crp/OpenMC
1
0
Fork 0
mirror of https://github.com/openmc-dev/openmc.git synced 2026-07-28 14:15:42 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions 5

Update documentation to better describe temperature treatments

Browse source
This commit is contained in:
Paul Romano 2016-09-15 09:20:58 +02:00
parent 309291d115
commit 6b4db5c2b0
2 changed files with 42 additions and 5 deletions
Download patch file Download diff file Expand all files Collapse all files

36
docs/source/methods/cross_sections.rst
View file

@ -66,6 +66,8 @@ Other Methods
A good survey of other energy grid techniques, including unionized energy grids,
can be found in a paper by Leppanen_.
.. _windowed_multipole:
Windowed Multipole Representation
---------------------------------
@ -141,6 +143,40 @@ but not always the case. Future library versions may eliminate this issue.
The data format used by OpenMC to represent windowed multipole data is specified
in :ref:`io_data_wmp`.
.. _temperature_treatment:
Temperature Treatment
---------------------
At the beginning of a simulation, OpenMC collects a list of all temperatures
that are present in a model. It then uses this list to determine what cross
sections to load. The data that is loaded depends on what temperature method has
been selected. There are three methods available:
:Nearest: Cross sections are loaded only if they are within a specified
tolerance of the actual temperatures in the model.
:Interpolation: Cross sections are loaded at temperatures that bound the actual
temperatures in the model. During transport, cross sections for
each material are calculated using statistical linear-linear
interpolation between bounding temperature. Suppose cross
sections are available at temperatures :math:`T_1, T_2, ...,
T_n` and a material is assigned a temperature :math:`T` where
:math:`T_i < T < T_{i+1}`. Statistical interpolation is applied
as follows: a uniformly-distributed random number of the unit
interval, :math:`\xi`, is sampled. If :math:`\xi < (T -
T_i)/(T_{i+1} - T_i)`, then cross sections at temperature
:math:`T_{i+1}` are used. Otherwise, cross sections at
:math:`T_i` are used. This procedure is applied for pointwise
cross sections in the resolved resonance range, unresolved
resonance probability tables, and :math:`S(\alpha,\beta)`
thermal scattering tables.
:Multipole: Resolved resonance cross sections are calculated on-the-fly using
techniques/data described in :ref:`windowed_multipole`. Cross
section data is loaded for a single temperature and is used in the
unresolved resonance and fast energy ranges.
----------------
Multi-Group Data
----------------