Background

The ACE File Verification Project is a Data Development Project (DDP) organised by the Nuclear Data Section (NDS) of the International Atomic Energy Agency. Traditionally, NJOY code was the only one that could process evaluated nuclear data files into ACE format (A Compact ENDF) for use in Monte Carlo transport codes such as MCNP, SERPENT, and others. Recently, several nuclear data processing codes became available that can generate ACE files, with different degrees of completeness.

Objectives

The main objective is to verify that every code produces consistent ACE files that can be used in Monte Carlo calculations without introducing biases. This is achieved by "reverse engineering" of converting the content of an ACE file back into ENDF format (as much as possible) and comparing to the reference pointwise PENDF file processed with the PREPRO suite of codes. The next step is to perform calculations on a selected suite of criticality benchmarks from the ICSBEP collection. The input models include tight convergence criteria, which are needed because this is a numerical exercise, where we are only looking at differences due to the data processing methods.

Project Stages

Stage 1: ACE verification without self-shielding

• Download U-235 and U-238 evaluations from the ENDF/B-VIII.b4 library.
• Make ACE files with and/or without probability tables.
• Submit the ACE files to the project co-ordinator at the IAEA.
• The co-ordinator will compare the content of the files to the reference set and run the criticality benchmarks.
• Stage 1 results are reported on the project web page.

Stage 2: ACE verification with self-shielding

• Same as above, assuming that the ACE files include the probability tables.

Stage 3: ACE verification of photon-production data

• Similar as above, assuming that the ACE files include photon-production data.

Stage n: Subsequent stages may follow, depending on the needs