# Question about nndc300K

**URL:** <https://openmc.discourse.group/t/question-about-nndc300k/166>\
**Category:** User Support\
**Created:** [September 6, 2015, 8:18am UTC](https://openmc.discourse.group/t/question-about-nndc300k/166 "2015-09-06T08:18:24Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![niuoba](https://avatars.discourse-cdn.com/v4/letter/n/f04885/32.png) [@niuoba](https://openmc.discourse.group/u/niuoba)\
**Post date:** [September 6, 2015, 8:18am UTC](https://openmc.discourse.group/t/question-about-nndc300k/166/1 "2015-09-06T08:18:24Z")

</div>

Hi all,

I have the following problems:

I Changed the get\_nndc\_data.py in data library to get 300K library from NNDC web site as following:

---

<div class="post-metadata">

**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:** [September 10, 2015, 6:23pm UTC](https://openmc.discourse.group/t/question-about-nndc300k/166/2 "2015-09-10T18:23:34Z")

</div>

Hi NiuOba,

You can try changing the openmc/data/cross\_sections\_nndc.xml file. In that file, search for U-235.72c and change the path attribute to the appropriate path, i.e. there should be a line that looks like:

\<ace\_table alias=“U-235.72c” … path=“300K/U\_235\_300K.ace” …

The path listed there is what is causing the problem.

Best regards,  
Paul

---

<div class="post-metadata">

**Author:** ![niuoba](https://avatars.discourse-cdn.com/v4/letter/n/f04885/32.png) [@niuoba](https://openmc.discourse.group/u/niuoba)\
**Post date:** [September 13, 2015, 3:33am UTC](https://openmc.discourse.group/t/question-about-nndc300k/166/3 "2015-09-13T03:33:25Z")

</div>

Dear Paul:

In my cross\_sections\_nndc.xml, it wright as following:

---

<div class="post-metadata">

**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:** [September 14, 2015, 3:06am UTC](https://openmc.discourse.group/t/question-about-nndc300k/166/4 "2015-09-14T03:06:41Z")

</div>

Perhaps it wasn’t clear – on that line, you need to change path attribute to path=“300K/U\_235\_ **293.6K**.ace”. Did you indeed make that change?

Best,  
Paul

---

<div class="post-metadata">

**Author:** ![niuoba](https://avatars.discourse-cdn.com/v4/letter/n/f04885/32.png) [@niuoba](https://openmc.discourse.group/u/niuoba)\
**Post date:** [September 16, 2015, 1:02am UTC](https://openmc.discourse.group/t/question-about-nndc300k/166/5 "2015-09-16T01:02:11Z")

</div>

Dear Pro. Romano

I didn’t make that change.  
I will have a try, I will submit that result, later.

Best Wishes  
NIUoba