# Not load cross section for each calculation

**URL:** <https://openmc.discourse.group/t/not-load-cross-section-for-each-calculation/5016>\
**Category:** User Support\
**Created:** [December 2, 2024, 3:28pm UTC](https://openmc.discourse.group/t/not-load-cross-section-for-each-calculation/5016 "2024-12-02T15:28:30Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![iqo](https://avatars.discourse-cdn.com/v4/letter/i/d2c977/32.png) [@iqo](https://openmc.discourse.group/u/iqo)\
**Post date:** [December 2, 2024, 3:28pm UTC](https://openmc.discourse.group/t/not-load-cross-section-for-each-calculation/5016/1 "2024-12-02T15:28:30Z")

</div>

Hello everyone,

I’m running several simulations with the same materials (the only changes are in the geometry), is there a way to pre-load all the effective sections of this geometry and not do it for each of the iterations?

(and, by chance, to pre-load all the isotopes during a depletion and run several of them).

Thank you in advance

---

<div class="post-metadata">

**Author:** ![Shimwell](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/shimwell/32/3876_2.png) [@Shimwell](https://openmc.discourse.group/u/Shimwell)\
**Post date:** [December 2, 2024, 11:25pm UTC](https://openmc.discourse.group/t/not-load-cross-section-for-each-calculation/5016/2 "2024-12-02T23:25:08Z")

</div>

Hi there

I would recommend openmc lib for running parameter studies where all the cross sections are loaded at once. This example varies the material enrichment but is perhaps a good starting point.

> <https://github.com/fusion-energy/neutronics-workshop/blob/main/tasks/task_05_CSG_cell_tally_TBR/3_example_tritium_production_study_with_openmc_lib.py>