Transient, group binning of precursor

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samuel.kelly
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Transient, group binning of precursor

Post by samuel.kelly » Wed Jul 07, 2021 3:36 pm

I seem to be having some issues when trying to run a transient calculation. It is best outlined by the following message in my .out file

Fatal error in function InitPrecDet:

Group binning of precursor different (102) vs (24)

Simulation aborted.


I have seen a similar issue previously discussed on this forum where the fix seemed to be due to detectors. I have tested whether it could be detector related by removing all detectors in my static and transient case but this didn't seem to fix the problem.

I don't entirely understand what user defined inputs produce this group binning value so I'm not entirely sure how best to fix this?

Ana Jambrina
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Re: Transient, group binning of precursor

Post by Ana Jambrina » Wed Jul 07, 2021 4:03 pm

The error states a mismatch between the number of the delayed neutrons from the source file (102) and the current simulation (24).

The total number of delayed groups, when processing the precursor detectors, comes from the number of delayed neutron groups for all reactions/nuclides involved in the simulation.

The cause might be having generated the source distribution with a different library from the one used during the transient calculation. But from the numbers you are obtaining, it seems unlikely.

Another potential cause of failure is derived from the materials involved in both simulations. Do you have the list of material definitions in the steady-state and transient calculations (including those related to the detectors)?
- Ana

samuel.kelly
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Re: Transient, group binning of precursor

Post by samuel.kelly » Wed Jul 07, 2021 6:26 pm

So all of my materials are defined in a .mater file, which is called to in both the transient and steady state. With this being the same file there shouldn't be any differences there?

Ana Jambrina
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Re: Transient, group binning of precursor

Post by Ana Jambrina » Wed Jul 07, 2021 6:32 pm

Could you post here all the inputs (steady-state/transient)? Which Serpent version are you running?
- Ana

samuel.kelly
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Re: Transient, group binning of precursor

Post by samuel.kelly » Wed Jul 07, 2021 9:05 pm

Unfortunately it is proprietary information so I will be unable to, but thank you for your help.

Ana Jambrina
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Re: Transient, group binning of precursor

Post by Ana Jambrina » Wed Jul 07, 2021 9:26 pm

If you have discarded the use of different cross-section libraries and the materials defining the geometry are common/shared for both simulations, double-check that you have not defined materials outside that ‘.mater’ file, e.g., non-physical/geometrical materials for the detectors.
- Ana

Ville Valtavirta
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Re: Transient, group binning of precursor

Post by Ville Valtavirta » Tue Jul 13, 2021 12:13 pm

Hi,

Ana already explained the basic cause of the error, but one way for debugging is to check your <input>.out file. At the beginning of the file, you have the summary of nuclide data included in the calculation. You can check the included nuclides there and there is even a separate flag that is printed for each nuclide that has delayed neutron data associated with it.

My wild guess for your source of error would be that one or more of your fissile materials was burnable in the source generation simulation, which causes Serpent to include potential transmutation and fission product nuclides in the material composition.

-Ville

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