
U.S. Nuclear Regulatory Commission

Home

Who We Are

What We Do

Nuclear Reactors

Nuclear Materials

Radioactive Waste

Facility Info Finder

Public Involvement

Electronic Reading Room

Defense-in-depth

A design and operational philosophy with regard to nuclear facilities that calls for multiple layers of protection to prevent and mitigate accidents. It includes the use of controls, multiple physical barriers to prevent release of radiation, redundant and diverse key safety functions, and emergency response measures.