Composite materials - okay to add S(alpha, beta) cross sections?

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1

All,

Just had a quick question about defining composite materials, especially for shielding, in OpenMC. If I was defining a composite material where ZrH2 only makes up a certain percentage of the material, is it okay to add the following lines:

composite.add_s_alpha_beta(‘c_H_in_ZrH’) # Add thermal scattering data for Zirconium Hydride
composite.add_s_alpha_beta(‘c_Zr_in_ZrH’) # Add thermal scattering data for Zirconium Hydride

Even though the material contains more than just Zr and H?

I.e is that thermal scattering data only supposed to be used when material only consists of ZrH2, or can it be used even when the ZrH2 is just a constituent of the material? I want to make sure I’m defining my material correctly. Thanks!

2

That’s fine as long as whatever you’re mixing ZrH2 with does not contain Zr or H. If it does, you should specify the extra fraction argument when calling add_s_alpha_beta to indicate that the thermal scattering data only applies to some fraction of the Zr or H atoms.