class openmc.deplete.Nuclide(name=None)[source]

Decay modes, reactions, and fission yields for a single nuclide.


name (str, optional) – GNDS name of this nuclide, e.g. "He4", "Am242_m1"

  • name (str or None) – Name of nuclide.

  • half_life (float or None) – Half life of nuclide in [s].

  • decay_energy (float) – Energy deposited from decay in [eV].

  • n_decay_modes (int) – Number of decay pathways.

  • decay_modes (list of openmc.deplete.DecayTuple) – Decay mode information. Each element of the list is a named tuple with attributes ‘type’, ‘target’, and ‘branching_ratio’.

  • n_reaction_paths (int) – Number of possible reaction pathways.

  • reactions (list of openmc.deplete.ReactionTuple) – Reaction information. Each element of the list is a named tuple with attribute ‘type’, ‘target’, ‘Q’, and ‘branching_ratio’.

  • sources (dict) – Dictionary mapping particle type as string to energy distribution of decay source represented as openmc.stats.Univariate

  • yield_data (FissionYieldDistribution or None) – Fission product yields at tabulated energies for this nuclide. Can be treated as a nested dictionary {energy: {product: yield}}

  • yield_energies (tuple of float or None) – Energies at which fission product yields exist

add_decay_mode(type, target, branching_ratio)[source]

Add decay mode to the nuclide

  • type (str) – Type of the decay mode, e.g., ‘beta-’

  • target (str or None) – Nuclide resulting from decay. A value of None implies the target does not exist in the currently configured depletion chain

  • branching_ratio (float) – Branching ratio of the decay mode

add_reaction(type, target, Q, branching_ratio)[source]

Add transmutation reaction to the nuclide

  • type (str) – Type of the reaction, e.g., ‘fission’

  • target (str or None) – Nuclide resulting from reaction. A value of None implies either no single target, e.g. from fission, or that the target nuclide is not considered in the current depletion chain

  • Q (float) – Q value of the reaction in [eV]

  • branching_ratio (float) – Branching ratio of the reaction

classmethod from_xml(element, root=None, fission_q=None)[source]

Read nuclide from an XML element.

  • element (lxml.etree._Element) – XML element to read nuclide data from

  • root (lxml.etree._Element, optional) – Root XML element for chain file (only used when fission product yields are borrowed from another parent)

  • fission_q (None or float) – User-supplied fission Q value [eV]. Will be read from the element if not given


nuc – Instance of a nuclide

Return type



Write nuclide to XML element.


elem – XML element to write nuclide data to

Return type


validate(strict=True, quiet=False, tolerance=0.0001)[source]

Search for possible inconsistencies

The following checks are performed:

  1. for all non-fission reactions and decay modes, does the sum of branching ratios equal about one?

  2. for fission reactions, does the sum of fission yield fractions equal about two?

  • strict (bool, optional) – Raise exceptions at the first inconsistency if true. Otherwise mark a warning

  • quiet (bool, optional) – Flag to suppress warnings and return immediately at the first inconsistency. Used only if strict does not evaluate to True.

  • tolerance (float, optional) –

    Absolute tolerance for comparisons. Used to compare computed value x to intended value y as:

    valid = (y - tolerance <= x <= y + tolerance)


valid – True if no inconsistencies were found

Return type



ValueError – If strict evaluates to True and an inconistency was found