Configuration of JEFF-3.3 Nuclear Data Library in MCNP6

[HEU_LL]

TL;DR

I am setting up MCNP6 for reactor core physics simulations and plan to use the JEFF-3.3 nuclear data library. I would appreciate detailed guidance or references on how to correctly configure the relevant cross-section and directory files to ensure MCNP6 runs properly with JEFF-3.3.

Hello everyone,
I’m trying to use the JEFF-3.3 Nuclear Data Librar with MCNP6 . Could someone please provide detailed guidance or a step-by-step tutorial on how to properly configure MCNP6 to work with JEFF-3.3?
Any advice, configuration files, or references would be greatly appreciated.
Thank you in advance!

 

[DEvens]

I don't have the info you want. I know the cross section libray program that comes with MCNP can do some of what you describe but I have never used it, just looked over the shoulder of the guy at our office who used to be our big expert. I had meant to learn it after that guy retired. Then I retired.

But, if you do get the info, I'd be glad to get a quick summary back here. Say a five line quicky like "get these files, get these executables, follow the instructions in this document."

 

[Alex A]

These libraries used to be distributed as ENDF ("Evaluated Nuclear Data File") format 'tapes' that needed to be processed into ACE files ("A Compact Endf") by a program called NJOY. This did steps like Doppler broadening and is usually done with a series of temperatures. To keep disk space manageable a lot of the original ENDF data is discarded. I don't know how to do this, it's a really specialised skill and a mistake can cause all the simulations based on the processed files to be wrong. The steps to make the ACE files from the ENDF files were not in the library documentation. My understanding was that part of the reason for secrecy was legal. ENDF data was considered fundamental research and open to all. Processed files were considered an 'applied technology' and were export restricted in some countries.

The definitions seem to have changed because processed ACE files are now often distributed along side ENDF raw data, even by LANL, which just has ENDF VI, VII and VIII ACE files for download. On the JEFF 3.3 page HERE, you need the ACE files for all the reactions you want to use and the xsdir file, (rename your existing xsdir file first, all other files can be kept in situ. If you keep the MCNP_DATA location at the start of xsdir, edit this into the new file) so long as things are in the right directories and you use the right names in the input files it should all just work.

I think @DEvens may be referring to steps including NJOY and/or makxs. makxs makes the final xsdir file which index the ACE libraries. So long as you don't need mixed EU and US libraries I think you shouldn't need to use it, what is supplied should work.