The sandy.njoymodule effectively generates and runs NJOY input files with only a minimal interaction from the user side, thus making the nuclear data processing accessible to a larger community.
With only few entries provided in the command line, sandy.njoy automatically determines the best NJOY input options for a succesfull run.
On top of that, several file-related parameters --- e.g. MAT number--- are read and imported from the desired evaluated file without having the user dig into the details of a very human-unfriendly format such as ENDF-6.
- Before starting
- NJOY versions
- Usage
- Producing PENDF files
- Producing GENDF files
- Producing ERRORR files
- Producing ACE files
sandy.njoy looks for the executable file njoy2016 in the PATH environmetal variable. If you want to use a different NJOY executable, then you must specify the desired file using the dedicated command line argument.
Notice that sandy.njoy only supports NJOY-2016.
sandy.njoy is run as a pythonscript using the -m command line option
$ python -m sandy.njoyFor an overview of the sandy.njoy usage and acceptable arguments, type
$ python -m sandy.njoy --helpusage: python -m sandy.njoy [-h] [-P PENDF] [-G GENDF] [-p] [-a] [-g] [-e]
[-H] [--temps TEMPS [TEMPS ...]]
[--sig0 SIG0 [SIG0 ...]]
[--kerma [KERMA [KERMA ...]]] [--err ERR]
[--free-gas] [--ptable] [--gaspr] [--ign IGN]
[--iwt IWT] [--igne IGNE] [--iwte IWTE]
[--suffixes .XX [.XX ...]] [-V VERBOSE] [-v]
tape
positional arguments:
tape ENDF-6 format file
optional arguments:
-h, --help show this help message and exit
-P PENDF, --pendftape PENDF
processed PENDF format file
-G GENDF, --gendftape GENDF
processed GENDF format file
-p, --pendf produce PENDF file
-a, --ace produce ACE file
-g, --gendf produce GENDF file
-e, --errorr produce ERRORR file
-H, --hendf produce HENDF file
--temps TEMPS [TEMPS ...]
list of temperature values
--sig0 SIG0 [SIG0 ...]
list of dilution values
--kerma [KERMA [KERMA ...]]
list of partial kermas (default=[302, 303, 304, 318, 402, 442, 443, 444, 445, 446, 447])
--err ERR fractional tolerance for RECONR and BROADR (default=0.001)
--free-gas compute thermal cross section for free-gas scatterer (THERMR)
--ptable compute probability tables (PURR)
--gaspr compute gas-production cross sections (GASPR)
--ign IGN neutron group structure option for GROUPR
- file : read from file
- 2 : csewg 239-group structure [default]
- 3 : lanl 30-group structure
- 4 : anl 27-group structure
- 5 : rrd 50-group structure
- 6 : gam-i 68-group structure
- 7 : gam-ii 100-group structure
- 8 : laser-thermos 35-group structure
- 9 : epri-cpm 69-group structure
- 10 : lanl 187-group structure
- 11 : lanl 70-group structure
- 12 : sand-ii 620-group structure
- 13 : lanl 80-group structure
- 14 : eurlib 100-group structure
- 15 : sand-iia 640-group structure
- 16 : vitamin-e 174-group structure
- 17 : vitamin-j 175-group structure
- 19 : ecco 33-group structure
- 20 : ecco 1968-group structure
- 21 : tripoli 315-group structure
- 22 : xmas lwpc 172-group structure
- 23 : vit-j lwpc 175-group structure
predefined group structures:
- scale_238
--iwt IWT Weight function option for GROUPR
- file : read from file
- 2 : constant
- 3 : 1/e
- 5 : epri-cell lwr
- 6 : (thermal) -- (1/e) -- (fission + fusion)
- 7 : same with t-dep thermal part
- 8 : thermal--1/e--fast reactor--fission + fusion
- 9 : claw weight function
- 10 : claw with t-dependent thermal part
- 11 : vitamin-e weight function (ornl-5505)
- 12 : vit-e with t-dep thermal part
predefined functions:
- jaea_fns_175
--igne IGNE neutron group structure option for ERRORR (same as --ign)
--iwte IWTE weight function option for ERRORR (same as --iwt)
--suffixes .XX [.XX ...]
suffixes for ACE files, as many as temperature values (default = None).
