I am a beginner user of MCNP and is still learning how to use it. When

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Discussion Overview

The discussion revolves around troubleshooting issues encountered while using the MCNP (Monte Carlo N-Particle Transport Code) software, particularly focusing on error messages and input file configurations. Participants share their experiences and suggestions related to the setup of lattice definitions, cell cards, and error diagnostics.

Discussion Character

  • Technical explanation, Debate/contested, Exploratory

Main Points Raised

  • One participant reports receiving a 'bad trouble in subroutine main of mcnp' error message and seeks clarification on its meaning and potential solutions.
  • Another participant suggests checking the output file for error messages and verifying the installation of the software, including running test cases.
  • A participant shares specific error messages related to storage requirements and lattice definitions, indicating potential issues with the setup.
  • Some participants propose that the error may stem from improperly defined lattice elements or invalid universe assignments in the input file.
  • One participant expresses difficulty in identifying errors within their input file, providing detailed excerpts of their cell, surface, and data cards for review.
  • Another participant mentions the need for correct definitions of lattices and surfaces, suggesting that there may be conflicts in universe assignments.
  • A participant notes the complexity of modeling a 17x17 lattice with specific geometrical and material considerations, raising concerns about the accuracy of density values and configurations.
  • There is a request for information on how to obtain the MCNP code, with a response indicating that it must be requested from Oak Ridge.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the specific cause of the errors, with multiple competing views on how to address the issues. The discussion remains unresolved regarding the exact configurations and definitions needed for successful MCNP runs.

Contextual Notes

Participants highlight potential limitations in their input files, including assumptions about lattice definitions and universe assignments, but do not resolve these issues within the discussion.

NuclearEng12
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I am a beginner user of MCNP and is still learning how to use it. When I run my program, I get a message that says 'bad trouble in subroutine main of mcnp'. What exactly does that mean and how can i correct it.
Thanks.
 
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Try searching for error messages in the output file. If you have no output file at all, verify that you have installed the software correctly. The package should have included some test cases which you can run to verify that MCNP is correctly installed.
 


The following are the error messages I am getting
warning. print table 128 requires 1088303 dec. words of storage.
bad trouble in subroutine newcel of mcrun

source particle no. 672

starting random number = 111194823047613

zero lattice element hit.
1problem summary

run terminated because of bad trouble.
 


It sounds like you have defined a lattice but not all of the elements are filled, or you have filled an array element with an invalid universe. Check your fill and lattice cards and make sure they are set up correctly.
 


I have reviewed my input file and can not identify where I might have went wrong.

c Cell Cards
1 1 -10.41 -1 -9 u=1 imp:n=1 $ Fuel Pellet
2 2 -0.130 (1 -2 -9):(9 -2) u=1 imp:n=1 $ Helium Gap
3 3 -6.52 2 -3 u=1 imp:n=1 $ ZIRLO Cladding
4 4 -0.727 3 u=1 imp:n=1 $ Water/ Coolant
5 4 -0.727 -11 u=2 imp:n=1 $ Outside Fuel Element
6 0 -4 5 -7 6 LAT=1 u=3 imp:n=1 Fill=-9:9 -9:9 0:0
2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 $ Physical Boundary
2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 $ Row 1
2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 $ Row 2
2 1 1 1 1 1 2 1 1 2 1 1 2 1 1 1 1 1 2 $ Row 3
2 1 1 1 2 1 1 1 1 1 1 1 1 1 2 1 1 1 2 $ Row 4
2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 $ Row 5
2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 $ Row 6
2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 $ Row 7
2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 $ Row 8
2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 $ Row 9
2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 $ Row 10
2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 $ Row 11
2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 $ Row 12
2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 $ Row 13
2 1 1 1 2 1 1 1 1 1 1 1 1 1 2 1 1 1 2 $ Row 14
2 1 1 1 1 1 2 1 1 2 1 1 2 1 1 1 1 1 2 $ Row 15
2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 $ Row 16
2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 $ Row 17
2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 $ Physical Boundary
7 0 15 14 -12 -13 8 -10 Fill=3 u=4 imp:n=1 $ Lattice Physical Boundary
8 4 -0.727 -16 u=5 imp:n=1 $ Outside Assembly
9 0 14 -12 -13 15 LAT=1 u=6 imp:n=1 Fill=-8:8 -8:8 0:0
2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 $ Physical Boundary
2 2 2 2 2 2 2 3 3 3 2 2 2 2 2 2 2 $ Row 1
2 2 2 2 2 3 3 3 3 3 3 3 2 2 2 2 2 $ Row 2
2 2 2 2 3 3 3 3 3 3 3 3 3 2 2 2 2 $ Row 3
2 2 2 3 3 3 3 3 3 3 3 3 3 3 2 2 2 $ Row 4
2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 $ Row 5
2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 $ Row 6
2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 2 $ Row 7
2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 2 $ Row 8
2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 2 $ Row 9
2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 $ Row 10
2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 $ Row 11
2 2 2 3 3 3 3 3 3 3 3 3 3 3 2 2 2 $ Row 12
2 2 2 2 3 3 3 3 3 3 3 3 3 2 2 2 2 $ Row 13
2 2 2 2 2 3 3 3 3 3 3 3 2 2 2 2 2 $ Row 14
2 2 2 2 2 2 2 3 3 3 2 2 2 2 2 2 2 $ Row 15
2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 $ Physical Boundary
10 0 -17 8 -10 Fill=6 imp:n=1 $ Lattice Physical Boundary
11 0 17:-8:10 imp:n=0 $ Outside Core

