crp/OpenMC
1
0
Fork 0
mirror of https://github.com/openmc-dev/openmc.git synced 2026-07-28 22:26:08 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions 5

Revise documentation to reflect new source options.

Browse source
This commit is contained in:
Paul Romano 2015-12-21 17:33:21 -06:00
parent ba316dd98e
commit 8765f9d87e
1 changed files with 109 additions and 81 deletions
Download patch file Download diff file Expand all files Collapse all files

190
docs/source/usersguide/input.rst
View file

@ -424,9 +424,17 @@ pseudo-random number generator.
The ``source`` element gives information on an external source distribution to
be used either as the source for a fixed source calculation or the initial
source guess for criticality calculations. It takes the following
source guess for criticality calculations. Multiple ``<source>`` elements may be
specified to define different source distributions. Each one takes the following
attributes/sub-elements:
:strength:
The strength of the source. If multiple sources are present, the source
strength indicates the relative probability of choosing one source over the
other.
*Default*: 1.0
:file:
If this attribute is given, it indicates that the source is to be read from
a binary source file whose path is given by the value of this element. Note,
@ -440,12 +448,13 @@ attributes/sub-elements:
has the following attributes:
:type:
The type of spatial distribution. Valid options are "box", "fission", and
"point". A "box" spatial distribution has coordinates sampled uniformly in
a parallelepiped. A "fission" spatial distribution samples locations from
a "box" distribution but only locations in fissionable materials are
accepted. A "point" spatial distribution has coordinates specified by a
triplet.
The type of spatial distribution. Valid options are "box", "fission",
"point", and "independent". A "box" spatial distribution has coordinates
sampled uniformly in a parallelepiped. A "fission" spatial distribution
samples locations from a "box" distribution but only locations in
fissionable materials are accepted. A "point" spatial distribution has
coordinates specified by a triplet. An "independent" spatial distribution
specifies independent distributions of x-, y-, and z-coordinates.
*Default*: None
@ -458,105 +467,124 @@ attributes/sub-elements:
For a "point" spatial distribution, ``parameters`` should be given as
three real numbers which specify the (x,y,z) location of an isotropic
point source
point source.
For an "independent" distributoin, no parameters are specified. Instead,
the ``x``, ``y``, and ``z`` elements must be specified.
*Default*: None
:x:
For an "independent" distribution, this element specifies the distribution
of x-coordinates. The necessary sub-elements/attributes are those of a
univariate probability distribution (see the description in
:ref:`univariate`).
:y:
For an "independent" distribution, this element specifies the distribution
of y-coordinates. The necessary sub-elements/attributes are those of a
univariate probability distribution (see the description in
:ref:`univariate`).
:z:
For an "independent" distribution, this element specifies the distribution
of z-coordinates. The necessary sub-elements/attributes are those of a
univariate probability distribution (see the description in
:ref:`univariate`).
:angle:
An element specifying the angular distribution of source sites. This element
has the following attributes:
:type:
The type of angular distribution. Valid options are "isotropic",
"monodirectional", and "tabular". The angle of the particle emitted from a
"monodirectional", and "mu-phi". The angle of the particle emitted from a
source site is isotropic if the "isotropic" option is given. The angle of
the particle emitted from a source site is the direction specified in the
<parameters> attribute if "monodirectional" option is given. The "tabular"
option produces directions with polar angles sampled from a tabulated
distribution.
``reference_uvw`` element/attribute if "monodirectional" option is
given. The "mu-phi" option produces directions with the cosine of the
polar angle and the azimuthal angle explicitly specified.
*Default*: isotropic
:interpolation:
For a "tabular" angular distribution, ``interpolation`` can be set to
"histogram" or "linear-linear" thereby specifying how tabular points are
to be interpolated.
:reference_uvw:
The direction from which the polar angle is measured. Represented by the
x-, y-, and z-components of a unit vector. For a monodirectional
distribution, this defines the direction of all sampled particles.
*Default*: histogram
:mu:
An element specifying the distribution of the cosine of the polar
angle. Only relevant when the type is "mu-phi". The necessary
sub-elements/attributes are those of a univariate probability distribution
(see the description in :ref:`univariate`).
:parameters:
For an "isotropic" angular distribution, ``parameters`` should not be
specified.
For a "monodirectional" angular distribution, ``parameters`` should be
