11.3. COMPOZ Data Guide

J. R. Knight 1 and L. M. Petrie


The COMPOZ program used to create the Standard Composition Library is described. Of particular importance is documentation of the COMPOZ input data file structure. Knowledge of the file structure allows users to edit the data file and subsequently create their own site-specific composition library.


This work was originally funded by the Office of Nuclear Material Safety and Safeguards of the U.S. Nuclear Regulatory Commission.

11.3.1. Introduction

COMPOZ is the program that creates (writes) the SCALE Standard Composition Library. Data are input in free form. A text data file containing the input to COMPOZ (and the Standard Composition Library) is available with the SCALE system. Execution of COMPOZ using this data file creates the Standard Composition Library currently available with the SCALE package. This section provides documentation of the data file structure. Knowledge of the data file structure allows users to edit the data file and subsequently create their own site-specific or user-specific composition library.

COMPOZ is intended to create or make permanent changes to and/or to print the composition library and should not be used for any other purpose. To avoid confusion with the Standard Composition Library provided with SCALE, it is strongly recommended that only new keywords and compositions be used in any site-specific or user-specific library.

11.3.2. Input Data Description

COMPOZ input data are entered in free form. All data must be followed by at least one blank. The COMPOZ input data file contains five data records or blocks:

  1. COMPOZ mode flag selects whether a new standard composition library will be created, or an old standard composition library will be listed. Only if a new library is being created are the following data records entered. A new library is created with a filename of “xfile089”. If an old library is being dumped as an ASCII file, it will be named “_sclN…N” where N…N is an 18 digit sequence number that is incremented starting from 0 for each library dumped in the same directory.

  2. The header record contains the library identification, a set of parameters describing the size of the library, and library title with 80 characters per line.

  3. The standard composition table contains the name, theoretical density, number of elements, and other information about each standard composition. Individual nuclides, mixtures, and compounds are all included in the table.

  4. The nuclide information table contains the nuclide identification number, atomic mass, and resonance energy cross sections.

  5. The isotopic distribution table contains the nuclide identification number and the atom percent of each isotope used in specifying the default enrichment.


For executing COMPOZ via SCALE, an =COMPOZ is required in the first eight columns of a record preceding the mode flag, and an END is required in the first three columns of a record inserted after the last data record. If debug output is desired, then use =COMPOZ PRINTDEBUG to execute compoz. COMPOZ mode selector

  1. LGEN =

0 – create a new library and list it

1 – list an existing library

>1 – list an existing library and write an ASCII input file.

If LGEN is 0, then input the following data to create a new standard composition library. Library heading information

  1. IDT – library identification number

  2. TITLE – 1 line of 80 characters used to identify the library Standard composition table

  1. SCID – Composition name, maximum of 12 characters.

  2. ROTH – Theoretical density, gm/cm3.

  3. ICP –

0 for a mixture,

1 for a compound.

  1. NCZA – Element or nuclide ID

  2. ATPM – Weight percent if ICP = 0. Number of atoms per molecule if ICP = 1.

  3. END – Keyword END to terminate this standard composition.

For each composition, items 4 and 5 are repeated until all components of the composition are described. Items 1 through 6 are entered in a similar fashion for all compositions. After all the standard compositions are read, terminate the table with an END [label], where [label] represents an optional label. Nuclide information table

1. NZA – Nuclide ID. This should be the mass number + 1000 * the atomic number.

  1. AM – Atomic mass, C-12 scale.

  2. SIGS – Resonance energy scattering cross section, barns.

  3. SIGT – Resonance energy total cross section, barns.

  4. NU*SIGF – Resonance energy nu*sigf cross section, barns.

The resonance energy cross sections are averaged over the appropriate energy range for the nuclide. Items 1–5 are repeated for all nuclides. After all nuclides are entered, terminate the nuclide table with an END [label]. Isotopic distribution table

  1. NZN – 1000 * atomic number of variable isotope elements.

  2. ISZA – Isotope ID.

  3. ABWP – Default abundance, atom percent.

  4. END – Keyword END to terminate this isotopic specification.

The default abundance is generally the naturally occurring abundance. For each element, items 2 and 3 are repeated until 100% total abundance is described, making a set for this element. The next element is described in the same fashion in the next set, etc. After all isotopic distributions are entered, terminate the isotopic distribution table with an END [label].

11.3.3. Sample Problem

The following sample problem first lists the SCALE standard composition library, then creates a new, short standard composition library, then lists and outputs an ASCII copy of this new library, and finally copies this new copy back to the output directory.

'  print the current standard composition library
'  create a new standard composition library
'  library identification number
'  library title
scale-X standard composition library
'  standard composition table
'  all nuclide IDs here must be in the nuclide table
    h               1.0000    0        1001 100.0000 end
    o               1.0000    0        8016 100.0000 end
    u              19.0500    0       92000 100.0000 end
    h2o             0.9982    1        1001    2
                                       8016    1 end
    uo2            10.9600    1       92000    1
                                       8016    2 end
'  end of standard composition table
   end stdcmp
'  nuclide table
'    ID       AWR     SigmaS      SigmaT      nuSigmaF
   1001   1.00783    20.38087    20.38782     0.00000
   1002   2.01410     3.39486     3.39487     0.00000
   8016  15.99491     3.88696     3.88696     0.00000
   8017  16.99913     3.74000     3.74501     0.00000
   8018  17.99916     3.79000     3.79000     0.00000
  92233 233.03964    12.46693    37.62292   100.78482
  92234 234.04095    12.18716    16.09542     2.66969
  92235 235.04393    11.90249    35.22383    90.23152
  92236 236.04556    12.27302    14.93351     1.33334
  92237 237.04874    14.24581    24.68619     1.93695
  92238 238.05080    12.32636    14.62708     0.65970
'  end of nuclide table
   end nuclides
'  isotope distribution table
'  all nuclide IDs here must be in the nuclide table
   1000   1001  99.9885
          1002   0.0115 end
   8000   8016  99.7570
          8017   0.0380
          8018   0.2050 end
  92000  92234   0.0054
         92235   0.7204
         92238  99.2742 end
'  end of isotope distribution table
    end isotopes
'  end of compoz input
'  print and create an ASCII copy of the current standard composition library
'  (created in the previous step)
 # copy the ASCII copy back to the output directory
  copy_file _scl000000000000000000 ${OUTBASE}.stdcmplib

Formerly with Oak Ridge National Laboratory.