How to Resolve MCNP Depletion Code Syntax Errors?

Click For Summary

Discussion Overview

The discussion revolves around troubleshooting syntax errors in MCNP depletion code related to a ceramic film attached to the moderator-side of a fuel clad. Participants are exploring issues with burnup calculations and the correct setup of input files, focusing on the theoretical and practical aspects of using MCNP for depletion analysis.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • A graduate student reports issues with obtaining a burnup of 0.000E+00 for the first step and N/A for subsequent steps in their MCNP input file.
  • One participant asks for clarification on the units for burn time and power parameters in MCNP's burnup function.
  • Another participant explains that burn time is in days and power parameters represent total recoverable fission system power, noting that certain isotopes were omitted to avoid library issues.
  • Some participants question whether MCNP allows depletion of non-fuel materials and how it defines the power of the cladding.
  • There is a suggestion that the PFRAC card must be present in the BURNUP section, and that the first time step should not be zero.
  • One participant mentions that the N/A error might indicate a problem with the depletion section of the input file.
  • Another participant notes that running the input file without errors still does not provide the desired isotropic depletion data for verification.
  • A suggestion is made to change the MATVOL card for proper material concentration representation after burn steps.

Areas of Agreement / Disagreement

Participants express differing views on the handling of non-fuel materials and the necessity of certain input parameters, indicating that multiple competing views remain without a clear consensus on the correct approach to resolve the syntax errors.

Contextual Notes

Participants mention specific requirements for the PFRAC card and the implications of omitting isotopes, highlighting potential limitations in the input file setup that may affect the burnup calculations.

shakystew
Messages
16
Reaction score
0
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.
 

Attachments

Engineering news on Phys.org
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
 

Attachments

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.
 

Similar threads

Replies
5
Views
1K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 15 ·
Replies
15
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 9 ·
Replies
9
Views
3K
Replies
3
Views
3K
Replies
2
Views
3K
  • · Replies 8 ·
Replies
8
Views
3K