# Depletion OpenMPI

**URL:** https://openmc.discourse.group/t/depletion-openmpi/749
**Category:** User Support
**Created:** [September 10, 2020, 7:29pm UTC](https://openmc.discourse.group/t/depletion-openmpi/749 "2020-09-10T19:29:06Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![YimingZ](https://avatars.discourse-cdn.com/v4/letter/y/f19dbf/32.png) [@YimingZ](https://openmc.discourse.group/u/YimingZ)
#### Post date: [September 10, 2020, 7:29pm UTC](https://openmc.discourse.group/t/depletion-openmpi/749/1 "2020-09-10T19:29:06Z")

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Hi,

I’m trying to accelerate the OpenMC depletion calculation on University’s high-performance computing cluster BlueBEAR. The staff from BlueBEAR group suggest using OpenMPI.

 ![MPI](https://global.discourse-cdn.com/free1/uploads/openmc/original/2X/8/80c826f5725b40e962e01c6446f281bdf8c45b2c.png)  
The question is, where I should set the argument in the depletion calculation? The integrator or operator? Thanks in advance for your help.

Best wishes,  
Yiming

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### Author: ![paulromano](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/paulromano/32/486_2.png) [@paulromano](https://openmc.discourse.group/u/paulromano)
#### Post date: [September 12, 2020, 1:54am UTC](https://openmc.discourse.group/t/depletion-openmpi/749/2 "2020-09-12T01:54:53Z")

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Hi @YimingZ. Depletion works by loading the OpenMC shared library directly from the Python process, so unlike `openmc.run`, which creates subprocesses (and can call mpiexec), you would need to call `mpiexec` on the Python script itself. Also note that with depletion there is no need to call `openmc.run` – when you have a depletion integrator, it handles calling the transport solver within OpenMC.

To work properly, you need to have the mpi4py package installed, and it needs to be built against the same MPI implementation (OpenMPI, in your case) that was used to build OpenMC.