-V VERBOSE, --verbose VERBOSE
set verbosity level (default = 1)
-v, --version
Let's take a look at the various sandy.njoy options to produce a pointwise ENDF (PENDF) file.
First off, a PENDF file is produced by running sandy.njoy with option -p or --pendf.
Cross sections are reconstructed and linearized using the RECONR module of NJOY.
$ python -m sandy.njoy ${file} -pThe PENDF output will be named ${file}.pendf.
Cross sections are Doppler-broadened at one or more temperatures using the BROADR module of NJOY.
For example, you can include Doppler-broadening for, say, two temperatures (300 and 600 K), using option --temps like this:
$ python -m sandy.njoy ${file} -p \
--temps 300 600To produce effective self-shielded cross sections for resonance reactions in the unresolved energy range --- using the UNRESR module of NJOY --- you must define the desired levels of dilutions with keyword --sig0, as
$ python -m sandy.njoy ${file} -p \
--temps 300 600 \
--sig0 1E10 1E4 1E3 1E2 1E1 1E0Nuclear heating and/or damage energy can be computed with the HEATR module of NJOY by using keyword --kerma.
$ python -m sandy.njoy ${file} -p \
--temps 300 600 \
--sig0 1E10 1E4 1E3 1E2 1E1 1E0 \
--kermaThe --kerma instruction accepts a list of heating and damage MT reaction numbers that will be computed and added to the PENDF file.
If --kerma is provided without additional entries, the default --kerma 302 303 304 318 402 442 443 444 445 446 447 is used.
The allowed MT reaction numbers with their meaning is reported in the table below.
| MT | Description |
|---|---|
| 301 | KERMA total (energy balance) |
| 302 | KERMA elastic |
| 303 | KERMA non-elastic |
| 304 | KERMA inelastic |
| 318 | KERMA fission |
| 401 | KERMA disappearance |
| 402 | KERMA radiative capture |
| 403 | KERMA proton production |
| 407 | KERMA alpha production |
| 442 | total photon KERMA contribution |
| 443 | total kinematic KERMA (kinematic Limit) |
| 444 | total damage energy production cross section |
| 445 | elastic damage energy production cross section |
| 446 | inelastic damage energy production cross section |
| 447 | neutron disappearance damage energy production cross section |
Thermal cross sections for a free-gas scatterer can be computed by the THERMR module of NJOY by adding the --free-gas instruction.
$ python -m sandy.njoy ${file} -p \
--temps 300 600 \
--sig0 1E10 1E4 1E3 1E2 1E1 1E0 \
--kerma \
--free-gasThe inelastic reaction is added to the PENDF file with MT reaction number 221.
Option --ptable adds probability tables --- calculated with the module PURR of NJOY --- to the PENDF file.
$ python -m sandy.njoy ${file} -p \
--temps 300 600 \
--sig0 1E10 1E4 1E3 1E2 1E1 1E0 \
--kerma \
--free-gas \
--ptableGas production cross sections can be added to the PENDF file --- with the module GASPR of NJOY --- using instruction --gaspr.
$ python -m sandy.njoy ${file} -p \
--temps 300 600 \
--sig0 1E10 1E4 1E3 1E2 1E1 1E0 \
--kerma \
--free-gas \
--ptable \
--gasprGENDF or groupwise-ENDF files are processed files produced by the GROUPR module of NJOY. Such files are written according to a modified ENDF-6 format conceived for storing group average nuclear data.
To produce GENDF files by running the sandy.njoy module, you can try and use instruction -g or --gendf, like this:
$ python -m sandy.njoy ${file} -gIn this case, an error messages wil be raised stating that a PENDF file is missing (NJOY needs a ENDF-6 and a PENDF file to produce a GENDF output).
