Solving "Fatal Error" in MCNPX Input Code

  • Thread starter NuclearEng12
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    Error Mcnpx
In summary, the conversation discusses a fatal error in a simple MCNPX input code that is caused by a missing M card for a specific material number. The solution involves checking the cell cards and the corresponding material card, ensuring that the fractions add up to 1, and checking for any other potential causes such as syntax errors or missing information. The conversation also includes information on the format and constraints of cell, surface, data, SDEF, and material cards, as well as the use of multipliers to calculate reaction rates.
  • #1
NuclearEng12
11
0
I am running a simple MCNPX input code and am getting a fatal error that says:

"Fatal Error: no m card for material no. X".

I thought it was something with my data card or my cell cards but can not figure out what the problem is.
 
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  • #2
NuclearEng12 said:
I am running a simple MCNPX input code and am getting a fatal error that says:

"Fatal Error: no m card for material no. X".

I thought it was something with my data card or my cell cards but can not figure out what the problem is.
Check the cell cards and the corresponding material card.

Cell card syntax:
j m d geom params
j = cell number; 1 ≤ j ≤ 99999.
m = 0 if the cell is a void.
or,= material number if the cell is not a void. This indicates that the cell is
to contain material m, which is specified on the Mm card.

"Cell, surface, and data cards must all begin within the first five columns. Entries are
separated by one or more blanks. Numbers can be integer or floating point. MCNP makes the
appropriate conversion. A data entry item must be completed on one line.

Blanks filling the first five columns indicate a continuation of the data from the last named
card. An '&' (ampersand) ending a line indicates data will continue on the following card,
where data on the continuation card can be in columns 1~80.

MCNP makes extensive checks of the input file for user errors. A FATAL error occurs if a
basic constraint of the input specification is violated, and MCNP will terminate before
running any particles. The first fatal error is real; subsequent error messages may or may not
be real because of the nature of the first fatal message."

"The material specification gives a material number to be referenced by cell cards, the atomic
number, the atomic mass and the weight fraction or the atomic fraction of each constituent
(element) in the material. The format of material cards is shown below:
Mm ZAID1 fraction1 ZAID2 fraction2 ... ZAIDn fractionnwhere m corresponds to the material number on the cell cards, ZAIDi (i = 1, ..., n) is in the format ZZZAAA where ZZZ is the atomic number and AAA is the atomic mass for constituent i, fractioni is the weight fraction if entered as a negative number, or the atomic fraction if entered as a positive number of constituent i in the material, and n is total number of constituents in the material."

The fractions must add to 1 with the appropriate precision, otherwise there will be a fatal error.

Ref: http://scholar.lib.vt.edu/theses/available/etd-07252000-10110036/unrestricted/14Appendix.pdf
 
  • #3
I have done all of those things. It is still giving me the same error. Could there be another cause?

Identifier Reaction Rate
c
c
c cell cards
5 5 -8.57 -1 2 -5 u=1 imp:n=1 VOL=0.0025 $ Niobium-94
6 6 -1.93 -1 2 5 -6 u=1 imp:n=1 VOL=0.0075 $ Cesium-137
7 7 -3.51 -1 2 -7 6 u=1 imp:n=1 VOL=0.0125 $ Barium-133
8 8 -5.264 -1 2 -8 7 u=1 imp:n=1 VOL=0.0175 $ Europium-152
9 9 -5.264 -1 2 -9 8 u=1 imp:n=1 VOL=0.0225 $ Europium-154
10 10 -8.79 -1 2 -10 9 u=1 imp:n=1 VOL=0.0275 $ Holmium-166

c surface cards
1 pz .17042
2 pz 0
5 cz .068333
6 cz .136666
7 cz .204999
8 cz .273332
9 cz .341665
10 cz .409998

