Why we should say YES to
nuclear power

2. Because nuclear fuel is virtually unlimited and packs a huge energy punch

Nuclear fuel is incredibly concentrated

In broad terms, nuclear power stations are similar to coal- or gas-fired power stations. All consume fuel to generate concentrated heat (thermal energy) which they then convert to electrical energy. They do this heat-to-energy conversion mostly via a steam generator and condenser, and sometimes via gas turbines.

In the 1940s scientists discovered how to unleash the vast energy within the atom. Indeed, splitting (“fissioning”) the nucleus of a heavy atom, like uranium, releases about four million times more energy than adding oxygen to carbon (which is what heat combustion really does).

Let’s put this difference in energy content into perspective.

Imagine you are handed a lump of silvery uranium metal the size of a ping pong ball. You are advised to put on plastic gloves to hold it, although that would not be really necessary if you wash your hands afterwards. You look down at the metal on your palm. It feels heavy because it’s very dense. You are then told that this small metal ball can provide all the energy you will ever use in your life. That includes running your lights, computer, air conditioner, TV, oven, electric car, synthetic jet fuel – everything – and with less than a single kilogram of uranium (or thorium). That’s what nuclear power offers – a highly concentrated form of energy producing a tiny amount of waste.

Fast spectrum and thorium reactors make it even more efficient

One gigawatt of electrical power is enough to satisfy today’s electricity demand of a typical Australian or US city of about half a million people. A one-gigawatt nuclear power plant needs only 180 tonnes of natural uranium to run for an entire year.5 To deliver the same amount of electrical energy, a coal-fired power station must burn about four million tonnes of coal a year.6 (The amount varies with the grade of coal.)

Most of today’s operating nuclear power stations are called “thermal reactors”, or “light water reactors” (LWRs). They use ordinary water (“light” water) as a coolant to take heat away from the reactor core. The water also acts as a “moderator”, slowing down subatomic particles, called neutrons, which shoot out of the atom’s nucleus when a chain reaction is underway. These neutrons are responsible for causing unstable, heavy atomic nuclei to split apart and release energy.

Other reactor designs use “heavy water”. This is water enriched with deuterium (also known as “heavy hydrogen”) or graphite (a form of carbon found in pencils) to moderate the neutrons.

Fuelling these nuclear power plants requires a form (or isotope) of uranium called “uranium 235” (which, confusingly, has 143 neutrons in its nucleus). Natural uranium ore contains only a tiny amount (0.7 per cent) of this usable uranium 235. The other 99.3 per cent is composed of an isotope with three additional neutrons, called “uranium 238”.

So, today’s light water reactors are inefficient, extracting less than 1 per cent of uranium’s atomic energy content. The rest, mostly uranium 238, is discarded, either as spent fuel (“nuclear waste”) or as “depleted uranium”. The latter, mostly uranium 238, is what is left over after the fuel has been “enriched” to raise the concentration of uranium 235 to three to five per cent.

However, there are other kinds of nuclear power plants called “fast spectrum” reactors (FSRs) and “liquid fluoride thorium reactors” (LFTRs). Through repeated recycling, these reactors can unlock virtually all the energy in nuclear fuel. Amazingly, instead of using 180 tonnes of natural uranium to produce one gigawatt of electricity for a year, these fast spectrum reactors and liquid fluoride thorium reactors require only one tonne, increasing the potential lifespan of existing uranium reserves 180 times. Not only can these plants fission (split) uranium 235, just as traditional light water reactors do, but they can “breed” other fissionable (splittable) isotopes out of the depleted and previously unused uranium 238 or thorium 232. Thorium, element 90, is a heavy metal that can be converted to uranium 233 in a nuclear reactor and then fissioned to produce energy.

I will later explain more about this critically important technology.

Nuclear is as “renewable” as solar and will supply us for billions of years

What of uranium? The world’s reserves are currently estimated at five million tonnes extractable at less than US$130 a kilogram, and another 35 million tonnes in lower-quality ores and mineral compounds (phosphates) which the Organisation for Economic Co-operation and Development (OECD) says could be economically extracted for a few hundred dollars a kilogram.

At present levels of nuclear power, the cheap five million tonnes will last about another 80 years. If the nuclear power industry was to expand 25-fold over the next four decades – from today’s 380 gigawatts of electrical power generation to about 10,000 gigawatts, or 10 terawatts – then even the 35 million tonnes of low-quality ores would be used up in a few decades. (I will later explore the logic behind this forecast of enormous growth.)

Clearly, although there is still plenty of fuel for nuclear power at its current capacity, an expanded role for nuclear power doesn’t seem to work as a long-term proposition.

The situation changes completely, however, with fast spectrum reactors and liquid fluoride thorium reactors which can generate about 180 times more energy from the mined resource than current light water reactors do.

So, if the global nuclear power demand rose to 10 terawatts of electricity a year, how long would current uranium reserves last? A really long while – 4,000 years! However, there is also four times more thorium than uranium, so that would last us another 16,000 years. That makes 20,000 years of energy, give or take a few millennia.

After that, should some far-future society still wish to use nuclear fission, it can look to the oceans, which contain 4.5 billion tonnes of uranium. Even today, we have the technology to extract uranium from seawater at a cost of less than $300 a kilo.7 This enormous resource would allow us to use nuclear power for another half a million years. But in fact, we’d never run out. Why? Because each year the world’s rivers naturally erode 30,000 tonnes of uranium from their channels and flush it into the ocean. That is three times more than we would be taking out. So nuclear fuel is truly inexhaustible, and can be quite rightly considered as “renewable” as sunlight.