United States Nuclear Regulatory Commission - Protecting People and the Environment

MELCOR Accident Consequence Code System (MACCS)

Sponsored by the Office of Nuclear Regulatory Research

The U.S. Nuclear Regulatory Commission developed the MELCOR Accident Consequence Code System (MACCS) to evaluate offsite consequences from a hypothetical release of radioactive material into the atmosphere.  The code models atmospheric transport and deposition, emergency response and other protective actions, exposure pathways, health effects, and economic costs.

MACCS is used to evaluate the consequences of severe radiological accidents as part of the environmental reports and environmental impact statements for early site permits, to support plant‑specific evaluation of severe accident mitigation alternatives required as part of the environmental assessment for license renewal, to assist in emergency planning, and to provide input to cost/benefit analyses.

The purpose of this poster is to provide information on the latest improvements to the MACCS code suite, discuss recent applications of MACCS, and describe how people can obtain the code.

Page Last Reviewed/Updated Tuesday, May 24, 2016