Radiation-resistant image sensor for nuclear reactor decommissioningEfforts continue around the world to develop the technology required to decommission the Fukushima Daiichi Nuclear Power Plant, which was critically damaged in the Great East Japan Earthquake in 2011. In decommissioning the plant, a major step is to rst remove the nuclear fuel debris from inside the nuclear reactor. This requires being able to see inside the reactor, which is a highly radioactive environment that is too harsh for conventional solid-state image sensors such as CCD or CMOS image sensors. Hamamatsu’s image pick up tubes have received attention as a possible solution to this urgent need. Image pick up tubes are vacuum tube devices which were used in TV cameras prior to the development of solid-state image sensors. Image pick up tubes are considerably more resistant to radiation than solid-state image sensors, and are considered to be the only device that could possibly meet the required specications (10 kGy/h dose rate, 2 MGy cumulative dose). However, ensuring that image pick up tubes can produce images in such harsh radioactive conditions for the desired period of roughly 1 week (≒ 200 hours) called for a dramatic increase in device performance. Hamamatsu is applying expertise gained from years of making specialized image pick up tubes to this problem and are currently testing a brand new type of image pick up tube, which has been conrmed to produce a mostly unchanged image after 200 hours of radiation exposure.(*1) It is hoped this new image pick up tube will be usable as a visual device for workers and robots to inspect inside the nuclear reactor at the Fukushima power plant for fuel debris.(*1)This development is supported by Japan’s Ministry of Economy, Trade and Industry (Team for Countermeasures for Decommissioning and Contaminated Water Treatment).TOPICSImage pick up tubeWithout irradiationWith irradiation (10 kGy/h)10


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