[MUSIC] As we have said, understanding what can go wrong in the case of a catastrophic accidents is key to make an informed judgment about the desirability of otherwise of nuclear problems. So in this session, we're going to look at briefly, as usual, what went physically wrong Chernobyl, how the accident was managed at the time, and what is this showing us about the intrinsic risk of catastrophic nuclear accidents. And the relevance of the risk culture around nuclear installation and the interplay between the two. One point that I would like to make is that looking at the intrinsic risk of power station in isolation doesn't make a lot of sense unless we couple this with the risk culture of the people who operate the power station itself. And I'll elaborate on this point later on. So what happened at Chernobyl? The accident at Chernobyl happened in 1986, in what is now Ukraine, but was of the time part of the soviet union. President of the Soviet Union at the time, was Gorbachev. Gorbachev is known in the West, at least as the initiator of glasnost openness and as the person who was ultimately responsible for the break up of the Soviet Union. But in the early days in 1986, what Gorbachev was attempting to do was not at all to break up the Soviet Union, was not really to change the communist system, but to make the communist system more efficient. Gorbachev was perceiving that the communist economies were not performing as efficiently as the Western one and it made it his goal to make the soviet communist economy as efficient as the Western one. So efficiency was a key imperative in 1986. Now in the central control structure of the Soviet Union at the time, the way efficiency was forced down into the periphery was by imposing targets. So each area, it's region at a certain target for production of whatever and in particular for energy production. So all reactors and actually all energy plants were under very strict targets. And they had to meet these targets and they would get compensation and bonuses and accolades if they could meet the targets and they would be reprimanded if they would fail to meet the targets. So this is the background in which the Chernobyl accident occurred. Now which Chernobyl accident happened during a test and the test was designed to show how the plant would operate if it lost power. The problem with the test is that during the test, the production of energy is switched off and therefore the people in charge of the nuclear reactor itself were fearing that by doing an extended test and by doing the test, using all going through all this required safety steps required by the test would entail a loss of energy productions, which would not have allowed them to fulfill the energy quota that have been imposed on them. So they can't corner us. Plant operators made several mistakes, creating a poisonous and unstable environment in the reactor core. Nonetheless, they proceeded with the experiment shutting down by hand safety systems that would be lost during a power outage, including the turbine system that provided the cooling water. When the flow reduced, the cooling water in the reactor began to boil and to turn into steam. At that point, the operators got really scared and trying to rein certain the roads to slow down and control the nuclear reaction. But a design flowing the control rods, a physical and mechanical design flow preventing them from going back in and caused them to jam. The steam is very likely to have caused an explosion, which in turn caused a second explosion seconds later. So these are the facts and the facts are not disputed. We could pose for a second to comment. We have a risk culture which is overridden if the risk culture exists. But whatever let's say, safety concerns are there at least put under huge pressure by the demands of not slackening the production of energy. And therefore we have procedures which are not followed and we have override of safety systems in order to get over with this test as quickly as possible. After the accident, the management was absolutely dreadful. For several days, the soviet authorities denied that anything had happened. Neighboring countries were observing heightened radio activity arriving in cloud forest in Sweden and Finland. The soviet authorities denied for many days that anything had happened at all. Internally, the contamination was such that as the radioactive material fell on grass, Chernobyl was an agricultural area. Therefore the ready activity that fell on grass was eaten by cows and then the cows would, it would go into the meat of the cows and into the milk produced by the cows. And what the soviet authorities stipulated was that meet with high levels of radio activity instead of being disposed of, it would be put into a freezer and to wait until the radiation level fell. Medium and low level meat was supposed to be mixed with clean meat and made into sausages, which was supposed to be safe. However, despite the fact those sausages were labeled as normal and when sent all over the country, they were told not to send the sausages to Moscow. So this, I am bringing this up in order to to stress the fact that we should always look at an event in conjunction with the way the event of a disaster of the stress situation. The risk management culture is as important as the event in itself. Okay, so how serious was the Chernobyl accident? The number of direct dates is not disputed and is a number between 30 and 56. The number of indirect dates is much more contentious. And the point I want to stress here is the absolute importance of looking carefully at sources when you're doing this type of analysis. And I'm showing here four different sources, one which is the World Nuclear Association, one which is the government of today's Ukraine, one which is the WHO in the United Nations, and the Scientific Journal Nature. Starting from the version, let's call it the version of the World Nuclear Association. Well, this is the most benign version and it says that there is no evidence of a major public health impact attributed to radiation exposure 20 years after the accident. And it's tragic that the 1986 disaster at Chernobyl was the product of flawed Soviet reactor design couple with serious mistake made by the plant operators. And it was direct consequence of the Cold War isolation and the resulting lack of any safety culture. And according to the World Nuclear Association, with the exception of thyroid cancer, it says that we have not revealed any statistically significant increase in either cancer morbidity or mortality