Study on silicon semiconductor detector for visualization the pollution distribution in the Fukushima Daiichi Nuclear Power Plant

Yoshihara, Yuri*; Shimazoe, Kenji*; Takahashi, Hiroyuki*; Kaburagi, Masaaki; Torii, Tatsuo

no journal, , 

The accident of Fukushima Daiichi Nuclear Power Plant (FDNPP) was occurred on March 11th and the decommissioning of Unit 1-4 of FDNPP has been started since December 2011. Portable radiation imaging technologies are necessary for monitoring the pollution distribution of the inside of the reactor buildings because the measurement environment is highly contaminated and the detector should be mounted on remote-controlled robots. However, existing radiation-imaging systems mainly adopt mechanical collimation to estimate the inserted direction of ray by using lead or tungsten, which make the systems heavy and limit the operation range of the robots. We have been investigated a stacked edge-on silicon strip detector based on hetero-junction technology, which has directivity without any mechanical collimations for imaging The directivity of the 6-layer stacked silicon strip detector was evaluated. The source of 1 MBq Cs-137 was put on the distance of 10 cm from the front of the detector and rotated with the angles of 0, 15, 30, 60, 90 degree, and the detection counts of each rotate angle were measured with thresholds of 180/360 keV.