Convergence plots

User Support
1

Hi,
Is there a convenient way to look at plots of k_eff and/or entropy vs. iteration # (including std. dev. in the case of k_eff), in order to determine convergence of fission source?
Thanks,
Shai

1 Like
2

Hi Shai,

Yes, you can use the Python API together with the HDF5 statepoint file to look at convergence of k-effective and entropy. A basic script to do this would look something like the following:

import openmc
import matplotlib.pyplot as plt

sp = openmc.StatePoint(‘statepoint.20.h5’)
k = sp.k_generation
plt.plot(k, label=‘keff’)
plt.xlabel(‘Generation’)
plt.ylabel(‘k-effective’)
plt.show()
H = sp.entropy
plt.plot(H, label=‘entropy’)
plt.xlabel(‘Generation’)
plt.ylabel(‘Shannon entropy’)
plt.show()

Unfortunately the statepoint file does not currently store the uncertainty on each of the values of k-effective.

Best regards,
Paul

1 Like
3

Hi Shai,
how many batches did it take for the shannon entropy to converge on your simplified PWR core? I am just curious

4

About 30 batches.