Fission or Fusion: Why is nuclear fission the preferred choice in energy generation?

What was the first thing that comes to your mind when you hear the word nuclear mentioned?

A weapon of mass destruction?

The North Korean Leader Kim Jun Un?

The part of physics involving the study of atomic nuclei and their makeup?

There is a high chance you may not include the generation of massive quantities of power.

We live in a power-hungry world. No matter the various alternative of power sources, it always appears not be ever enough.

In 2014, nuclear accounts for 10.62% of the total world electricity production.

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I will like to move into the business of the day by starting with the method of nuclear power generation.

More than 70% of all the world's electric power generation is via the steam turbine. This method involves the steam which turns a turbine attached to a generator to produce electricity.

Here we can use various methods of heating the water to produce the steam which in turn pushes a turbine attached to an alternator to generate electricity. Coal, which tops of the list in 2015 for the highest production of electricity at 9538300 Gigawatt-hour (GWh) production, is the most common source of heat producer for heating water that drives the turbine. Other sources include geothermal, natural gas, nuclear, etc.

In a nuclear power plant, a controlled reaction inside the nuclear reactor produces heat which is sufficient enough to heat the water.

The water then turns to steam which drives the turbine. The steam passes through a condenser that changes it into the water, and the whole process is repeated.

The reaction inside the reactor is known as the nuclear fission.

Nuclear fission is the release of energy when a fissionable element such as uranium reacts in a nuclear reactor.

In the nuclear fission, uranium absorbs a neutron which makes its nucleus to be unstable. This instability leads to a split of it into two new atoms which a release of energy, and some more neutrons in the process.

There is a massive amount of energy released in this reaction. Notice how the isotope of uranium, Uranium-235 (the other type of fissionable isotope is the plutonium-239) only requires one neuron, but the resulting reaction shows the production of 3 neutrons.

This store is fissionable in that it can support a chain reaction which means that there will be more release of neutrons as it progresses.

You can calculate the energy released by using the Einstein's equation, E=mc²

E= energy produced
the m= mass
and c= speed of light.

Recall that the speed of light is 299,792,458 metres per second (approximately 3.00×10⁸ m/s). Any small value of mass will result in a massive creation of energy.

Nuclear Fusion

You might already know that nuclear fusion is just the opposite of nuclear fission.

The nuclear reaction involves a collision between two or more atomic nuclei, instead of split in fission, to form together or fuse a new nucleus such as helium and production of massive amounts of energy as well.

Fusion occurs when the low-mass isotopes of hydrogen, typically tritium and deuterium, combine under extreme temperature and pressure.

The atoms of these two isotopes react under fusion to generate an enormous amount of energy. In nature, we have the application of nuclear fusion in the massive energy production of the Sun.

The fusion of lighter elements such as hydrogen atoms produces more energy than the splitting (fission) of heavier elements typically uranium or plutonium.

This low energy production is because the splitting of uranium or plutonium produces little mass which when converted creates smaller energy.

The fusion of hydrogen destroys higher amounts of mass of matter which leads to a more massive release of energy.

The packing fraction, which is the measure of how many fractions of space a given number of atoms occupies.
Packing function= (isotopic mass- mass number)/ mass number * 10⁴

If the packing factor is negative, it indicates stable nuclei. But when positive, it represents unstable nuclei. Both hydrogen and uranium have a negative packing factor hence can undergo fusion and fission respectively.

The hydrogen nuclei react and force the nuclei to fuse. From the equation, the two hydrogen isotopes combine to create helium with the corresponding release of energy.

Note:

• Deuterium is known as heavy-hydrogen or hydrogen-2 with²H or D symbol. It has one neutron and one proton.
• Tritium, symbol T or ³H is called Hydrogen-3. It has 2 neutrons and 1 proton.

A helium atom weighs less than the combined two hydrogen atoms. The matter loss is then converted to tremendous energy using the same Einstein energy equation E=mc²

The fission reaction between uranium/plutonium provides a small mass loss hence a small release of energy.

On the other hand, the fusion of hydrogen atoms leads to more loss of matter and therefore a lot more amount of energy released.

Why Nuclear Fission?

The question is if fusion reaction in the above scenario produces more energy release, why do nuclear power station still employ the less energy-producing nuclear fission?

The fusion is more efficient in the use of fuel than fission. The fuel, deuterium, an isotope of hydrogen is made from the separation of naturally-occurring heavy water from a sizeable quantity of natural water.

Plutonium for nuclear fission, on the other hand, is not a naturally occurring element. If you want one, you'd have to make it, and uranium is as expensive to make too.

But why aren't we running a nuclear fusion reactor?

It sounds like a sweet deal. Imagine all the birthday balloons you could blow up with the byproduct of fusion which is helium. Fission byproduct is nasty and as radioactive as they come.

Fusion reaction requires an extremely high energy requirement. In fission, all that we need is to shoot a neutron to an atom and bam; we will have a reaction going!

In fusion that is not so easy as it requires the coming together of two positively charged nuclei to wrap them in place to fuse.

But in the absence of an electron, the positive charge repel each other. For us to overcome this issue created by the phenomenon, high atomic energies are required to get the nuclear fusion rolling.

The Sun can handle this high energy. Imagine generating a temperature of 100,000,000 degree Celsius to get a fusion reaction ready.

But we have experimental setup, which you could have guessed now the outcome; it consumes a crazy amount of input power. Some even consume more than they produce. Doesn't that defeat the process of energy generation? I think it does.

The experimental setup like Iter Tokamak has a substantial input of 50 megawatts and a promised output power of 500 MW. The core temperature specification is 150 million Celsius which is 10 times the core of the Sun. The machine weighs 23,000 tonnes.

International Thermonuclear Experimental Reactor(ITER) based in France is a collaborative project of several countries and partner which include Japan, the Republic of Korea, Russia, China, European Atomic Energy, and the United States.

The cost of running such an ambitious project can be overwhelming. As of 2017, the project has gulped more than 20 billion Euros.

Canada had to pull out of the scheme as a result of the federal government refusal to continue funding the project.

The US withdrew in 2000 and rejoined in 2006 after the congress voted for it.

Even at that, the tokamak proposed operation is in 2027 which is 11 years from the earlier scheduled 2016 date.

We can only keep our fingers crossed while we hope they do it right.

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^References

• ^{Basics of Nuclear Fission}

• ^{Nuclear Power}

• ^{World Electricity Generation}

• ^{Is Uranium the Heaviest Natural Element?}

• ^ITER

• ^{Nuclear Fission Vs Fusion and Why}

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