The discussion focuses on resolving the "Fatal error too many numbers first entry" issue encountered while using MCNPX for reactor simulations. Key errors identified include typos in line entries, specifically missing periods and exponents, as well as a duplicate mt3 card. The solution involved correcting the ksrc line to "ksrc 0 0 150" and ensuring proper formatting for the BURN card, including the addition of a MATVOL parameter. Participants emphasized the importance of finite volume specifications for cells and the correct syntax for the OMIT line.
PREREQUISITESThis discussion is beneficial for nuclear engineers, reactor physicists, and anyone involved in MCNP simulations, particularly those troubleshooting input file errors and optimizing reactor models.
94241 60c 3 3997e 94241.60c 3.3997e-4I want to add a burn up card to the sample reactor in mcnp. For this, I wanted to learn how to add a nail to the burn up card first.Alex A said:Continued lines are 5 spaces, not 3.
Line 25,
Seems to have 3 typos. 2 missing .'s and a missing exponent.Code:94241 60c 3 3997e 94241.60c 3.3997e-4
You have a duplicate mt3 card, one with a typo.
The source is being rejected, and I'm not seeing it by eye. Usually means a geometry error. I'll continue to look at it.
https://mcnp.lanl.gov/pdf_files/la-ur-09-2051.pdf The application I tried to make an example is from this pdf PFRAC=F1,F2,F3,. what does this code mean?Alex A said:Your ksrc is the 'other' side of cell 3, on the edge of or into the void. Changing it to "ksrc 0 0 150" fixes that.
mcnpx gave me an error that makes me think we might need an ignore line. mcnp6 is running the kcode, which might take a while. So this is mostly fixed.
my aim is to add burn up card to this reactor. but i don't know how to do itAlex A said:The ksrc line is an error in the document that has a different correct description later on. KSRC 0 0 182.5 is the middle of the pin location.
fatal error. zero volume for burn cell 1. use vol card.How can I add a vol card to this input file?Alex A said:The six lines immediately after the BURN card are variables that belong to it, so they need five spaces or MCNP/X will think they are commands.
The OMIT line has been messed with, look up the syntax and fix it. You may need to add additional nuclides that X has no tables for. That may be a BOPTS issue, X can ignore those kinds of errors.
Some of the cells are badly specified, and I've tweaked them to be limited in z to give them finite calculable volume. X still complainswhich I did to every cell with no calculated volume except the void cell (which is infinite). I also added a MATVOL=28426.299 parameter to the BURN, which is needed when a lattice is being used. Now I am stuck because this error is not going away. I will try again tomorrow.Code:fatal error. zero volume for burn cell 1. use vol card.
Edit,
Literally giving cell 1 a vol card with the value it calculated itself solves the error.
1 1 0.068525 -18 1 -2 vol=136.011 u=1 $ Fuel PinShould I add a vol card for other cells or only the first cell is enough for this reactor?Alex A said:Don't make new threads for this problem. My line reads like this,
Code:1 1 0.068525 -18 1 -2 vol=136.011 u=1 $ Fuel Pin
1 and -2 are limits in Z to make the volume finite so the program can calculate the volume itself. At that point it still didn't run to the end. I then just fed this value back into the line with the vol= part.
vol=136.011 how did you calculate this? is there a formula or something?the code didn't work either, I did the sameAlex A said:That is only cell with material 1 in it. BURN was told about material 1, so you don't need any other cell.
According to the manual you need a MATVOL with the BURN card, because this is a lattice. I'm assuming that value is 209 * 136.011. I'm not familiar with BURN, so it now runs but I don't know enough to be sure the result is correct.
Do you add burn time in your input file?the application gave an error in the burn time partAlex A said:You can do it with maths, cell 1 is formed from surface 18, which is cz, a cylinder and you know the radius.
MCNP will try to calculate the volume of every cell. If you read through the output file, you'll see the list. What they are or why the program failed to work it out.
I made the volume finite by adding 1 and -2, and then I simply read the output file.
emilmammadzada said:vol=136.011 how did you calculate this? is there a formula or something?the code didn't work either, I did the same
Why do you multiply the value by 209 in matvol. What does the number .209 mean?Alex A said:That is only cell with material 1 in it. BURN was told about material 1, so you don't need any other cell.
According to the manual you need a MATVOL with the BURN card, because this is a lattice. I'm assuming that value is 209 * 136.011. I'm not familiar with BURN, so it now runs but I don't know enough to be sure the result is correct.