Fukushima: current state of the clean-up

The clean-up continues
The clean-up continues

Eight years have passed since a tsunami smashed into the Fukushima Daiichi nuclear plant in Japan, sparking a meltdown and the worst atomic crisis since Chernobyl.

Eight years on, the disaster zone remains a huge building site with the immediate danger cleared but an immensely difficult clean-up job still looming.

What is the state of the clean-up?

The clean-up operation is progressing at a painstakingly slow pace.

Robotic arms have recently been employed to successfully pick up pebble-sized pieces of radioactive fuel at the bottom of reactor two, one of three that melted down after the 2011 quake and tsunami.

This is the first step to prepare the extremely delicate task of extracting the fuel that will not begin in earnest until 2021 at the earliest, the government and the TEPCO operator have said.

Another problem is the fuel pools in reactors one, two and three.

The pool in reactor one is covered in rubble which needs to be removed "with extreme care," explained Akira Ono, head of the TEPCO subsidiary in charge of decommissioning.

Removing fuel from the pools in reactors one and two will not start until 2023.

As for three, the operation to remove fuel should have started this month but it was delayed "due to various problems", admitted Ono.

Some workers have called for increased surveillance
Some workers have called for increased surveillance

What about contaminated water?

Contaminated water still poses a huge problem for Fukushima operators.

The water comes in three forms: residual water from the tsunami; water used to cool the reactors, and precipitation as well as groundwater. All water needs to be pumped, purified and stored.

An ice wall stretching 1.5 kilometres and located 30 metres underground is designed to block from nearby mountains from flowing into the shattered complex.

The operators are winning the battle against contaminated water, Ono insisted, but non-profits like Greenpeace disagree.

"It has gone down to 220 cubic metres on average per day in 2017/18 compared to 470 cubic metres four years ago," he said.

"We think we can get it down to 150 cubic metres by 2020."

However, inevitable typhoons and other periods of heavy rain make it an uphill battle.

Shaun Burbie from Greenpeace said: "The government and TEPCO had set a target of 2020 as a timeframe for solving the water crisis.... That was never credible."

The reprocessing of all contaminated water will take five to six years, he estimated, and there are "remaining questions over its efficacy."

"Volumes of contaminated water will continue to increase in the coming years."

The work is painstaking and likely to take several more years
The work is painstaking and likely to take several more years

How is water decontaminated?

Around 1.12 million cubic metres are stored onsite but the maximum of 1.37 million cubic metres will be reached at the end of 2020.

The water is purified by a decontamination system that eliminates all with the exception of tritium.

However, TEPCO realised last year that 85 percent of the water still contained too much potentially radioactive material and so decided to filter it a second time.

Experts are still trying to work out what to do with this tritium-contaminated .

"There are several possible solutions (injecting it into deep pockets in the Earth, dumping it at sea, evaporating it) being examined by an expert working group but we have not yet decided anything," said Yumiko Hata, head of Fukushima waste management at the industry ministry.

As for solid radioactive waste, TEPCO plans to store 750,000 cubic metres of waste at the site until 2029—some of which is radioactive.

What about the workers?

The number of people working on the site has nearly halved from four years ago but there are still some 5,000 labourers.

"A lot of the big jobs have been done (ice wall, protective coating on the ground, construction of various buildings)," said Ono.

Workers are exposed to average levels of radiation below 5 millisieverts per year but TEPCO admits that this average masks a wide difference in individual levels depending on what jobs the workers carry out.

One former worker, Minoru Ikeda, said surveillance should be strengthened.

"We have a radiation book but only my employer looked at this. We are not especially monitored by the government and that's not normal," he complained.

Explore further

Robot probes radioactive fuel at Japan's Fukushima plant

© 2019 AFP

Citation: Fukushima: current state of the clean-up (2019, March 8) retrieved 16 September 2019 from https://phys.org/news/2019-03-fukushima-current-state-clean-up.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Mar 08, 2019
"TMI was an over reaction to a faulty gauge."
"Chernobyl was the result of management incompetence and cutting corners on design."
"Fukushima, that was just due to locating the plant in a tsunami zone."
"All were object lessons for all countries around the world."
Nuclear is the safest per unit of energy produced, safer and more ecologically friendly than intermittent renewables(bird-choppers, land-intensive monstrosities).

...non-profits like Greenpeace...
Greenpeace profits are secret donations from coal/oil/gas/fracking industries, the biggest beneficiaries by the renewable scam.
solar/wind = 20% solar/wind + 80% fossil fuels to compensate intermittencies.

