The operator of the crippled Fukushima Daiichi nuclear power plant says that a retrieval device placed inside No. 2 reactor has successfully grabbed a small amount of fuel debris left at the bottom of a containment vessel.



Tokyo Electric Power Company, or TEPCO, reported the progress on Thursday in its second experimental retrieval operation, which started on Tuesday.



TEPCO earlier inserted a piece of pipe-shaped equipment inside the reactor's containment vessel. It then used a cable to lower the retrieval device from the tip of the equipment toward the bottom of the vessel.



TEPCO estimates that the fuel debris scooped up by the device weighed several grams.



The sample was taken at different locations from where a sample in the previous experiment in November came from. The sites were up to 2 meters away from each other.



TEPCO shifted the area based on the likelihood that the makeup and condition of the nuclear debris at the bottom of the vessel differ depending on their location.



In the next step, TEPCO plans to spend several days taking out the retrieval equipment from the containment vessel and then wait until the equipment's radiation levels come down below a set level, before placing it inside a transport container to complete removal.



The experimental operation at No. 2 reactor represents a crucial step in the enormous challenge of extracting an estimated 880 tons of nuclear debris -- a mixture of molten fuel and surrounding structures -- believed to be left at the bottom of Number 1, 2 and 3 reactors.



The extremely high levels of radiation still being emitted by the debris make their retrieval by far the biggest obstacle in efforts to decommission Fukushima Daiichi.