c SDEF card
c SDEF AXS=0 0 1 ERG=D1 RAD=D2 WGT=1 TME=0 PAR=1
c # SI1 SP1
c 0 0
c .4 .8718
c .8 .0320
c 1.2 .0181
c 1.6 .0145
c 2 .0121
c 2.4 .0113
c 2.8 .009
c 3.2 .007
c 3.6 .0044
c 4 .0035
c 4.4 .0035
c 4.8 .0028
c 5.2 .0028
c 5.6 .0023
c 6 .0011
c 6.4 .0011
c 6.8 .0007
c 7.2 .0005
c 7.6 .0002
c 8 .0004
c 8.4 .0002
c 8.8 .0002
c 9.2 .000026
c 9.6 .000081
c 10 .0002
c 10.4 .000089
c 10.8 .0001
c 11.2 .000077
c 11.6 .000018
c 12 .000018
c 12.4 .000026
c 12.8 0
c 13.2 0
c 13.6 .000017
c 14 0
c 14.4 0
c 14.8 0
c 15.2 0
c 15.6 0
c 16 0
c 16.4 0
c 16.8 0
c 17.2 0
c 17.6 0
c 18 0
c 18.4 0
c 18.8 0
c 19.2 0
c 19.6 0
c 20 0
c SI2 -21 0
c
c Burn Cards
c BURN TIME=200 200 200 200 200 200 200 200 200 100 100 100 100
c MAT=5 6 7 8 9 10 POWER=1100
c PFRAC= 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0
c MATVOL=103.62 310.86 518.1 725.34 932.58 1139.82
c OMIT=5 4 39092 41096 43097 43098
c 6 2 53133 53134
c 7 1 58137
c BOPT=1.0 24 -1

c data cards
m5 41094.70c 1 $ Niobium-94
m6 55137.70c 1 $ Cesium-137
m7 56133.70c 1 $ Barium-133
m8 63152.70c 1 $ Europium-152
m9 63154.70c 1 $ Europium-154
m10 67566.70c 1 $ Holmium-166
mode n
c
c Tallies, Multipliers, & Energy Bins
c The multipliers will provide the reaction rate.
c
c f4:n 5 $ Niobium-94
c fm4 8.0411E+7 5 102
c
c f14:n 6 $ Cesium-137
c fm14 1.2090E+5 6 102
c
c f24:n 7 $ Barium-133
c fm24 4.2336E+4 7 102
c
c f34:n 8 $ Europium-152
c fm34 5.4438E+4 8 102
c
c f44:n 9 $ Europium-154
c fm44 3.4537E+4 9 102
c
c f54:n 10 $ Holmium-166
c fm54 5.8429E+6 10 102
c
NPS 100000
 

1. What is a "fatal error" in MCNPX input code?

A "fatal error" in MCNPX input code refers to an error that prevents the code from running and producing results. This can be caused by a variety of issues such as incorrect input parameters, missing data, or invalid syntax.

2. How can I identify and troubleshoot a fatal error in MCNPX input code?

The first step in identifying and troubleshooting a fatal error in MCNPX input code is to carefully review the error message and any accompanying documentation. This can help pinpoint the root cause of the error. Additionally, checking the input parameters and comparing them to the expected format can help identify any potential issues.

3. Can a fatal error in MCNPX input code be fixed?

In most cases, yes, a fatal error in MCNPX input code can be fixed. However, the time and effort required to fix the error will depend on the complexity of the error and the user's level of expertise with the code. In some cases, it may be necessary to consult with other users or the code developers for assistance in resolving the error.

4. Are there any common causes of fatal errors in MCNPX input code?

Some common causes of fatal errors in MCNPX input code include typos or syntax errors in the input file, specifying incorrect or unsupported parameters, or missing data files. It is important to carefully review the input file and ensure all parameters are correctly specified to avoid these types of errors.

5. How can I prevent fatal errors in MCNPX input code?

To prevent fatal errors in MCNPX input code, it is important to thoroughly review the input file for any typos or syntax errors before running the code. It can also be helpful to consult with other users or the code developers for guidance on best practices and common pitfalls to avoid when using the code.

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