Mar 08, 2019
Without any need for conspiracies, modern nuclear power plants are very safe. The older ones, like Fukushima, should just be renewed. I'm currently working on a interesting project aiming to absorb radioactive material out of water and we have also tested it with Fukushima waters. It would be nice to see my work help there.

Mar 09, 2019
Why are they agonizing about the tritium? There are a whopping 2.5 grams total - about a third of a shot glass of water with a low energy beta emitter. And it's in a million cubic meters of other water? That's a billion liters - roughly 15 parts per trillion, unless my math is way off. Store it in an open pond, normal water would preferentially evaporate, helium 3 would escape, this is a problem best left alone.

Mar 09, 2019
"Cosmic rays interacting with nitrogen atoms in the upper atmosphere produce orders of magnitude more natural tritium to be produced..... which ends up in the ocean too and decays away with a 12.5 year half-life."

If tritium is an 'unimaginably" toxic waste, why is it sold on eBay?
"Tritium illumination is the use of gaseous tritium, a radioactive isotope of hydrogen, to create visible light..."
"...does not pose a significant health concern. "

"EXIT signs that glow in the dark often contain a radioactive gas called tritium ...They serve an important safety function by marking exits to be used during power outages and emergencies. The signs pose little or no threat to public health and safety or security."

Mar 09, 2019
Without any need for conspiracies, modern nuclear power plants are very safe.

Even chernobyl was very safe. The problem was user error.
Fukushima was also very safe...Just no one figured with a Tsunami of that size.

On paper nuclear powerplants are safe. On paper rockets are 100% safe (yet occasionally one does blow up - and there is *always* a reason that no one thought of)

If you think that reality follows plans on paper then you haven't worked in the industry (where occasionally someone will make a honest mistake, cut corners, outright save a few cents by using sub-par materials because "no one will ever know if nothing happens"...or where nature just throws one of those things in the works that no one expected)

No, I'm not saying we should never do anything that looks good on paper. But we should *only* do things we can clean up with reasonable effort when they go other than expected.

Nuclear is not one of those things.

Mar 09, 2019
Why are they agonizing about the tritium?

Tritium is *chemically* identical to hydrogen. There is a huge amount of stuff in your body (i would go as far as to say almost everything) that contains hydrogen bonds. When you take in food or drink and incorporate this into more stuff in your body tritium fills those bonds just as happily as a normal hydrogen atom does. And you really, really don't want that to happen in elevated amounts

Store it in an open pond, normal water would preferentially evaporate, helium 3 would escape

And water where one or both the H are replaced with tritium would also evaporate...and eventually rain down around the area or who knows where.
Not good.
Not good at all.

Mar 09, 2019
Tritium is *chemically* identical to hydrogen.

Not quite. Deuterium and tritium don't form exactly the same hydrogen bonds because of nuclear kinetic effects, and their water molecules behave differently.

Bonds involving deuterium and tritium are somewhat stronger than the corresponding bonds in hydrogen, and these differences are enough to cause significant changes in biological reactions. They're toxic to eukaryotic cells, and tritium won't stay in the body for long - it has a biological half-life of 40 days - six month and you've very much peed it out.


And it's such a weak source of radiation that it probably can't cause you cancer - you need to drink gallons of the water at Fukushima to get the same dose as eating a banana - although you can extrapolate some risk with the LNT model. Moral of the story: just dilute the tritium into even more water and dump it in the sea.

Mar 10, 2019
The current level of clean-up is going great, and it includes dead animals on beaches across the Pacific.
Before long we will have a sterile ocean and only have to worry about cleaning the plastic bags from the ocean.

Mar 10, 2019
The story concerning the tritium-contaminated water is an insult to science and to one's intelligence. And here, on a science site.....

One liter of water per day meets all of a person's hydration needs. A person could drink one liter of (undiluted) water straight from those tanks, and their total annual dose would be far below the level at which any health impacts are seen. And of course, if it were released into the Pacific, the tritium concentration would be billions of times smaller.

Environmental or health impacts of releasing the "contaminated" water into the Pacific are a complete non-issue. It's all a fabrication, based on pure politics.

Mar 10, 2019
The fact that tritium is chemically identical to water is a *good* thing. It means that it doesn't bio-accumulate, or stay in your body ("stick to things"). It goes right in, and then it goes right out. Tritium concentrations in your body would never exceed those in the overall water you drink or consume in food. Which is to say, completely negligible.

All these effects (how the material behaves in the body, etc..) are accounted for in the published dose conversion factors, which convert radioactivity levels of the specific isotopes that you swallow or breathe in, to radiation doses (in Rem), which are a measure of biological impact. And the calculations clearly show that there is no potential for any even remotely significant dose.

Mar 10, 2019
People get twitchy about dumping radiation in the sea when they'll later be eating the fish.