given as three real numbers which specify the angular cosines with respect
to each axis.
For a "tabular" angular distribution, ``parameters`` provides the
:math:`(\mu,p)` pairs defining the tabular distribution. All :math:`\mu`
points are given first followed by corresponding :math:`p` points. The
following example gives a histogram distribution with even probability of
selecting a polar angle in the range [-1,-0.5] and [0.5,1] (Note that the
last :math:`p` point is inconsequential):
.. code-block:: xml
<angle type="tabular" interpolation="histogram">
<parameters>
-1.0 -0.5 0.5 1.0
1.0 0.0 1.0 0.0
</parameters>
</angle>
*Default*: None
:phi:
An element specifying the distribution of the azimuthal angle. Only
relevant when the type is "mu-phi". The necessary sub-elements/attributes
are those of a univariate probability distribution (see the description in
:ref:`univariate`).
:energy:
An element specifying the energy distribution of source sites. This element
has the following attributes:
:type:
The type of energy distribution. Valid options are "monoenergetic",
"watt", "maxwell", and "tabular". The "monoenergetic" option produces
source sites at a single energy. The "watt" option produces source sites
whose energy is sampled from a Watt fission spectrum. The "maxwell" option
produce source sites whose energy is sampled from a Maxwell fission
spectrum. The "tabular" option produces source sites whose energy is
sampled from a tabulated distribution.
*Default*: watt
:interpolation:
For a "tabular" angular distribution, ``interpolation`` can be set to
"histogram" or "linear-linear" thereby specifying how tabular points are
to be interpolated.
*Default*: histogram
:parameters:
For a "monoenergetic" energy distribution, ``parameters`` should be
given as the energy in MeV of the source sites.
For a "watt" energy distribution, ``parameters`` should be given as two
real numbers :math:`a` and :math:`b` that parameterize the distribution
:math:`p(E) dE = c e^{-E/a} \sinh \sqrt{b \, E} dE`.
For a "maxwell" energy distribution, ``parameters`` should be given as one
real number :math:`a` that parameterizes the distribution :math:`p(E) dE =
c E e^{-E/a} dE`.
For a "tabular" energy distribution, ``parameters`` provides the
:math:`(E,p)` pairs defining the tabular distribution. All :math:`E`
points are given first followed by corresponding :math:`p` points.
*Default*: 0.988 2.249
An element specifying the energy distribution of source sites. The necessary
sub-elements/attributes are those of a univariate probability distribution
(see the description in :ref:`univariate`).
:write_initial:
An element specifying whether to write out the initial source bank used at
the beginning of the first batch. The output file is named
"initial_source.binary(h5)"
"initial_source.h5"
*Default*: false
.. _univariate:
Univariate Probability Distributions
++++++++++++++++++++++++++++++++++++
Various components of a source distribution involve probability distributions of
a single random variable, e.g. the distribution of the energy, the distribution
of the polar angle, and the distribution of x-coordinates. Each of these
components supports the same syntax with an element whose tag signifies the
variable and whose sub-elements/attributes are as follows:
:type:
The type of the distribution. Valid options are "uniform", "discrete",
"tabular", "maxwell", and "watt". The "uniform" option produces variates
sampled from a uniform distribution over a finite interval. The "discrete"
option produces random variates that can assume a finite number of values
(i.e., a distribution characterized by a probability mass function). The
"tabular" option produces random variates sampled from a tabulated
distribution where the density function is either a histogram or
linearly-interpolated between tabulated points. The "watt" option produces
random variates is sampled from a Watt fission spectrum (only used for
energies). The "maxwell" option produce variates sampled from a Maxwell
fission spectrum (only used for energies).
*Default*: None
:parameters:
For a "uniform" distribution, ``parameters`` should be given as two real
numbers :math:`a` and :math:`b` that define the interval :math:`[a,b]` over
which random variates are sampled.
For a "discrete" or "tabular" distribution, ``parameters`` provides the
:math:`(x,p)` pairs defining the discrete/tabular distribution. All :math:`x`
points are given first followed by corresponding :math:`p` points.
For a "watt" distribution, ``parameters`` should be given as two real numbers
:math:`a` and :math:`b` that parameterize the distribution :math:`p(x) dx = c
e^{-x/a} \sinh \sqrt{b \, x} dx`.
For a "maxwell" distribution, ``parameters`` should be given as one real
number :math:`a` that parameterizes the distribution :math:`p(x) dx = c x
e^{-x/a} dx`.
:interpolation:
For a "tabular" distribution, ``interpolation`` can be set to "histogram" or
"linear-linear" thereby specifying how tabular points are to be interpolated.
*Default*: histogram
``<state_point>`` Element
-------------------------