From 97a835cc24b23038bf815a14e8fbaaae0c89860b Mon Sep 17 00:00:00 2001 From: Sam Powell-Gill Date: Tue, 3 Mar 2020 10:53:02 +0000 Subject: [PATCH] Added section to user guide on Mixing materials. --- docs/source/usersguide/materials.rst | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/docs/source/usersguide/materials.rst b/docs/source/usersguide/materials.rst index 69647342a4..e73d5a9acf 100644 --- a/docs/source/usersguide/materials.rst +++ b/docs/source/usersguide/materials.rst @@ -141,6 +141,34 @@ attribute, e.g., :attr:`Material.temperature` or :attr:`Cell.temperature` attributes, respectively. +----------------- +Material Mixtures +----------------- + +In OpenMC it is possible to mix any number of materials to create a new material +with the correct nuclide composition and density. The +:meth:`Material.mix_materials` method takes a list of materials and +a list of their mixing fractions. Mixing fractions can be provided as atomic +fractions, weight fractions or volume fractions. The fraction type +is specifed by adding 'ao', 'wo' or 'vo' respectively as the third argument. +For example, assuming the required materials have already been defined, a MOX +material with 3% plutonium oxide by weight could be created using the following: + +:: + + mox = openmc.Material() + mox.mix_materials([uo2, puo2], [0.97, 0.03], 'wo') + +It should be noted that if mixing fractions are specifed as atomic or weight +fractions, the sum of the given fractions should be one. If volume fractions +are provided and the sum fractions is less than one, the remaining fraction is +set as void material. + +.. warning:: Materials with :math:`S(\alpha,\beta)` thermal scattering data + cannot be used in :meth:`Material.mix_materials`. However, thermal + scattering data can be added to a material created by + :meth:`Material.mix_materials`. + -------------------- Material Collections --------------------