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

In summary, the conversation is about a beginner user of MCNP who is experiencing trouble when running their program. They are getting an error message of 'bad trouble in subroutine main of mcnp' and are seeking help in identifying the issue. They are also looking for guidance on how to access the MCNP code and have received pointers on correcting their lattice definitions and filling errors in their input file. They are also discussing the details of their specific model, which includes a 17x17 lattice with a 366 cm active fuel zone and various materials such as water, helium, and stainless steel.
  • #1
NuclearEng12
11
0
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.
 
Engineering news on Phys.org
  • #2


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.
 
  • #3


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.
 
  • #4


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.
 
  • #5


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
 
  • #6


how do i get my hands on the MCNP code?
 
  • #7


You have to request it from Oak Ridge i think.
 
  • #8


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:
  • #9


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.
 

1. What is MCNP and what is it used for?

MCNP (Monte Carlo N-Particle) is a computer code used for simulating the transport of particles through matter. It is primarily used in the field of nuclear engineering and radiation physics to study radiation interactions and their effects.

2. How does MCNP work?

MCNP uses the Monte Carlo method, which involves simulating the random movement and interaction of particles through matter. It uses input files that contain the geometry, materials, and source information for the simulation. The code then tracks the particles' paths and records their interactions until they either leave the system or are terminated by a specified event.

3. Is MCNP difficult to learn and use?

MCNP can be complex and challenging to learn, especially for beginners. However, with proper training and practice, it can be a powerful tool for simulating various radiation scenarios. There are also many online resources and training courses available to help users learn and improve their skills.

4. What are the advantages of using MCNP?

MCNP allows for precise and accurate simulations of radiation interactions, making it a valuable tool for understanding and predicting radiation behavior. It also has a vast library of pre-defined materials and nuclear data, making it convenient for users to simulate a wide range of materials and scenarios.

5. Are there any limitations to using MCNP?

Like any software, MCNP has its limitations. It can be computationally intensive, requiring a significant amount of time and resources to run simulations. It also relies heavily on the accuracy of input parameters and may not always accurately reflect real-world scenarios. Therefore, it is crucial to understand the limitations of the code and validate results with experimental data when possible.

Similar threads

Replies
1
Views
1K
Replies
5
Views
2K
Replies
3
Views
1K
  • Nuclear Engineering
Replies
1
Views
75
Replies
6
Views
1K
Replies
6
Views
1K
  • Nuclear Engineering
Replies
5
Views
371
Replies
2
Views
2K
Replies
2
Views
2K
Replies
10
Views
2K
Back
Top