In Brief
  • Radiation levels amidst the wreckage of the Fukushima Daiichi Nuclear Reactor, which was catastrophically damaged by the 2011 earthquake and tsunami, are spiking at levels 100 times the fatal dosage.
  • Scientists suspect the reactor's radioactive fuel has melted through its containment vessel, unleashing a flood of damaging radiation.

100 Times Fatal Levels

Radiation readings from the damaged Fukushima nuclear power station are at their highest level since the plant suffered its catastrophic meltdown nearly six years ago, in the devastating Great Tōhoku Earthquake of 2011.

Tokyo Electric Power (Tepco) reports that figures high as 530 sieverts an hour have been recorded inside the containment of reactor number two. This is one of the reactors that was damaged after the massive tsunami hit the north-east coast of Japan in 2011. Previous readings in the reactor topped out at 73 sieverts an hour.

The sievert is a unit of measurement that determines the effects of ionizing radiation on the human body. One sievert is enough to cause radiation sickness and nausea; and exposure to 10 sieverts can be fatal within a few weeks. So you can imagine what 530 will do.

Scientists are still unsure of what’s causing the levels to rise, but theorize that it may be because of the nuclear fuel making a hole in the vessel. Using a camera with a telescopic arm, the team found that sections of the vessel’s grating was missing, with a black mass found directly under it—indicating that nuclear fuel had melted out of it, and that the deposits could be melted fuel rods.

Underwater footage of the Fukushima Daiichi Reactor No. 2. Credit: Tepco

“It may have been caused by nuclear fuel that would have melted and made a hole in the vessel, but it is only a hypothesis at this stage,” Tepco’s spokesman Tatsuhiro Yamagishi told AFP (as reported by The Guardian). “We believe the captured images offer very useful information, but we still need to investigate given that it is very difficult to assume the actual condition inside.”

Containing the Risk

These unprecedented levels of radiation will make it very difficult for Tepco to decommission the nuclear reactor as planned.

As reported in Japan Times, experts have no experience dealing with radiation levels this high. Even the remote-operated camera they plan to deploy to assess conditions inside the vessel is only designed to withstand 1,000 sieverts, which means it will last no more than two hours after exposure and will likely malfunction.

While these figures are indeed worrying, Tepco representatives say that the radiation is contained within the reactor and there’s no immediate risk facing the public. However, it does present a problem for the company’s efforts to decommission the plant, which, as it stands, will already take several decades to complete.

The plan was to find a way to remove the fuel by 2018. But given the complications presented by their latest findings, it’s evident that more delays are expected, and additional costs will also be added. The Japanese government has pegged spending for the dismantling of the Fukushima plant and decontaminating the surrounding area at $190 billion (21.5 trillion yen).

The legacy of the 2011 earthquake and tsunami is still with us; for the foreseeable future, the people of Japan will be saddled with the enormous costs and health dangers associated with the Fukushima Daiichi reactor meltdown. The costs and technical hurdles of cleanup almost beggar the imagination, but we can hope that the expertise acquired in the effort will lead to future procedures and technologies that can mitigate—if not, indeed, prevent altogether—any future such disasters.

The following is footage from Tepco’s deployed ROV inspecting the submerged reactor: