IMT Atlantique | risk management, sociology, nuclear safety
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Stéphanie Tillement: Fukushima was not just a shock for Japan. Of course, the event influenced everywhere that uses nuclear energy as an important part of energy production, such as Europe, North America, and Russia; but it also affected less nuclearized countries. Fukushima called into question the safety, security and reliability of nuclear power plants. Groups which are strongly involved in the industry, such as nuclear operators, counter-experts, associations and politicians, were all affected by the event. Therefore, we expected that Fukushima would have a strong impact on nuclear governance. There is also another, more historical, reason; both the Chernobyl and Three Mile Island accidents had an impact on the organization of the nuclear industry. So, Fukushima could be part of this trend.
ST: The consequences of nuclear disasters are generally felt 10 to 20 years after the event itself. In France, Chernobyl contributed to the 2006 French Nuclear Safety and Transparency Act, which marked a major change in the nuclear risk governance system. This law notably led to the creation of the French Nuclear Safety Authority, ASN. A few years earlier, the French Radioprotection and Nuclear Safety Institute, IRSN, was created. The 2006 law still regulates the French nuclear industry today. The Three Mile Island disaster caused the industry to question people’s involvement in these complex systems, notably in terms of human error. This led to major changes in human-computer interfaces within nuclear infrastructure, and the understanding of human error mechanisms.
ST: The disaster was in 2011; it’s not even been 10 years since it happened. However, we can already see that Fukushima will probably not have the same affect in France as the other accidents. Rather than criticizing the French system, industry analysis of Fukushima has emphasized the benefits of France’s current mode of governance. Although technical aspects have undergone changes, particularly regarding Complementary Safety Assessments (CSR), the relationships between nuclear operators, the ASN and the IRSN have not changed after Fukushima.
ST: At first, the French nuclear industry thought that the Fukushima disaster was unlikely to happen in France, as the Japanese power plant was managed in a completely different way. In Japan, several operators share the country’s nuclear power plants. When analyzing crisis management, the post-accident report showed that the operator’s independence was not enforced, and that there was collusion between the government, the regulators and the operators. In France, the Nuclear Safety and Transparency Act strictly regulates relationships between industry operators and assures that each operator has their independence. This is a strength of the French governance model that is recognized internationally. As well as this, French nuclear power plants are managed by only one operator, EDF, which controls 58 identical plants. The governance issues in Japan reassured French operators, as they confirmed that legally enforcing the independence of the regulatory authority was the right thing to do.
ST: During our investigations into Fukushima, we realized that the accident did not create any new anti-nuclear movements or opinions. Opposition already existed. There is no denying that the event gave these anti-nuclear organizations, collectives and experts some material, but this didn’t radically change their way of campaigning nor their arguments. This again shows how Fukushima did not cause major changes. The debate surrounding the nuclear industry is still structured in the same way as it was before the disaster.
ST: No, and that’s also one of the findings of the AGORAS project. Recent political decisions on nuclear sector strategy have been mainly made according to processes established before the Fukushima accident. For example, the cancellation of the ASTRID project was not due to a radical political change in the nuclear sector, but actually because of economic arguments and a lack of political desire to tackle the subject. Clearly, politicians do not want to tackle these issues, as the decisions they make have an impact in 10, 20, or even 30 years’ time. This just doesn’t work with their terms of office. The political turnover also means that very few politicians know enough about the subject, which raises questions about the government’s ability to get involved in nuclear, and therefore energy politics.
Read on I’MTech: What nuclear risk governance exists in France?
ST: The AGORAS project started by asking the question: Did Fukushima cause a change in governance in the same way as the accidents that preceded it? If we look at it from this perspective, our studies say no, due to all the reasons that I’ve already mentioned. However, we need to put this into context. Many things have changed, just not in the same radical way as they did after Chernobyl or Three Mile Island. Amongst these changes, is the modification of certain technical specifications for infrastructure. For example, one of the reasons why ASN called for EDF to review the welding of their EPR reactors was due to technical developments decided following Fukushima. There have also been changes in crisis management and post-accident management.
