The MACCS consequence analysis code simulates the offsite consequences of radioactive releases to the environment. MACCS is a powerful tool that informs the development of regulations and guidance for operating reactors and advanced nuclear technologies. This exhibit highlights the importance of consequence analyses in safety regulation, demonstrating how the MACCS code is used to protect people and the environment. It also showcases the staff's recent code development efforts to extend the NRC's modeling and simulation capabilities for accident source terms and consequence analysis for advanced nuclear technologies.