Fukushima: 10 years later, a disaster still in progress
Reuters / NTV via Reuters TV
Text by: Arnaud Jouve Follow
19 min
10 years after the nuclear disaster of Fukushima Daiichi, Japan continues to fight against the disaster.
3 nuclear reactors at the plant melted.
Massive releases of radioactivity spread into the atmosphere and into the Pacific Ocean.
The plant is still grappling with a critical situation with no real solution.
The ocean and the territories are permanently contaminated.
The health of populations is always threatened.
Interview with Bruno Chareyron.
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Nuclear physics engineer Bruno Chareyron is the director of the CRIIRAD laboratory, the Commission for Independent Research and Information on Radioactivity (CRIIRAD).
Bruno Chareyron, what happened in the Japanese nuclear power plant of Fukushima Daiichi on March 11, 2011?
That day, an earthquake caused a very large tsunami which submerged part of the installations of the Fukushima-Daiichi plant located on the Pacific coast and this rendered inoperative the cooling system of nuclear reactors number 1, 2 and 3. In the event of an earthquake in general, and this was the case in Fukushima, the nuclear reactors automatically shut down.
Emergency stop bars are automatically introduced into the reactor core to stop nuclear reactions.
The problem is that even if this is done, in the reactor core, the radioactivity is so great that a lot of heat is continuously given off by the used fuel assemblies and, even when shutdown, the reactor must continue to be cooled continuously, because this fuel will cool very slowly over time.
This is why it is extremely important to have operational cooling systems.
However, with the tsunami, these cooling systems were rendered inoperative and the temperature in the core of the reactors increased.
This led to the evolution of hydrogen by chemical reactions.
To lower the pressure in the reactor core, TEPCO (the industrialist in charge of the plant) decided to release a certain number of gases into the atmosphere, which led to very significant radioactive releases at the plant. outside the enclosure.
But there were also hydrogen explosions which led in particular to the destruction of part of the reactor buildings number 1, 2 and 3 with a meltdown of the core of these reactors.
The spent fuel, which is initially in assemblies inside a vessel, has largely melted under the effect of heat and ended up in the form of what is called a corium, it that is, a form of highly radioactive lava, which pierced the lower part of the vessel and spread, it is not known exactly where, into the lower part.
So what happened was massive releases of radioactivity both into the Pacific Ocean and into the atmosphere of extreme gravity that made this accident one of the biggest nuclear disasters. history with that of Chernobyl in 1986 and that of Chelyabinsk in 1957 in the USSR (Union of Soviet Socialist Republics).
In Chernobyl, authorities at one point considered evacuating the city of Kiev. In Japan, with the disaster at the Fukushima Daiichi power plant, were there also fears of even more dramatic developments?
In Fukushima, the situation was really catastrophic, but it could have been even more serious if during the periods of massive discharges, the wind had been maintained in certain directions.
Most often, the wind blew from the land towards the Pacific and suddenly the radioactive substances propelled into the atmosphere went towards the ocean and at other times the wind blew south towards the sea. capital and much of the radioactivity reached the city of Tokyo and far beyond to the south.
At other times, the wind blew north-northwest and radioactive particles reached other towns and prefectures beyond Fukushima.
If the winds had been blowing constantly towards the land, the scale of the radioactive fallout would have been even more serious.
In Fukushima, in addition to the 3 reactor cores that melted, there was also the problem of spent fuel being stored in spent fuel pools.
In a nuclear power plant, the fuel must be changed periodically.
This spent fuel, which is then very radioactive, is taken out and it is placed in deactivation pools while its radioactivity and heat drop a little and it may take several years before it is evacuated to other devices.
During this period, the fuel is in a pool which is not in a bunker structure.
However, the explosions of the reactors had very damaging consequences on the swimming pools and in particular on the swimming pool of reactor number 4, which was seriously damaged by the explosion of reactor 3. Unlike reactor 1, 2 and 3, reactor 4 was at l. 'shutdown during the earthquake and all its fuel was discharged into the spent fuel pool.
There has been enormous concern that the swimming pool will completely empty its water and that the irradiated fuels will end up in the open air, heat up and release their radioactivity.
This could have created an even more dramatic situation which led then Prime Minister Naoto Kan, as he publicly admitted, to consider evacuating Tokyo.
Prime Minister Naoto Kan in the face of the Fukushima disaster.
REUTERS / Kim Kyung-Hoon
10 years after the disaster, in what state is the plant located?
Today, 10 years later, the plant is in an extremely degraded state and it is still not safe.
At all times, the industrial TEPCO must continue to inject 200 m3 of water per day to cool the highly radioactive material in the coriums of reactors 1, 2 and 3. This water, which is injected and which circulates around the coriums which are no longer protected by protective metal sheaths which have melted, is very heavily contaminated.
In addition, as this water is injected into the basements of the plant, it mixes with runoff water, groundwater and TEPCO is forced to constantly pump all these volumes of water.
