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Precursor group sampling failed

Posted: Wed Jan 02, 2013 6:48 pm
by orca.blu
Hi, I found these warning messages in the log file of my simulations
[...]

***** Wed Jan 2 15:23:20 2013 (seed = 1357139819, MPI task = 2)
Warning message from function SamplePrecursorGroup:

Precursor group sampling failed (92235.03c, mt 18, E = 6.277916E-01)

------------------------------------------------------------

Serpent 2.1.10 -- Static criticality source simulation

[...]
It seems to be something rare:
it happens at most twice in simulations with 500e6 neutron histories...

I believe it has no impact at all, right?

Re: Precursor group sampling failed

Posted: Sat Jan 05, 2013 3:35 pm
by Jaakko Leppänen
It's most likely a numerical problem in the delayed neutron precursor data (sum of precursor group fractions is slightly below 1). If you get this warning message only once, it shouldn't matter. Which data library are you using?

Re: Precursor group sampling failed

Posted: Sat Jan 05, 2013 7:57 pm
by orca.blu
Ok thank you.
Jeff 3.1 (the one provided with serpent 1)

Re: Precursor group sampling failed

Posted: Thu Mar 26, 2020 12:32 pm
by novako
Hi,
I do experience the same warning. I experienced this during simulation of 5e9 neutrons 5 times. All cases were on U239, see lower.

Precursor group sampling failed (92235.00c, mt 18, E = 1.208597E-08)
Precursor group sampling failed (92235.00c, mt 18, E = 1.179692E-08)
Precursor group sampling failed (92235.00c, mt 18, E = 1.107475E-07)
Precursor group sampling failed (92235.00c, mt 18, E = 2.894528E-08)
Precursor group sampling failed (92235.00c, mt 18, E = 3.356145E-08)

I use JEFF3.3 Library.

Is this number of warning high enough to worry or rare enough to keep calm :)?
Or should we do something with libraries?
Thank you
Ondrej

Re: Precursor group sampling failed

Posted: Fri Mar 27, 2020 10:32 am
by Jaakko Leppänen
With that many histories you should get something like 10 million delayed neutrons sampled. 5 failures doesn't seem that much.