induced by radiation. So from this version that is really nothing much to worry about. We have those unfortunate 30 to 60 days, which are tragic and very terrible, but there is no big major impact. Well, who are the World Nuclear Association? Well, if you look up in the affiliation, this is our members are responsible for virtually all of the world's uranium mining conversion, in which means fuel fabrication or reactive enders, major nuclear engineering constructing etc, etc. I'm not saying for a second that therefore their information is unreliable, but certainly it should be taken with a very healthy pinch of salt. Let's move from here to the Ukraine version. As I said at the time, Chernobyl was part of the Soviet Union, but now it is part of Ukraine and it doesn't require a lot of knowledge of geopolitics to remember that Ukraine is not currently the friendliest terms with Russia. And therefore, it is not surprising that the version that is put forth by the Ukrainian authorities is the most damning version of what happened. And the Deputy General of the National Research Center for Radiations says that three million in Ukraine have suffered as a result of Chernobyl. Note that the term has suffered is extremely vague, and in Belarus, around 800,000 people would register is being affected by radiation. Again being affected is not very very clear. Let's try to go to a more unbiased report, the United Nations and the WHO, World Health Organization in 2006. Therefore, 20 years after the Chernobyl accident produced a report. And the first piece of information was, everybody agrees on 50 deaths directly attributed to the disaster. And it finds that it is difficult to assess the impact of morbidity and mortality due to cancer because there is a latency period in the cancer. So the first cancers don't appear immediately, but they appear after about 10 years. So doing 20 years, this study is just just enough in order to be able to capture this effect. And they come up with an estimate of about 4000 extra deaths due to radiation because of cancers induced by Chernobyl fallout. Immediately after that very reputable, very famous Nature Journal challenge the accuracy and precision of the United Nations report and came up with the new estimates and estimated that perhaps another 5,000 days, which is a very high number. So you put them together, we are getting close to 10,000 deaths were caused by the Chernobyl accidents, amongst the approximately 7 million people living around the Chernobyl power plant. 10, 000 deaths is a very, very high number, but let's try to put this number in context. This is what we're going to do next. As they said, what I would like to do now is to put into context this terrible numbers. So it is not just a 50 direct deaths that we are concerned with, but it is the 5,000 to let's call it 10,000 deaths that could have been caused by an accident such as Chernobyl. And also Chernobyl has been the most severe accident that has occurred in the history of nuclear industry, but there is no guarantee that nothing worse might happen in the future. And typically in this kind of analysis, a very, very rough and ready and said rule of thumb is take the worst that has happened and double it. So we are of the order of tens of thousands of deaths, which is an absolutely terrible number. I'm trying to put this number in context by looking again using the WHO as a source and the number of deaths per year which are attributable to outdoor air pollution. And this number is absolutely staggering, is 4.2 million deaths which droves literally by order of magnitude the any realistic estimate of what an extremely severe nuclear reactor accident might create. Worlds wide air pollution accounts for 30% of lung cancer, 30% of stroke, a quarter of heart attacks, and 17% of acute respiratory infections. So these are absolutely staggering numbers. And clearly nuclear powers for all their blemishes do not produce any outdoor pollution. So they could play a really important part In cutting the air pollution that cuts 4.2 million deaths. So if we look from a strictly, if you want to rather, it sounds rather cynical but comparing that there is really no compelling reason why nuclear power plants should be considered so much more dangerous and unreliable than other sources of energy that we routinely accept. However, I am the first to admit that looking at the problem in its entirety is more complex than this. The element that worries me most is not so much the storage of the really nasty part of a radioactive waste. It is not the possibility that there might be in the future a really severe catastrophic A la' Chernobyl nuclear accident. What really worries me is the potential that comes from nuclear proliferation. Now, the sad fact is those countries that turned their back on nuclear power plants as energy sources unfortunately tend to be the countries with the highest energy safety standards, highest and best risk cultures, and that posed the least geopolitical risk. When it comes to the possibility of using radioactive material, not for the purpose of energy creation, but for the purpose of military nuclear proliferation, this is one aspect that worries me a lot and that makes me pause more than all the other considerations put together when it comes to making a choice between nuclear and not nuclear energy sources. From this strictly energetic point of view, especially when nuclear power plants are installed in countries with high risk culture, developed risk culture, good safety system, etc. I think there are much less risk and much more desirable than many other sources. Nonetheless, the existence of these radioactive material that can be used for nonenergy purposes does worry me. And it becomes, obviously my worries become increase because once we establish a widespread nuclear industry, it is very difficult, if not impossible to say yes, this country you are allowed and know that country, no, you're not allowed. And when I see countries that are perhaps rich in oil and are in geopolitically unstable parts of the world who currently undertake nuclear development programs, which supposedly are for energy purposes, it does raise a question mark. And this is to me, the real question that should be asked in order to assess the desirability of nuclear power plants. From the purely energetic point of view, just thinking of climate change and nothing else, I think that should play a very important role. There are as they have tried to discuss other considerations that you are as well equipped as I am to a point about. [MUSIC]