Seems reasonable to me.

Especially considering how badly similar suave dismissals of contaminants have turned out in the past.

Mar 10, 2019
The problem with Fukushima was not it's location in a tsunami zone, per se. Other, newer reactors saw and even higher wave, and they survived just fine. Plants can be designed to handle whatever environmental factors (e.g., tsunamis) they are potentially exposed to.

The problem at Fukushima Daichi is that its sea wall was not high enough, and their emergency diesel generators were placed in a low spot that was vulnerable to flooding. Nuclear power can be used safely in earthquake and tsunami zones, given that appropriate measures are taken. As for overall public health risk and environmental harm, nuclear will always beat fossil generation (even gas, let alone coal) hands down. Japan's decision to shut down all their nuclear and use fossil fuels, including coal, instead was indefensible.

Mar 10, 2019
The problem at Fukushima was the accountants trying to save money at the expense of public safety.

Simple as that.

These asshole accountants should be the ones prosecuted.

Nuclear energy is safe enough- if the ones making the safety standards are nuclear scientists and nuclear engineers. Not accountants. If it costs too much to be safe maybe you shouldn't have built it in the first place.

Mar 10, 2019
It's completely unreasonable. One more example of double standards and prejudices against all things nuclear (and nuclear only). Mercury and arsenic in fish are an orders of magnitude larger health risk, but that's OK?

Radiation in the sea? You realize that the ocean is filled with naturally occurring radioactivity, that is millions of times larger than any release from Fukushima, right? Also, radioactivity levels in fish from naturally-occurring isotopes that have always been there exceed radioactivity levels from any Fukushima isotopes by orders of magnitude (not just the tritium, but all the isotopes released by the main accident event). That is perhaps the most ridiculous part of all. Any radioactivity from this tritiated water is negligible compared to the radioactivity already released into the ocean by the accident. And yet, all the fish, including that caught in the immediate area, meet absurdly strict limits, far too small to have any health impact.

Mar 10, 2019
The mercury and arsenic are mostly in surface waters, indicating they are mostly industrial pollution.

You expect people to differentiate between these?

If you really want safe nuclear then the accountants have to go. Until they do everyone will suspect more of the same.

I don't say they're right; but the optics are really bad. And after watching what's been done, folks naturally assume you're just doing the same bullshit again.

And too often they're right.

Mar 10, 2019
It is impossible to render nuclear power as dangerous as fossil generation. Over the 50 years nuclear has been around, fossil power generation has caused on the order of 10 million deaths. By contrast, nuclear (outside the old Soviet Union) has had only one significant release of pollution, Fukushima, and even that (worst-case meltdown) caused no direct deaths and will have no measurable impact on public health, ever. (In summary, few if any deaths). Oh, and then there's global warming, where fossil generation is a primary contributor and nuclear has no impact).

Not using nuclear, and using fossil fuels instead, because it was "too expensive" to make nuclear perfectly safe (i.e., zero risk, thousands of times better than fossil not being good enough), is indefensible and morally reprehensible.

The Japanese leaders who made the decision to close all the nukes and use fossil fuels in their place are the ones who should be prosecuted.

Mar 10, 2019
And here's the problem: you say "in the sea." "In the sea" doesn't seem to have diluted the industrial mercury and arsenic. Why then should anyone believe it would dilute radioactivity?

And when you fight in court to disenfranchise massive numbers of legitimately damaged people, you're only fueling the contention that you're "getting away with it and screwing all of them." It's perceived as dishonest.

I'm not against nuclear; I'm against allowing accountants to determine its safety margins.

No one is ever going to have perfect safety in any industrial activity. But killing millions of people isn't going to work out well, even if they don't find out for 50 years. Thing is, it does work on a balance sheet. And that's the accountant problem.

Mar 11, 2019
Even chernobyl was very safe. The problem was user error.
Fukushima was also very safe...Just no one figured with a Tsunami of that size.

In Chernobyl, things were done that should not ever be done like shutting down of the emergency cooling system. It was known that tsunamis could cause problems to Fukushima but the warnings were ignored. So two cases of human stupidity, nothing to blame on the nuclear power plants.

Here in Finland nuclear power plants are made to withstand tsunamis and earthquakes which we don't even have. The point being they can be made really safe.

Apr 08, 2019
The problem at Fukushima was the accountants trying to save money at the expense of public safety.

Simple as that.

These asshole accountants should be the ones prosecuted.

Nuclear energy is safe enough- if the ones making the safety standards are nuclear scientists and nuclear engineers. Not accountants. If it costs too much to be safe maybe you shouldn't have built it in the first place.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more