The Fukushima nuclear power plant remains a key issue due to the instability of its reactors following the 2011 nuclear accident. Even today, high radiation levels at the facility pose a challenge for decommissioning the reactors. In order to assess the condition of the reactors and plan future work, various robots designed specifically for this harsh environment have been used.
The last device introduced into one of the reactors had to be abandoned because it decomposed inside due to high levels of radiation. Despite this, companies continue to develop new robotic technologies in the hope of safely investigating and dismantling the reactors. What is the current state of the situation at Fukushima and what progress have robots made?
New robot to investigate Fukushima
The new robot recently introduced into the reactors is a self-propelled and remote-controlled device equipped with video cameras, a thermometer and a dosimeter to measure the temperature and radiation conditions inside the reactor. Its main mission is to provide precise information about the state of the damaged core and any radioactive waste that might still be present in the reactors' containment vessel.
The person responsible for the development and management of the robot is TEPCO (Tokyo Electric Power Company), the company that runs the Fukushima nuclear power plant. The company hopes that the data obtained from the device will provide key information about the molten fuel in the reactor and any radiation leaks that may be occurring. So far, the radiation inside has been so extreme that anyone entering manually could die within minutes.
This robot is part of a series of attempts to improve working conditions at the Fukushima plant. Two previous devices were introduced into reactor 1, but both were inoperative. One of them got stuck and the other succumbed to extreme radiation. Nevertheless, the importance of these robots is crucial, as they allow the state of nuclear fuel rods to be assessed and their removal planned.
Previous robots and their challenges
Since the accident on 11 March 2011, reactors 1, 2 and 3 have suffered partial meltdowns in their cores, which has made dismantling work extremely difficult. In this process, several machines were abandoned within the nuclear complex, while others managed to collect essential information for technicians.
One of the first robots used was the PackBot, developed by the American company iRobot. Initially designed for military operations, this robot was one of the first to enter the reactors in the weeks following the accident. Equipped with cameras and radiation sensors, it made it possible to obtain images and data that would not have been possible otherwise due to the high levels of radiation. However, the PackBot was not prepared to withstand the extreme conditions inside the reactor, which limited its operation.
Another relevant robot in the history of Fukushima is the robot Fifteen, the first Japanese robot to be deployed at the nuclear power plant. This device was designed to search for survivors in disasters and climb debris, but was also adapted to handle radiation conditions. However, it suffered from communication problems with its operators, which ultimately resulted in its loss inside the reactor.
New robotic technologies in Fukushima
In recent years, there has been significant progress in developing robots that can withstand the harsh environment of Fukushima. In 2018, TEPCO and Japan's technological institutions introduced the robot teleoperated “Telesco”, designed to collect samples of melted fuel inside reactors. With the ability to extend up to 22 meters, this robot was able to reach previously inaccessible areas inside the reactor vessel and collect fuel fragments for further analysis.
In addition, underwater robots have been developed, used in Unit 3 to inspect the highly radioactive water that has accumulated in the reactor core. These devices, such as the Toshiba-designed underwater robot, feature cameras and LED lights to illuminate submerged areas and gather information about the state of the reactor underwater.
The challenges of dismantling Fukushima
Despite advances in robotic technology, the decommissioning of the Fukushima Daiichi nuclear power plant remains a long and complicated process. Experts estimate it will take 30 to 40 years before full decommissioning is complete. One of the biggest challenges is the safe removal of the melted radioactive fuel, an unprecedented and extremely dangerous task due to radiation levels at the site.
Robots will continue to play a key role in this process. Each is designed to perform a specific function, from taking samples in hard-to-reach areas to cleaning contaminated surfaces. However, even with these advances, many robots cannot operate for long periods of time due to the destruction of their electronics by high levels of radiation.
In addition to robots developed specifically for Fukushima, work has been done on adapting existing models for special missions. Warrior, a larger and more robust robot than the PackBot, has been used to move debris and heavy objects inside the reactor. This robot, also developed by iRobot, has the capacity to lift up to 100 kilograms, making the work of other smaller devices easier.
Another example of a robot designed for Fukushima decontamination is the Raccoon, a device shaped like a giant vacuum cleaner used to collect radioactive dust from the buildings at Fukushima Reactor 1. This device, along with robots using high-pressure water and dry ice, have been instrumental in reducing radiation in areas later visited by humans wearing protective gear.
As new technologies continue to develop, robots will play an increasingly important role in decontaminating Fukushima and solving the unique challenges the site poses.
Fukushima represents the biggest challenge in modern nuclear power history in terms of decommissioning. Although robots occasionally fail, progress has been significant in recent years, and TEPCO and its technology partners in Japan continue to seek innovative technologies that can speed up the process and ensure people's safety.