# Could not find nuclide U235 **URL:** \ **Category:** User Support\ **Created:** [October 30, 2022, 12:36pm UTC](https://openmc.discourse.group/t/could-not-find-nuclide-u235/2410 "2022-10-30T12:36:18Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Dalia](https://avatars.discourse-cdn.com/v4/letter/d/a698b9/32.png) [@Dalia](https://openmc.discourse.group/u/Dalia)\ **Post date:** [October 30, 2022, 12:36pm UTC](https://openmc.discourse.group/t/could-not-find-nuclide-u235/2410/1 "2022-10-30T12:36:18Z")
I downloaded all the date libraries from the command lines in here: [GitHub - openmc-data-storage/openmc\_data\_downloader: A Python package for downloading h5 cross section files for use in OpenMC.](https://github.com/openmc-data-storage/openmc_data_downloader) and I get this error when running the code: ![image](https://global.discourse-cdn.com/free1/uploads/openmc/original/2X/3/34162c555c6ba00985332b6b2348be577831e109.png) ---
**Author:** ![Dalia](https://avatars.discourse-cdn.com/v4/letter/d/a698b9/32.png) [@Dalia](https://openmc.discourse.group/u/Dalia)\ **Post date:** [October 30, 2022, 12:39pm UTC](https://openmc.discourse.group/t/could-not-find-nuclide-u235/2410/2 "2022-10-30T12:39:27Z")
I have seen fixes in here to replace .71 c with .70 c but I don’t see where to change it in the command lines I used in the Github post. ---
**Author:** ![Dalia](https://avatars.discourse-cdn.com/v4/letter/d/a698b9/32.png) [@Dalia](https://openmc.discourse.group/u/Dalia)\ **Post date:** [October 30, 2022, 2:23pm UTC](https://openmc.discourse.group/t/could-not-find-nuclide-u235/2410/3 "2022-10-30T14:23:47Z")
I changed the cross sections path to find U235 and it did find it but now it can’t find U238, is there a library that contains both? ---
**Author:** ![oyardas2](https://avatars.discourse-cdn.com/v4/letter/o/8491ac/32.png) [@oyardas2](https://openmc.discourse.group/u/oyardas2)\ **Post date:** [October 30, 2022, 11:32pm UTC](https://openmc.discourse.group/t/could-not-find-nuclide-u235/2410/4 "2022-10-30T23:32:30Z")
Hi Dalia, I’d recommend you use the officially supported HDF5 library. You can download it at [this page](https://openmc.org/official-data-libraries/). Best, –Olek ---
**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:** [October 31, 2022, 1:18am UTC](https://openmc.discourse.group/t/could-not-find-nuclide-u235/2410/5 "2022-10-31T01:18:58Z")
I’m fairly sure the h5 files are exactly the same, I made the package but I also helped make the official data processing scripts. The benefit of the package is that it lets you download individual h5 cross section files which is particularly useful if you don’t want to download a entire library of a few Gigabytes. This is particularly useful for CI usage @Dalia could you let us know the terminal command you used to download as I think it might be a case of extending the terminal command to list both nuclides ---
**Author:** ![Dalia](https://avatars.discourse-cdn.com/v4/letter/d/a698b9/32.png) [@Dalia](https://openmc.discourse.group/u/Dalia)\ **Post date:** [October 31, 2022, 9:52am UTC](https://openmc.discourse.group/t/could-not-find-nuclide-u235/2410/6 "2022-10-31T09:52:02Z")
@oyardas2 Thank you so much for your help! I tried downloading the HDF5 library but I had a hard time making the jupyter notebook read the xml file, even though I would specify the directory correctly, I kept having these error on here: [Error no cross section.xml file was specified](https://openmc.discourse.group/t/error-no-cross-section-xml-file-was-specified/2397) @Shimwell Thank you so much for your help! here’s a screenshot of the nuclides that I get and, in here the error that I get is that it can’t find U238, I was also wondering if I needed nuclides that are downloaded separetly with different lines and they creat two different cross\_sections.xml files, when I need both should I call both in the terminal? I tried doing this but I guess it only read my last call. ![image](https://global.discourse-cdn.com/free1/uploads/openmc/original/2X/b/b7d418d4ec7e5c95da5de23dcb5bc9af26c1433a.png) ---