c Surface Cards
1 cz .410
2 cz .418
3 cz .475
4 px .630
5 px -.630
6 py -.630
7 py .630
8 pz 0
9 pz 366
10 pz 400
11 cz 100
12 px 10.71
13 py 10.71
14 px -10.71
15 py -10.71
16 cz 500
17 cz 199.4

c Data Cards
m1 92235.70c -0.003338 92238.70c -0.063422 8016.70c -0.008980 $ 5% Enriched UO2 Fuel
92235.71c -0.040734 92238.71c -0.773946 8016.71c -0.109580
m2 2004.70c -0.07574 $ Helium
2004.71c -0.92426
m3 40090.70c 0.038189 40091.70c 0.008328 40092.70c 0.012730 $ ZIRLO Cladding
40094.70c 0.012900 40096.70c 0.002078 50112.70c 0.000007
50114.70c 0.000005 50115.70c 0.000003 50116.70c 0.000110
50117.70c 0.000058 50118.70c 0.000183 50119.70c 0.000065
50120.70c 0.000247 50122.70c 0.000035 50124.70c 0.000044
41093.70c 0.000757 40090.71c 0.466021 40091.71c 0.101628
40092.71c 0.155340 40094.71c 0.157424 40096.71c 0.025362
50112.71c 0.000090 50114.71c 0.000061 50115.71c 0.000031
50116.71c 0.001344 50117.71c 0.000710 50118.71c 0.002239
50119.71c 0.000794 50120.71c 0.003011 50122.71c 0.000428
50124.71c 0.000535 41093.71c 0.009243
m4 1001.70c 0.050487 1002.70c 0.000006 8016.70c 0.025247 $ H2O
1001.71c 0.616102 1002.71c 0.000071 8016.71c 0.308087
kcode 1000 1.0 20 120
ksrc 1.26 0 183
44.1 -86.94 183
86.94 -22.68 183
22.68 -44.1 183
108.36 -86.94 183
129.78 1.26 183
44.1 44.1 183
86.94 65.52 183
65.52 108.36 183
22.68 65.52 183
-86.94 86.94 183
-22.68 22.68 183
-65.52 65.52 183
-22.68 151.2 183
-1.26 0 183
-1.26 -86.94 183
-65.52 -44.1 183
-44.1 -22.68 183
-151.2 -22.68 183
-86.94 -44.1 183
PRINT 128
 


how do i get my hands on the MCNP code?
 


You have to request it from Oak Ridge i think.
 


It looks to me like you are not defining your lattices correctly, or at least the surfaces the cells are assigned to. It looks like you are trying to use universe 2 for both a reflector region as well as a guide tube region although their geometry does not match. Maybe you meant to use universe 5 for this purpose since it is not used anywhere.
 
Last edited:


I don't have an example of a whole core case, I think that would run very very slowly on my computer :(
 
Last edited:
  • #10


Thanks for the pointers. It will really help me.
 
  • #11


So one is trying to model a 17x17 lattice with a 366 cm active fuel zone. There are 157 assemblies in the core.

2 is in the lattice map is water. The guide tube and water between assemblies would have different geometries and size.

The densities in the cell cards seem correct, and the radial and axial dimensions in the fuel rods and the cell pitch of ~12.6 cm seem correct. Above the active fuel zone would be the plenum (filled with He and stainless steel spring ~ 0.09 - 0.15 of the void volume with a height of about 20 cm). There are upper and lower endplugs (Zr-4 or ZIRLO) and stainless steel nozzle below and above the core.

It looks like you might have some gad in there. BTW - 5% is a bit high for a fresh core, without extensive holddown.
 
  • #12


marvin_NIFB said:
how do i get my hands on the MCNP code?
Access is restricted and usually limited to government facilities, e.g., DOE labs, universities and corporations who a then subject to export controls.
 
  • #13


I have corrected the universes in the 2nd lattice by replacing universe 2 with universe 5 however it is still saying 'Zero Lattice Element Hit'. I looked at the code closely and still have no idea what the problem is.
 

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