To do this, it was necessary to set up various measures, including a frozen wall around the 3 damaged reactors, to keep the ground at very low temperature and for this wall of ice to limit the penetration of water, which comes from the hill located at the top. above the plant, and infiltrate under the reactors.
This makes it possible to limit repumping except when there is very heavy rains.
So TEPCO must constantly inject water, which becomes highly radioactive, it must recover this water before it infiltrates and it flows towards the Pacific Ocean and must treat all this water.
TEPCO is now faced with an almost insoluble problem, with at the moment more than 1.2 million m3 of radioactive water stored in more than a thousand tanks.
This is why TEPCO plans, with the agreement of the Japanese government, to gradually empty these tanks into the Pacific Ocean.
In addition, TEPCO has not finished removing spent fuel from the spent fuel pools, which were severely damaged by the explosions, to bring them to safety.
But the most complex problem remains the question of the coriums, these molten cores which have spread in the basements of reactors 1, 2 and 3. TEPCO has tried on several occasions to send robots to obtain information on the state of these coriums and their location, but the radioactivity is so high that several robots have been rendered inoperative.
Recently, new inspections revealed extremely high levels of radioactivity above the reactor slab of more than 10 sieverts per hour, a level rapidly fatal to humans.
We are facing an unprecedented situation: TEPCO announces that they will recover these coriums maybe by 2050, but nobody knows anything about it, nor what we will do with them if we manage to isolate them.
Perhaps in the end the government will decide to leave them there,
ad vitam aeternam
, and to cover the whole with a sarcophagus with permanent pumping systems.
We don't know what to do with these coriums.
The Chernobyl corium is still active under its sarcophagus.
And in Chernobyl, nothing is resolved either.
What were the radiological consequences for Japan and beyond?
In the case of Fukushima, there were two modes of contamination: releases into the atmosphere and into the Pacific Ocean.
Regarding the atmosphere, there was very intense radioactive fallout in Fukushima prefecture, but also in many other prefectures located to the north and south and less intensely to Tokyo.
Even in France, from the end of March to the end of April 2011, we were able to measure, with the CRIIRAD beacons in the Rhône valley, the arrival of air masses contaminated by radioactive iodine from Japan.
Today, there are heavily contaminated places in Japan, which should not be inhabited by humans for at least a hundred years or even much longer in some places.
But the Japanese authorities trivialize the seriousness of this contamination and very strongly encourage the populations to return to these territories.
Currently, the main problem comes from cesium 137: it is a radioactive metal that has been deposited, in the form of very fine dust or sometimes larger particles, on all surfaces that were in the open air (on roofs , on floors).
The contamination was amplified by precipitation (snow and rain).
This radioactive substance is still present, it has a half-life of 30 years and it will take hundreds of years for it to disappear and lose its dangerousness.
The problem is that this cesium-137, when it decays, emits gamma rays which are extremely powerful and penetrating.
This radiation passes through the walls of houses and travels in the air for tens of meters and it can even exceed a hundred meters.
Therefore it is very difficult to decontaminate.
The Japanese authorities have launched decontamination programs in certain areas which consist in stripping the earth but only a few meters around the houses, but this does not prevent exposure by radiation emitted nearby and which reaches the inhabitants to the inside their house.
Decontamination of such vast areas is technically impossible.
Unlike Chernobyl, in Fukushima, the authorities act as if the problems were solved to bring the population back when the land is contaminated with levels of radioactivity that are far above normal.
Breeder rejecting his contaminated milk ®Reuters / Yomiuri Shimbun
What happens to these contaminated lands that are collected by the authorities?
The decontamination programs that have been implemented and which consist in scraping the surface layer of the earth, pose several problems.
There is first the question of the exposure of the people who do this work and who take doses of radioactivity and then once these lands are put in bags, what do we do with it?
There are storage and security issues.
What we see are deposits of these bags everywhere, in a vacant lot, next to a housing estate, not far from a school, etc ... The partial decontamination generated more than 17 million m3 of radioactive waste and bags of contaminated soil.
A part is being regrouped on a temporary storage site planned for 30 years.
However, this period is insufficient, these bags should be secured over a hundred years or even much longer for some of them.
So this question of the land is not resolved.
The problem of organic waste is not solved either.
These wastes, such as tree leaves, are also collected and the strategy is to incinerate them.
The filtration systems of incinerators are never perfect and this creates redistribution in the atmosphere and we do not know how to store the ashes which are very radioactive.
To be able to manage the disaster, the authorities change the standards.
The maximum allowable dose for a human being is normally 1 millisievert per year.
But in Fukushima, the Japanese authorities have increased this dose to 20 millisieverts per year.
So we began to accept that citizens are exposed to a risk of cancer 20 times higher than what was previously considered unacceptable.
For the management of polluted land, in Japan from 100 becquerels per kg, a specific management mode must be applied.
