Problem about generating group constants using mlotres_xs.py

[js-jixu]

Hi, everyone. I want to use OpenMC to generate group constants for Moltres using moltres_xs.py , the number of groups is 7 and the number of precursor groups is 6 .

Following what Godiva said in the README.md, I wrote three OpenMC input files (with different temperatures, jixu_openmc_900 and so on) including the openmc_xs.generate_openmc_tallies_xml() function. But I don't know how to set the parameters of domain_dict part . The example only uses one material but I want to use three materials, which are fuel(id=1) , clad(id=2) and cool(id=3). I don't know how to set other materials in domain_dict part(900k.py, line 85-92). Should I write code like this?

tallies_file = openmc.Tallies()
domain_dict = openmc_xs.generate_openmc_tallies_xml(
    [1e-5,2.26,3.043e2,2.035e3,9.12e3,6.74e4,1.36e6,2e7],
    list(range(1, 9)),
    [fuel] [clad] [cool],
    [fuel.id] [clad.id] [cool.id],
    tallies_file,
)

Should I replace [fuel.id] with 1 ?

Besides that, when I run the script, there is an DiffusionCoefficient error:

Am I missing any necessary parameters?

If I get OpenMC output files: statepoint_900_openmc.100.h5 , summary_900.h5 and so on, should I write moltres_xs.py input file jixu_openmc.inp like this?

[TITLE]
  jixu_openmc.json

[MAT]
  3
  fuel clad cool

[BRANCH]
  3
  fuel clad cool            900 1 1 1 2 3 1
  fuel clad cool            1000 1 1 1 2 3 1
  fuel clad cool            1100 1 1 1 2 3 1

[FILES]
  3
  statepoint_900_openmc.100.h5 openmc jixu_openmc_900.py summary_900.h5
  statepoint_1000_openmc.100.h5 openmc jixu_openmc_1000.py summary_1000.h5
  statepoint_1100_openmc.100.h5 openmc jixu_openmc_1100.py summary_1100.h5

The 1 2 3 in fuel clad cool 900 1 1 1 2 3 1 represents the ids of fuel, clad and cool.

The OpenMC input files for different tempratures, moltres_xs.py, README.txt and jixu_openmc.inp for moltres_xs.py are attached. Any advice or correction are appreciated.
Moltres_Discussion.zip

[gwenchee]

The DiffusionCoefficient function in OpenMC is only available in v0.12.1 and newer.

As for the domain_dict, if you have more than one material, your input would look like:

domain_dict = openmc_xs.generate_openmc_tallies_xml(
    [1e-5, 748.5, 5.5308e3, 24.7875e3, 0.4979e6, 2.2313e6, 20e6],
    list(range(1, 9)),
    [fuel_mat, fuel_mat2],
    [fuel_mat.id, fuel_mat2.id],
    tallies_file,
)

Should I replace [fuel.id] with 1 ?

No. It should be the fuel's id. See OpenMC's Material properties: https://docs.openmc.org/en/latest/pythonapi/generated/openmc.Material.html

If I get OpenMC output files: statepoint_900_openmc.100.h5 , summary_900.h5 and so on, should I write moltres_xs.py input file jixu_openmc.inp like this?

You should not repeat 1100K. It looks good otherwise

[gwenchee]

I suggest installing openmc v-0.12.2. I'm using it now and it works with DiffusionCoefficient. @js-jixu

[js-jixu]

I made a little modification on the original code and it is now compatible with the latest version of openmc(v-0.13.1). But it still has a bug, that is, it cannot generate group constants for two or more temperatures at the same time. Anyway, it works for me now.

moltres_xs.zip

[gwenchee]

Excellent. You're welcome to make a PR into moltres_xs.py if you fix the bug :)

[smpark7]

Note that any change should ensure backward compatibility to the older 0.12.x versions by checking which OpenMC version the user ran to generate the statefiles.

[js-jixu]

Yeah, to be on the safe side, I still use openmc v.0.12.2 .