openmc.Universe

class openmc.Universe(universe_id=None, name='', cells=None)

A collection of cells that can be repeated.

Parameters:

• universe_id (int, optional) – Unique identifier of the universe. If not specified, an identifier will automatically be assigned
• name (str, optional) – Name of the universe. If not specified, the name is the empty string.
• cells (Iterable of openmc.Cell, optional) – Cells to add to the universe. By default no cells are added.

Variables:

• id (int) – Unique identifier of the universe
• name (str) – Name of the universe
• cells (collections.OrderedDict) – Dictionary whose keys are cell IDs and values are Cell instances
• volume (float) – Volume of the universe in cm^3. This can either be set manually or calculated in a stochastic volume calculation and added via the Universe.add_volume_information() method.
• bounding_box (2-tuple of numpy.array) – Lower-left and upper-right coordinates of an axis-aligned bounding box of the universe.

add_cell(cell)

Add a cell to the universe.

Parameters:cell (openmc.Cell) – Cell to add

add_cells(cells)

Add multiple cells to the universe.

Parameters:cells (Iterable of openmc.Cell) – Cells to add

add_volume_information(volume_calc)

Add volume information to a universe.

Parameters:volume_calc (openmc.VolumeCalculation) – Results from a stochastic volume calculation

clear_cells()

Remove all cells from the universe.

clone(clone_materials=True, clone_regions=True, memo=None)

Create a copy of this universe with a new unique ID, and clones all cells within this universe.

Parameters:

• clone_materials (bool) – Whether to create separates copies of the materials filling cells contained in this universe.
• clone_regions (bool) – Whether to create separates copies of the regions bounding cells contained in this universe.
• memo (dict or None) – A nested dictionary of previously cloned objects. This parameter is used internally and should not be specified by the user.

Returns:

clone – The clone of this universe

Return type:

openmc.Universe

create_xml_subelement(xml_element, memo=None)

Add the universe xml representation to an incoming xml element

Parameters:

• xml_element (xml.etree.ElementTree.Element) – XML element to be added to
• memo (set or None) – A set of object id’s representing geometry entities already written to the xml_element. This parameter is used internally and should not be specified by users.

Returns:

Return type:

None

find(point)

Find cells/universes/lattices which contain a given point

Parameters:point (3-tuple of float) – Cartesian coordinates of the point Returns:Sequence of universes, cells, and lattices which are traversed to find the given point Return type:list

classmethod from_hdf5(group, cells)

Create universe from HDF5 group

Parameters:

• group (h5py.Group) – Group in HDF5 file
• cells (dict) – Dictionary mapping cell IDs to instances of openmc.Cell.

Returns:

Universe instance

Return type:

openmc.Universe

get_all_cells(memo=None)

Return all cells that are contained within the universe

Returns:cells – Dictionary whose keys are cell IDs and values are Cell instances Return type:collections.OrderedDict

get_all_materials(memo=None)

Return all materials that are contained within the universe

Returns:materials – Dictionary whose keys are material IDs and values are Material instances Return type:collections.OrderedDict

get_all_universes()

Return all universes that are contained within this one.

Returns:universes – Dictionary whose keys are universe IDs and values are Universe instances Return type:collections.OrderedDict

get_nuclide_densities()

Return all nuclides contained in the universe

Returns:nuclides – Dictionary whose keys are nuclide names and values are 2-tuples of (nuclide, density) Return type:collections.OrderedDict

get_nuclides()

Returns all nuclides in the universe

Returns:nuclides – List of nuclide names Return type:list of str

plot(origin=(0.0, 0.0, 0.0), width=(1.0, 1.0), pixels=(200, 200), basis='xy', color_by='cell', colors=None, seed=None, **kwargs)

Display a slice plot of the universe.

To display or save the plot, call matplotlib.pyplot.show() or matplotlib.pyplot.savefig(). In a Jupyter notebook, enabling the matplotlib inline backend will show the plot inline.

Parameters:

• origin (Iterable of float) – Coordinates at the origin of the plot
• width (Iterable of float) – Width of the plot in each basis direction
• pixels (Iterable of int) – Number of pixels to use in each basis direction
• basis ({'xy', 'xz', 'yz'}) – The basis directions for the plot
• color_by ({'cell', 'material'}) – Indicate whether the plot should be colored by cell or by material
• colors (dict) –

  Assigns colors to specific materials or cells. Keys are instances of Cell or Material and values are RGB 3-tuples, RGBA 4-tuples, or strings indicating SVG color names. Red, green, blue, and alpha should all be floats in the range [0.0, 1.0], for example:

  # Make water blue
  water = openmc.Cell(fill=h2o)
  universe.plot(..., colors={water: (0., 0., 1.))
  

• seed (hashable object or None) – Hashable object which is used to seed the random number generator used to select colors. If None, the generator is seeded from the current time.
• **kwargs – All keyword arguments are passed to matplotlib.pyplot.imshow().

Returns:

Resulting image

Return type:

matplotlib.image.AxesImage

remove_cell(cell)

Remove a cell from the universe.

Parameters:cell (openmc.Cell) – Cell to remove