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10 particles got lost

  1. Nov 6, 2016 #1

    I am trying to run a fast reactor model but I cannot figure out what is happening because I get the error: run terminated because 10 particles got lost. I am using the sdef card (with and without parameters) and the model is not running. Hope you can help me to fix any mistake I did. The goal in this model is to obtain the axial flux distribution as well as the axial power distribution so I divided the model in different zones to use a F7 and a F4 tally in each one of this zone. I attach the file.


    Attached Files:

  2. jcsd
  3. Nov 7, 2016 #2


    Staff: Mentor

    Perhaps by describing it in more detail and questioning how you setup your model you will find your missing particles.

    Is it possible that this can happen in a normal simulation without it being wrong?

    Could the particles have trajectories that just escape out into space that is outside of your simulation just like real particles in a real reactor?
  4. Nov 24, 2016 #3
    This happens usually only if there is a geometry error. Perhaps the region where there is an error is so small, it might not be visible in the plot. If you carefully go through the output file, MCNP prints out details of every single lost particle, it's last known location, cell and transport vector. That should lead you right to the location of the geometry error.
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