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.
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.
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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Another one from the sublime tutor @greenrun
Until now, I never knew it's the energy dissipated from fission of uranium & fusion of the hydrogen descendants is the 'enough' energy for power generation. I was just a genius at calculating half life and others during high school. Thanks for saving my ass
From your simple and clear explanation. Fission of radioactive element has proven a lot to be preferred over fusion. Like they say, building trust takes forever, breaking it only take a second.
Efficiency is the biggest advantage of fission over fusion. The radioactive by-product although remains a challenge.
Nice one sire.
You are welcome.
🔥
Fission or fusion? I think I will choose the cheaper one.. I have no idea how nuclear plant works before @greenrun now i do.. We had a dam here in our area as a source of electricity,wind mill is also here located at ilocos norte,philippines.. We had a nuclear plant located in bataan started 1970's I think, completed but never get fueled..
If it is safe then its good! Thanks for sharing this..
You guys use windmill? That's good to know. Thank you.
Yes in some areas in ilocos sur..
Note that are alternatives to Tokamaks for nuclear fusion: stellerators. We are however very far from mastering nuclear fusion so that for now, we need to live with fission and is problems: the treatment of the radioactive waste.
You may want to read the blog of @maticpecovnik.
I agree with you on the problems of radioactive waste treatment. I will check on that blog too. Thanks.
Well, Ofcourse it is easier to break something than to join two things 😁.
Although i do not know much about the Iter Tomakak project, i wonder how they intend to handle the temperature of the core.
The reactor should be able to take that :)
Oh wow. This is a great post. You know each step of the way was an answer to the questions I had from reading the step before. When I got to why nuclear fission I smiled because I was coming to ask that in the comment section. Thank you for educating me once again @greenrun. Nuclear is not always about destruction after all
Thank you too. Nuclear got its good use. Sadly most times it is only the bad that is the subject of discussion. I guess bad news sells the newspapers.
Yeah bad news sells. Are there countries already using nuclear fission as a source of energy?
Of course, all the countries that utilise nuclear electricity generation all run with the nuclear fission principle.
Well detailed post, and also, I read on @markkujantunen post some days ago, that nuclear energy is the most safest energy source, but the cost is something a lot of countries cannot afford.
It is quite safe and clean contrary to reports you see. People just hate to hear nuclear.
@greenrun, as you have noted, the fission process self-sustaining property makes it preferable over the fusion process. But looking at the experiment by Iter Tokamak, putting 50 MW and deriving 500MW is super efficient but that is on a laboratory scale. The requirement on a large scale cannot not be predictable.
One cannot tell what will be required to generate say up to 5000MW. Just imagine having a 23, 000 tonnes of equipment to generate 500MW. What will be the weight for 5000 MW? Even the temperature in the experiment appears prohibitive.
However, I am certain that given time a lot will be unravel and understood.
well done sir.
That's true, there is also the fear the device may not hold up for long to be used for commercial purpose. But anyways let's see how it goes. You gotta give it a try first.
Yeah, there is no harm in trying. Let's stay optimistic.
I was just about to write an article about fusion as well!
Lets see whose will be better ;)
(Though, I have a different focus.)
That would be good to see.
Nuclear fusion and fission was my favorite topic in chemistry back in the day. I found this very enlightening and I’ve always wondered why fusion reactions weren’t carried out in reactors if they produced more energy but thanks for explaining that ! Good work man
Thank you.
Always been easier to 'destroy' than 'create'.
How do you push the text to the side and have image around it? or is it vice versa? Tried it once. It was a disaster.
And your super tiny reference too.
Just the use of markdown. Nothing really special, here is the markdown
<div class="pull-right"><center><img src="IMAGE HERE" /><br/><em><sup><sup><a href="SOURCE LINK HERE">WIKIPEDIA CREATIVE COMMONS HERE</a></sup></sup></em></center></div>
Thank you.