Removal of nuclear fuel toughest job in Fukushima clean-up plan

TOKYO－Japan's economy and industry ministry proposed a revision on Monday to its decades-long road map to clean up the radioactive mess at the Fukushima nuclear power plant, which was wrecked by a massive earthquake and tsunami in 2011.

Nearly nine years after the accident, the decommissioning of the plant, where three reactors melted, remains largely uncertain. The revised road map, to be formally approved later this month, lacks details on how the complex should appear at the end but maintains a 30-year to 40-year target to finish the clean-up.

By far the toughest challenge is to remove the 800 tons of nuclear fuel in the three reactors that melted, fell from the cores and hardened at the bottom of their primary containment vessels.

In the past two years, plant operator Tokyo Electric Power Co, or TEPCO, has made progress in gathering information mainly from two of the three reactors. In February, a small telescopic robot sent inside Unit 2 showed that small pieces of debris can be removed and be lifted out. The milestone step of debris removal is scheduled to begin at Unit 2 by the end of 2021.

Earlier, assessment at Unit 3 was hampered by high radiation and water levels in its primary containment vessel. A robotic survey at Unit 1 was unsuccessful due to extremely high radiation levels.

Experts say a 30-to 40-year completion target for the decommissioning is too optimistic. Some have raised doubts if removing all of the melted fuel is practical and suggest an approach similar to that followed at Chernobyl: contain the reactors and wait until radioactivity naturally decreases.

Together, the three melted reactors contain more than 1,500 units of mostly used nuclear fuel rods that must be kept cool in pools of water. They're among the highest risks at the plant because the pools are uncovered, and loss of water from structural damage or sloshing in the event of another major earthquake could cause fuel rods inside to melt, releasing massive radiation.

TEPCO started removing the fuel rods from the Unit 3 pool in April 2019 and aims to get all 566 removed by March 2021. Removal of the rods from Units 1 and 2 is to begin in 2023. By 2031, TEPCO also plans to remove thousands at two other units that survived the tsunami. They will then be stored in dry casks on the compound. More than 6,300 fuel rods were in six reactor cooling pools at the time of the accident, and only the Unit 4 pool has been emptied.

The government and TEPCO have been unable to dispose of the more than 1 million tons of radioactive water that has been treated and stored, fearing public repercussions.

The utility has managed to cut the volume of water by pumping up groundwater upstream and installing a costly underground "ice wall" around the reactor buildings to keep the water from running into the surrounding area.

TEPCO says it has space to store only up to 1.37 million tons until the summer of 2022, raising speculation that the water may be released after the Tokyo Olympics next year. TEPCO and experts say the tanks get in the way of decommissioning work and they need to free up the space to build storage for debris removed and other radioactive materials.