## Mythconceptions

Two widely-cited defects of nuclear power are construction costs, and waste. Let's examine some aspects of these issues.

Building a nuclear power station requires huge amounts of concrete and steel, materials whose creation involves huge CO2 pollution.

The steel and concrete in a 1GW nuclear power station have a carbon footprint of roughly 300000tc02.

Spreading this "huge" number over a 25-year reactor life we can express this contribution to the carbon intensity in the standard units (g C02 per kWh(e)), carbon intensity associated with construction

### 300 x 109 g

106kW(e) x 220000 h = 1.4g/kWh(e), which is much smaller than the fossil-fuel benchmark of 400 g CO2 /kWh(e). The IPCC estimates that the total carbon intensity of nuclear power (including construction, fuel processing, and decommissioning) is less than 40 g C02/kWh(e) (Sims et al., 2007).

Please don't get me wrong: I'm not trying to be pro-nuclear. I'm just pro-arithmetic.

Isn't the waste from nuclear reactors a huge problem?

As we noted in the opening of this chapter, the volume of waste from nuclear reactors is relatively small. Whereas the ash from ten coal-fired power stations would have a mass of four million tons per year (having a volume of roughly 40 litres per person per year), the nuclear waste from Britain's ten nuclear power stations has a volume of just 0.84 litres per person per year - think of that as a bottle of wine per person per year (figure 24.13).

Most of this waste is low-level waste. 7% is intermediate-level waste, and just 3% of it - 25 ml per year - is high-level waste.

The high-level waste is the really nasty stuff. It's conventional to keep the high-level waste at the reactor for its first 40 years. It is stored in pools of water and cooled. After 40 years, the level of radioactivity has dropped 1000-fold. The level of radioactivity continues to fall; after 1000 years, the

Figure 24.12. Chernobyl power plant (top), and the abandoned town of Prypiat, which used to serve it (bottom). Photos by Nik Stanbridge.

radioactivity of the high-level waste is about the same as that of uranium ore. Thus waste storage engineers need to make a plan to secure high-level waste for about 1000 years.

Is this a difficult problem? 1000 years is certainly a long time compared with the lifetimes of governments and countries! But the volumes are so small, I feel nuclear waste is only a minor worry, compared with all the other forms of waste we are inflicting on future generations. At 25 ml per year, a lifetime's worth of high-level nuclear waste would amount to less than 2 litres. Even when we multiply by 60 million people, the lifetime volume of nuclear waste doesn't sound unmanageable: 105000 cubic metres. That's the same volume as 35 olympic swimming pools. If this waste were put in a layer one metre deep, it would occupy just one tenth of a square kilometre.

There are already plenty of places that are off-limits to humans. I may not trespass in your garden. Nor should you in mine. We are neither of us welcome in Balmoral. "Keep out" signs are everywhere. Downing Street, Heathrow airport, military facilities, disused mines - they're all off limits. Is it impossible to imagine making another one-square-kilometre spot -perhaps deep underground - off limits for 1000 years?

Compare this 25 ml per year per person of high-level nuclear waste with the other traditional forms of waste we currently dump: municipal waste - 517 kg per year per person; hazardous waste - 83 kg per year per person.

People sometimes compare possible new nuclear waste with the nuclear waste we already have to deal with, thanks to our existing old reactors. Here are the numbers for the UK. The projected volume of "higher activity wastes" up to 2120, following decommissioning of existing nuclear facilities, is 478000 m3. Of this volume, 2% (about 10000 m3) will be the high level waste (1290 m3) and spent fuel (8150 m3) that together contain 92% of the activity. Building 10 new nuclear reactors (10 GW) would add another 31 900 m3 of spent fuel to this total. That's the same volume as ten swimming pools.

low-level waste: 760 ml intermediate waste: 60 ml high-level waste: 25 ml low-level waste: 760 ml intermediate waste: 60 ml high-level waste: 25 ml

Figure 24.13. British nuclear waste, per person, per year, has a volume just a little larger than one wine bottle.

If we got lots and lots of power from nuclear fission or fusion, wouldn't this contribute to global warming, because of all the extra energy being released into the environment?

