# Fuel pin example

**URL:** <https://openmc.discourse.group/t/fuel-pin-example/1851>\
**Category:** User Support\
**Created:** [March 21, 2022, 12:51pm UTC](https://openmc.discourse.group/t/fuel-pin-example/1851 "2022-03-21T12:51:57Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![nuclearsneke](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/nuclearsneke/32/1757_2.png) [@nuclearsneke](https://openmc.discourse.group/u/nuclearsneke)\
**Post date:** [March 21, 2022, 12:51pm UTC](https://openmc.discourse.group/t/fuel-pin-example/1851/1 "2022-03-21T12:51:57Z")

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Hi!

I have followed the instructions in

> **[Jupyter Notebook Viewer](https://nbviewer.org/github/openmc-dev/openmc-notebooks/blob/main/pincell.ipynb)**
>
> Check out this Jupyter notebook!

But openmc.run() won’t start - it can’t find cross\_sections.xml.  
Adding a “Materials.cross\_sections” line in code does not work either.  
Commands  
!cat $OPENMC\_CROSS\_SECTIONS | head -n 10  
print(’ …’)  
!cat $OPENMC\_CROSS\_SECTIONS | tail -n 10  
Also don’t work. How to get the cross\_sections.xml file?

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**Author:** ![Pranto](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/pranto/32/489_2.png) [@Pranto](https://openmc.discourse.group/u/Pranto)\
**Post date:** [March 21, 2022, 2:02pm UTC](https://openmc.discourse.group/t/fuel-pin-example/1851/2 "2022-03-21T14:02:42Z")

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@nuclearsneke Did you download data library?

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**Author:** ![nuclearsneke](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/nuclearsneke/32/1757_2.png) [@nuclearsneke](https://openmc.discourse.group/u/nuclearsneke)\
**Post date:** [March 21, 2022, 2:06pm UTC](https://openmc.discourse.group/t/fuel-pin-example/1851/3 "2022-03-21T14:06:07Z")

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nope, I did not. I have followed only the installation process for Ubuntu/Linux and have thought that it will be included. Where should I download it from?

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**Author:** ![Pranto](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/pranto/32/489_2.png) [@Pranto](https://openmc.discourse.group/u/Pranto)\
**Post date:** [March 21, 2022, 2:08pm UTC](https://openmc.discourse.group/t/fuel-pin-example/1851/4 "2022-03-21T14:08:11Z")

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You can download library from [this link](https://openmc.org/official-data-libraries/). openmc needs the full path location of `cross_sections.xml` file to run.

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**Author:** ![nuclearsneke](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/nuclearsneke/32/1757_2.png) [@nuclearsneke](https://openmc.discourse.group/u/nuclearsneke)\
**Post date:** [March 21, 2022, 2:12pm UTC](https://openmc.discourse.group/t/fuel-pin-example/1851/5 "2022-03-21T14:12:56Z")

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Thanks a lot! I will download it and try it out

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**Author:** ![nuclearsneke](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/nuclearsneke/32/1757_2.png) [@nuclearsneke](https://openmc.discourse.group/u/nuclearsneke)\
**Post date:** [March 21, 2022, 3:27pm UTC](https://openmc.discourse.group/t/fuel-pin-example/1851/6 "2022-03-21T15:27:24Z")

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I think something went wrong since I am getting some error now when trying to run a fuel pin example. It worked well and now it does not want to work with Zr.

 ![image](https://global.discourse-cdn.com/free1/uploads/openmc/original/2X/1/1cdee77b3a9e34309ebd6380e4c3c70244d61379.png)  
what is inside the file:  
 ![image](https://global.discourse-cdn.com/free1/uploads/openmc/original/2X/5/5affa72633293c05c3a2a1a41362e87b732f143d.png)

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<div class="post-metadata">

**Author:** ![nuclearsneke](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/nuclearsneke/32/1757_2.png) [@nuclearsneke](https://openmc.discourse.group/u/nuclearsneke)\
**Post date:** [March 21, 2022, 4:17pm UTC](https://openmc.discourse.group/t/fuel-pin-example/1851/7 "2022-03-21T16:17:28Z")

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Alrightie, solved. I have double-checked the path to cross-sections and fixed it. Now it works!

 ![image](https://global.discourse-cdn.com/free1/uploads/openmc/original/2X/7/79066398f764167ab8e11cdcebd3afc19ba50654.jpeg)