# XS generation in Cylindrical Mesh

**URL:** <https://openmc.discourse.group/t/xs-generation-in-cylindrical-mesh/1004>\
**Category:** User Support\
**Created:** [February 9, 2021, 4:19pm UTC](https://openmc.discourse.group/t/xs-generation-in-cylindrical-mesh/1004 "2021-02-09T16:19:32Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![rizkiokt](https://avatars.discourse-cdn.com/v4/letter/r/bbce88/32.png) [@rizkiokt](https://openmc.discourse.group/u/rizkiokt)\
**Post date:** [February 9, 2021, 4:19pm UTC](https://openmc.discourse.group/t/xs-generation-in-cylindrical-mesh/1004/1 "2021-02-09T16:19:32Z")

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Hello everyone,

I am new to OpenMC and am still learning the features offered in this code. I’m wondering how to do cross-section generation in cylindrical geometry mesh. I would like to use the homogenized XS to run a diffusion code for HTR core analysis. I’m looking for some features similar to Serpent’s circular cluster array [Input syntax manual - Serpent Wiki](http://serpent.vtt.fi/mediawiki/index.php/Input_syntax_manual#lat_.28regular_lattice_definition.29), or if there is some other approach I can use in OpenMC, please let me know.

Thank you.

Rizki Oktavian  
PhD student, School of Nuclear Engineering  
Purdue University

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**Author:** ![mkreher13](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/mkreher13/32/4093_2.png) [@mkreher13](https://openmc.discourse.group/u/mkreher13)\
**Post date:** [February 16, 2021, 11:50pm UTC](https://openmc.discourse.group/t/xs-generation-in-cylindrical-mesh/1004/2 "2021-02-16T23:50:03Z")

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Hi, I have experience generating multigroup cross section in OpenMC. Hopefully I can help you!  
OpenMC has a fantastic multigroup library feature that should make this easy for you.

Here is the most relevant OpenMC example: [MGXS Part III: Libraries — OpenMC Documentation](https://docs.openmc.org/en/stable/examples/mgxs-part-iii.html)

All you need to do is define the mesh you want (in your case you will probably use the “unstructured mesh” to make it cylindrical) and then define a openmc.mgxs.Library object and assign your mesh as the domain.

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**Author:** ![mkreher13](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/mkreher13/32/4093_2.png) [@mkreher13](https://openmc.discourse.group/u/mkreher13)\
**Post date:** [February 18, 2021, 9:42pm UTC](https://openmc.discourse.group/t/xs-generation-in-cylindrical-mesh/1004/3 "2021-02-18T21:42:11Z")

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Update: I think I was wrong in my first reply. It appears only RegularMesh is accepted as a domain, so I don’t think there is currently any support for other types of mesh. Sorry!

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**Author:** ![rizkiokt](https://avatars.discourse-cdn.com/v4/letter/r/bbce88/32.png) [@rizkiokt](https://openmc.discourse.group/u/rizkiokt)\
**Post date:** [February 21, 2021, 10:44pm UTC](https://openmc.discourse.group/t/xs-generation-in-cylindrical-mesh/1004/4 "2021-02-21T22:44:43Z")

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Hi,  
Thanks for the response. I guess I’ll try to use other approaches.