Maximum number of sites in fission bank reached.

User Support
1

Hello
I’m working on the spent fuel pool
the geometry is in form of cylinder filled with water and i placed the fuel elements within 2 circles of radius 83 and 92 respectively
while i try to run the simulation it gives me this warning(as is showing below ) and the simulation stopped.
it will be great helping me find the problem

thank you in advance

Error.png

2

Hi Hajar,

This can happen when your initial k-effective value (that estimated based on the initial source that you specified) is too low, in this case 0.06. You might want to try any of the following:

  • Look at your material definitions to see if one of them should have a higher concentration of fissionable materials
  • Change your source definition to produce a higher initial k-eff. The easiest way to do this is to put a point source in the fuel directly, or if you have a lattice of fuel pins you can pick the center of the model.
  • Increase the number of particles per generation.
    Normally, the warning you are seeing should not result in the simulation stopping altogether. Is there another error that occurs afterwards?

Best regards,
Paul

3

In this case, increasing the number of particles per generation should help get around that error. If you are running in parallel with multiple MPI processes, each MPI process must produce at least one fission site per generation. Thus, if you have too few particles per generation, it’s possible that one process doesn’t create a fission site at all.

Best regards,
Paul

4

Thank you for the clarification.