Help, my ACE file is too big!

[sombrereau]

Hey NJOY team / authors of "Release of ENDF/B-VIII.0-Based ACE Data Files" (@whaeck @jlconlin),

I'm looking for some advice. I'm working on generating some ACE cross sections for MCNP with a developmental nuclear data evaluation. I've successfully generated ACE files using the methodology outlined in this previous post ( #174 ). But when it comes time for MCNP to read in the new cross section data I get an error saying that recompile MCNP with more memory for all the reaction channels.

fatal error. dimension overflow in expung. increase m3 to 2876

I'm wondering if when your team generated the ACE files for ENDF/B VIII.0 you ever ran into the issue of there being too much information in a nuclear data evaluation and having to simplify the cross section for the standard "out of the box" MCNP? Or if you guys know where I could find the default limitations for what MCNP could read in?

-Tommy

[sombrereau]

We've seemed to resolved the immediate issue by moving where discrete photon lines are stored in the ENDF/B file.