However, this standard has been increased to 8,000 Bq / kg.
This waste will be able to be reused as a road underlay, for example, and will therefore be dispersed and irradiate other people.
Finally, there is the issue of contaminated water that TEPCO wishes to discharge into the Pacific when it does not meet the standards in terms of radioactivity concentration.
A nuclear disaster is by definition unmanageable and to limit management costs, the authorities change the safety and health protection standards for populations and accept what was previously unacceptable.
To revive the economy in contaminated territories, for example, the population has been encouraged to return while the doses suffered remain too high.
What is very shocking in Fukushima is this trivialization, this minimization of risk to make people believe that all is well.
What do we know about the contamination of populations
?
The number of people who have been exposed to radiation is in the millions, but then it is very difficult to have an accurate estimate of the doses to these populations.
In addition, there have been underestimates of reality.
For example, when the World Health Organization (WHO) published a report to try to estimate the number of cancers that will occur as a result of the doses received, it did not take into account the real levels of contamination.
A few days after the disaster, when the first analyzes on the contamination of foodstuffs fell, there were in certain territories, including more than 30 kilometers from the Fukushima plant, plants and food which were contaminated to several million of becquerels per kilogram of iodine 131. Certain population groups in Japan at the time received doses of radiation by inhalation, then by ingestion and by what is called external irradiation, that is to say by the radiation continuously emitted from the contaminated soil, which is very far above the health limits.
So obviously there will be heavy health consequences on the Japanese population, whether it is an increase in cancers, but also other pathologies: of the digestive system, the cardiovascular system or on cognitive capacities.
There may also be a trans-generational effect such as that observed on rodents in Belarus following the Chernobyl disaster.
In the air of Fukushima prefecture, for example, the cesium-137 concentration has not returned to the pre-disaster level.
Today, the Japanese are still exposed to radiation emanating from contaminated soils.
In many towns, you have radiation levels 1 meter above the ground which are more than 100 times higher than the usual level.
Now, to assess the health consequences, there would have to be rigorous studies and this is not the case.
The existing studies are not up to the task and do not make it possible to identify all the pathologies linked to the disaster, nor to compensate the populations, but that is a political will.
Anti-nuclear demonstration in Tokyo on 03/08/2015. REUTERS / Thomas Peter
How did civil society organize itself to have reliable and independent information?
At CRIIRAD, we were approached very quickly, from the first days after the disaster, by Japanese citizens and by French people living in Japan.
They wanted advice, independent information and measuring devices.
We set up technical assistance with equipment and training, which contributed to the emergence of a network of citizen laboratories in Japan which were called at the time CRMS, Citizen's Radiation Monitoring Station.
There have also been other initiatives carried out by other French and German organizations and today there is a network of independent information centers in Japan which has produced in particular a map of soil contamination in Japan: more of 4,000 volunteers collected the samples according to a rigorous protocol, 31 citizen laboratories analyzed them.
Map which is currently available in French.
At first, there was a strong demand for information, but since then, many people no longer want to be told about radioactivity and some independent laboratories are having financial difficulties to continue their work.
What lessons do you draw from this disaster?
What Fukushima shows us is that man is not capable of dominating nuclear energy and that from the moment a disaster strikes, we find ourselves in a situation which is totally unmanageable, either in relation to the recovery of molten corium, the cooling of reactors, the management of contaminated soil.
We find ourselves in a universe of the absurd, a universe of lawlessness, that is to say that all the standards of protection that existed before, all the values that existed before are upset.
The nuclear industry is one of the few industries, if not the only one, that governments allow to operate when it is not insured to the extent of the damage it can cause.
The financial assessments of the consequences of the Fukushima disaster in Japan alone which were published a few years ago by the Japan Center for Economic Research were over 640 billion euros (estimate of dismantling costs, compensation for populations , decontamination, waste management, etcetera).
However, nuclear third party liability limits the costs attributable to the operator to almost nothing (in France to 700 million euros, ie almost 1,000 times less).
And this is something that is not acceptable.
If we agree to operate nuclear installations, if the populations and governments accept it, they must be properly informed and accept the risk of a nuclear catastrophe.
But do they have a correct perception of the environmental, health, social and economic consequences of nuclear disasters?
Under the impetus of France, the international nuclear lobby has succeeded in raising the acceptable levels of radiation after a nuclear disaster: just like in Japan, the limit of 1 mSv / year will no longer be in force;
the reference (because it will not even be a limit anymore) will be 20 mSv / year.
Those who do not wish to live in such contaminated territories will have to assume all the consequences because they will not be compensated.
Information sites communicated by Criirad:
The educational film
Invisibles Fallout
(French version with English subtitles)
The webinar organized by CRIIRAD on March 6, 2021
The interactive citizen map of soil contamination in
Japan
Major Reports produced by RFI in Fukushima in March 2012:
Fukushima, the nuclear disaster
Fukushima: The impossible management of a disaster
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