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dag-openmc-example

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Some simple examples of DAG-OpenMC.

DAGMC can be installed as a libray of OpenMC.
Let’s call it DAG-OpenMC.
This blog shows a simple example of DAG-OpenMC problem.

Test problem description

I am using a toy problem for SDR calculation with a collimator as the example:


Create a DAGMC geometry file in Trelis to use.

Define material

Here, we use PyNE to generate h5 material and then combine it with the geometry file.
As it is an example, we use the default nndc_hdf5 nuclide library.
So, we don’t need to use expand_elements when generte the pyne material.
Otherwise, there will be inconsistency between nuclide name definition.

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#!/usr/bin/python
#
from pyne.material import Material,MaterialLibrary
print "Welcome!"
mat_lib=MaterialLibrary()
#
lead = Material({'Pb':1},density=11.35)
#lead = lead.expand_elements()

# define a simple water since O-18 not in mcnp xs libs
watervec={10010:2,80160:1} # simple water
water = Material()
water.density = 1.0
water.from_atom_frac(watervec)

# Air
air = Material({'C':0.000124, 'N':0.755268, 'O':0.231781, 'Ar':0.012827},
               density=0.001205)
#air = air.expand_elements()

# Put materials in the mat_lib
mat_lib["Lead"] = lead
mat_lib["Air"] = air
mat_lib["Water"] = water

#
mat_lib.write_hdf5("demo_collimator_mat_lib.h5")
#
print "All done!"

Combine the geometry and material

Use uwuw_preproc to combine the material and geometry in dagmc.h5m.
Note that the name of this file must be dagmc.h5m for use of DAG-OpenMC.

define other items for OpenMC using Python API

Things to be defined:

  • general settings (include dagmc option to be True)
  • source
  • tally
  • run and plots

The following is the input.py for this problem:

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import numpy as np
import openmc
import openmc.capi
from openmc.stats import Point
#
model = openmc.model.Model()

# settings
model.settings.batches = 5
model.settings.inactive = 0
model.settings.particles = 100 # particle per batch
model.settings.run_mode = 'fixed source'
model.settings.output = {'tallies':True, 'summary':True}

# source, 14MeV at (-30, 0, 0), isotropic
source = openmc.Source()
source.space = Point(xyz=(-30.0, 0.0, 0.0))
source.energy = openmc.stats.Discrete([14.0*1e6], [1.0])
model.settings.source = source

# set model.settings.dagmc to be true, the default 'dagmc.h5m' will be used
model.settings.dagmc = True
model.settings.export_to_xml(path='settings.xml')

# tally
tally = openmc.Tally()
# define score
tally.scores = ['flux']
# define filter
# 175 energy group, energy unit of openmc is eV
energy_bins = np.array([0.0,
        1.00001E-007, 4.13994E-007, 5.31579E-007, 6.82560E-007, 8.76425E-007,
        1.12535E-006, 1.44498E-006, 1.85539E-006, 2.38237E-006, 3.05902E-006,     
        3.92786E-006, 5.04348E-006, 6.47595E-006, 8.31529E-006, 1.06770E-005,     
        1.37096E-005, 1.76035E-005, 2.26033E-005, 2.90232E-005, 3.72665E-005,     
        4.78512E-005, 6.14421E-005, 7.88932E-005, 1.01301E-004, 1.30073E-004,     
        1.67017E-004, 2.14454E-004, 2.75364E-004, 3.53575E-004, 4.53999E-004,     
        5.82947E-004, 7.48518E-004, 9.61117E-004, 1.23410E-003, 1.58461E-003,     
        2.03468E-003, 2.24867E-003, 2.48517E-003, 2.61259E-003, 2.74654E-003,     
        3.03539E-003, 3.35463E-003, 3.70744E-003, 4.30742E-003, 5.53084E-003,     
        7.10174E-003, 9.11882E-003, 1.05946E-002, 1.17088E-002, 1.50344E-002,     
        1.93045E-002, 2.18749E-002, 2.35786E-002, 2.41755E-002, 2.47875E-002,     
        2.60584E-002, 2.70001E-002, 2.85011E-002, 3.18278E-002, 3.43067E-002,     
        4.08677E-002, 4.63092E-002, 5.24752E-002, 5.65622E-002, 6.73795E-002,     
        7.20245E-002, 7.94987E-002, 8.25034E-002, 8.65170E-002, 9.80365E-002,     
        1.11090E-001, 1.16786E-001, 1.22773E-001, 1.29068E-001, 1.35686E-001,     
        1.42642E-001, 1.49956E-001, 1.57644E-001, 1.65727E-001, 1.74224E-001,     
        1.83156E-001, 1.92547E-001, 2.02419E-001, 2.12797E-001, 2.23708E-001,     
        2.35177E-001, 2.47235E-001, 2.73237E-001, 2.87246E-001, 2.94518E-001,     
        2.97211E-001, 2.98491E-001, 3.01974E-001, 3.33733E-001, 3.68832E-001,     
        3.87742E-001, 4.07622E-001, 4.50492E-001, 4.97871E-001, 5.23397E-001,     
        5.50232E-001, 5.78443E-001, 6.08101E-001, 6.39279E-001, 6.72055E-001,     
        7.06512E-001, 7.42736E-001, 7.80817E-001, 8.20850E-001, 8.62936E-001,     
        9.07180E-001, 9.61672E-001, 1.00259E+000, 1.10803E+000, 1.16484E+000,     
        1.22456E+000, 1.28735E+000, 1.35335E+000, 1.42274E+000, 1.49569E+000,     
        1.57237E+000, 1.65299E+000, 1.73774E+000, 1.82684E+000, 1.92050E+000,     
        2.01897E+000, 2.12248E+000, 2.23130E+000, 2.30693E+000, 2.34570E+000,     
        2.36533E+000, 2.38513E+000, 2.46597E+000, 2.59240E+000, 2.72532E+000,     
        2.86505E+000, 3.01194E+000, 3.16637E+000, 3.32871E+000, 3.67879E+000,     
        4.06570E+000, 4.49329E+000, 4.72367E+000, 4.96585E+000, 5.22046E+000,     
        5.48812E+000, 5.76950E+000, 6.06531E+000, 6.37628E+000, 6.59241E+000,     
        6.70320E+000, 7.04688E+000, 7.40818E+000, 7.78801E+000, 8.18731E+000,     
        8.60708E+000, 9.04837E+000, 9.51229E+000, 1.00000E+001, 1.05127E+001,     
        1.10517E+001, 1.16183E+001, 1.22140E+001, 1.25232E+001, 1.28403E+001,     
        1.34986E+001, 1.38403E+001, 1.41907E+001, 1.45499E+001, 1.49182E+001,     
        1.56831E+001, 1.64872E+001, 1.69046E+001, 1.73325E+001, 1.96403E+001])
energy_filter = openmc.EnergyFilter(energy_bins*1e6)
tally.filters.append(energy_filter)
# mesh filter
mesh = openmc.Mesh(mesh_id=14, name="n_flux")
mesh.dimension= [16, 5, 1]
mesh.lower_left = (-40.0, -12.5, -2.5)
mesh.upper_right = (40.0, 12.5, 2.5)
mesh_filter = openmc.MeshFilter(mesh)
tally.filters.append(mesh_filter)
# add the tally to tallies list
tallies = openmc.Tallies()
tallies.append(tally)
tallies.export_to_xml()

# run the problem
#openmc.run(mpi_args=['mpiexec', '-n', '4'])
openmc.run()

Run the problem

Run the problem using:

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python input.py