Nuclear Power

This is the text of the talk that I wrote for Interesting2009. It’s not quite the talk that I gave; I cut some material for the sake of time and because I forgot to mention a couple of points.

Good morning. My name is Alby Reid, I’m a physics teacher and I think nuclear power is Inter­esting. Today I’m going to try and convince you that nuclear power is – by far – the best solution to the problems posed by anthro­po­genic green­house gas emis­sions and that it’s clean, safe and reliable too.

When most people think of nuclear power they think of this: a mushroom cloud.

When they should be thinking of this: this is class 4G. As part of learning about elec­tri­city and energy they all measured their elec­tri­city usage at home for a week. On average class 4G used 978 watts.

This is a graph of elec­tri­city con­sump­tion in the UK for this day last year. It ranged from 27 gigawatts at about half-four in the morning and peaked at 37 gigawatts at about half-seven in the evening.

Real time demand data and his­tor­ical demand data is avail­able from the National Grid website. The important column is “TGSD” — Total Grid System Demand.

If you look at the UK as a whole you find an average power con­sump­tion of 39 gigawatts and a maximum con­sump­tion of 58 gigawatts. That’s equi­valent to 955 watts for every single man, woman and child in the United Kingdom. The UK simply cannot cope with this demand.

How Long Till The Lights Go Out is avail­able at The Economist’s website.

In the first six months of this year we imported more than 3500 gigawatt-hours of elec­tri­city from France, along a 2-gigawatt DC cable that runs from Sangatte to Folkstone.

The his­tor­ical demand data ref­er­enced above includes data on imports from France.

France gen­er­ates 78% of its elec­tri­city from nuclear power, is the world’s largest elec­tri­city exporter and has some of the cheapest elec­tri­city and cleanest air in Europe.

So the first thing anyone says when I talk about nuclear power is what about Chernobyl?

Chernobyl has to be one of the most mis­un­der­stood acci­dents in history. Every­body has heard of Chernobyl. Every­body knows that Chernobyl is some sort of nuclear waste­land like Hiroshima, or Nagasaki. It’s not like Chernobyl has a hotel or a shop or a bar.

It’s not like you can go on holiday to Chernobyl. I love that the Top Rated Attrac­tion is “Reactor Number 4”. It’s cer­tainly not like you can stand a few hundred metres from the reactor itself and take pho­to­graphs.

It’s impossible for “another Chernobyl” to occur. The reason that the explo­sion at Chernobyl was so sig­ni­ficant is that Chernobyl didn’t have a con­tain­ment dome and this meant that the explo­sion that occurred wasn’t con­tained. Nobody builds reactors without con­tain­ment domes any more.

And it’s worth pointing out that this was not a nuclear explo­sion; nuclear power plants cannot explode like nuclear weapons.

Uranium comes in two flavours – isotopes – called U-235 and U-238. When you dig uranium up out of the ground the vast majority is U-238, only a tiny fraction is U-235.

Uranium-235 is “fissile”; it can fission spon­tan­eously and release energy in the process. In order to be used in nuclear power plants the fuel must be enriched, increasing the per­centage of U-235 from 0.7% to between 3% and 5%. In order to be used in the nuclear weapons the fuel must be much further enriched, to a minimum of at least 90%. This enrich­ment process is very, very dif­fi­cult, that’s why nuclear weapons are hard to make, not because the uranium itself is hard to find. This is why the idea of ter­ror­ists stealing nuclear fuel to make a bomb is nonsense.

There is no doubt that what happened at Chernobyl was a horrible accident. But it wasn’t as horrible as you think. Nothing about Chernobyl has been quite as exag­ger­ated as the number of deaths caused. How many people do you think have died because of Chernobyl? The answer is 56.

The figure of fifty-six deaths comes from the Chernobyl Forum’s report Chernobyl’s Legacy: Health, Envir­on­mental and Socio-Economic Impacts (.PDF, 902kB). The Chernobyl Forum is an inter­na­tional mul­tidiscip­linary group made up of rep­res­ent­at­ives from Inter­na­tional Atomic Energy Agency, the World Health Organ­isa­tion and UN agencies such as the Food and Agri­cul­ture Organ­isa­tion, the Office for the Coordin­a­tion of Human­it­arian Affairs, the Sci­entific Com­mittee on the Effects of Atomic Radi­ation and the Devel­op­ment and Envir­on­ment Programs.

