Photo/Illutration A worker transports a pipe used for pushing debris-collection equipment into a passageway to the containment vessel inside the No. 2 reactor building at the Fukushima No. 1 nuclear power plant on July 24. (Provided by Tokyo Electric Power Co.)

Tokyo Electric Power Co., about three years behind its initial schedule, restarted work on Sept. 10 to collect melted fuel from a reactor at the crippled Fukushima No. 1 nuclear power plant.

The utility will spend about two weeks to retrieve up to 3 grams of nuclear debris from the bottom of the containment vessel of the No. 2 reactor on an experimental basis.

The government and TEPCO plan to decommission the plant, where three reactors melted down after the 2011 Great East Japan Earthquake and tsunami, by 2051.

The collection of nuclear debris marks the start of the last of the three phases of the decommissioning process, according to the government’s road map.

TEPCO was forced to postpone the fuel retrieval project on Aug. 22 after finding that five pipes used for the work had been placed in a wrong order during preparations.

The utility said it determined the cause of the mistake and took preventive measures.

According to TEPCO, work resumed inside the No. 2 reactor building around 6:30 a.m. on Sept. 10.

Workers used the pipes to push a debris-collection device into a passageway leading to the containment vessel. The equipment moved just beyond an isolation valve located halfway through the passageway at 7:20 a.m.

The telescopic device works like a fishing rod, with a hand for catching debris hanging at the end.

The No. 1, No. 2 and No. 3 reactors contain an estimated 880 tons of nuclear debris, but their conditions remain unknown.

If a sample of melted fuel is retrieved from the No. 2 reactor, TEPCO plans to analyze its structure and characteristics at a research facility in Ibaraki Prefecture.

The company hopes to use the findings to come up with detailed debris-collection methods. But it remains unclear whether all nuclear debris can be removed.

The government and TEPCO originally planned to start collecting nuclear debris in 2021.

However, the work has been postponed three times due to the low accuracy of robotic arms and other problems.

(This article was written by Fumi Yada and Keitaro Fukuchi.)

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