ST: Following Fukushima, a rapid response force for nuclear accidents (FARN) was created in France to manage the emergency phase of an accident. Changes were also made to the measures taken during a crisis, so that the civil security and prefects can act more quickly. The most notable changes have been in the post-accident phase. Historically, accident preparation measures were mainly focused on the emergency phase. As a result, different roles are well-defined in this phase. However, Fukushima showed that managing the after-crisis was also equally as important. What’s unique about a nuclear accident, is that it has extremely long-term consequences. However, in Fukushima, once the emergency phase was over, the organization became less defined. No one knew who was responsible for controlling food consumption, soil contamination, or urban planning. Therefore, the local information commissions (CLIS) have worked with nuclear operators to improve the post-accident phase in particular. But, once again, our research has shown that this work was started before the Fukushima disaster. The accident just accelerated these processes and increased the importance of this issue.
ST: We would particularly like to continue to address other issues and to develop our results further. We have already carried out field research with ASN, IRSN, local information commissions, politicians, associations, and manufacturers such as Framatome or Orano. However, one of the biggest limitations to our work is that we cannot work with EDF, who is a key player in nuclear risk governance. In the future, we want to be able to work with plant operators, so we can study the impact of an accident on their operations. As well as this, politicians’ understanding could also be improved. Understanding politicians’ opinions regarding nuclear governance, and the nuclear strategy decision-making process is a real challenge.
The lithium-ion battery is one of the best-sellers of recent decades in microelectronics. It is present in most of the devices we use in our daily lives, from our mobile phones to electric cars. The 2019 Nobel Prize in Chemistry was awarded to John Goodenough, Stanley Wittingham, and Akira Yoshino, in recognition of their initial research that led to its development. In this new episode of our “What’s?” series, Thierry Djenizian explains the success of this component. Djenizian is a researcher in microelectronics at Mines Saint-Étienne and is working on the development of new generations of lithium-ion batteries.
Thierry Djenizian: It offers a very good balance between storage and energy output. To understand this, imagine two containers: a glass and a large bottle with a small neck. The glass contains little water but can emptied very quickly. The bottle contains a lot of water but will be slower to empty. The electrons in a battery behave like the water in the containers. The glass is like a high-power battery with a low storage capacity, and the bottle a low-power battery with a high storage capacity. Simply put, the lithium-ion battery is like a bottle but with a wide neck.
TD: The battery consists of two electrodes separated by a liquid called electrolyte. One of the two electrodes is an alloy containing lithium. When you connect a device to a charged battery, the lithium will spontaneously oxidize and release electrons – lithium is the chemical element that releases electrodes most easily. The electrical current is produced by the electrons flowing between the two electrodes via an electrical circuit, while the lithium ions from the oxidation reaction migrate through the electrolyte into the second electrode.
The lithium ions will thus be stored until they no longer have any available space or until the first electrode has released all its lithium atoms. The battery is then discharged and you simply apply a current to force the reverse chemical reactions and have the ions migrate in the other direction to return to their original position. This is how lithium-ion technology works: the lithium ions are inserted into and extracted from the electrodes reversibly depending on whether the battery is charging or discharging.
TD: Wittingham discovered a high-potential material composed of titanium and sulfur capable of reacting with lithium reversibly, then Goodenough proposed the use of metal alloys. Yoshino marketed the first lithium-ion battery using graphite and a metal oxide as electrodes, which considerably reduced the size of the batteries.
TD: One of the main trends is to replace the liquid electrolyte with a solid electrolyte. It is best to avoid the presence of flammable liquids, which also present risks of leakage, particularly in electronic devices. If the container is pierced, this can have irreversible consequences on the surrounding components. This is particularly true for sensors used in medical applications in contact with the skin. Recently, for example, we developed a connected ocular lens with our colleagues from IMT Atlantique. The lithium-ion battery we used included a solid polymer-based electrolyte because it would be unacceptable for the electrolyte to come into contact with the eye in the event of a problem. Solid electrolytes are not new. What is new is the research work to optimize them and make them compatible with what is expected of lithium-ion batteries today.
TD: Another promising trend is to replace the lithium with sodium. The two elements belong to the same family and have very similar properties. The difference is that lithium is extracted from mines at a very high environmental and social cost. Lithium resources are limited. Although lithium-ion batteries can reduce the use of fossil fuels, if their extraction results in other environmental disasters, they are less interesting. Sodium is naturally present in sea salt. It is therefore an unlimited resource that can be extracted with a considerably lower impact.
