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Robots to the rescue!
The tsunami caused a loss of backup power at the Fukushima Daiichi nuclear plant, resulting in three out of six reactors suffering problems, including meltdown.
Since that day, an extensive recovery programme has been underway to safely decommission the plant. However, with some levels of radiation at life threatening levels, it is not possible for humans to enter some parts of the site.
Enter the robots!
Hardly a day goes by without a news story or research study on how robots are putting people out jobs. But in this scenario, they’re playing a vital role assessing risk in an environment which wouldn’t be accessible to the workforce.
Immediately following the disaster, there was a clear role for bespoke robots to inspect the damage caused and go into the most inaccessible areas. Nearly 100 types of robots of all different shapes and sizes have worked at Fukushima so far. They are venturing into areas where there are high levels of radiation to gather data to locate the hazardous melted fuel rods, an essential step in making the plant safe again. What we’re seeing at Fukushima is the use of the most modern robotic technology to undertake challenges which can’t be left to humans alone – reducing risk and delivering clean up after a nuclear accident, whilst their operators remain at a safe and suitable distance.
Hitachi and Hitachi-GE Nuclear Energy have together created a number of robots to assist with the recovery of the plant. One robot was developed to survey the interior of one of the damaged nuclear reactor containment vessels, and Hitachi made sure the robot’s design was suited to its mission. It was able to form a long ‘I’ shape when it had to propel itself through a narrow gap and it could then transition into a ‘C’ shape when it needed to slither across the floor. This robot travelled around the floor inside the containment vessel, collecting valuable information on radiation levels and assessing the spread of fuel debris in the basement.
Another one of Hitachi’s robots was designed to find the spots where cooling water was leaking into the basement; this robot needed to be able to swim as well as crawl. It was therefore kitted out with a pair of crawler mechanisms and six propellers so it could manoeuvre itself in all directions and swim around any obstacles. The information relayed back by this robot played a vital role in the planning to plug these leaks.
Looking to the future
Even today, five years on from the accident, the radiation inside the damaged plant is significant enough to destroy the wiring inside robots. And yet, they are a vital tool in the ongoing program to decommission the reactors and clean up the site.
There are 444 nuclear reactors operating worldwide and 63 are currently under construction. With the global drive for secure, low-carbon, affordable energy, the number of nuclear plants is likely to increase, and robots provide a means of dealing with the most challenging aspects of the nuclear legacy.