Abstract: A radioactive material detection system includes a plurality of radioactive material detection apparatuses and a command center. Each apparatus is disposed in or on a cargo receptacle. Each apparatus includes a wireless transmitter, a radiation sensor, a detection controller and an identification tag. The radiation sensor is configured to detect radiation over a predetermined or commanded period of time. The command center is configured to receive the wirelessly transmitted information directly or indirectly from each of the wireless transmitters of the plurality of radioactive material detection apparatuses. The system is configured to detect fissile or nuclear material that emits radiation. The system is reconfigurable from a passive sensing system to an at least partially active sensing system in the event that the system detects a nuclear anomaly within a cargo receptacle.