Thermal scattering data c_H_in_H2O in cross_sections issue in pincell.ipynb

User Support
1

Hi, I am trying to run the pincell example from openmc-notebooks/pincell.ipynb at develop · openmc-dev/openmc-notebooks · GitHub. I am using container to run this file on notebook http://127.0.0.1:8888/lab/tree/pincell.ipynb.

I came across to the following error.

RuntimeError: Could not find thermal scattering data c_H_in_H2O in cross_sections.xml file.

I checked the tree and I don’t see the cross_sections.xml file.

  1. How do I add t thermal scattering data c_H_in_H2O in cross_sections.xml or in the pincell.ipynp code?
    2)Where am I going to find the cross_sections.xml file?

Thank you
Birsen

2

Hi Birsena, have you tried to download the nuclear data from openmc official nuclear data library?

You can set your default cross sections for openmc using the OPENMC_CROSS_SECTIONS variable as described in the documentation.

3

Hi Wahid,

I use Docker with openMC to run the problem.

I found the statement:

“ The **cross_sections.xml** tells OpenMC where it can find nuclide cross sections and S(a,b)) tables. This can be set either by the **OPENMC_CROSS_SECTIONS** environment variable or the **Materials.cross_sections** attribute.”

Using the following command I can see the library (which tells they are in the path) but I don’t know where S(a,b) are?

!cat $OPENMC_CROSS_SECTIONS

print(’ …')

….

4

Hi Birsena,
The cross_sections.xml shows the relative path of each nuclear data. so for your s(alpha,beta) data, you can make sure that each file exist on its location. i.e. c_H_in_H2O.h5 for H in H2O

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image1175×505 75 KB

5

Hi Wahid,
Thank you. I downloaded the data file into the docker container under /tasks and set the path in my code. It is working. Thank you

I considered adding the cross section data in .bash file on Windows but I am not sure if it would work since I am using docker container.

First I downloaded the cross section data in one of the Windows folder in C drive, but did not take it to the file location in C drive. So I had to move the data inside the docker container.

Is there way to define the path that would work in Docker Container if the data is located in C drive somewhere?

Thank you again for your help

Birsen

6

Hi Birsena,
Sometimes, I declared the path to cross_sections.xml directly inside the python script. it looks like this.

import openmc
openmc.config['cross_sections'] = '/home/path/to/your/openmclib/endfb-vii.1-hdf5/cross_sections.xml'

But if you want to declare it as environment variable, I recommend you to add this to you .profile file at your home directory. I am adding this line at the bottom of .profile

# set PATH so it includes user's private bin if it exists
if .....
fi

# OpenMC Cross-sections
export OPENMC_CROSS_SECTIONS=/home/path/to/your/endfb-vii.1-hdf5/cross_sections.xml

I think it could work