Setting temperature for a specific nuclide in OpenMC?

User Support
1

Hi everyone,
I need to set the temperature for a specific nuclide within the material. Any quick tips on how to do this, or do I need to prepare cross-sections for each nuclide at the desired temperature?

Thanks!

2

Hello.
My recollection is that the C++ source code forces all isotopes within a material to a common temperature. To implement a difference, you would need to prepare a dedicated cross section data table or fork the code and implement your change directly in the C++ code.

3

@AlexandreTrottier is correct – OpenMC does not allow you to set the temperature on a single nuclide. It is a property of a cell/material.

4

@AlexandreTrottier Thanks for the tip! Here’s what I did: got the cross-sections in ACE format for a nuclide at the desired temperature using NJOY, then manually changed the temperature in the ACE file. Even though they’re prepared at 500 K, the file specifies 300 K. After that, I converted them to H5 format. It’s a workaround, but it’s getting the job done for now.

@paulromano I believe having this feature in upcoming versions could open up possibilities for studying various phenomena, especially reactivity temperature coefficients.