# Albedo search for coupled depletion transport calculation

**URL:** <https://openmc.discourse.group/t/albedo-search-for-coupled-depletion-transport-calculation/6378>\
**Category:** User Support\
**Created:** [June 23, 2026, 7:58am UTC](https://openmc.discourse.group/t/albedo-search-for-coupled-depletion-transport-calculation/6378 "2026-06-23T07:58:38Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![rmk](https://avatars.discourse-cdn.com/v4/letter/r/b5e925/32.png) [@rmk](https://openmc.discourse.group/u/rmk)\
**Post date:** [June 23, 2026, 7:58am UTC](https://openmc.discourse.group/t/albedo-search-for-coupled-depletion-transport-calculation/6378/1 "2026-06-23T07:58:38Z")

</div>

Hello everyone,

I’m performing a coupled transport depletion calculation on a PWR assembly model.

In order to impose criticality to the system, i’m using the search\_for\_keff method before running the depletion calculation as such :

“”"

crit\_albedo, guesses, results = openmc.search\_for\_keff(  
self.albedo\_model\_builder,  
bracket=[0.1, 1.0],  
target=1.0,  
tol=1e-3,  
print\_iterations=True  
)

“”"

Then passing the crit\_albedo parameter to the model before the run.

The problem I encounter is that this method only calculates critical albedo for the system **BEFORE** the depletion calculation. This implies that, at the beginning the system is critical, but as materials change because of the depletion calculation, the keff=1 condition is **no more verified** (system becomes subcritic at the last burnup step).

I would like to **INTEGRATE** the albedo search calculation to the depletion calculation so that the search\_for\_keff will be performed at each timestep, ensuring criticality of the system during all the depletion calculation.

I am aware that the latest develop version integrates the **openmc.deplete.abc.Integrator** that takes the argument **add\_keff\_search\_control** but the fonction given to the integrator must use openmc.lib in order not to make friction with the openmc.model **BUT** openmc.lib doesn’t have any method in order to access geometry or albedo, we can only access nuclides composition and materials (for example performing a boron search calculation would be possible but i really need to perform an albedo keff search).

Has someone already encountered this problem ?

Thank you a lot for the attention given to my request.

Best regards,