hydep

A hybrid depletion framework for reactor physics applications and analysis.

Installation

The recommended approach is to install using a virtual environment. From the command line, execute the command

$ python -m venv /path/to/venv
$ source /path/to/venv/bin/activate

The dependencies and package can then be installed with

(venv) $ pip install .

The framework was designed to be a general and extensible tool, with abstract interfaces for general transport codes. With this base installation, one obtains the necessary classes to design concrete interfaces, but no real useful interfaces. These are instead delegated to extra packages

Serpent interface

The primary neutronics interface here is for the Serpent Monte Carlo code [Serpent]. The necessary dependencies can be installed with

(venv) $ pip install .[serpent]

The hydep interfaces to Serpent will still be installed without this command, but attempting to import from hydep.serpent will likely fail.

Two interfaces as presented, one for the current Serpent version and another for an extended version of Serpent yet to be distributed. This later version allows the framework to pass updated compositions to Serpent via a data file without Serpent reloading the model and cross sections at each depletion step. Discussion are being had regarding the best way to distribute these changes. In the mean time, the SerpentSolver` can be used to perform hybrid transport-depletion simulations, but with some waiting and restarting.

SFV interface

The primary reduced-order solver developed for this work is to the spatial flux variation (SFV) method [SFV]. This requires a small FORTRAN library wrapped in a Python package. The source code for this package is available at CORE-GATECH-GROUP/sfv. Users can follow its installation instructions or run the command

(venv) $ pip install .[sfv]

Note

Please be familiar with some of the issues uninstalling and upgrading this package, presented here

Kitchen sink

To install all dependencies for the base package, the Serpent interface, and the SFV interface, the command

(venv) $ pip install .[serpent,sfv]

Testing

Tests require pytest which can be pulled from the test extras package

(venv) $ pip install .[test]

Using pytest marks, parts of the library that relate to specific interfaces can be excluded or isolated using the -m switch. The following will run just tests related to the SFV interface

(venv) $ pytest -m sfv

The current test layout does not well support testing just the base library with

(venv) $ pytest -m "not serpent" -m "not sfv"

unless both the Serpent and SFV extras have been installed. Also, the Serpent tests include a test with the coupled solver, which is not yet excluded with a dedicated mark.

Documentation

Documentation is built using sphinx and currently is not hosted online. It can be built locally by following these steps.

(venv) $ pip install .[docs]
(venv) $ cd docs
(venv) $ make html

This will produce documentation that can be viewed locally by opening docs/_build/html/index.html. The command make latexpdf will produce docs/_build/latex/hydep.pdf. There are two examples in docs/examples presented as jupyter notebooks that build and simulate a 3-D pincell and then process the results.

Caveats / Warnings

This is a highly experimental and developmental library / tool. While a modest set of cases are covered by tests and examples, there are likely cases that are missed and could cause bugs. Please report these and be forgiving.

This framework does not seek to be a general geometric modeling tool for nuclear analysis, nor even a really good one. Some limits are self imposed or assumed to move from developing geometry to implementing the physics. First, the framework is primarily focused on modeling Cartesian assemblies with annular fuel. This is sufficient for most light water reactor analysis, as fuel pins are basically concentric cylinders of materials, and these assemblies are regular Cartesian lattices.

Second, many of the input files generated for transport solutions should not be considered human readable. Some aesthetic considerations have been taken, but universe names and identifiers may be hard to understand.

See ./docs/scope.rst for more description on the scope and limits of this project.

References

[Serpent]

Leppanen, J. et al. "The Serpent Monte Carlo code: Status, development and applications in 2013." Ann. Nucl. Energy, 82 (2015) 142-150

[SFV]

Johnson, A. and Kotlyar, D. "A Transport-Free Method for Predicting the Post-depletion Spatial Neutron Flux." Nuc. Sci. Eng, 194 (2020) 120-137

drewejohnson / hydep