# Building a Honeycomb Structure in MCNP: Error Solving

• oksuz_
In summary, it seems that the issue with building a honeycomb structure in MCNP is related to the lattice definition in cell 2. The document provided may offer some insights, but more information or assistance may be needed from the authors or other online resources. Using RHP or HEX in the input may also be worth trying.
oksuz_
Hi,

I am trying to build a honeycomb structure in MCNP. The code is given below. Hexagonal lattice
1 0 -1 -19 29 fill=1 imp:n=1
2 1 -2.26 -10 11 -12 13 -14 15 u=1 lat=2 imp:n=1
3 0 1:19:-29 imp:n=0

1 c/z 50 50 200
19 pz 31
29 pz -31
10 px 1
11 px -1
12 p 1 1.7320508076 0 2
13 p -1 1.7320508076 0 2
14 p 1 1.7320508076 0 -2
15 p -1 1.7320508076 0 -2

m1 6012 1
sdef
f1:n 1
nps 2000

However, it keeps giving the error of "Lattice in cell 2 has no fill"

I have come across this document

which seems to address the problem, however, it does not give any information about the surface they chose.

Can anyone give suggestion to solve the issue?

What type of system is one attempting to model/simulate? VVER?

Has one tried using RHP or HEX in input?

Last edited:

Hi,

I am not an expert in MCNP, but I do have some experience with building honeycomb structures in other codes. From what I can see, it looks like your lattice in cell 2 is not properly defined. The fill and imp:n parameters are necessary for MCNP to understand the material and boundaries within the cell. I would suggest checking your lattice definition and making sure it is correct.

Also, have you tried reaching out to the authors of the document you mentioned? They may be able to provide more information or insights on the surface they chose. Another option could be to search for similar examples or tutorials online to see how others have defined honeycomb structures in MCNP.

I hope this helps and good luck with your project!

## 1. What is a honeycomb structure in MCNP?

A honeycomb structure in MCNP is a type of geometric representation used to model a repeating pattern of cells in a material. It consists of a series of hexagonal prisms arranged in a honeycomb pattern, with each cell having its own material composition and density.

## 2. What is the significance of building a honeycomb structure in MCNP?

Building a honeycomb structure in MCNP allows for a more accurate and efficient simulation of complex materials, such as nuclear fuels or biological tissues. It also allows for the study of properties such as neutron moderation and energy deposition in a more realistic manner.

## 3. What are common errors encountered when building a honeycomb structure in MCNP?

Some common errors include issues with cell numbering, incorrect material assignments, and improper cell overlap. These errors can lead to inaccurate results and should be carefully checked for and corrected before running a simulation.

## 4. How can I troubleshoot errors while building a honeycomb structure in MCNP?

First, check for any typos or incorrect cell assignments in the input file. It can also be helpful to visualize the honeycomb structure using a visualization tool to ensure it matches the intended design. Additionally, referring to the MCNP user manual or seeking help from experienced users can aid in troubleshooting errors.

## 5. Are there any tips for efficiently building a honeycomb structure in MCNP?

Yes, it is recommended to use macros or scripts to automate the process of building a honeycomb structure, especially for larger and more complex designs. It is also important to carefully plan and organize the cell assignments and materials to avoid errors and ensure an efficient simulation. Finally, regularly checking for errors and debugging as needed can save time in the long run.

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