You can provide the PENDF file either usign keyword --pendftape ${pendf_file}, as
$ python -m sandy.njoy ${file} -g \
--pendftape ${pendf_file}
--temps 300 600 \
--sig0 1E10 1E4 1E3 1E2 1E1 1E0or including -g to the PENDF production sequence:
$ python -m sandy.njoy ${file} -pg \ # process both pendf and gendf
--temps 300 600 \
--sig0 1E10 1E4 1E3 1E2 1E1 1E0 \
--kerma \
--free-gas \
--ptable \
--gasprThe generated GENDF file will be called ${file}.gendf.
Notice that, independently on the way the GENDF file is produced, sandy.njoy requires an explicit specification of the temperature and dilution values.
As an extra instruction, you can define a neutron group structure for the output GENDF file other than the default CSWEG 239-group structure.
Then, add argument --ign with the desired structure number according to the NJOY manual, e.g.
$ python -m sandy.njoy ${file} -pg \ # process both pendf and gendf
--temps 300 600 \
--sig0 1E10 1E4 1E3 1E2 1E1 1E0 \
--kerma \
--free-gas \
--ptable \
--gaspr \
--ign 19 # produce GENDF output file on the ECCO 33-group structureA tabulated group structure can be read from a text file if the filename replaces the NJOY structure number, --ign ${text_filename}.
In such a case, each group boundary should be provided in eV as a new line of the file, like this:
1E-5
1E-3
0.1
1.0000
100
1e4
1e7
Alternatively, precompiled structures that are not implemented in NJOY can be used,
For example, to use the 238-group structure included in the SCALE suite, just type --ign scale_238.
Analogously, the default weighting function (thermal -- 1/E -- fission + fusion) specified for the group collapsing can be modified using keyword --iwt followed by one of the dedicated numbers defined in the NJOY manual, for instance
$ python -m sandy.njoy ${file} -pg \ # process both pendf and gendf
--temps 300 600 \
--sig0 1E10 1E4 1E3 1E2 1E1 1E0 \
--kerma \
--free-gas \
--ptable \
--gaspr \
--ign 19 \
--iwt 2 # use a constant functionThe weighting function can be also read from a text file typing --iwt ${text_filename}.
Then, the requested format for the file is the following:
- two columns, the first for the energy (in eV) and the second for the weight;
- the weight in line i is considered constant between the two energies in lines i and i+1.
1E-5 1
1E-3 3
0.1 3.5
1.0000 4
100 4.5
1e4 5
1e7 0
Precompiled data also exist for weighting functions.
The ERRORR module of NJOY produces multigroup covariance matrices by convoluting the covariance information available in ENDF-6 evaluated files and the corresponding central values.
To produce ERRORR files with sandy.njoy, add option -e or --errorr to the PENDF or GENDF sequence:
$ python -m sandy.njoy ${file} -pe \ # process pendf and errorr
--temps 300 600The generated ERRORR file will be called ${file}.errorr.
Alternatively, run the module providing the PENDF file as an extra argument:
$ python -m sandy.njoy ${file} -e \ # process errorr
--temps 300 600 \
--pendftape ${pendf_file}For both cases, the temperature values must be given explicitely using keyword --temps.
As for the production of GENDF files, a user-defined group structure can be provided using keyword --igne.
For such a keyword the same rules as or --ign apply.
You can also supply a weighting funcion using command --iwte, for which the rules defined for --iwt apply.
ACE (A Compact ENDF) formatted files are used by many continous-energy Monte Carlo transport codes including MCNP.
You can process ACE files running sandy.njoy with option -a or --ace, as
$ python -m sandy.njoy ${file} -a \ # process ace
--temps 300 600 \
--pendftape ${pendf_file}The generated ACE file will be called ${file}.ace.
If you do not have a suitable PENDF file available, simply reprocess it with sandy.njoy and attach option -a to the sequence.
$ python -m sandy.njoy ${file} -pa \ # process pendf and ace
--temps 300 600Remember that the temperature specification is mandatory, as well as the respective suffixes used in the xsdir file. Suffixes can be specified as it follows:
$ python -m sandy.njoy ${file} -pa \ # process pendf and ace
--temps 300 600 \
--suffixes .03 .06Keyword --suffixes takes as many entries as given with --temps.