Systems and methods for radiation monitoring with a fuel-based liquid scintillant are disclosed. Fuel-scintillant compositions according to this disclosure may serve dual purposes of a fuel to power an engine and a scintillator to detect radiation. For example, fuel-scintillant compositions may be incorporated into a radiation monitoring vehicle that combusts the fuel-scintillant composition to power the vehicle. Further, systems may be configured to detect scintillation events within the fuel-scintillant composition and may be configured to detect weak and/or distance radiation sources.