REMOTE DECOMMISSIONING | COVER STORY
should be decommissioned,” said DSRL Project Manager Jason Simpson. OC Robotics flexible snake-arm robot has been deployed
to help decommission the Dragon reactor at Winfrith in the UK using its high-powered cutting laser. Passing through a narrow hole in the 3 metre-thick concrete around the core, it sliced through a 400mm diameter Purge Gas Pre-Cooler (PGPC) vessel attached to the reactor core. Developed by OC Robotics and TWI with R&D funding from the NDA, LaserSnake allowed the work to be carried out inside the existing radiation shielding, saving time and money. Magnox Senior Project Manager, Andy Philps said: “We believe this is the first time that laser-cutting technology has been deployed directly on the core of a nuclear reactor.” In 2021, Framatome confirmed the operation of robotic
systems for handling and sorting high-dose waste components, paving the way for increasing automation. The Virtual Remote Robotics (VIRERO) project, funded by the German Federal Ministry of Education and Research, develops technologies for dismantling and sorting high- dose operational wastes, post-conditioning of packaged radioactive waste, and radiological sorting for handling, storage and disposal. The VIRERO project is expected to be completed by the end of 2023. According to Kilochytska, for the time being,
many remotely-controlled devices can be used for characterisation of surfaces during decommissioning, for dismantling structures, systems and components that may be radioactively contaminated. “Moreover, robotic techniques such as drones can investigate the radiological situation and measure levels of contamination inside the
premises and rooms,” she told NEI. “In this way, doses to workers can be avoided and time and money needed for conducting these actions, for example, characterisation or dismantling, can be decreased. Together with 3D modelling this makes it possible to create a full picture of a particular room or facility, making planning of further activities easier, taking into account dose rates and levels of contamination.” She noted some important points for the future use
of robotic techniques. “First, it is necessary to assess real needs and potential benefits, taking into account a particular plan for decommissioning a particular facility. Usually, development of such techniques requires significant investment. In addition, the further use of devices requires maintenance costs to support operation and repairs, as needed, such as a qualified staff to do this.” She added that there may also be an issue with decontamination of such devices to make possible regular use. “All this should be considered in advance before any decision is taken about developing or buying devices.” It is clear that robotics and other digital tools are
playing an increasingly important role in advancing nuclear decommissioning projects, not only by enabling experts to characterise environments and decommissioning challenges but also by improving their execution. As Mikhail Chudakov, IAEA Deputy Director General and Head of the Department of Nuclear Energy, said: “Innovative digital technologies can provide crucial insights for the planning and implementation of decommissioning projects. They can provide support in decommissioning situations that are difficult or dangerous for human workers and can help ensure that projects are executed safely and effectively”. ■
IRID robotic breakthroughs The International Research Institute for Nuclear Decommissioning (IRID) comprises 18 specialist research and development companies and organisations. These comprise: ● Two national research and development agencies: Japan Atomic Energy Agency and National Institute of Advanced Industrial Science and Technology.
● Four plant manufacturers: Toshiba Energy Systems & Solutions Corporation; Hitachi-GE Nuclear Energy Ltd; Mitsubishi Heavy Industries Ltd; and ATOX Co Ltd.
● Twelve electric utility companies: Hokkaido Electric Power Co; Tohoku Electric Power Co; Tokyo Electric Power Co (TEPCO) Holdings; Chubu Electric Power Co; Hokuriku Electric Power Co; Kansai Electric Power Company; Chugoku Electric Power Co; Shikoku Electric Power Company; Kyushu Electric Power Company; Japan Atomic Power Company; Electric Power Development Co Ltd.; and Japan Nuclear Fuel Ltd.
Many areas of the Fukushima Daiichi NPP are still too dangerous for humans to enter due to high radiation levels, and robots are being used to perform some of the decommissioning work. IRID has developed robots to investigate conditions inside the Primary Containment Vessels (PCVs) and the spread of fuel debris. Various types of robots have been introduced. Two of the earliest ones – Rosemary and Sakura – worked together inside the unit 1 reactor building inspecting radioactive sources. Both robots were developed by the Chiba Institute of Technology (CIT) in Narashino. IRID (Hitachi-GE) later modified them to investigate dose rates inside the building.
Rosemary is equipped with a gamma camera (N-Visage) made in the UK
to detect radiation dosage rates. Rosemary operates this camera via a wireless system as it is not large enough to be equipped with communication cables. However, as wireless communication is difficult to maintain inside the building. Sakura supports Rosemary acting as a wireless transmission station. In 2014, MHI tested the MEISTeR (maintenance equipment integrated system of telecontrol) robot which subsequently completed decontamination work and concrete core sampling at units 1&2. MEISTeR is capable of concrete drilling, cutting of handrails and piping, removal of obstacles, decontamination, repair work, and so on. The core samples were collected using the core boring apparatus equipped on one of MEISTeR’s arms, and a chisel on the other. Also in 2014, a swimming robot and a crawling robot, both developed by Hitachi-GE Nuclear Energy performed condition checks and a flow detection survey inside the unit 2 torus room wall. The robot swam underwater, using a camera to inspect the penetration points and checking for flow using a tracer while the crawling robot measured and monitored the flow of the tracer using an ultrasonic sonar system. The following year surveys were conducted at the unit 1 PCV using two shape-changing robots developed by Hitachi-GE Nuclear Energy. Many modifications and improvements were made by the development
team to enable the robots to withstand the high-radiation environment within the reactor. The shape-changing robot first takes on a tubular form to traverse narrow pipes in order to reach the inside of the containment vessel. Subsequently. to achieve stability, the robot forms a U-shape as it collects the necessary information about the conditions inside the containment vessel. ■
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