# Create a X-type hexagonal lattice

**URL:** <https://openmc.discourse.group/t/create-a-x-type-hexagonal-lattice/326>\
**Category:** User Support\
**Created:** [April 29, 2018, 3:54pm UTC](https://openmc.discourse.group/t/create-a-x-type-hexagonal-lattice/326 "2018-04-29T15:54:17Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Fredrik\_Dehlin](https://avatars.discourse-cdn.com/v4/letter/f/58956e/32.png) [@Fredrik\_Dehlin](https://openmc.discourse.group/u/Fredrik_Dehlin)\
**Post date:** [April 29, 2018, 3:54pm UTC](https://openmc.discourse.group/t/create-a-x-type-hexagonal-lattice/326/1 "2018-04-29T15:54:17Z")

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Dear Developers and members of this group.

I am trying to model a small lead fast reactor as a part of a course in Monte Carlo methods.  
The task is to make a comparison between Serpent and OpenMC.

My issue is that I need to create a X-type hexagonal lattice (two sides parallel to the x-axis) in order to model the core correctly. My fuel- and control assemblies are of X-type and they are later placed in the core in a Y-type mesh.

The standard hexagonal mesh in OpenMC seem to be a Y-type, but is it possible to rotate it 90 degrees in order to obtain a X-type? I did not find anything about this in the user manual so perhaps you could provide some assistance.

Kind regards,

Fredrik Dehlin  
Royal Institute of Technology

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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:** [May 16, 2018, 4:11am UTC](https://openmc.discourse.group/t/create-a-x-type-hexagonal-lattice/326/2 "2018-05-16T04:11:44Z")

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Hi Fredrik,

My apologies for the delay in responding to you. Take a look at this [example notebook](https://github.com/paulromano/cnl-workshop/blob/master/notebooks/05-lattices/Solution/Lattices-Solution.ipynb) which demonstrates how you can build a hexagonal lattice and then rotate it by 30 degrees to achieve the effect that you desire. Let me know if you have any specific questions about it.

Best regards,  
Paul

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**Author:** ![Fredrik\_Dehlin](https://avatars.discourse-cdn.com/v4/letter/f/58956e/32.png) [@Fredrik\_Dehlin](https://openmc.discourse.group/u/Fredrik_Dehlin)\
**Post date:** [May 22, 2018, 11:54am UTC](https://openmc.discourse.group/t/create-a-x-type-hexagonal-lattice/326/3 "2018-05-22T11:54:12Z")

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Hi Paul!

Thank you for your example notebook. I totally understand how to rotate the lattice now.

Many thanks,  
Fredrik