Abstract: An irradiator, for containment and exposure of a radiation source, that is self-contained and portable. The irradiator provides radiation shielding, physical strength and thermal dissipation to allow transport of a radiation source carried therein without further containment or shielding. A radiator frame carrying a radiation source is lowered below the container for exposure to particularly adapt the device for tunnel irradiation of product from a position thereabove. The radiation preferably source is cesium-137 which provides medium energy gamma radiation adapted particularly for radiation processing and sterilizing of food products with minimal additional shielding requirements.