Abstract: Provided are a radioactive contamination monitoring device and a radioactive contamination monitoring method for enabling easy detection of radiation from an object to be monitored in a little surrounding space. The radioactive contamination monitoring device comprises a radiation detection unit, a photoelectric conversion unit for converting the light generated in the radiation detection unit to electricity, and a signal processing unit connected to the photoelectric conversion unit. The radiation detection unit includes a quadrangular prism-shaped light guide bar having a rectangular cross-section and a scintillator attached only to two adjacent side faces of the four side faces of the light guide bar.

Abstract: Even when a radiation detector contacts a pipe arrangement or another member that is an object to be monitored, the damage of the detector is prevented without impairing the detection performance. An inside-tube-wall radioactive contamination monitor comprises: a rod-like light guide bar having a polygonal cross-section; a plurality of scintillators secured to the outer circumferential surface of the light guide bar; a net-like protective tube worn so as to cover the outer circumference of the scintillators with a space between the surfaces of the scintillators and the tube; and a guide portion attached to an end of the net-like protective tube, supporting an end of the light guide bar, and having a shape the diameter of which decreases as approaching the end. The monitor includes: a photoelectric conversion unit coupled to the base end of the net-like protective tube and incorporating a photoelectric conversion element; and a signal processing unit connected to the photoelectric conversion unit.