-01 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00
10.2.10. Fission Yield Resource Format
The independent fission product yields are stored as a formatted text file. The header record for each set of fission product yields includes the fissionable nuclide ID and an unused entry (0.0), followed by the number of incident neutron energies included for this nuclide. The fission yields for each energy are preceeded by a single record containing the incident neutron energy (eV), an unused entry (0.0), an index for the incident energy, the number of data entries per fission product, the total number of entries for each incident energy, and the number of fission products. The fission product yields for each fissionable nuclide and incident neutron energy are then listed as pairs of entries for the fission product nuclide ID and the independent (direct) fission yield as atom percent per fission. An example of the format is shown below in Example 10.2.2 for 227Th.
The number and order of the fission product yields must be the same for all fissionable nuclides and must correspond to the fission products in the nuclear decay data. The fission product yields for each fissionable nuclide, excluding the yields for the terniary fission products 3H, 3He, and 4He, sum to 200.
The fissionable nuclides and the tabulated incident neutron energies for which yields are available are listed in Table 10.2.2.
ENDF/B-VII.0 modified library
9.02270+05 0.00000+00 1 0 0 0
2.53000-02 0.00000+00 1 2 2302 1151
1.00300+04 0.00000+00 2.00300+04 0.00000+00 2.00400+04 0.00000+00
2.60650+05 0.00000+00 2.70650+05 0.00000+00 2.80650+05 0.00000+00
2.90650+05 0.00000+00 2.40660+05 0.00000+00 2.50660+05 6.97001-13
2.60660+05 2.57000-10 2.70660+05 3.23000-10 2.80660+05 2.71000-10
2.90660+05 7.76001-13 3.00660+05 0.00000+00 3.10660+05 0.00000+00
3.20660+05 0.00000+00 2.40670+05 0.00000+00 2.50670+05 1.35000-13
2.60670+05 1.13000-10 2.70670+05 8.12001-10 2.80670+05 1.21000-09
2.90670+05 2.23000-11 3.00670+05 5.02000-14 3.10670+05 0.00000+00
3.20670+05 0.00000+00 2.50680+05 1.01000-14 2.60680+05 6.08001-11
2.70680+05 8.95001-10 2.80680+05 7.02001-09 2.90680+05 7.68001-11
2.90681+05 1.79000-10 3.00680+05 4.04000-12 3.10680+05 0.00000+00
3.20680+05 0.00000+00 2.50690+05 0.00000+00 2.60690+05 1.23000-11
2.70690+05 1.24000-09 2.80690+05 1.83000-08 2.90690+05 3.80000-09
3.00690+05 2.61000-11 3.00691+05 1.11000-10 3.10690+05 3.65000-14
3.20690+05 0.00000+00 3.30690+05 0.00000+00 2.60700+05 1.74000-12
2.70700+05 4.09000-10 2.80700+05 3.57000-08 2.90700+05 3.24000-09
2.90701+05 9.71001-09 3.00700+05 2.91000-09 3.10700+05 1.84000-12
3.20700+05 0.00000+00 2.60710+05 9.67001-14 2.70710+05 1.71000-10
2.80710+05 3.28000-08 2.90710+05 6.54001-08 3.00710+05 5.49000-09
3.00711+05 2.34000-08 3.10710+05 1.30000-10 3.20710+05 3.13000-14
3.20711+05 3.13000-14 3.30710+05 0.00000+00 2.60720+05 0.00000+00
2.70720+05 2.90000-11 2.80720+05 3.94000-08 2.90720+05 1.53000-07
3.00720+05 3.73000-07 3.10720+05 1.85500-09 3.10721+05 1.85500-09
3.20720+05 1.35000-11 3.30720+05 0.00000+00 3.40720+05 0.00000+00
2.70730+05 2.19000-12 2.80730+05 7.05001-09 2.90730+05 1.68000-07
10.2.11. Gamma Resource Format
An example of the photon data entries for the emissions from 140La decay is shown below in Example 10.2.3. The header record for each nuclide contains the nuclide ID, the total number of emission lines in the evaluation, as well as the number of discrete x-ray lines, discrete gamma lines, and number of pseudo lines used to represent continuum data if present in an evaluation used to reconstruct continuous energy emission spectra from the discrete representation. The last entries in the header record include the total gamma energy (MeV), and the character nuclide name. The emission spectrum is listed using pairs of entries for the photon energy (MeV) and photon emission (photons per disintegration).
571400 52. 14. 38. 0. 0.2.3083E+00 la 140
4.3847E-03 2.1017E-04 4.8247E-03 1.7789E-03 5.3304E-03 1.5654E-03
6.0946E-03 2.3418E-04 3.4291E-02 5.9015E-03 3.4743E-02 1.0817E-02
3.9196E-02 1.0523E-03 3.9285E-02 2.0389E-03 3.9550E-02 1.2513E-05
3.9570E-02 1.6866E-05 4.0227E-02 2.2404E-04 4.0247E-02 4.3591E-04
4.0340E-02 2.6312E-06 4.0344E-02 3.5410E-06 2.4595E-02 1.4971E-05
6.4135E-02 1.4310E-04 6.8916E-02 7.5366E-04 1.0942E-01 2.1942E-03
1.3112E-01 4.6746E-03 1.7354E-01 1.2688E-03 2.4193E-01 4.1404E-03
2.6654E-01 4.6555E-03 3.0690E-01 2.4804E-04 3.2876E-01 2.0320E-01
3.9752E-01 7.3458E-04 4.3249E-01 2.9002E-02 4.3850E-01 3.9114E-04
4.4550E-01 2.8620E-05 4.8702E-01 4.5506E-01 6.1812E-01 3.7206E-04
7.5164E-01 4.3312E-02 8.1577E-01 2.3278E-01 8.6785E-01 5.5046E-02
9.1955E-01 2.6617E-02 9.2519E-01 6.8974E-02 9.5099E-01 5.1898E-03
9.9290E-01 1.3356E-04 1.0451E+00 2.4804E-04 1.0972E+00 2.2896E-04
1.3035E+00 4.1976E-04 1.4052E+00 5.9148E-04 1.5962E+00 9.5400E-01
1.8773E+00 4.1022E-04 1.9246E+00 1.3356E-04 2.0832E+00 1.1543E-04
2.3479E+00 8.4906E-03 2.4641E+00 1.1448E-04 2.5214E+00 3.4630E-02
2.5473E+00 1.0112E-03 2.8996E+00 6.6780E-04 3.1185E+00 2.4804E-04
3.3204E+00 3.8160E-05