The sample was sent to the Japan Atomic Energy Agency’s Oarai Nuclear Engineering Institute, where gamma ray spectrometry analysis found it contained, among other elements, americium-241 and europium-154, indicating the presence of nuclear fuel material. TEPCO announced the analysis results on May 29.
Similar to the first sample, taken in October 2024, the sample was heterogenous with a brown-bronze color, although lighter in color and more porous. This latest sample had a dose rate of approximately 0.3 millisieverts per hour.
To retrieve the fuel debris samples, workers used a telescoping robotic arm that passed through a penetration of Unit 2’s primary containment vessel and through an opening in the reactor pedestal.
Reasoning: According to TEPCO, the initial nondestructive analysis is meant to obtain basic information of the sample and confirm the presence or absence of nuclear fuel (uranium, radioactive nuclides, etc.) early on, as well as help inform additional analysis.
Further solid and liquid analysis of the sample will provide more information on how the material was formed and its characteristics, including isotope ratios and radioactive nuclide concentrations. Detailed solid and liquid analysis is expected to take 12 to 18 months.
The information will aid TEPCO in planning the large-scale removal and storage of the fuel debris from the Unit 2 reactor pressure vessel. According to estimates, about 880 tons of fuel debris remain in the three Fukushima reactors that suffered meltdown.
Other developments: TEPCO also announced that fuel handling equipment that will be used to remove fuel from Unit 2’s spent fuel pool arrived at the Fukushima Daiichi site on May 24 and was affixed to the top of the unit’s fuel removal work platform six days later. The equipment, which sits on a trolley, includes a crane, vertical hoist, and a fuel handling machine.
The company said it aims to start removing fuel from the Unit 2 spent fuel pool during the next fiscal year.
