Detection of Simulated Fukushima Daichii Fuel Debris Using a Remotely Operated Vehicle at the Naraha Test Facility.

The use of robotics in harsh environments, such as nuclear decommissioning, has increased in recent years. Environments such as the Fukushima Daiichi accident site from 2011 and the Sellafield legacy ponds highlight the need for robotic systems capable of deployment in hazardous environments unsafe for human workers. To characterise these environments, it is important to develop robust and accurate localization systems that can be combined with mapping techniques to create 3D reconstructions of the unknown environment. This paper describes the development and experimental verification of a localization system for an underwater robot, which enabled the collection of sonar data to create 3D images of submerged simulated fuel debris. The system was demonstrated at the Naraha test facility, Fukushima prefecture, Japan. Using a camera with a bird's-eye view of the simulated primary containment vessel, the 3D position and attitude of the robot was obtained using coloured LED markers (active markers) on the robot, landmarks on the test-rig (passive markers), and a depth sensor on the robot. The successful reconstruction of a 3D image has been created through use of a robot operating system (ROS) node in real-time.

Long-term clinical evaluation of implant over denture.

PURPOSE: The use of implants to treat edentulous jaws has become a well-established and accepted contemporary clinical method. The aim of this study was to analyze information about the implants used, patients, denture modality, and complications after denture insertion in partially and fully edentulous patients with implant overdentures placed. METHODS: A survey was performed about patients rehabilitated using implant dentures at the Tsurumi University Dental Hospital during 8 years. A total of 201 implants were placed: 112 in the maxilla and 89 in the mandible. Descriptive statistics were used for each patient, such as the implant positions and numbers, retainer designs, denture modalities, implant survival rate and prosthetic complications. RESULTS: The positions of implant placement were: incisor (44%); canine (26%); premolar (18%); and molar (12%). Approximately 70% of the retainers were bar attachments and magnet attachments. The majority of the prostheses were metal-based dentures (84%) compared to only 10 acrylic dentures (16%). Fully edentulous, fourteen (12 maxillary, 2 mandibular) of 171 implants failed. Partially edentulous, three (3 maxillary, 0 mandibular) of 30 implants failed. The denture complications observed during maintenance were denture fracture, retainer breakage and artificial tooth fracture. CONCLUSION: Although the mandibular implant dentures placed were exceedingly reliable for rehabilitation with a high survival rate, the maxillary implant dentures exhibited a low survival rate and more frequent complications. Significantly higher implant failures and prosthetic complications were observed in the initial period after placement than in the following years.