openmc.deplete.Results - material differences

User Support
1

Hello.

I have the following material to begin with:

  <material depletable="true" id="51" name="m24" volume="33702.263">
    <density units="g/cm3" value="17.666549999999997" />
    <nuclide ao="0.0011999999999999995" name="W180" />
    <nuclide ao="0.26499999999999996" name="W182" />
    <nuclide ao="0.14309999999999998" name="W183" />
    <nuclide ao="0.3064" name="W184" />
    <nuclide ao="0.2843" name="W186" />
  </material>

I am running a depletion calculation and collecting depleted materials as follows:

for i in range(len(model.timesteps)):
    new_material = results.export_to_materials(i)

I noticed that for i = 0, I get a different atom percent:

  <material depletable="true" id="51" name="m24" volume="33702.263">
    <density units="sum" />
    <nuclide ao="6.944479173057228e-05" name="W180" />
    <nuclide ao="0.015335724840501386" name="W182" />
    <nuclide ao="0.00828129141387075" name="W183" />
    <nuclide ao="0.01773157015520613" name="W184" />
    <nuclide ao="0.016452628574168095" name="W186" />
  </material>

Shouldn’t they be the same since it corresponds to t = 0? Or was there already some transport and depletion at time t = 0 time_step? I just want to make sure everything is working properly.

2

The thing you need to check is that second material is having number densities in the units if number/barn-cm while the first one is in the units if atom percents. Take the ratio of second material number densities and see if comes out to be the same as original

3

You are absolutely correct, the second one is in other units. I calculated the ratio, and it is exactly the same as the first one. I was confused because the second xml file is still written with “ao”. Thank you very much.