Development of compact Compton camera for 3D image reconstruction of radioactive contamination

Journal of Nuclear Science and Technology

Terasaka

Utsugi

et al. 2019

The Fukushima Daiichi Nuclear Power Station (FDNPS), operated by Tokyo Electric Power Company Holdings, Inc., went into meltdown in the aftermath of a large tsunami caused by the Great East Japan Earthquake of 11 March 2011. Measurement of radiation distribution inside the FDNPS buildings is indispensable to execute decommissioning tasks in the reactor buildings. We conducted a radiation imaging experiment inside the reactor building of Unit 1 of FDNPS by using a compact Compton camera mounted on a crawler robot and remotely visualized gamma-rays streaming from deep inside the reactor building. Moreover, we drew a radiation image obtained using the Compton camera onto the three-dimensional (3-D) structural model of the experimental environment created using photogrammetry. In addition, the 3-D model of the real working environment, including the radiation image, was imported into the virtual space of the virtual reality system. These visualization techniques help workers recognize radioactive contamination easily and decrease their own exposure to radiation because the contamination cannot be observed with the naked eye.

Section: Drawing Hotspot Image On 3-d Structural Model Of Inside the mentioning

confidence: 63%

“…The specifications of our Compton camera are described in detail in Refs. [3,9]. The performance of the Compton camera used for the demonstration test is also shown in Table A1 (see Appendix).…”

Section: Methodsmentioning

confidence: 99%

Radiation imaging using a compact Compton camera mounted on a crawler robot inside reactor buildings of Fukushima Daiichi Nuclear Power Station

Journal of Nuclear Science and Technology

Terasaka

Utsugi

et al. 2019

“…Methodology. The 3D position of a radiation source using a Compton camera has been already determined in simulations and experiments [6,7]. The Compton camera measures radioactive substances from multiple viewpoints, and the Compton cones are projected onto a 3D space.…”

Section: Three-dimensional Gamma-ray Imaging Using Sfm With a Freely Moving Compton Cameramentioning

confidence: 99%

“…From this information, we can calculate the scattering angle of the gamma rays, which is necessary for drawing the Compton cone. The intensity of the image drawn by the Compton cone depends on the direction of the constructed Compton cone, because the detection efficiency of a coincidence event between the scatterer and absorber depends on the incident direction of the gamma rays [7].…”

Section: Three-dimensional Gamma-ray Imaging Using Sfm With a Freely Moving Compton Cameramentioning

confidence: 99%

Visualization of Radioactive Substances Using a Freely Moving Gamma-Ray Imager Based on Structure From Motion

Journal of Nuclear Engineering and Radiation Science

Minemoto²,

Nemoto³

et al. 2021

Technology for measuring and identifying the positions and distributions of radioactive substances is important for decommissioning work sites at nuclear power stations. A three-dimensional (3D) image reconstruction method that locates radioactive substances by integrating Structure-from-Motion (SfM) with a Compton camera (a type of gamma-ray imager) has been developed. From the photographs captured while freely moving in an experimental environment, a 3D structural model of the experimental environment was created. By projecting the radioactive substance image acquired by the Compton camera on the 3D structural model, the positions of the radioactive substance were visualized in 3D space. In a demonstration study, the 137Cs-radiation source was successfully visualized in the experimental environment captured by the freely moving cameras. In addition, how the imaging accuracy is affected by uncertainty in the self-localization of the Compton camera processed by SfM, and by positional uncertainty in the gamma-ray incidence determined by the sensors of the Compton camera was investigated. The created map depicts the positions of radioactive substances inside radiation work environments, such as decommissioning work sites at nuclear power stations.

“…To compensate for this angular dependence on detection efficiency, Compton cones with high intensity were drawn under large-angle conditions. A detailed description of this correction method can be found in the literature [14].…”

Section: Remote Radiation Imaging Systemmentioning

confidence: 99%

Remote detection of radioactive hotspot using a Compton camera mounted on a moving multi-copter drone above a contaminated area in Fukushima

Journal of Nuclear Science and Technology

Ozawa²,

Terasaka

et al. 2020