# Problem of cross-section.xml

**URL:** <https://openmc.discourse.group/t/problem-of-cross-section-xml/1008>\
**Category:** User Support\
**Created:** [February 12, 2021, 8:08pm UTC](https://openmc.discourse.group/t/problem-of-cross-section-xml/1008 "2021-02-12T20:08:22Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![SaitoAsuka](https://avatars.discourse-cdn.com/v4/letter/s/90ced4/32.png) [@SaitoAsuka](https://openmc.discourse.group/u/SaitoAsuka)\
**Post date:** [February 12, 2021, 8:08pm UTC](https://openmc.discourse.group/t/problem-of-cross-section-xml/1008/1 "2021-02-12T20:08:22Z")

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Dear sir/madam,

I downloaded the cross section data of jeff3.3 in ”[https://openmc.org/official-data-libraries“](https://openmc.org/official-data-libraries%E2%80%9C). How can I change the path of “cross\_section.xml” to the path of the data?

Best regards,

Lei

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**Author:** ![khurrum](https://avatars.discourse-cdn.com/v4/letter/k/bc79bd/32.png) [@khurrum](https://openmc.discourse.group/u/khurrum)\
**Post date:** [February 13, 2021, 3:52am UTC](https://openmc.discourse.group/t/problem-of-cross-section-xml/1008/2 "2021-02-13T03:52:48Z")

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Hi

You need to set OPENMC\_CROSS\_SECTION environment variable to the Jeff 3 .3 folder containing cross\_section.xml file

Relevant documentation is [3. Cross Section Configuration — OpenMC Documentation](https://docs.openmc.org/en/stable/usersguide/cross_sections.html). Hope this helps

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<div class="post-metadata">

**Author:** ![SaitoAsuka](https://avatars.discourse-cdn.com/v4/letter/s/90ced4/32.png) [@SaitoAsuka](https://openmc.discourse.group/u/SaitoAsuka)\
**Post date:** [February 13, 2021, 10:45am UTC](https://openmc.discourse.group/t/problem-of-cross-section-xml/1008/3 "2021-02-13T10:45:22Z")

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Hi,

I’m not sure I understand. I set the openmc-env and get the cross-section data in H5 format now. But the JEFF3.3 folder doesn’t contain a file called cross\_section.xml. How can I Indicate the path of cross\_section data to these H5 files?

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<div class="post-metadata">

**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:** [February 13, 2021, 12:15pm UTC](https://openmc.discourse.group/t/problem-of-cross-section-xml/1008/4 "2021-02-13T12:15:01Z")

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Hi @SaitoAsuka

Open your terminal from `jeff33_hdf5` folder and type

```bash
ls cross*

```

If `cross_sections.xml` exists, You will get an output like

```bash
cross_sections.xml

```

If not, then you have to download jeff33\_hdf5 library again. It can happen if you use an external download manager e.g `fdm`.  
Now open `.bashrc` file with your favourite text editor and Add

```bash
export OPENMC_CROSS_SECTIONS='/path/to/jeff33_hdf5/cross_sections.xml'
export OPENMC_CROSS_SECTIONS

```