The operator of the crippled Fukushima No. 1 nuclear plant said Wednesday that it will start dismantling treated water tanks next week to clear space needed to store nuclear fuel debris to be extracted from the reactors.

The step is a milestone of a sort as Tokyo Electric Power Company (Tepco) moves ahead with a decades-long project to dismantle the entire plant, which went into meltdown after it was hit by a catastrophic tsunami in 2011.

"The company will start dismantling welded water tanks on February 13, if the weather allows," a Tepco spokesman said.

Since the accident, Tepco has stored around 1.3 million tons of water — a combination of groundwater, seawater and rainwater — at the site along with water used for cooling the reactors.

The water is filtered to remove various radioactive materials, but has remained inside more than 1,000 tanks that occupy much of the plant's ground.

Tepco has taken down other kinds of water tanks before, but scrapping welded tanks has been seen as a key to advancing the overall work on the plant as a whole.

After removing the tanks, the utility plans to build facilities to store highly dangerous molten fuel debris to be extracted from inside the reactors.

Scrapping the water tanks became possible after Tepco began releasing the stored water from the plant into the Pacific Ocean in August 2023.

Japan has insisted that the water does not harm the environment, a position backed by U.N. atomic watchdog the International Atomic Energy Agency.

But the move has met angry reactions from China, which banned imports of Japanese seafood.