The temblor occurred near where an earthquake and a tsunami caused a nuclear meltdown six years ago.
The cylindrical-shaped object would most likely be U.S.-made.
Japan's "Little Sunfish" brought back never-before-seen footage of the Fukushima nuclear plant, which has claimed a number of prior devices.
How much harm could 777,000 tons of water laced with tritium, a nuclear byproduct, do to the environment?
Before yelling at journalists and storming out of a press conference, the "emotional" minister said refugees should bear “self-responsibility for their own decisions."
Only 10 percent of the population supports maintaining nuclear energy, six years after the nuclear plant disaster.
Fukushima was the world's worst nuclear disaster since 1986.
The indictments, forced through by a civilian judicial panel, are the first against officials at Tepco and come just before the fifth anniversary of the meltdowns.
The robot will clean up highly radioactive spots too dangerous for humans to enter.
A 54 centimeter robot with a scorpion-like tail will be sent inside one of Fukushima's reactors this August.
Trace amounts of Cesium-134 and Cesium-137 were detected in samples.
No U.S. agency monitors ocean radioactivity, so the data comes from an independent lab
The plant would be the first nuclear power station to reopen following the Fukushima disaster in 2011, despite warnings that nearby volcanoes show an increase in activity
A new day and a new spill of radioactive water
Tokyo Electric Power Co told reporters the latest leak was unlikely to have reached the ocean