# Sodium Fast Reactor Core Code Help

**URL:** <https://openmc.discourse.group/t/sodium-fast-reactor-core-code-help/2894>\
**Category:** User Support\
**Created:** [April 5, 2023, 7:21pm UTC](https://openmc.discourse.group/t/sodium-fast-reactor-core-code-help/2894 "2023-04-05T19:21:38Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Michael\_White](https://avatars.discourse-cdn.com/v4/letter/m/c6cbf5/32.png) [@Michael\_White](https://openmc.discourse.group/u/Michael_White)\
**Post date:** [April 5, 2023, 7:21pm UTC](https://openmc.discourse.group/t/sodium-fast-reactor-core-code-help/2894/1 "2023-04-05T19:21:38Z")

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We are currently using the following code to model an arbitrary SFR core:

> <https://github.com/mit-crpg/openmc-reactor-examples/blob/main/SFR.ipynb>

However, when we run the code as-is, we get an accurate OpenMC output but the figures aren’t correct.

By deleting the id numbers, the figures come out correctly, but the OpenMC output fails. We get the error “The maximum number of lost particles has been reached.”.

Is there a better way to generate the figures, without running into the warnings, that will yield proper results?

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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:** [April 10, 2023, 12:08pm UTC](https://openmc.discourse.group/t/sodium-fast-reactor-core-code-help/2894/2 "2023-04-10T12:08:07Z")

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To better understand the issue, could you provide some additional context on the code you’re running, perhaps the `notebook file` you’re running? This will help me provide you with tailored advice on how to generate the figures you need without encountering the warning messages.

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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:** [April 10, 2023, 7:58pm UTC](https://openmc.discourse.group/t/sodium-fast-reactor-core-code-help/2894/3 "2023-04-10T19:58:40Z")

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@Michael_White I would take a look at the user’s guide section on lost particles:  
[https://docs.openmc.org/en/stable/usersguide/troubleshoot.html#error-maximum-number-of-lost-particles-has-been-reached](https://docs.openmc.org/en/stable/usersguide/troubleshoot.html#error-maximum-number-of-lost-particles-has-been-reached)