31 firemen and power plant workers died within a few days of acute radi­ation sickness and a further 25 have died of thyroid cancer. Compare this with the 75 people who died less than a month ago when a turbine exploded at the Sayano-Shushenskaya hydro­elec­tric power station in Russia. Or compare it with the thou­sands of people that die every year mining coal in China, more than 4700 in 2006.

What about all the horrible birth defects?

Birth defects are another issue entirely. There is a common mis­con­cep­tion held that the Chernobyl accident resulted in the birth of thou­sands of children with birth defects. This simply isn’t true. The same mis­con­cep­tion is also held about sur­vivors of the nuclear attacks on Hiroshima and Nagasaki during World War II. In both cases the rates of birth defects are in line with the expected averages.

There is inform­a­tion on birth defects in the Chernobyl Forum’s Chernobyl’s Legacy report ref­er­enced above. More inform­a­tion was taken from a paper in the journal Tera­to­logy by Frank Castro­novo Tera­togen Update: Radi­ation and Chernobyl (.PDF, 54kB). Inform­a­tion on birth defects among sur­vivors of Hiroshima and Nagasaki comes from the US-Japan Radi­ation Effects Research Organisation’s report Birth defects among the children of atomic-bomb sur­vivors (1948 – 1954).

Radi­ation can cause tem­porary and per­manent ster­ility but gen­er­ally it does not cause birth defects. Birth defects are usually caused by chem­icals caused tera­to­gens; the most famous being thalidomide of course. Agent Orange, the so-called “last ghost” of the Vietnam War, has caused at least half a million birth defects.

This is the Inter­na­tional Nuclear Event Scale. It ranges from Level 1 to Level 7. Chernobyl is the only Level 7 accident ever to occur, more than twenty years ago. The most recent Level 6 event was in 1957. The most recent Level 5 event was Three Mile Island (which killed noone) in 1979. The most serious event in the UK was more than fifty years ago, the Level 5 incident at Sel­lafield (called Wind­scale at the time) in 1957 in which nobody was harmed and no evac­u­ation took place.

The IAEA pub­lishes an Inter­na­tional Nuclear Event Scale Factsheet (.PDF, 188kB).

When was the last time you heard of a nuclear accident? Japan and France are the second– and third-largest gen­er­ators of nuclear power in the world. Can you name a French or Japanese nuclear accident? Before I started talking could you have named a nuclear accident other than Chernobyl?

In his excel­lent book, Stum­bling on Hap­pi­ness, Dan Gilbert, an eco­nomist from Harvard who works in the field of affective fore­casting, explains that the easier some­thing is to bring to mind, the more likely you are to think it is. Chernobyl is a very mem­or­able event and people there­fore tend to over­es­timate the chance of a Chernobyl-like event occurring.

In the book Gilbert is writing about a paper he co-authored: The Least Likely of Times: How Remem­bering the Past Biases Fore­casts of the Future which appeared in the journal Psy­cho­lo­gical Science.

So if acci­dents aren’t a concern, what about delib­erate attacks? What if, for example, someone crashed an aero­plane into a nuclear power plant?

I can show you exactly what happens: the plane turns into dust.*

In this exper­i­ment an F-4 Phantom was crashed into a concrete block the same thick­ness as a con­tain­ment dome at 480 miles per hour. Even without the steel rein­force­ment that nuclear power plant walls have the F-4 with its heavy engines and con­cen­trated mass was only able to make a two inch dent. A slow, empty tin can like a 747 would barely make a scratch.

The Indian Point nuclear power station is less than forty miles from the World Trade Centre, under five minutes at cruising speed in a 767. It’s a large, very recog­nis­able target.

If you’re planning on attempting a ter­rorist attack you want to aim for one of the large domes, but I wouldn’t bother if I were you – you’ll simply turn your aero­plane into tinfoil. If your aim is to create a fire, rather than actually pen­et­rate the domes then you’ll want to bear in mind the fact that the domes are fire­proof and that nuclear power stations have their own fire brigades. Only non-nuclear com­pon­ents are kept outside the domes.

So what about the waste?

Both state­ments are true: nuclear power stations do produce thou­sands of tons of nuclear waste. Nuclear waste is dan­gerous for thou­sands of years. But some­where in the middle Green­peace and Friends of the Earth have pulled a classic bait and switch.

The thou­sands of tons of waste includes all grades of waste, including low level waste made up of things like lab coats and air filters that must, by law, be clas­si­fied as nuclear waste and disposed of securely.

But the waste that’s dan­gerous for thou­sands of years is only the high-level stuff.

