# Fatal Error in MCNPX

1. Dec 30, 2012

### NuclearEng12

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.

2. Dec 31, 2012

### Astronuc

Staff Emeritus
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. Jan 3, 2013

### NuclearEng12

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