TD: It’s hard to say. We have to change the way we think about our relationship to energy. We used to solve everything with thermal energy. We cannot use the same thinking for electric batteries. For example, we currently use lithium-ion button cell batteries for the internal clocks of our computers. For this very low energy consumption, a button cell has a life span of several hundred years, while the computer will probably be replaced in ten years. A 1mm² battery may be sufficient. The size of energy storage devices needs to be adjusted to suit our needs.
Read on I’MTech: Towards a new generation of lithium batteries?
We also have to understand the characteristics we need. For some uses, a lithium-ion battery will be the most appropriate. For others, a battery with a greater storage capacity but a much lower output may be more suitable. For still others, it will be the opposite. When you use a drill, for example, it doesn’t take four hours to drill a hole, nor do you need a battery that will remain charged for several days. You want a lot of power, but you don’t need a lot of autonomy. “Doing better” than the lithium-ion battery, perhaps simply means doing things differently.
TD: They are names that we often mention in our scientific publications, because they are the pioneers of the technologies we are working on. But beyond that, it is great to see a Nobel Prize awarded to research that means something to the general public. Everyone uses lithium-ion batteries on a daily basis, and people recognize the importance of this technology. It is nice to know that this Nobel Prize in Chemistry is understood by many people.
Tomorrow’s medicine will be at least 4P: personalized, preventive, predictive, participative. ‘At least,’ because some would readily add “precise,” “proof” (evidence-based), “pathway-based” etc. Beyond naming this type of medicine and determining the correct number of Ps, medicine is clearly undergoing a profound change. A transformation supported in part by engineering, which is bringing major innovations to the healthcare industry. New technologies — whether in relation to digital technology or materials — have led to advances in many areas of medicine.
Researchers at Mines Saint-Étienne’s Centre for Biomedical and Health Engineering (CIS) are carrying out their research in the heart of the Saint-Étienne hospital campus. They are working to improve health systems and technology, in daily contact with medical professionals. Jérémie Pourchez is developing an artificial lung model to study certain respiratory diseases and the toxicity of inhaled particles. David Marchat is developing a new generation of bone implants to facilitate bone regeneration in grafts. As such, they are directly addressing needs for knowledge and tools expressed by practitioners.
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Meanwhile, at IMT Lille Douai, Caroline Duc is developing an “artificial nose,” an electronic device that can monitor patients by analyzing their breath – an innovation which could eventually be used to help diagnose diseases.
Sometimes innovation comes from unexpected places. This is the case for a new type of liquid xenon scanner developed at IMT Atlantique. The technology developed by physicists was drawn directly from their efforts to search for dark matter. In the future, we may be able to detect the smallest diseased cells based on our observations of the most distant galaxies!
To learn more about new healthcare technologies and how they are impacting patients and practitioners, I’MTech suggests a selection of our archives on this topic:
This article is part of our dossier “When engineering helps improve healthcare“
For the past 10 years, researchers at IMT Atlantique have been tracking dark matter as part of the XENON international collaboration. Their approach, which uses liquid xenon, currently makes them world leaders in one of the biggest mysteries of the universe: what is dark matter made of? Although the answer to this question is still waiting to be discovered, the team’s fundamental work in physics has already given rise to new ideas… in medicine! As well as detecting dark matter, the innovations produced by the XENON collaboration have proven to be extremely useful for medical imaging, as they are much more efficient than current scanners.
Improving current medical imaging techniques is one of the great challenges for medicine’s future. The personalization of patients’ healthcare and follow-up care, as well as the prediction of illnesses, mean that doctors are needing to acquire more patient data more often. However, having to remain still for 30 minutes straight is not enjoyable for patients- especially when they are now being asked to get scans more often! For hospitals, more examinations means more machines and more staff. This means that faster imaging techniques are not only more practical for patients, but also more economic for health services.
All over the world, several initiatives are competing to try and find the scanners of the future. These all have similar structures to scanners that are currently being used. “This is an area of study where investment is important” states Dominique Thers, a researcher in fundamental physics at IMT Atlantique and French coordinator of the XENON collaboration. Manufacturers are improving the scanners logically, for example, by increasing their camera size or resolution. “Since we are researching dark matter, our technology comes from another field. This means that our solution is completely different to the routes that are currently being explored”, highlights Thers, whilst reminding us that his team’s work is still in the research phase, and not for industrial use.
