WILL THE WASTEWATER RELEASE PUSH DECOMMISSIONING FORWARD?
Not right away, because the water release is slow and the decommissioning is making little progress. TEPCO says it plans to release 31,200 tonnes of treated water by the end of March 2024, which would empty only 10 tanks out of 1,000 because of the continued production of wastewater at the plant.
The pace will later pick up, and about one-third of the tanks will be removed over the next 10 years, freeing up space for the plant’s decommissioning, said TEPCO executive Junichi Matsumoto, who is in charge of the treated water release.
He says the water would be released gradually over the span of 30 years, but as long as the melted fuel stays in the reactors, it requires cooling water, which creates more wastewater.
Emptied tanks also need to be scrapped for storage. Highly radioactive sludge, a byproduct of filtering at the treatment machine, also is a concern.
WHAT CHALLENGES ARE AHEAD?
About 880 tonnes of fatally radioactive melted nuclear fuel remain inside the reactors. Robotic probes have provided some information but the status of the melted debris remains largely unknown.
Earlier this year, a remote-controlled underwater vehicle successfully collected a tiny sample from inside Unit 1’s reactor — only a spoonful of the melted fuel debris in the three reactors. That’s 10 times the amount of damaged fuel removed at Pennsylvania’s Three Mile Island cleanup following its 1979 partial core melt.
Trial removal of melted debris using a giant remote-controlled robotic arm will begin in Unit 2 later this year after a nearly two-year delay. Spent fuel removal from Unit 1 reactor’s cooling pool is set to start in 2027 after a 10-year delay. Once all the spent fuel is removed, the focus will turn in 2031 to taking melted debris out of the reactors. But debris removal methods for two other reactors have not been decided.
Matsumoto says “technical difficulty involving the decommissioning is much higher” than the water release and involves higher risks of exposures by plant workers to remove spent fuel or melted fuel.
“Measures to reduce radiation exposure risks by plant workers will be increasingly difficult,” Matsumoto said. “Reduction of exposure risks is the basis for achieving both Fukushima’s recovery and decommissioning.”
