Help debugging MCNP code - particle lost and zero latice element found

[AlexFi]

TL;DR Summary

Help identify gap in geometry or something

I keep getting particle lost error even though there were no hole in the lattice.
Can someone identify any mistake in my code?

 

[Grelbr42]

The first thing to do is fire-up the plotting package that comes with MCNP. Look for those dotted lines around some cells. These indicate geometry errors.

In an MCNP model, every part of 3-D space must be filled with exactly one cell. There must be no gaps that are not part of a defined cell. And no point can be part of more than one cell.

 

[rpp]

To give a few more hints, search for "interactive plotter" in the manual and use the "ip" option on the command line.

 

[Alex A]

I ran mcnp5 ip inp=file
i means process the input file, p means plot the geometry in the interactive plotter.
I click on the "Click here or picture or menu" and type "pz 0" to get a cross section through the reactor. Nothing is coloured in, everywhere I click on the plot is cell 99. This strongly suggests an error in the definition of cell 99, the void cell. Without having much time to look into it :5:6 where 5 and 6 are macrobody surfaces "Top reflector" and "Bottom reflector" feels wrong. Defining those reflectors with simple surfaces rather than macrobodies might make defining the void cell easier.