OpenMC material nuclide equivalent of natZr, natMo, natCr, natFe, natNi, natSi, natMg in MCNP4C

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1

Hello, I have atom number density of different material as natural (natZr=4.3044407e-2, natMo=6.4024e-2, natCr=1.7381e-2, natFe=5.9195e-2, natNi=7.5996e-3, natSi=2.3150e-4, natMg=5.3490e-4). I heard in MCNP cross-section data for different material can be used directly as natural. I know OpenMC uses nuclides as isotopes of material. How to use natural atom number density value of the above materials in openmc?

Any help is really appreciated. Thanks.

2

I have tried using

....

I got an error Could not find nuclide Zr-Nat in cross_sections data file!

Please guide. Thanks.

3

Hello Sharif

OpenMC can use both elements and isotopes to make materials.
So you can make your materials from individual nuclides or from elelemts.

Here is a simple example for natural copper made from the element or made from the two nuclides

material = openmc.Material(name=‘Copper’)
material.set_density(‘g/cm3’, 8.5)
material.add_element(‘Cu’, 1.0)

material = openmc.Material(name=‘Copper’)
material.set_density(‘g/cm3’, 8.5)
material.add_nuclide(‘Cu63’, 0.69, ‘ao’)

material.add_nuclide(‘Cu65’, 0.31, ‘ao’)

4

Hi Sharif

Sorry I had assumed you were using the Python API (which is great by the way)

Have you tried


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Jon |

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5

Most modern cross section libraries do not contain data for an element as a whole. The one exception is Carbon, which only got broken down into C12 and C13 in ENDF/B-VIII.0. What OpenMC allows you to do is to add an element at a specified density, and it will automatically break it down into individual isotopes based on the natural abundances of each. This is described further here.

6

Hello, Yes I now understand. I was able to achieve all the nuclides in xml file when I used this. For Zr it’s 4, Mo it’s 7, Cr it’s 4, Fe it’s 4 … Thanks for the guide. I really appreciate it.

SS304.add_element(‘Zr’, 4.3044407e-2 , ‘ao’)
SS304.add_element(‘Mo’, 6.4024e-2 , ‘ao’)
SS304.add_element(‘Cr’, 1.7381e-2 , ‘ao’)
SS304.add_element(‘Fe’, 5.9195e-2 , ‘ao’)
SS304.add_element(‘Ni’, 7.5996e-3 , ‘ao’)
SS304.add_element(‘Si’, 2.3150e-4 , ‘ao’)
SS304.add_element(‘Mg’, 5.3490e-4 , ‘ao’)