nuclear-news

Fate of Fukushima reactor cleanup uncertain after 11 years

March 13, 2022

OKUMA, Japan—Eleven years after the Fukushima Daiichi nuclear power plant was ravaged by a meltdown following a massive earthquake and tsunami, the plant now looks like a sprawling construction site. Most of the radioactive debris blasted by the hydrogen explosions has been cleared and the torn buildings have been fixed.

During a recent visit by journalists from The Associated Press to see firsthand the cleanup of one of the world’s worst nuclear meltdowns, helmeted men wore regular work clothes and surgical masks, instead of previously required hazmat coveralls and full-face masks, as they dug near a recently reinforced oceanside seawall.

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.

On March 11, 2011, a magnitude 9.0 earthquake caused a tsunami 17 meters (56 feet) high that slammed into the coastal plant, destroying its power supply and cooling systems, causing reactors No. 1, 2 and 3 to melt and spewing massive amounts of radiation.

Three other reactors were offline and survived, though a fourth building suffered hydrogen explosions.

The spreading radiation caused some 160,000 residents to evacuate. Parts of the surrounding neighborhood are still uninhabitable.

The melted cores in Units 1, 2 and 3 largely fell to the bottom of their primary containment vessels, together with control rods and other equipment, some possibly penetrating or mixing with the concrete foundation, making the cleanup extremely difficult.

Probes of the melted fuel must rely on remote-controlled robots carrying equipment such as cameras and dosimeters—which measure radiation—because radiation levels in those areas are still fatally high for humans.

In February, a remote-operated submersible robot entered the Unit 1 primary containment vessel, its first internal probe since a failed 2017 attempt. It captured limited images of what are believed to be mounds of melted fuel rising from the concrete floor.

Probes have moved ahead at Unit 2, where Tokyo Electric Power Co. (Tepco) plans to send in an extendable robotic arm later this year to collect melted fuel samples.

Tepco Chief Decommissioning Officer Akira Ono said in a recent online interview that robotic probes at Unit 1 and 2 this year are a major “step forward” in the decades-long cleanup. 

Fate of Fukushima reactor cleanup uncertain after 11 years

March 14, 2022 - Posted by dunrenard | Fuk 2022 | 311 Anniversary, decommissioning, Fukushima Daiichi