openmc.deplete
– Depletion¶
Primary API¶
The two primary requirements to perform depletion with openmc.deplete
are:
- A transport operator
- A time-integration scheme
The former is responsible for executing a transport code, like OpenMC,
and retaining important information required for depletion. The most common examples
are reaction rates and power normalization data. The latter is responsible for
projecting reaction rates and compositions forward in calendar time across
some step size \(\Delta t\), and obtaining new compositions given a power
or power density. The Operator
is provided to handle communicating with
OpenMC. Several classes are provided that implement different time-integration
algorithms for depletion calculations, which are described in detail in Colin
Josey’s thesis, Development and analysis of high order neutron
transport-depletion coupling algorithms.
PredictorIntegrator |
Deplete using a first-order predictor algorithm. |
CECMIntegrator |
Deplete using the CE/CM algorithm. |
CELIIntegrator |
Deplete using the CE/LI CFQ4 algorithm. |
CF4Integrator |
Deplete using the CF4 algorithm. |
EPCRK4Integrator |
Deplete using the EPC-RK4 algorithm. |
LEQIIntegrator |
Deplete using the LE/QI CFQ4 algorithm. |
SICELIIntegrator |
Deplete using the SI-CE/LI CFQ4 algorithm. |
SILEQIIntegrator |
Deplete using the SI-LE/QI CFQ4 algorithm. |
Each of these classes expects a “transport operator” to be passed. An operator specific to OpenMC is available using the following class:
Operator |
OpenMC transport operator for depletion. |
The Operator
must also have some knowledge of how nuclides transmute
and decay. This is handled by the Chain
.
Minimal Example¶
A minimal example for performing depletion would be:
>>> import openmc
>>> import openmc.deplete
>>> geometry = openmc.Geometry.from_xml()
>>> settings = openmc.Settings.from_xml()
# Representation of a depletion chain
>>> chain_file = "chain_casl.xml"
>>> operator = openmc.deplete.Operator(
... geometry, settings, chain_file)
# Set up 5 time steps of one day each
>>> dt = [24 * 60 * 60] * 5
>>> power = 1e6 # constant power of 1 MW
# Deplete using mid-point predictor-corrector
>>> cecm = openmc.deplete.CECMIntegrator(
... operator, dt, power)
>>> cecm.integrate()
Internal Classes and Functions¶
When running in parallel using mpi4py, the MPI intercommunicator used can
be changed by modifying the following module variable. If it is not explicitly
modified, it defaults to mpi4py.MPI.COMM_WORLD
.
-
openmc.deplete.
comm
¶ MPI intercommunicator used to call OpenMC library
Type: mpi4py.MPI.Comm
During a depletion calculation, the depletion chain, reaction rates, and number densities are managed through a series of internal classes that are not normally visible to a user. However, should you find yourself wondering about these classes (e.g., if you want to know what decay modes or reactions are present in a depletion chain), they are documented here. The following classes store data for a depletion chain:
Chain |
Full representation of a depletion chain. |
DecayTuple |
Decay mode information |
Nuclide |
Decay modes, reactions, and fission yields for a single nuclide. |
ReactionTuple |
Transmutation reaction information |
FissionYieldDistribution |
Energy-dependent fission product yields for a single nuclide |
FissionYield |
Mapping for fission yields of a parent at a specific energy |
The following classes are used during a depletion simulation and store auxiliary data, such as number densities and reaction rates for each material.
AtomNumber |
Stores local material compositions (atoms of each nuclide). |
OperatorResult |
Result of applying transport operator |
ReactionRates |
Reaction rates resulting from a transport operator call |
Results |
Output of a depletion run |
ResultsList |
A list of openmc.deplete.Results objects |
The following class and functions are used to solve the depletion equations,
with cram.CRAM48()
being the default.
cram.IPFCramSolver |
CRAM depletion solver that uses incomplete partial factorization |
cram.CRAM16 |
Solve depletion equations using IPF CRAM |
cram.CRAM48 |
Solve depletion equations using IPF CRAM |
cram.deplete |
Deplete materials using given reaction rates for a specified time |
cram.timed_deplete |
Wrapper over deplete() that also returns process time |
The following classes are used to help the openmc.deplete.Operator
compute quantities like effective fission yields, reaction rates, and
total system energy.
helpers.AveragedFissionYieldHelper |
Class that computes fission yields based on average fission energy |
helpers.ChainFissionHelper |
Computes energy using fission Q values from depletion chain |
helpers.ConstantFissionYieldHelper |
Class that uses a single set of fission yields on each isotope |
helpers.DirectReactionRateHelper |
Class that generates tallies for one-group rates |
helpers.EnergyScoreHelper |
Class responsible for obtaining system energy via a tally score |
helpers.FissionYieldCutoffHelper |
Helper that computes fission yields based on a cutoff energy |
Abstract Base Classes¶
A good starting point for extending capabilities in openmc.deplete
is
to examine the following abstract base classes. Custom classes can
inherit from abc.TransportOperator
to implement alternative
schemes for collecting reaction rates and other data from a transport code
prior to depleting materials
abc.TransportOperator |
Abstract class defining a transport operator |
The following classes are abstract classes used to pass information from
OpenMC simulations back on to the abc.TransportOperator
abc.EnergyHelper |
Abstract class for obtaining energy produced |
abc.FissionYieldHelper |
Abstract class for processing energy dependent fission yields |
abc.ReactionRateHelper |
Abstract class for generating reaction rates for operators |
abc.TalliedFissionYieldHelper |
Abstract class for computing fission yields with tallies |
Custom integrators or depletion solvers can be developed by subclassing from the following abstract base classes:
abc.Integrator |
Abstract class for solving the time-integration for depletion |
abc.SIIntegrator |
Abstract class for the Stochastic Implicit Euler integrators |
abc.DepSystemSolver |
Abstract class for solving depletion equations |