Summing USR bins using meshtk

Dear Fluka experts and users,

I am trying to use the meshtk utility to add up usrbin files.
I have two usrbin files as follows:

  • 10X0_21.bnn
  • 2X0_21.bnn

each usrbin has three scoring sections (ambient dose) for neutron, photon and total.

I issued the command to sum two usrbins as follows (according to the meshtk manual):

meshtk 1.11e+05 10X0_21.bnn:1-3 + 1.18e+05 2X0_21.bnn:1-3 -o sum.bnn

the sum.bnn is the summation of two usrbins and is generated in the same working directory.

However, when I try to plot sum.bnn I see the following error in Flair saying the usrbin is not valid:

Am I missing something in this process?

I appreciate any comments.


Dear @mahdi

could you please send us the two input bnn files to be able to debug the issue

Dear @vasilis
Thanks for your reply.

I sent the bnn files via email as they are quite big size files to be uploaded here.

Thank you.

Thank @mahdi for the files.

it helped to find a formatting error in meshtk.
The corrected version of the program you can find in the flair download page as beta version 3.x-5


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Thank you @vasilis,

Now it’s working.

May I ask how the errors of the summation are treated? Are they sum in quadrature?

I tried to plot the 2D error distribution using the sum.bnn, but the plot was empty. Do I need to run another command to get the overall statistical error?


Normally yes, however if you don’t get the statistical error, then something is wrong I will check and let you know

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