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MACCS

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Recent Software Updates

SecPop Logo

Version:4.4.1

Last Release:May 19, 2025

SecPop calculates estimated population and economic data around any point specified by latitude and longitude. The Nuclear Regulatory Commission (NRC) adopted SecPop to perform siting reviews for nuclear power-plant construction and license applications within the continental United States.

MACCS Logo

Version:5.0.0

Last Release:Oct 8, 2024

MACCS is a fully integrated, engineering-level computer code developed at Sandia National Laboratories (SNL) for the Nuclear Regulatory Commission (NRC). MACCS simulates the impact of severe accidents at nuclear power plants (NPPs) and other nuclear facilities on the surrounding environment.

MelMACCS Logo

Version:4.0.0

Last Release:Sep 28, 2022

MelMACCS is a Windows based program developed by SNL in 2002 that is used to create a MACCS source term input file from the MELCOR plot file. MELCOR plot files contain large amounts of data, only a small fraction of which is needed for MACCS calculations.

AniMACCS Logo

Version:1.3.1

Last Release:Jan 17, 2022

AniMACCS is a utility code in the MACCS software suite that allows for certain MACCS output information to be visually displayed and animated onto a geospatial map background. AniMACCS was developed by Sandia National Laboratories for the U.S. Nuclear Regulatory Commission.