The physicists’ solution has been named XEMIS (Xenon Medical Imaging System). Although he uses the word ‘camera’, Dominique Thers’ description of the device is completely different to anything we could have imagined. “XEMIS is a cylindrical bathtub filled with liquid xenon”. Imagine a donut led on its side and then stretched out lengthways with a hole in the middle to form a tube. The patient is led down inside the hole and surrounded by the tube’s 12cm thick wall, which is filled with liquid xenon. Although XEMIS is shaped like any other scanner, the imaging principle is completely different. In this device, the entire tube is the ‘camera’.
To understand this, let’s go into more detail. Currently, there are two main types of medical scanners: the CT scanner and the PET scanner The CT scanner uses an X-ray source which passes through the patient’s body, and is received by a receptor on the other side of the tube. Whereas, for the PET scanner, the patient needs to be injected with a weak radioactive substance. This substance then emits ionizing radiation, which is detected by a circle of sensors that moves along the patient in the tube.
However, both devices have a size limit, which is called the parallax effect. Since the sensors face the center of the tube, their detection capacity is not the same in every direction around the patient. Therefore, image resolution is better in the center of the field of view, compared to the edge. This is why a PET scanner can only produce medical images by section, as the receptors need to be repositioned to get an accurate scan of each area of the patient.
Although XEMIS uses an injection like the PET scanner, there is no need to move sensors during the scan, as each atom of liquid xenon surrounding the patient acts as a sensor. This means that it has a large field of view that offers the same image quality in every direction. The device offers a huge advantage; now, there is no longer any need to move the sensors and work bit-by-bit. In the same amount of time as a traditional scan, XEMIS provides a more precise image; or the same quality image in a shorter amount of time.
The highly consistent level of detection is not the only advantage of this new scanner. “The substances in traditional injections, such as those with a fluorine-18 base, emit two diametrically opposed gamma rays”, explains Dominique Thers. “When they come into contact with the xenon surrounding the patient, two things happen: light is emitted, and an electrical current is produced”. This method, which is based on contact with xenon, comes directly from the approaches used to detect dark matter.
Therefore, on both sides of the tube there are interaction points with xenon. The line between these two points passes through the patient and, more precisely, through the point where the gamma rays are emitted. Algorithms then record these signals and join them together with associated points in the patient. This is then used to build an image. “Because XEMIS technology eliminated the parallax effects, the signal-to-noise ratio of the image created by this detection method is ten times better than the images produced by classical PET scanners”, explains Dominique Thers.
As well as this, XEMIS cameras give doctors a new imaging modality called three-photon imaging! Instead of using fluorine-18, the researchers would inject the patient with scandium-44, which is made by the ARRONAX cyclotron in Nantes. This isotope emits two diametrically opposed photons, as well as a third. “Not only do we have a line that passes through the patient, but XEMIS also measures a hollow cone which contains the third proton. This passes through the emission point”. The additional geometric information allows the machine to efficiently calculate the emission point using triangulation, which ultimately leads to an even better signal-to-noise ratio.
According to Dominique Thers, “By removing the parallax effect, the device can improve the signal-to-noise ratio of a medical image of a human by a factor of ten. It can improve this ratio by another factor of ten if it uses a camera that can capture the entire patient in its field of view, and another factor of ten with the third photon. In total, this means that XEMIS can improve the signal-to-noise ratio by a factor of 1,000.” This makes it possible to make adjustments that can reduce the injected dose, or to improve the imaging protocol in order to increase the frame rate of the cameras.
Researchers at IMT Atlantique have already demonstrated the effectiveness of XEMIS using three-photon radioactive tracers, but they have not yet tried this with living things. A second phase of the project, called XEMIS2, is now coming to an end. “Our goal now is to produce the first image of a living thing using a small animal, for example. This will demonstrate the huge difference between XEMIS and traditional scanners”, Thers explains. This is a key step in ensuring that the technology is adopted by the medical imaging community. The team are working with the Nantes University Hospital, which should help them to achieve this objective.
In the meantime, the IMT Atlantique team has already patented several innovations with Air Liquide for a xenon renewal and emptying system for the XEMIS camera. 30% of this technology uses cryogenic liquids. It is important that the team have already planned technical processes that will make it easier for health services to use XEMIS, just in case the scanner is adopted by the medical profession. This is a step forward in the international development of this unique technology.