Japan’s Tokyo Electric Power Company (Tepco) has deployed an underwater robot to investigate a badly damaged reactor at the Fukushima Daiichi nuclear power plant.

Named ‘the Little Sunfish’, the robot was co-developed by Toshiba and the International Research Institute for Nuclear Decommissioning.

Discover B2B Marketing That Performs

Combine business intelligence and editorial excellence to reach engaged professionals across 36 leading media platforms.

Find out more

Tepco seeks to discover the exact location and condition of melted fuel debris inside the Unit 3 reactor, reported Japan Today.

Unit 3 is one of three reactors that suffered meltdowns following an earthquake and tsunami in 2011. Extreme levels of radiation inside the reactors make it impossible for humans to enter the area to investigate.

"Tepco seeks to discover the exact location and condition of melted fuel debris inside the Unit 3 reactor."

The water levels inside Unit 3 are also higher than those of other reactors.

Equipped with lights, two cameras, and other equipment, the remotely controlled robot will capture images of the impact of the meltdown, AP reported.

GlobalData Strategic Intelligence

US Tariffs are shifting - will you react or anticipate?

Don’t let policy changes catch you off guard. Stay proactive with real-time data and expert analysis.

By GlobalData

Little Sunfish is about the size of a slice of bread. It will travel to the bottom of the containment vessel, where the deposits of melted fuel debris are assumed to have accumulated.

According to Tepco, the containment chamber has been inundated by highly radioactive water as deep as 20ft.


Image: Fukushima nuclear power plant before the 2011 explosion. Photo: courtesy of KEI/ Japanese Wikipedia.

Power Technology Excellence Awards - Nominations Closed

Nominations are now closed for the Power Technology Excellence Awards. A big thanks to all the organisations that entered – your response has been outstanding, showcasing exceptional innovation, leadership, and impact.

Excellence in Action
Recognised with three 2025 Power Technology Excellence Awards, Hover Energy is at the forefront of intelligent microgrids and distributed renewables. Explore how its AI-enabled Microgrid Management System™ , strategic partnerships and networked microgrids are rebuilding the grid from the ground up for a more flexible, resilient energy future.

Discover the Impact