By Mari Yamaguchi, Associated Press
Workers were preparing for the planned construction of an Olympic pool-sized shaft for use in a highly controversial plan set to begin in the spring of 2023 to gradually get rid of treated radioactive water — now exceeding 1.3 million tons stored in 1,000 tanks — so officials can make room for other facilities needed for the plant’s decommissioning.
Despite the progress, massive amounts of radioactive melted fuel remain inside of the reactors. There’s worry about the fuel because so much about its condition is still unknown, even to officials in charge of the cleanup.
Nearly 900 tons of melted nuclear fuel remain inside the three damaged reactors, and its removal is an unprecedented challenge involving 10 times the amount of damaged fuel removed in the Three Mile Island cleanup following its 1979 partial core melt.
The government has set a decommissioning roadmap aiming for completion in 29 years.
The challenge of removing melted fuel from the reactors is so daunting that some experts now say that setting a completion target is impossible, especially as officials still don’t have any idea about where to store the waste.
Nuclear Regulation Authority Chairman Toyoshi Fuketa said recently that extra time would be needed to determine where and how the highly radioactive waste removed from the reactors should be stored.
Japan has no final storage plans even for the highly radioactive waste that comes out of normal reactors. Twenty-four of the country’s 60 reactors are designated for decommissioning, mostly because of the high cost needed to meet safety standards set up in the wake of the Fukushima disaster.
Hideyuki Ban, the co-founder of the Citizens’ Nuclear Information Center who previously served on government nuclear safety panels, proposes the underground burial of solidified treated water for stable long-term storage, while entombing the three reactors for several decades — like Chernobyl — and waiting for radioactivity to decrease for better safety and access for workers instead of rushing the cleanup.
Since the disaster, contaminated cooling water has constantly escaped from the damaged primary containment vessels into the reactor building basements, where it mixes with groundwater and rainwater that seep in.
The water is pumped up and treated, partly recycled as cooling water, with the remainder stored in 1,000 huge tanks crowding the plant. The tanks will be full at 1.37 million tons by next spring, TEPCO says.
The government has announced plans to release the water after treatment and dilution to well below the legally releasable levels through a planned undersea tunnel at a site about 1 kilometer offshore. The plan has faced fierce opposition from local residents, especially fishermen concerned about further damage to the area’s reputation.
TEPCO and government officials say tritium, which is not harmful in small amounts, is inseparable from the water, but all other 63 radioactive isotopes selected for treatment can be reduced to safe levels, tested and further diluted by seawater before release.
Scientists say the health impact from consuming tritium through the food chain could be greater than drinking it in water, and further studies are needed.
At one of the water treatment facilities where radiation levels are much higher, a team of workers in full protective gear handled a container filled with highly radioactive slurry. It had been filtered from the contaminated water that’s been continuously leaking from the damaged reactors and pumped up from their basements since the disaster. Large amounts of slurry and solid radioactive waste also accumulate in the plant.