To calculate the radiation figure inside, TEPCO looked at the degradation of the images caused by radiation, arriving at a figure of 530 sieverts with a margin of error of plus or minus 30 percent – although even the lower figure is still extremely high.
"The fact that a high value has been measured in an area that has previously not been measured is extremely exciting and important," Dr Ben Britton, director of MSc in Advanced Nuclear Engineering at Imperial College London, told IFLScience. "Measurements in new locations means that we can pin-point hot-spots and understand the nature of the radioactive materials within the reactor complex and to better inform us on suitable strategies for long-term decommissioning and clean-up."
The purpose of this was to plot out a route for a robot the company is planning to send into the reactor. Measuring 70 centimeters (28 inches) long, the stick-like robot called the Scorpion would be sent into areas deemed unsafe for humans.
But the robot is only able to survive an exposure of up to 1,000 sieverts. At 530 sieverts per hour, it would be destroyed in just two hours. Thus, this latest finding is likely to complicate matters even further, not least the large hole in the grating in the robot’s path.
“Much more melted fuel debris is assumed to have settled beneath the pedestal grating on the concrete basemat of the reactor,” noted Safecast. “It was hoped that the Scorpion would be able to provide imagery of this. Not surprisingly, TEPCO is once again revising its plans based on the recent findings.”
Why is this so important? Well, in order to decommission Fukushima, engineers first need to find the melted fuel. There are three reactors this must be done for, with the process expected to take until 2021. The melted fuel from the other two reactors has not yet been found.
Once the fuel has been found, it’s thought it will take four decades to completely decommission Fukushima. The total cost of the project is expected to cost an eye-watering 21.5 trillion yen ($188 billion), which is almost double an estimate in 2013.
In the last few days, there’s been further Fukushima news too, as a 42-year-old man who worked as a welder at Fukushima is suing TEPCO, blaming them for the leukaemia he has since developed. According to BBC News, he is the “first person to be recognized by labor authorities as having an illness linked to clean-up work at the plant.”
So radiation levels aren't soaring, but it’s a grim picture all around really. As the latest announcement from TEPCO shows, the clean-up of Fukushima is going to be anything but easy – and there’s a long, long way to go.