This standard establishes the performance requirements and provides the testing and evaluation criteria for installed radiation portal monitors (RPMs) that detect photon- and neutron-emitting radioactive substances by monitoring people@ packages@ containers@ and vehicles. Performance requirements for portal monitors with radionuclide identification capabilities are addressed by the ANSI N42.38 standard [B19]. Performance requirements for mobile and transportable systems are addressed by the ANSI N42.43 standard [B20].