TOKYO, Aug 20, 2025 (BSS/AFP) - Japanese technicians at the stricken Fukushima nuclear plant have sent in remote-controlled robots to one of the damaged reactor buildings as part of preparations to remove radioactive debris.

Dangerously high radiation levels mean that removing melted fuel and other debris from the plant hit by a huge tsunami in 2011 is seen as the most daunting challenge in the decades-long decommissioning project.

Around 880 tonnes of hazardous material remain inside the power station, site of one of the world's worst nuclear accidents after a tsunami triggered by a 9.0-magnitude earthquake in 2011.

A spokesman for plant operator TEPCO told AFP that the company had deployed two robots -- "Spot" and "Packbot" -- at one of the damaged reactor buildings on Tuesday to measure the level of radiation.

Both are equipped with dosimeters, a device used to measure radiation, and "Spot" -- which resembles a dog -- has a camera.

The results of the investigation would be used to help decide upon "a full-scale fuel debris retrieval method", TEPCO said in a press release.

Public broadcaster NHK and other local media reported that the survey would continue for about a month.

Tiny samples of radioactive material have twice been collected under a trial project using special tools, but full-fledged extractions are yet to take place.

The samples have been delivered to a research lab for analysis.

TEPCO announced in July that the massive operation to remove debris had been delayed until at least 2037. The company previously said it hoped to start in the early 2030s.

The new schedule throws into doubt previously stated goals by TEPCO and the government to declare the Fukushima plant defunct by 2051.

But TEPCO said last month the deadline was achievable despite acknowledging it would be "tough".