Making materials from elements

Making materials from elements#

As we saw in Part 1, materials can be defined in OpenMC using isotopes. However, materials can also be made from elements - this is more concise and still supports isotopic enrichment.

This python notebook allows users to create different materials from elements using OpenMC.

First import OpenMC and configure the nuclear data path

import openmc
from pathlib import Path
# Setting the cross section path to the correct location in the docker image.
# If you are running this outside the docker image you will have to change this path to your local cross section path.
openmc.config['cross_sections'] = Path.home() / 'nuclear_data' / 'cross_sections.xml'

The following code block is a simple example of creating a material (water H2O) from elements. (Note how Hydrogen and Oxygen elements have been specified rather than each specific isotope).

# Making water from elements

water_mat = openmc.Material()
water_mat.add_element('H', 2.0, percent_type='ao')
water_mat.add_element('O', 1.0, percent_type='ao')
water_mat.set_density('g/cm3', 0.99821)

water_mat

Material
	ID             =	1
	Name           =	
	Temperature    =	None
	Density        =	0.99821 [g/cm3]
	Volume         =	None [cm^3]
	Depletable     =	False
	S(a,b) Tables  
	Nuclides       
	H1             =	1.99968852   [ao]
	H2             =	0.00031148   [ao]
	O16            =	0.9976206    [ao]
	O17            =	0.000379     [ao]
	O18            =	0.0020004    [ao]

The next code block is an example of making a ceramic breeder material.

# Making Li4SiO4 from elements

Li4SiO4_mat = openmc.Material()
Li4SiO4_mat.add_element('Li', 4.0, percent_type='ao')
Li4SiO4_mat.add_element('Si', 1.0, percent_type='ao')
Li4SiO4_mat.add_element('O', 4.0, percent_type='ao')
Li4SiO4_mat.set_density('g/cm3', 2.32)

Li4SiO4_mat

Material
	ID             =	2
	Name           =	
	Temperature    =	None
	Density        =	2.32 [g/cm3]
	Volume         =	None [cm^3]
	Depletable     =	False
	S(a,b) Tables  
	Nuclides       
	Li6            =	0.30356      [ao]
	Li7            =	3.69644      [ao]
	Si28           =	0.9222968    [ao]
	Si29           =	0.0468316    [ao]
	Si30           =	0.0308716    [ao]
	O16            =	3.9904824    [ao]
	O17            =	0.001516     [ao]
	O18            =	0.0080016    [ao]

It is also possible to enrich specific isotopes while still benefitting from the concise code of making materials from elements.

Here is an example of making the same ceramic breeder material but this time with Li6 enrichment.

# Making enriched Li4SiO4 from elements with enrichment of Li6 enrichment

Li4SiO4_mat = openmc.Material()
Li4SiO4_mat.add_element('Li', 4.0, percent_type='ao',
                        enrichment=60,
                        enrichment_target='Li6',
                        enrichment_type='ao'
                        )
Li4SiO4_mat.add_element('Si', 1.0, percent_type='ao')
Li4SiO4_mat.add_element('O', 4.0, percent_type='ao')
Li4SiO4_mat.set_density('g/cm3', 2.32)  # this would actually be lower than 2.32 g/cm3 but this would need calculating

Li4SiO4_mat

Material
	ID             =	3
	Name           =	
	Temperature    =	None
	Density        =	2.32 [g/cm3]
	Volume         =	None [cm^3]
	Depletable     =	False
	S(a,b) Tables  
	Nuclides       
	Li6            =	2.4          [ao]
	Li7            =	1.6          [ao]
	Si28           =	0.9222968    [ao]
	Si29           =	0.0468316    [ao]
	Si30           =	0.0308716    [ao]
	O16            =	3.9904824    [ao]
	O17            =	0.001516     [ao]
	O18            =	0.0080016    [ao]

In the case of materials that can be represented as a chemical formula (e.g. ‘H2O’, ‘Li4SiO4’) there is an even more concise way of making these materials by using their chemical formula.

# making Li4SiO4 from a formula

Li4SiO4_mat = openmc.Material()
Li4SiO4_mat.add_elements_from_formula('Li4SiO4')
Li4SiO4_mat

Material
	ID             =	4
	Name           =	
	Temperature    =	None
	Density        =	None [sum]
	Volume         =	None [cm^3]
	Depletable     =	False
	S(a,b) Tables  
	Nuclides       
	Li6            =	0.033728888888888885 [ao]
	Li7            =	0.4107155555555555 [ao]
	Si28           =	0.10247742222222223 [ao]
	Si29           =	0.005203511111111111 [ao]
	Si30           =	0.0034301777777777775 [ao]
	O16            =	0.4433869333333333 [ao]
	O17            =	0.00016844444444444442 [ao]
	O18            =	0.0008890666666666665 [ao]

This add_elements_from_formula (which was added to OpenMC source code by myself) can also support enrichment.

# making Li4SiO4 from a formula with enrichment

Li4SiO4_mat = openmc.Material()
Li4SiO4_mat.add_elements_from_formula('Li4SiO4',
                        enrichment=60,
                        enrichment_target='Li6',
                        enrichment_type='ao'
                        )
Li4SiO4_mat

Material
	ID             =	5
	Name           =	
	Temperature    =	None
	Density        =	None [sum]
	Volume         =	None [cm^3]
	Depletable     =	False
	S(a,b) Tables  
	Nuclides       
	Li6            =	0.26666666666666666 [ao]
	Li7            =	0.17777777777777778 [ao]
	Si28           =	0.10247742222222223 [ao]
	Si29           =	0.005203511111111111 [ao]
	Si30           =	0.0034301777777777775 [ao]
	O16            =	0.4433869333333333 [ao]
	O17            =	0.00016844444444444442 [ao]
	O18            =	0.0008890666666666665 [ao]

Making more detailed materials such as a low activation steel Eurofer would require about 20 elements. While this is fewer user inputs than making the material from isotopes it is still quite a lot of coding for the user. Unfortunately, they cannot be input as a chemical formula either.

Learning Outcomes for Part 2:

  • Materials can be made in OpenMC using element fractions and densities.

  • Making materials from elements is more concise than making materials from isotopes.

  • If materials can be represented as a chemical formula, OpenMC also offers a way to construct those materials from that.

  • Making materials from elements also supports isotopic enrichment.