Fukushima: Tepco takes up the challenge of withdrawing from treated water tanks to store radioactive debris

The dismantling of the treated water reservoirs of the Japanese nuclear power plant in Fukushima, started on Friday, should make it possible to release space for the storage of nuclear debris, after the 2011 devastating tsunami.

“Today, there is no longer any (free) ground in Fukushima Daiichi”said Thursday at AFP Naoki Maeshiro, project manager for the operator Tokyo Electric Power Company (TEPCO), in charge of the operation of water tanks.

Tepco must find a place to store around 880 tonnes of radioactive debris which are still inside the damaged reactors of the Fukushima Daiichi (northeast) power station.

Three of the six reactors of the installation worked when the tidal wave hit the power station on March 11, 2011, melt the cooling systems.

Since then, Tepco has kept some 1.3 million tonnes of water – rain, underground and sea – on the site, as well as the water required to cool reactors.

This water treated using the ALPS system (“Advanced Liquid Treatment System”) to rid it of its radioactive substances, remains stored in more than a thousand tanks that occupy most of the site.

In the area “J9”the imposing steel monsters stand behind the employees at work, obstructing the view of the rest of the power plant.

“To carry out the following steps, such as the recovery of fuel debris, we need space”adds Mr. Maeshiro.

The dismantling of tanks has become possible with the start of rejection of water in the Pacific Ocean in August 2023. Japan and the International Atomic Energy Agency (AIEA) assure that this water does not harm the environment.

Release the area for radioactive debris

The company has shot down other water containers in the past, but get rid of these in particular – united tanks – is considered an essential step in the progress of the general dismantling project.

Once this space has been released, in March 2026 according to TEPCO estimates, the operator plans to build storage places for radioactive waste – particularly dangerous – which must be extracted from the reactors.

“As long as fuel debris remain in their current state, the risks remain very high”explains to AFP Nobuhide Sato, risk specialist at Tepco.

To do this, the operator has set up a telescopic device capable of collecting debris remotely, in order to guarantee the safety of operations and prevent any leak from radioactive material.

Tepco has reproduced the device used in damaged reactors inside reactor 5, at the time of disaster, to which AFP had access.

Before entering this area under close surveillance, employees of the power plant put on a mask, a protective helmet, a white full combination and three pairs of gloves and socks, radiation obliges.

Equipped with a flashlight, Mr. Sato stops at an orifice about 60 cm in diameter drilled in the structure protecting the heart of the reactor.

It is inside this hole that the telescopic device developed by Tepco will extend over several meters, until reaching the radioactive debris lying in the reactor.

The mechanism of the device resembles that of a japanese arcades room machine: using a claw attached to its end, the “Bras grabs the debris, lifts and recovers them”M. Sato.

“Reassure residents”

In early November, the operator announced the successful extraction of a sample of debris weighing 0.7 grams, sent to a laboratory near Tokyo.

According to Tepco, the analysis must make it possible to determine the levels of radioactivity and the chemical structure of fuel debris, a key element for the preparation of the long and colossal process of overall dismantling of the power station.

“Depending on the data collected, we will see if it is preferable to use water to collect (fuel debris) in the reactor or do so in dry condition”M. Sato.

The Tepco employee then rushes into the reactor base, where workers at the power plant spend a maximum of two hours a day due to radiation levels.

“If we can properly recover fuel debris and store them securely, this will greatly help reassure surrounding residents”ajoute Nobuhide Sato.

A second sample of nuclear samples is planned between “March and April” According to Tepco, which will obtain enough information on their composition to take the next step: a larger scale extraction of radioactive debris by 2030.

The global dismantling project must last between thirty and forty years, according to the operator.