[MUSIC] Now that we understand in the broadest terms how a nuclear fission reactor works, we can begin to look at the problems other than costs with nuclear energy. There is the problems which I have listed here and these are purely problem linked with a nuclear power plant, it looked at as an energy producing entity. So I'm neglecting for the moment what I personally think are probably the most important reservations, which is a possibility of military proliferation. But let's just look at the nuclear power plant as any other power plant. So, from this perspective, the problems are storage, sustainability, the possibility of catastrophic accidents, the melting of the core, reprocessing of fuel, and then we put proliferation in a separate discussion. So let's begin with storage, which is something that many people are justly and rightly concerned about. One redeeming feature from the point of view of the logistics of containing and storing the really nasty part of the nuclear waste is that the volume of waste produced by nuclear reactors is very small. The ash from ten coal-fired power stations would have a mass of four million tons per year, so roughly 40 liters per person per year. The nuclear waste from Britain's ten nuclear power stations has the same value as one bottle of wine. Most of this is low level waste, 7% is intermediate level waste, and 3% of it, 25 milliliters per person per year is high level waste. So there is a nice way of picturing what I call the nuclear waste wine bottle. I have 760 milliliters liters of low level waste, 60 milliliters of intermediate, and somehow we have to do something clever with the remaining 25 milliliters per person. I simply mentioned the volume by stressing the logistical aspect of the problem. So this high level waste is really, really nasty stuff. Conventionally, it is kept in the reactor for about 40 years, it is stored in pools of water where it is cooled, and in about 40 years, it loses its level of radio activity by a factor of about 1,000. It is still totally unacceptable level of radio activity even after 40 years. If we re process the waste, separating of the uranium plutonium for use in new nuclear fuel, after about 1,000 years, the radio activity of the high level waste, the remaining 3% with 25 milliliters is about the same as a radio activity of natural uranium ore. Therefore, we can conceptualize the problem as waste storage engineers need to find a solution in to find the plan to secure high level waste for about 1,000 years. This is a difficult problem, but it is not an insurmountable problem. 1,000 years is certainly a very long time compared with a lifetime of government sort of countries. But the volumes are so small that probably nuclear waste is a problem that can be rationally, logistically tackled. Even over a lifetime, 25 millimeters per year would give less than 2 liters per person, we multiply as usual by 60 million people. So the lifetime volume, lifetime volume of nuclear waste is the same as 35 Olympic swimming pool. So if we know how to contain 35 Olympic swimming pools for 1,000 years, which don't take an enormous amount of space, we can have a handle on the problem. Now, Catastrophic accidents, it is something which is attracts attention a lot, and obviously, the dangers are very salient after something, such as what has happened at Chernobyl. However, I would like to put the discussion in perspective and to point out all energy sources inflict costs in terms of loss of human life. And it is important to distinguish, you look at the safety of different energy sources. The safety of a power plant operating as expected or with let's say run of the mines accidents and catastrophic accidents. Catastrophic accidents are clearly worse in the case of nuclear power plants. But let's look at the range of accident that we can expect from different power stations and let's try to compare them. In order to quantify the public risk from different power sources, one needs a new unit, the deaths per gigawatt per year. What does it mean to say that a power source has a death rate of one gigawatt per year? Well, one gigawatt per year is the energy produced by one gigawatt power station if it operates flat out for a full year. And therefore, we look at how many deaths are associated with different generation of power sources. And we have to keep in mind that in the UK, 3,000 people die per year on British roads. So that is one in terms of reference. So since we're not campaigning for the evolution of roads, one made it use that one death per gigawatt year is a death rate. That is very, very sad, but it's something that we could accept, a tenth of that would obviously be better. But it takes only a moment's reflection to think that disasters on oil rigs, a helicopter lost at sea pipeline fires, refinery explosions, coal mine accidents, etc, inflicts a lot more than one death per gigawatt per year. What are the actual death rates from a range of electricity sources? The death ranges vary a lot from country to country. For instance, if you look at coal mines, the death rate in China is about 50 times as large as the death rate from most countries. And we're going to see in the next figure, the averages from a number of EU studies. Nuclear and wind in the normal course of operation are the best with death rates below 0.2 per year. So this picture here shows death rate per annum coming from coal, lignite, peat, oil, gas, nuclear, biomass, hydro, and wind. And as you can see in a normal course of operation, wind and nuclear have the lowest death per annum. However, one might argue the normal course of operation is really not that one is worried about when it comes to nuclear, because one is really worried about the possibility of catastrophic accident at Chernobyl. And this is a very valid concern, and that is why we're going to look at this dimension of the problem here separately. [MUSIC]
