change the material in individual cells during a depletion calculation

[cfichtlscherer]

I would find it very helpful if there was the possibility to change the material in individual cells during a depletion calculation. For example, to simulate the pulling out of a control rod.

Alternatively, it would also work (perhaps this is easier to implement) if the density of single isotopes could be changed after solving depletion equations.

Maybe someone has an idea how such a thing would be easy to implement.

Thanks a lot!

[drewejohnson]

This could be super useful! I don't know what the plan for adding these type of transient-like problems, but you may be able to throw something together externally by passing previous results to another Operator after modifying and re-exporting your geometry.

Large caveats with this approach. First, the restart procedure takes compositions from the file, which is what you want. But it also takes reaction rates and uses these reactions rates instead of running the "first" or restarted transport simulation. The downside is that these reaction rates reflect the previous un-modified system and will not be accurate for the new system. This will be especially incorrect for regions near the modified regions. You could mitigate some of this by running one very small time step after restarting, but I would use this approach with caution.

[world3zZ]

This could be super useful! I don't know what the plan for adding these type of transient-like problems, but you may be able to throw something together externally by passing previous results to another Operator after modifying and re-exporting your geometry.

Large caveats with this approach. First, the restart procedure takes compositions from the file, which is what you want. But it also takes reaction rates and uses these reactions rates instead of running the "first" or restarted transport simulation. The downside is that these reaction rates reflect the previous un-modified system and will not be accurate for the new system. This will be especially incorrect for regions near the modified regions. You could mitigate some of this by running one very small time step after restarting, but I would use this approach with caution.

Hello,Drew.I have used the workaround you proposed,and I got the better result.May I ask how this method works? I’m really curious about it.Thanks a lot!

[paulromano]

@world3zZ running a small timestep after making material modifications will force OpenMC to run an extra transport step, which causes all the reaction rates to be updated using the modified compositions

[paulromano]

Also, I'm going to close this as it's essentially the same as #1631, where there's been more discussion about how to do this (it is now possible to do by several methods)