What is Vladimir Putin playing? Not content with having declared war on Ukraine on February 24, arguing that the country must be “denazified” and that NATO was preparing to attack it, in defiance of all reality, the head of the Kremlin also ordered his armies to take control of Ukrainian nuclear power plants. For the moment, no reactor or sensitive installation has been bombed, but an administrative building at the Zaporijia power station, the largest power station in Europe, was still hit and caught fire at the start of the week.
At Chernobyl, more than 200 technicians and guards are stuck on the site. The rotations have been interrupted, for lack of personnel, and those present on the spot have already worked fourteen days in a row, eat a single daily meal in order to hold out as long as possible on the reserves, according to the BBC, and only sleep two hours a day. This Wednesday, the International Atomic Energy Agency (IAEA) announced that communications with the plant have been cut off. Hours later, the plant’s Ukrainian operator said it was “completely shut down” due to the Russian offensive.
To these already worrying problems is added that of the management of irradiated fuels which are in the cooling pools or in concrete containers on the surface and which also represent a significant risk, underlines the radiochemist Bernd Grambow, professor emeritus at Subatech, a joint research unit in nuclear physics and radiochemistry between IMT Atlantique, the University of Nantes and CNRS-IN2P3.
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L’Express: How might the IAEA lose communications with Chernobyl?
Bernd Grambow : Two hypotheses are possible: either the telephone and/or Internet lines have been broken, or the agents supposed to report the information can no longer do so. The latter are normally required to give news every day to the local and international monitoring authorities in order to report any failures or problems, such as exceeding the radiation level threshold.
Why is this problematic?
This is very worrying because the communication of information is the foundation of radiation protection [NDLR : les mesures prises pour assurer la protection de l’homme et de son environnement contre les effets des rayonnements ionisants]. Breaking this chain of information does not represent a risk in itself, but the fact that the security authorities, deprived of information, can no longer provide assistance in the event of a serious problem, is.
Everything therefore depends on the local teams. Gold, the technical staff, which is under the control of the Russian military, has not been rotated since February 23. Working conditions are therefore seriously threatened. The Russian military probably does not want to trigger a catastrophe that would contaminate everyone, including them, but they do not know Chernobyl, its vital equipment, its alarms, and do not necessarily have knowledge of the importance of irradiated fuels, which represent a significant risk.
The other source of concern is that the IAEA no longer has access to the instruments that make it possible to verify that the nuclear materials on site remain in the same place, which is one of the conditions allowing the non-proliferation of nuclear weapons, because fissile materials, in large quantities, can be used to make weapons.
What do these fuels look like, how are they usually protected?
Irradiated or spent fuel is fuel that has been used in nuclear reactors for several years. They take the form of batches – we call them assemblies – of a hundred pencils four meters in length and one centimeter in diameter. They are very hot and naturally take between a hundred and a thousand years to cool. During this time, their radioactivity remains very high. No one can stand nearby without being seriously irradiated. Reason for which it is necessary to surround them with barriers of lead, concrete, or water.
There are several ways to manage these fuels. They can be reprocessed, in order to separate the uranium from the plutonium, as in France at La Hague. They can be stored over the long term, thanks to deep burial in storage containers for example. Or they are stored in the short term, which is done in two stages. First, the rod assemblies are stored in pools located inside nuclear reactors. They make it possible to accelerate the cooling time and bring it back to around thirty years, and they also avoid a potential chain reaction of the materials.
View of a cooling pool (here that of a pool at the Saint-Laurent-des-Eaux nuclear power plant, April 20, 2015). The spent nuclear fuel rods are stored at the bottom of the twenty meter deep pool.
WILLIAM SOUVANT/AFP
Then, several assemblies, i.e. a few hundred or even thousands of rods, are placed in concrete containers, which are themselves generally stored in shielded enclosures on the surface, where engineers regularly check the tightness of the containers and the transfer of heat to ensure that no chain reaction occurs.
How are these fuels managed in Ukraine?
Ukraine reprocesses a small part of its fuels in Russia, but most of it is stored on site, in pools or in concrete containers above ground. They don’t have a long-term storage solution yet. Moreover, very few countries in the world have them, apart from Finland and Sweden. In France, the basic decision was made with the law of 2006 and we are moving more or less towards deep storage. There is a project in Bure, but a few decision steps are still missing before the first waste is buried, which will not be possible before 2025 at the earliest.
What risks are associated with spent fuel in Ukraine?
The storage process – swimming pool and surface – takes decades and must be strictly supervised by competent personnel during this period. Industrial processes are under control in normal times. But is this possible in times of war?
The nuclear fleet in Ukraine comprises four power plants.
L’Express
None of the reactors of Zaporijia – the largest nuclear power plant in Europe with six units – nor any fuel storage site were bombed. But an administrative building was attacked and caught fire, which may compromise the proper functioning of the plant. And Ukrainian personnel, under the control of the Russian army, no longer have complete control over maintenance. It seems that they are still working, but there are problems with communication, food supply, like in Chernobyl. This is worrying, because irradiated fuels are in a pool and in a dry storage site, yet it is imperative that the proper functioning of these facilities is ensured.
It’s the same in Chernobyl, where spent fuel is also in a pool [NDLR : 20 000 assemblages combustibles sont stockés dans la piscine d’entreposage de Tchernobyl, mais compte tenu du temps qui s’est écoulé depuis l’accident de 1986, la charge thermique de la piscine et le volume de l’eau de refroidissement sont suffisants pour assurer une évacuation efficace de chaleur sans électricité, a indiqué l’AIEA ce mercredi].
What would happen if a rocket landed in containers on the surface or if control of a swimming pool was lost?
I don’t think we should worry the population by saying that might cause a Chernobyl bis, because it was an uncontrolled nuclear reactor, but irradiated fuel has a much lower temperature than that of nuclear reactors. However, if a container were targeted, there would be a risk of radioactive leaks. And if a swimming pool were out of control, temperatures might rise and that might spell disaster.
During the Fukushima incident, the anxiety was that one of the pools where irradiated fuel was located would lose its cooling capacity and that this would cause a chain reaction capable of contaminating a very large area; which is why I am also very much in favor of deep disposal in France and elsewhere, which makes it possible to shelter this waste. There was no chain reaction in Fukushima, but a large geographical area was still contaminated.
It should be remembered that no one died directly from the Fukushima accident. [NDLR : un travailleur de la centrale est décédé d’un cancer du poumon et 2 300 personnes sont mortes lors de l’évacuation]. Nevertheless, Japan spends 12 billion euros a year to decontaminate the territory around the plant, in particular to remove the first centimeters of soil from square kilometers of irradiated areas. However, the surface soil is the most organic, so there are cascading consequences on biodiversity. Today, we are well aware of the direct impacts of radioactivity on humans (life expectancy, cancer, etc.) and on food. But I believe that we lack solid analyzes to understand the indirect risks and what they imply for humans.
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However, the situation in Ukraine should not be taken lightly. We must use diplomatic channels, or even establish a war crime relating to the takeover of a nuclear power plant, or the fact of no longer ensuring its proper functioning. Because, when you attack a power station, you put all the neighboring countries at risk.
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