**Author:** ![Dalia](https://avatars.discourse-cdn.com/v4/letter/d/a698b9/32.png) [@Dalia](https://openmc.discourse.group/u/Dalia)\ **Post date:** [October 31, 2022, 10:06am UTC](https://openmc.discourse.group/t/could-not-find-nuclide-u235/2410/7 "2022-10-31T10:06:25Z")
When I use this directory it can’t find U235: ![image](https://global.discourse-cdn.com/free1/uploads/openmc/original/2X/b/b2d8a202e826fff40cf9573b0cdf7aecccb7e2e2.png) ---
**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:** [October 31, 2022, 10:08am UTC](https://openmc.discourse.group/t/could-not-find-nuclide-u235/2410/8 "2022-10-31T10:08:34Z")
I’m sure we can get either the official or this downloader working for you. Are you able to attend the monthly drop is session today, we can do a screen share and get things working? I would be tempted to move uranium and iron to the element section So you have ‘’’ openmc\_data\_downloader -l TENDL-2019 -e U Li Na Si Fe ‘’’ Then export the environmental variable. ‘’’ export OPENMC\_CROSS\_SECTIONS=home/dalia/cross\_sections.xml ‘’’ ---
**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:** [October 31, 2022, 10:32am UTC](https://openmc.discourse.group/t/could-not-find-nuclide-u235/2410/9 "2022-10-31T10:32:43Z")
I would not move or rename the h5 files or XML file around after creating them as this could mix up the paths Each time you run the command it overwrites the cross\_section.xml file with just the nuclides downloaded in that command. Unless you specify a different file name H5 files previously downloaded should be detected and won’t be downloaded again but the XML file will be updated to include only the nuclides in the last command You can open the cross section XML file to see the contents, it is basically a look up file. ---
**Author:** ![Dalia](https://avatars.discourse-cdn.com/v4/letter/d/a698b9/32.png) [@Dalia](https://openmc.discourse.group/u/Dalia)\ **Post date:** [October 31, 2022, 10:42am UTC](https://openmc.discourse.group/t/could-not-find-nuclide-u235/2410/10 "2022-10-31T10:42:36Z")
Thank you so much for your help! I used the line: openmc\_data\_downloader -l TENDL-2019 -e U Li Na Si Fe, and it actually worked. It just showed that it’s missing: O, H, B, Zr and I added them the same way and got to run it without errors. At what time is the monthly drop session? Is there a link I can use to join? ![image](https://global.discourse-cdn.com/free1/uploads/openmc/original/2X/2/27e9cc08ecf25092685d89e43c34903535383fc5.png) ---
**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:** [October 31, 2022, 10:45am UTC](https://openmc.discourse.group/t/could-not-find-nuclide-u235/2410/11 "2022-10-31T10:45:57Z")
Congrats on that. Here is the monthly meet up link, first post in this thread > [@OpenMC monthly drop in session dates 2022](https://openmc.discourse.group/t/openmc-monthly-drop-in-session-dates-2022/1629): > > Dear OpenMC community We are organising monthly drop in sessions for 2022 tada This will be an opportunity for: point_right Contributors to present their plans / ideas for code contributions (limited to 5 mins per talk) point_right Developers to present future plans for OpenMC (limited to 5 mins per talk) point_right New users to ask questions and learn about the ecosystem point_right Poster session with poster stands The format could evolve over the year with feedback … ---
**Author:** ![Dalia](https://avatars.discourse-cdn.com/v4/letter/d/a698b9/32.png) [@Dalia](https://openmc.discourse.group/u/Dalia)\ **Post date:** [October 31, 2022, 11:40am UTC](https://openmc.discourse.group/t/could-not-find-nuclide-u235/2410/12 "2022-10-31T11:40:05Z")
Got it, thank you so much!