TOKYO (AP) — A robot that spent months in the ruins of a nuclear reactor at the tsunami-hit Fukushima Daiichi nuclear power plant delivered a tiny sample of melted nuclear fuel Thursday, which officials said power plant said to be a step toward beginning the cleanup of the power plant. hundreds of tons of melted fuel debris.
The sample, the size of a grain of rice, was placed in a secure container, marking the end of the mission, according to Tokyo Electric Power Company Holdings, which runs the plant. It is carried in a glove box for height and weight measurements before being sent to outside laboratories for detailed analysis over the coming months.
Plant head Akira Ono said the plant would provide key data to plan a decommissioning strategy, develop the necessary technology and robots, and find out how the accident developed.
Despite multiple investigations in the years since the 2011 disaster that destroyed the plant and forced thousands of nearby residents from their homes, much of the site’s highly radioactive interior remains a mystery.
The sample, the first to be recovered inside a reactor, was significantly less radioactive than expected. Officials feared it was too radioactive to test safely, even with heavy protective equipment, and set an upper limit for its removal from the reactor. The sample was well below the limit.
That has led some to question whether the robot had extracted the nuclear fuel it was looking for in an area where previous probes had detected much higher levels of radioactive contamination, but TEPCO officials insist they think the sample is melted fuel.
The extendable robot, nicknamed Telesco, began its mission in August with a plan for a two-week round trip, after previous missions were delayed from 2021. But progress was twice suspended due to incidents – the first involving an assembly error that took almost three weeks to repair, and the second a camera failure.
On October 30, he took a sample weighing less than 3 grams (0.01 ounce) from the surface of a mound of melted fuel debris at the bottom of the Unit 2 reactor’s primary containment vessel, TEPCO said.
Three days later, the robot returned to a closed container, as workers in full hazmat gear slowly removed it.
On Thursday, the gravel, whose radioactivity was recorded at the start of the week well below the upper limit set for its environmental and health safety, was placed in a safe container to be removed from the compartment.
The return of the sample marks the first time the molten fuel has been recovered from the containment vessel.
Fukushima Daiichi lost its main cooling systems in the 2011 earthquake and tsunami, causing its three reactors to melt down. An estimated 880 tonnes of lethally radioactive melted fuel remain there.
The government and TEPCO have set a target of 30 to 40 years to complete the cleanup by 2051, which experts say is too optimistic and should be updated. Some say it would take a century or more.
No specific plan for the complete removal of fuel debris or its final disposal has been decided.
