The operator of the crippled Fukushima Daiichi Nuclear Power Station on April 15 successfully removed four nuclear fuel rods each weighing about 250 kilograms from a pool for spent fuel at the nuclear plant's No. 3 reactor.

It was the first time for Tokyo Electric Power Company Holdings Inc. (TEPCO) to remove fuel rods from a damaged reactor following the March 2011 Great East Japan Earthquake and tsunami, which triggered meltdowns at the plant's No. 1 to 3 reactors.

Originally, the government planned for the work at the plant in the northeastern Japan prefecture of Fukushima to begin at the end of 2014, but trouble with equipment caused significant delays, pushing the work back by 4 years and 4 months.

Since the meltdowns, TEPCO has continued to cool 566 fuel rods -- 514 used and 52 unused -- on the upper level of the building housing the No. 3 reactor. The building was damaged by a hydrogen explosion during the nuclear disaster, and removal of the fuel rods has remained an urgent task.

Workers started the removal work at the No. 3 reactor shortly before 9 a.m. on April 15. The level of radiation around the pool for spent fuel remains high, approaching as much as 1 millisievert per hour, so the task was carried out remotely. Four rectangular rods, each 4 meters in length and weighing about 250 kilograms, were lifted up using a special crane, and carried through the water to a steel container about 10 meters away in a process that took about one hour.

At one point, a handle attached to the top of one of the fuel rods got caught on the crane's claws, causing the operation to be suspended for about 20 minutes. But after around nine hours, the four fuel rods had been contained. The crane then lifted the container onto a truck outside the reactor building. This removed fuel will be temporarily placed in a pool on the grounds of the nuclear plant.

The process will be repeated, and officials hope to remove all fuel rods from the pool by fiscal 2020.

Since August last year, delays have occurred in the work at the No. 3 reactor as checks of the performance of equipment uncovered cable insulation and crane problems.

When the meltdowns first occurred, there was no technology in Japan to remotely remove the fuel rods, so officials decided to use equipment brought in from overseas, but repeated problems ensued. Akira Ono, head of the decommissioning project at the plant, said he is not thinking of using the same equipment at the plant's other crippled reactors. Work to remove fuel from the buildings of the No. 1 and No. 2 reactors is slated to begin as early as fiscal 2023.

(Japanese original by Toshiyuki Suzuki, Science & Environment News Department)