The Fukushima nuclear disaster was caused by a dual earthquake-tsunami combo that struck Japan in 2011. This caused the cooling systems in the nuclear power plant to break down, leading to a catastrophic meltdown. This was the most severe nuclear accident since the Chernobyl disaster in 1986, with the two being the only nuclear accidents to ever be classified as a seven on the International Nuclear Event Scale.
During the meltdown, most of the radioactive fuel fell to the bottom of their containment vessels, which made its removal extremely difficult.
Previously, authorities tried to send a small robot with cameras into the Unit 1 reactor, but to no success.
However, a Remote Operated Vehicle (ROV) was able to capture images and video this week that revealed the damaged structures, along with mounds of what is believed to be the melted fuel.
According to Tokyo Electric Power Company Holdings (TEPCO), the plant operator, other debris was also found submerged in cooling water.
They said: “On February 9, the two-day Fukushima Daiichi NPS Unit 1 PCV internal investigation was completed as scheduled.
“This time, clumps of deposits were found in workspace under the PCV (Primary Containment Vessel).”
The three damaged reactors still hold about 900 tonnes of melted nuclear, fuel including about 280 tons in Unit 1.
Officials claim that removing this fuel will take about three to four decades, however, experts believe that timeline is overly optimistic.
READ MORE: Iran Fukushima warning: Iran’s nuclear plants could be WIPED OUT
A spokesperson for TEPCO, Kenichi Takahara stated that the piles of debris rose from the bottom of the container.
Some of the debris was inside the pedestal, which lay directly underneath the core, suggesting the mounds were melted fuel that fell in the area.
According to the energy company, the robot, carrying several tiny cameras, was able to get pictures of the internal images of the reactor’s primary containment vessel while it was on a mission to establish a path for future probes.
Mr Takahara noted that further probes will be needed to confirm what the objects in the images are.
The radiation at the site is still at extremely deadly levels, according to Mr Takahara.
At one location, the robot measured a radiation level of two sieverts, far higher than the annual exposure limit for plant workers set at 50 millisieverts.
TEPCO stressed that it was taking safety as its utmost priority.
They said: “This investigation was performed after constructing boundaries to prevent gases from inside the PCV from leaking to the outside.
“There were no significant fluctuations in data from monitoring post or dust monitors, or with plant parameters before and after the investigation, so there was no radiological impact on the surrounding environment.
“We will continue to prioritize safety while carefully conducting these investigations.”