A small grain of nuclear fuel is removed from Japan's damaged nuclear power plant, in a cleanup step

TOKYO (AP) – A robot that has spent months inside the ruins of the tsunami-hit Fukushima Daiichi nuclear plant delivered a small sample of melted nuclear fuel Thursday, in what facility officials said was the first step in cleaning up hundreds of tons of melted waste.

The sample, about the size of a grain of rice, was placed in a secure container, marking the end of the operation, according to Tokyo Electric Power Company Holdings, which owns the plant. It is transported to a glove box to be measured for size and weight before being sent to external laboratories for further analysis in the coming months.

Plant chief Akira Ono said it will provide important information to plan an outage strategy, develop the necessary technology and robots and learn how the accident developed.

Despite many investigations in the years since the 2011 disaster that destroyed the plant and forced thousands of nearby residents to flee their homes, much about the highly radioactive site's interior remains a mystery.

The sample, the first to be found inside the reactor, was much less radioactive than expected. Officials were concerned that it might be too radioactive to be tested safely even with heavy protective gear, and an upper limit was placed on the reactor's output. The sample fit well below the threshold.

That has led some to question whether the robot has extracted the nuclear fuel it is looking for in an area where previous probes have found extremely high levels of radiation contamination, but TEPCO officials insist they believe the sample is melted fuel.

The extended robot, nicknamed Telesco, began its mission in August with a two-week round trip, after previous missions were delayed from 2021. three weeks for repairs, and the second for camera failure.

On October 30, it cut a sample weighing less than 3 grams (.01 ounces) on top of a mound of molten fuel debris sitting at the bottom of the Unit 2 reactor's first containment vessel, TEPCO said.

Three days later, the robot returned to the sealed container, as workers wearing hazmat gear slowly removed it.

On Thursday, the gravel, whose radioactivity earlier this week was recorded well below the limit set for environmental safety and health, was placed in a safe container to be removed without commission.

A recovery sample marks the first time that molten fuel is removed from the vessel.

Fukushima Daiichi lost its critical cooling systems during the 2011 earthquake and tsunami, causing three of its power plants to shut down. There are about 880 tons of deadly melted fuel left in it.

The government and TEPCO have set a 30- to 40-year goal of ending the refinery by 2051, which experts say is too optimistic and should be revised. Some say it could take a century or more.

There are no specific plans for the complete removal of fossil fuels or their final disposal.