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

1. May 19, 2012

### NuclearEng12

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.

2. May 21, 2012

### QuantumPion

Re: Mcnp

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. May 21, 2012

### NuclearEng12

Re: Mcnp

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. May 21, 2012

### QuantumPion

Re: Mcnp

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. May 22, 2012

### NuclearEng12

Re: Mcnp

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. May 23, 2012

### marvin_NIFB

Re: Mcnp

how do i get my hands on the MCNP code?

7. May 23, 2012

### NuclearEng12

Re: Mcnp

You have to request it from Oak Ridge i think.

8. May 23, 2012

### QuantumPion

Re: Mcnp

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: May 23, 2012
9. May 23, 2012

### QuantumPion

Re: Mcnp

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

Last edited: May 23, 2012
10. May 23, 2012

### NuclearEng12

Re: Mcnp

Thanks for the pointers. It will really help me.

11. May 23, 2012

### Astronuc

Staff Emeritus
Re: Mcnp

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. May 23, 2012

### Astronuc

Staff Emeritus
Re: Mcnp

Access is restricted and usually limited to government facilities, e.g., DOE labs, universities and corporations who a then subject to export controls.

13. May 25, 2012

### NuclearEng12

Re: Mcnp

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.