Fukushima robot
July 24, 2017

First potential nuclear waste discovered at Fukushima plant

A remotely-controlled underwater robot investigating has captured what appears to be the first images of melted nuclear fuel debris inside a reactor at the Fukushima power plant in Japan – a discovery that some are hailing as “a potential milestone” in the clean-up efforts there.

The plant was severely damaged by a tsunami in 2011 in what has been dubbed one of the worst nuclear disasters of all time. At least 200,000 people were forced to leave their homes due to the threat of nuclear contamination after three reactors failed at the flooded plant, according to BBC News. Even now, six years later, parts of the damage reactors remain contaminated.

The robot, which is operated by the Tokyo Electric Power Company (Tepco), was investigating the interior of one of the reactors – reactor 3 – when it spotted icicle-like structured hanging near a control rod drive attached to the bottom of the pressure vessel that secures the reactor’s core.

The pressure vessel originally contained fuel rod assemblies, the media outlet explained, but the rods melted and burned through the bottom of the structure once the plant lost power in the midst of the March 2011 tsunami. This is the first time that Tepco has discovered sometime believed to be melted fuel, the company told reporters during a press conference last Friday evening.

While the robot captured images showing the material accumulating at the bottom of the reactor, the state-run Xinhua news agency noted that it was not equipped with radiation sensor equipment and was thus unable to confirm that the material was radioactive. Nonetheless, based partially on previous analysis, a Tepco spokesman said that it was “highly likely” that the substance is indeed nuclear waste.

Cleanup expected to take 40 years, cost a reported $72 billion

Previously, a different Tepco robot investigating the interior of reactor 2 discovered black lumps stuck to the primary containment vessel’s grating, but the company said that it could not identify those masses, according to Japan Times. This time, the robot also spotted lumps of material that apparently melted and resolidified near a concrete wall supporting the pressure vessel.

“From the pictures taken today, it is obvious that some melted objects came out of the reactor,” Tepco spokesman Takahiro Kimoto said at the press conference. “In that sense, it is possible that the melted objects found this time are melted fuel debris or probably around it.” Kimoto went on to say that Tepco is thinking of ways to confirm that the substances are the former fuel rods.

Due to the highly radioactive nature of the damaged power plant, only specially designed robots are allowed to investigate the facility, and the company is developing new technology to remove the melted fuel from the reactors – technology that Japan Times said could be completed as early as next summer and usable sometime during the 2018 fiscal year ending March 2019.

Friday’s discovery suggests that the robots “can now deal with the higher radiation levels, at least for periods of time that allow them to search parts of the reactor that are more likely to contain fuel debris,” M.V. Ramana, a professor at the University of British Columbia, told the Japan Times via email. “If some of these fragments can be brought out... and studied, it would allow nuclear engineers and scientists to better model what happened during the accident.”

Tepco and the Japanese government will reveal a reclamation plan in September, according to the Xinhua news agency. That plan, which will be implemented starting in 2021, is expected to take at least four decades and is estimated to cost a reported $72 billion dollars.

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Image credit: AFP