And I should point out at this stage that at least nuclear waste even­tu­ally becomes safe. The heavy metals and pois­onous chem­icals like cadmium, arsenic, hydro­fluoric acid and boron tri­flouride that are used to produce solar panels and ash from fossil fuel power stations stay pois­onous for ever.

As you can see, this high-level waste makes up only three percent of the total. And this idea of being dan­gerous for thou­sands of years is greatly exag­ger­ated. Waste is stored on-site, in spent fuel ponds for about forty years. After forty years the level of radio­activity has fallen by a factor of a thousand.

But this waste still has to be stored some­where. I haven’t got time to discuss all the possible options, so I’ll just give you my favourite: sub­seabed disposal. In sub­seabed disposal the waste is dumped into imper­meable red-clay sediment on the ocean floor, four miles under­water. It sinks thirty metres into this layer and is then con­tinu­ally buried deeper and deeper as more sediment is depos­ited. All takes place in what are called sub­duc­tion zones where one tectonic plate moves over another, meaning that even­tu­ally the waste is simply subsumed into the Earth’s core from whence it came.

It’s all a matter of energy density: bear in mind that one kilogram of uranium in a fast-breeder reactor contains as much energy as 180 of the largest tanker trucks full of crude oil.

So will nuclear fuel run out? The simple answer is yes. Even­tu­ally nuclear fuel will run out. But not for thou­sands of years, even if we gen­er­ated all the world’s elec­tri­city from it. People have this idea that uranium is some sort of bizarre rare element: it’s not. Uranium is more common than tin. We’ve basic­ally stopped pro­specting for uranium because supply is exceeding demand, there are vast areas yet to be explored. Uranium makes up 3.3 parts per billion of seawater, and there’s a lot of seawater out there, seawater which is con­stantly being replen­ished as rain­water runs through uranium-containing rock. Even if all the uranium was used up, there’s still plutonium and thorium, and thorium is three and a half times more common than uranium.

World­wide energy usage for all forms of energy, not just elec­tri­city, is about 500 billion billion joules per year. One kilogram of natural uranium in a fast breeder reactor provides about 24,000 billion joules. To provide one year’s worth of energy would there­fore require just over 20 million kilo­grams (20,000 tons) of natural uranium. Known reserves on land are cur­rently estim­ated at just under five and half million tons, equi­valent to more than 260 years of energy. This does not include the uranium dis­solved in the oceans, a further four and half billion tons.

Some people have claimed that nuclear power doesn’t prevent carbon dioxide emis­sions. Even when the entire elec­tri­city gen­er­a­tion chain is taken into account, including con­struc­tion, fuel pro­cessing and decom­mis­sioning, nuclear power still produces less carbon per unit of elec­tri­city than other methods. Again, this is a function of energy density – a small nuclear power plant can produce a huge amount of elec­tri­city for many, many years.

I wish I had more time. I wish I had time to explain why hydrogen powered cars are impossible without huge amounts of elec­tri­city to produce the hydrogen. I wish I had time to explain the problems of baseload power and load-balancing that solar power and wind power simply cannot solve. I wish I had time to explain why “dirty bombs” are weapons of mass dis­rup­tion, not mass destruction.

But I don’t have time for any of this. I hope that some of you will go on to find out these things for yourselves.

Thank you.

Further Reading:

Sus­tain­able Energy — Without the Hot Air by Prof. David MacKay is an excel­lent intro­duc­tion to the energy crisis and possible solu­tions. The author has just been appointed Chief Sci­entific Advisor of the Depart­ment of Energy and Climate Change which is excel­lent news. The entire book is avail­able for free online.

Power to Save the World: The Truth About Nuclear Power by Gwyneth Cravens is the perfect layman’s intro­duc­tion to the real­ities of nuclear power. It’s my go-to book for non-physicist friends looking for more inform­a­tion. A fant­astic con­ver­sa­tion between Cravens and Rip Anderson that took place at the Long Now Found­a­tion is avail­able on FORA.tv.

Video:

A longer (and ridicu­lously over-stylised) version of the video of the F-4 Phantom collision:

[googlevideo]http://video.google.co.uk/videoplay?docid=3939904420012109745[/googlevideo]

And a video showing the testing of the flasks used to trans­port nuclear waste, including a head-on col­li­sion between a full-size railway train at 100mph and a dousing in burning jet fuel for an hour and a half:

[youtube]http://www.youtube.com/watch?v=as3VQeYfd2c[/youtube]