Measurement of radiation distribution inside the Fukushima Daiichi Nuclear Power Station using a single-end readout position-sensitive optical fiber radiation sensor based on wavelength-resolving analysis

Terasaka, Yuta   ; Sato, Yuki  ; Uritani, Akira*

We have developed a new position-sensitive optical fiber radiation sensor that achieved single-end readout and high dose rate application. The sensor identifies the incident position of radiation to the optical fiber using wavelength dependency of light attenuation inside the optical fiber. By the analysis of the output wavelength spectrum from the fiber end, the incident position of radiation to the optical fiber can be estimated reversely based on the spectrum unfolding procedure. Using this optical fiber sensor, measurement of radiation distribution was conducted inside the reactor building of Fukushima Daiichi Nuclear Power Station. The actual trend of radiation distribution was successfully reproduced in a high dose rate area with a maximum dose rate of over 100 mSv/h, and the effectiveness of the new position-sensitive optical fiber radiation sensor was confirmed.