Radiation levels at Fukushima are still higher than expected, especially in reactor two of the plant. The operator of the Fukushima nuclear power plant will introduce a new robot into reactor two in order to assess its condition. The previous robot that analyzed the state of the reactors had to be withdrawn last week due to excess radiation levels.
If humans are exposed to radiation of one sievert per day, we can suffer serious health consequences. To our surprise, in reactor two of the Fukushima plant, radiation levels are 650 sieverts per hour. This amount is enough to destroy the electronics of most of the robots used to monitor the site.
High levels of radiation
The high levels of radiation found in the plant's reactors damage the analysis equipment and make it difficult to assess their condition. A robot developed in collaboration with IRID and Toshiba, It will help in evaluating the state of the reactor. This device, nicknamed Scorpion, has the ability to deploy multiple sensors and a camera on its articulated tail that facilitates exploration in places inaccessible to humans.
However, the task is not easy. Previously, another robot was removed after having recorded radiation levels equivalent to 650 sieverts per hour, irreversibly damaging their electronic systems. These robots face enormous challenges when operating in such extreme conditions, where radiation can damage both circuits and cameras in just a few minutes.
Robotic systems are designed to operate for a limited number of hours before being rendered completely useless by radiation, and technicians at Fukushima are racing against time to maximise the performance of each pilot mission. A robot developed in 2012 was eventually abandoned after a failure in its communications system inside reactor 1.
These robots not only explore, but are also equipped to measure radiation. and take images of the reactor interior. This is crucial for determining the affected areas and planning future actions for the safe decommissioning of the reactors. In addition, the Scorpion robot has the ability to measure temperatures along with radiation levels – vital information for engineers looking to phase out the plant.
Measuring radiation is essential
Following the earthquake in 2011, reactors 1, 2 and 3 of the plant suffered a partial meltdown of their cores, which generated an unprecedented disaster and an urgent need to know the status of the radioactive fuel rods in order to remove them. In the case of unit 2, TEPCO technicians believe that The fuel melted enough to puncture the pressure vessel and accumulate at the bottom of the containment vessel.
This phenomenon, called “corium” in nuclear incidents such as Chernobyl, is a mass of molten nuclear fuel mixed with other materials. Corium is highly radioactive and its removal is a formidable technical challenge. The images that robots manage to capture at Fukushima are vital to verify the exact location of this fuel, and provide essential data for future removal missions.
The new robot is equipped with advanced technologies to collect key information about conditions inside the reactor, and its success is crucial to the continued cleanup efforts. TEPCO plans to continue introducing more robots as advances in robotics accelerate and developments in more radiation-resistant materials are achieved.
While there is still a long way to go to completely dismantle the plant, these types of robots represent a hope of clearing the contaminated facilities and removing radioactive debris. The complete decommissioning of Fukushima is expected to take several decades, but each step toward developing more efficient robots brings Japan and the world closer to solving this problem.
In addition to analysis and exploration robots, there is another category of automata completely dedicated to the cleaning of contaminated areas. Equipped with special vacuum cleaners and decontamination systems, these robots help clean radioactive dust from surfaces affected by intense radiation. The Fukushima plant has several of these robots, which allow the site to be prepared so that technicians can carry out inspections and operations more safely.
The future of Fukushima recovery is intrinsically linked to robotics, and the introduction of new technologies will be key to speeding up the decommissioning process in one of the most radioactive areas on the planet.