How to Resolve MCNP Depletion Code Syntax Errors?

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SUMMARY

The discussion focuses on resolving syntax errors in the MCNP depletion code related to a ceramic film attached to the moderator-side of the fuel clad. The user reports receiving a burnup of 0.000E+00 for the first step and N/A for subsequent steps, indicating potential issues with the depletion section. Key points include the necessity of the PFRAC card (PFRAC=1 1 1) in the BURNUP section and the importance of ensuring the first time step is not zero. Additionally, adjustments to the MATVOL card are recommended for accurate material concentration calculations.

PREREQUISITES
  • Understanding of MCNP (Monte Carlo N-Particle Transport Code) syntax and functionality
  • Familiarity with depletion calculations in nuclear engineering
  • Knowledge of the PFRAC card and its role in burnup simulations
  • Experience with material volume specifications in MCNP input files
NEXT STEPS
  • Review the MCNPX manual for detailed information on burn schemes and depletion processes
  • Learn how to properly configure the PFRAC card for accurate depletion modeling
  • Investigate the implications of material volume (MATVOL) adjustments on simulation results
  • Explore methods for analyzing isotropic depletion within specific regions in MCNP
USEFUL FOR

Graduate students, nuclear engineers, and researchers working with MCNP simulations, particularly those focusing on depletion calculations and material behavior in nuclear fuel cycles.

shakystew
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Hello,

I am a graduate student attempting to run evaluate the depletion of a ceramic film attached to the moderator-side of the fuel clad. I am having some issues with my MCNP syntax/code and I was wondering if one could assist.

My input file is attached. I am not looking for someone to fully analyze the issue, just wanted to see if anyone notices anything wrong. I am getting a burnup of 0.000E+00 for the first step, then N/A for the remaining.
 

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I'm not familiar with MCNP's burnup function, what are the units for the burn time and power parameters?
 
The burn time are in days and the power parameters represent the total recoverable fission system power (MW). (DEFAULT:POWER=1.0). I was forced to OMIT those isotopes in the respective material regions in order to not run into library issues.
 
I'm just throwing out ideas here, but does MCNP let you deplete non-fuel materials (mat 4) like that? How it is defining the power of the cladding?
 
You have three burnup steeps 0 50 100 days. I know that also must be present PFRAC card ( PFRAC=1 1 1 ) in BURNUP
burnup=0 day*1MW/mass of heavy fuel = 0.0 MWD/MTU
your first time step is problem (must be different from 0)
 
Last edited:
Stephan_doc said:
You have three burnup steeps 0 50 100 days. I know that also must be present PFRAC card ( PFRAC=1 1 1 ) in BURNUP
burnup=0 day*1MW/mass of heavy fuel = 0.0 MWD/MTU
your first time step is problem (must be different from 0)

I think PFRAC defaults to 1 for every step if you don't enter it at all. The N/A error leads me to believe it is having a problem with the depletion section somehow though.
 
QuantumPion said:
I think PFRAC defaults to 1 for every step if you don't enter it at all.
Yes, you are right
Run my attached input
MCNPX will give materials concentrations for fresh fuel. (no burnup, 0 MWD/MTU)
Please read burn scheme from MCNCPX manual for a better understand
 

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It ran without errors, but I would like to see the isotropic depletion within each region (especially the film, to verify it will last an entire fuel cycle). The 'print table 210' only shows the library burnup.
 
Also change card MATVOL=11.02876358 192.687656 with MATVOL= 192.687656 11.02876358 for MAT=1 4. See concentrations for material 4 (ZrO2 Film) after burn steps requested.
 

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