13 January, 2015
Robot Demonstration Tests Carried Out toward Decommissioning Fukushima Daiichi NPS
Four years will soon have passed since the accident at the Fukushima Daiichi Nuclear Power Station (NPS). Thus far, much of the focus has been on emergency responses. The view is now shifting to the medium and long term, in order to deal with situations three to four decades from now. In order to complete the decommissioning of the crippled nuclear reactors, research is required to resolve numerous first-ever issues.
The Japan Atomic Energy Agency (JAEA) is constructing the Naraha Remote Technology Development Center in Naraha Town, Fukushima Prefecture, which is intended to be a state-of-the-art facility for the development and demonstration testing of remote-controlled equipment and devices. It is expected to serve as the central R&D facility toward the establishment of a technological infrastructure to accelerate decommissioning, while contributing, through its operation, economically to the reconstruction of Fukushima.
With the aim of accelerating R&D toward decommissioning the Fukushima Daiichi NPS, along with carrying out the development and demonstration testing of a technological infrastructure for remote-controlled equipment and devices, the center will be completed by the end of FY2015 (i.e., by March 31, 2015), with full operation to begin during the upcoming fiscal year. A groundbreaking ceremony and prayers for safety took place on September 26, 2014.
The facility is located in the Naraha-Minami Industrial Park. It will have two buildings: a four-story Research Management Building and a two-story Experiment Building.
The first building will include living accommodations for researchers, engineers and staff, a multi-purpose area and common-use conference rooms available as virtual reality training space, as well as a reference room and areas for the presentations of research results.
In the second building, there will be a mock-up of the lower part of a reactor containment vessel (primary containment vessel, or PCV), reproducing the situation at the Fukushima Daiichi NPS as closely as possible. There will also be an indoor demonstration test area for disaster-response robots, which will also be used to train operators, workers, and others.
A key challenge at Units 1-3 of the Fukushima Daiichi is the preparation for the removal of the nuclear fuel debris that has melted inside the reactors. Immediate tasks to be taken before that work can be done include the investigation of the conditions inside the reactors, decontamination, and the development of remote- controlled equipment to stop water leakages at the lower parts of the PCVs, all of which require robots.
At the Experiment Building, robot simulators will be developed in cooperation with other research institutions to ascertain the performance of the remote-controlled equipment and devices before they are produced (improving the efficiency of development). The remote-controlled robots will be used in demonstration tests of technology for repairing the location of leakages in the lower parts of the PCVs, and for investigations and decontamination inside the Fukushima Daiichi NPS reactor buildings.
At the Research Management Building, meanwhile, state-of-the-art virtual-reality (VR) systems will be developed to evaluate operating procedures using remote-controlled equipment and devices and to train operators and workers.
In an interview, Director Hiroshi Kawamura of JAEA’s Nuclear Plant Decommissioning Safety Research Establishment talked about the mission of the facility in Naraha and his hopes for the future.
Inside the buildings at the Fukushima Daiichi NPS, people can barely approach some of the workplaces due to high radiation levels, and remote-controlled technology is an obvious solution. Robots are being developed by manufacturers and universities to respond to such circumstances.
Dr. Kawamura said that the facility has drawn attention from overseas as a place where, following the performance tests, it will be possible to carry out demonstration tests of robots in an environment simulating such workplaces. He also emphasized the facility’s role in training operators, in addition to demonstration testing of the robots. It will be the first full-fledged decommissioning research center within a 20km-radius of Fukushima Daiichi NPS. “We had to send a message to Fukushima that we were determined to tackle these issues,” said Kawamura. Another mission of the facility is to contribute to the revitalization of the local economy through robotic development.
Often, conditions where the robots will enter are not known in advance. Given that the area at the Experiment Building where demonstration tests of remote-controlled equipment and devices will be carried out will include a water tank, barriers, slopes, stairs, and rubble. All those will be necessary to thoroughly ascertain the performance capabilities of the robots.
Referring to the feature known as “motion capture,” which can determine minute robotic movements in anticipation of work in narrow or limited spaces, Kawamura said, “This may be the only place in Japan to have it.”
A full-size mockup of a one-eighth segment of the lower part of a PCV will be assembled in the Experiment Building. In demonstration tests, leakage will be simulated using water, with tests carried out on stopping leakages, such as by pouring in cement.
“Stopping the leakage is the most important issue before removing fuel debris,” Kawamura said, reiterating the point. Work on assembling a mock-up for Unit 2 will begin in October 2015 or so, with tests to begin around February 2016.
Kawamura continued his talk by citing forestry as an example where the technology developed at the facility can be applied to other fields. He said that he foresaw the nationwide use of remote-controlled helicopters developed in Fukushima, and the eventual creation of a major industry. He enthusiastically said, “Part of our job is to make advanced technology available for industry.”
In terms of developing human resources for decommissioning, Kawamura asserted, “We should see our work as taking steps forward, not as cleaning up a mess.” He referred to the necessity of getting young people interested and keeping them that way. He also pointed out that graduates of university programs intended to “nurture nuclear-related human resources” do not necessarily take jobs in the industry.
He said he was keen to attract creative researchers and engineers from Japan and elsewhere, developing and training them further, thereby emphasizing the importance of going beyond the development of human resources to securing and maintaining them.
Kawamura often cited the Fukushima International Research Industry City vision, called the “Innovation Coast” design. He pointed out, “With the facility at the core, we definitely need a place where people from universities and smaller and medium-size companies can gather and freely discuss various matters.” With that, he added, “We will develop remote-control technology and advance the decommissioning of the Fukushima Daiichi NPS.”
Thinking of the potential of the facility in other respects — for example, as a source of pride for the local people, a place for career education, and a destination for school excursions — Kawamura said that he would do his best, with the hope of making the facility an attractive one that everyone would want to see, and making the town of Naraha synonymous with “robotic R&D.”