That's a fun question. And because we've carefully expressed everything in this book in a single set of units, it's quite easy to answer. First, let's recap the key numbers about global energy balance from p20: the average solar power absorbed by atmosphere, land, and oceans is 238 W/m2; doubling the atmospheric CO2 concentration would effectively increase the net heating by 4 W/m2. This 1.7% increase in heating is believed to be bad news for climate. Variations in solar power during the 11-year solar cycle have a range of 0.25 W/m2. So now let's assume that in 100 years or so, the world population is 10 billion, and everyone is living at a European stan-

dard of living, using 125 kWh per day derived from fossil sources, from nuclear power, or from mined geothermal power. The area of the earth per person would be 51 000 m2. Dividing the power per person by the area per person, we find that the extra power contributed by human energy use would be 0.1 W/m2. That's one fortieth of the 4 W/m2 that we're currently fretting about, and a little smaller than the 0.25 W/m2 effect of solar variations. So yes, under these assumptions, human power production would just show up as a contributor to global climate change.

I heard that nuclear power can't be built at a sufficient rate to make a useful contribution.

The difficulty of building nuclear power fast has been exaggerated with the help of a misleading presentation technique I call "the magic playing field." In this technique, two things appear to be compared, but the basis of the comparison is switched halfway through. The Guardian's environment editor, summarizing a report from the Oxford Research Group, wrote "For nuclear power to make any significant contribution to a reduction in global carbon emissions in the next two generations, the industry would have to construct nearly 3000 new reactors - or about one a week for 60 years. A civil nuclear construction and supply programme on this scale is a pipe dream, and completely unfeasible. The highest historic rate is 3.4 new reactors a year." 3000 sounds much bigger than 3.4, doesn't it! In this application of the "magic playing field" technique, there is a switch not only of timescale but also of region. While the first figure (3000 new reactors over 60 years) is the number required for the whole planet, the second figure (3.4 new reactors per year) is the maximum rate of building by a single country (France)!

A more honest presentation would have kept the comparison on a perplanet basis. France has 59 of the world's 429 operating nuclear reactors, so it's plausible that the highest rate of reactor building for the whole planet was something like ten times France's, that is, 34 new reactors per year. And the required rate (3000 new reactors over 60 years) is 50 new reactors per year. So the assertion that "civil nuclear construction on this scale is a pipe dream, and completely unfeasible" is poppycock. Yes, it's a big construction rate, but it's in the same ballpark as historical construction rates.

How reasonable is my assertion that the world's maximum historical construction rate must have been about 34 new nuclear reactors per year? Let's look at the data. Figure 24.14 shows the power of the world's nuclear fleet as a function of time, showing only the power stations still operational in 2007. The rate of new build was biggest in 1984, and had a value of (drum-roll please...) about 30 GW per year - about 30 1-GW reactors. So there!

 350 - s 300 - o a 250 - 200 - oO 0 150 - o 100 - CL 50 - 0 -

### 1970 1980 1990 2000

Figure 24.14. Graph of the total nuclear power in the world that was built since 1967 and that is still operational today. The world construction rate peaked at 30 GW of nuclear power per year in 1984.

### 1970 1980 1990 2000

Figure 24.14. Graph of the total nuclear power in the world that was built since 1967 and that is still operational today. The world construction rate peaked at 30 GW of nuclear power per year in 1984.

We say that we will put the sun into a box. The idea is pretty. The problem is, we don't know how to make the box.

Sebastien Balibar, Director of Research, CNRS

Fusion power is speculative and experimental. I think it is reckless to assume that the fusion problem will be cracked, but I'm happy to estimate how much power fusion could deliver, if the problem is cracked.

The two fusion reactions that are considered the most promising are:

the DT reaction, which fuses deuterium with tritium, making helium; and the DD reaction, which fuses deuterium with deuterium.

Deuterium, a naturally occurring heavy isotope of hydrogen, can be obtained from seawater; tritium, a heavier isotope of hydrogen, isn't found in large quantities naturally (because it has a half-life of only 12 years) but it can be manufactured from lithium.

ITER is an international project to figure out how to make a steadily-working fusion reactor. The ITER prototype will use the DT reaction. DT is preferred over DD, because the DT reaction yields more energy and because it requires a temperature of "only" 100 million 0C to get it going, whereas the DD reaction requires 300 million 0 C. (The maximum temperature in the sun is 15 million 0C.)

Let's fantasize, and assume that the ITER project is successful. What sustainable power could fusion then deliver? Power stations using the DT reaction, fuelled by lithium, will run out of juice when the lithium runs out. Before that time, hopefully the second installment of the fantasy will have arrived: fusion reactors using deuterium alone.

I'll call these two fantasy energy sources "lithium fusion" and "deuterium fusion," naming them after the principal fuel we'd worry about in each case. Let's now estimate how much energy each of these sources could deliver.