(This blog was originally written on Nov 07, 2017. Any updates have been mentioned alongside the text as felt necessary)
Before beginning, I would recommend this video, so that we can rethink the common
perspective that we all have against nuclear power generation in our minds.
Saw the video? Let’s begin!!
What is Nuclear Energy?
Nuclear energy is the energy which resides in the nucleus of an atom. Atoms are the smallest constituents of matter. At the core (i.e. nucleus) of each atom there are two types of particles - neutrons and protons that are held together by strong nuclear forces. Nuclear energy is the energy which exists due to this strong nuclear force. We can harness this energy for our own benefits. For example, nuclear energy can be used to produce electricity.
This nuclear energy can be obtained in two ways: Nuclear fusion and nuclear fission.
In nuclear fusion, energy is released when atoms are combined or fused together to form a larger atom. The Sun derives all its energy from nuclear fusion only.
In nuclear fission, atoms are split into smaller atoms, which results in the release of energy.
When one of these two physical reactions succeeds, there is slight loss of mass, which is called defect mass. This mass lost generates a large amount of heat energy, which can be calculated using Einstein’s famous equation E = mc2.
Types of Nuclear Reaction
As already mentioned there are two types of nuclear reactions -
Nuclear Fusion (tap for details)
In nuclear physics, fusion is a nuclear reaction in which two or more atomic nuclei collide at a very high energy and fuse together to form a new nucleus, e.g. two hydrogen atoms collide to form a helium atom. Fusion yields energy only for atoms whose atomic no. is less than IRON because the mass of the combination is less than the sum of the masses of the individual nuclei. If the combined nuclear mass is less than that of iron (which is at the peak of the binding energy per nucleon curve), then the nuclear particles will be more tightly bound than they were in the lighter nuclei, and that decrease in mass comes off in the form of energy according to E = MC2. Fusion reactions have an energy density many times greater than nuclear fission and fusion reactions are themselves millions of times more energetic than chemical reactions.
Power from Nuclear Fusion is an almost inexhaustible source of energy for future, but the technology required to harness this energy presents a real scientific and engineering challenge. The deuterium-tritium fusion reaction controlled by a magnetic confinement seems the most likely way.
Nuclear Fission (tap for details)
Nuclear fission is the subdivision of a heavy atomic nucleus, such as that of uranium or plutonium, into smaller fragments/nuclei. The process is accompanied by the release of a large amount of energy. The process may take place spontaneously in some cases or may be induced by the excitation of the nucleus with a variety of particles (e.g., neutrons, protons, deuterons, or alpha particles) or with electromagnetic radiation in the form of gamma rays. In the fission process, a large quantity of energy is released, radioactive products are formed, and several neutrons are emitted. These neutrons can induce fission in a nearby nucleus of fissionable material and release more neutrons that can repeat the same sequence, causing a “chain reaction” in which a large number of nuclei undergo fission and an enormous amount of energy is released. If controlled in a nuclear reactor, such a chain reaction can provide power for society’s benefit. If uncontrolled, as in the case of the so-called atomic bomb, it can lead to a deadly explosion.
The discovery of nuclear fission has led to the beginning a new era—the “Atomic Age.” The potential of nuclear fission for good or evil and the risk/benefit ratio of its applications has not only provided the pathway for many scientific advances, but it has also led to many grave sociological, political and economic concerns as well. Even from a purely scientific perspective, the process of nuclear fission has given rise to many puzzles and complexities, and a complete theoretical explanation is still not at hand.
Use of nuclear energy to generate electricity
As mentioned above the nuclear fission reaction generates heat, which most frequently is then used in steam turbines to produce electricity in a nuclear power plant. Presently, the elements in the actinide series of the periodic table produce the vast majority of sources/fuels for nuclear energy.
In nuclear power plants, neutrons collide with uranium atoms, splitting them into smaller nuclei. This splitting/fission generates three more neutrons that in turn collide with other uranium atoms, causing a “chain” reaction. This chain reaction is controlled with "control rods" that absorb neutrons. They are composed of chemical elements such as boron, silver, indium and cadmium that are capable of absorbing many neutrons without themselves undergoing fission.
In the core of nuclear reactors, the fission of uranium atoms releases energy that heats water to about 520 degrees Fahrenheit. This hot water is then used to spin turbines that are connected to generators, producing electricity.
Nuclear Energy Production Around the World
As of April 2017, 30 countries worldwide are operating 449 nuclear reactors for electricity generation and 60 new nuclear plants are under construction in 15 countries. Nuclear power plants provided 11 percent of the world's electricity production in 2014. In 2016, 13 countries relied on nuclear energy to supply at least one-quarter of their total electricity. As of 2016, India had 22 nuclear reactors in operation in 8 nuclear power plants, having an installed capacity of 6780 MW and producing a total of 30,292.91 GW of electricity while 6 more reactors are under construction and are expected to generate an additional 4,300 MW of electricity.
Major Concerns Related to Nuclear Energy
Meltdown is an accident in which severe overheating of the nuclear reactor results in the melting of the reactor's core. A meltdown could occur if there is a defect in the cooling system of the reactor that allows one or more of the nuclear fuel elements to exceed its melting point. If a meltdown occurs, it can lead to explosion which can release harmful radiation into the environment.
Health Concerns (Personal & Environmental)
The biggest concern associated with a nuclear power accident is the negative effects that exposure to radiation can have on the human body. It is interesting to note that we are exposed to radiation naturally 24x7. Natural background radiation comes from outer space, and even radiates up from the ground below us. You may also have been exposed to a medical procedure, such as a CT scan, X-ray or nuclear medicine, such as an MRI, that utilizes different types of radiation to diagnose problems or treat a disease. The more deadly/harmful of these are the “ionizing radiations”.
For most people, the low-level exposure to radiation that comes from the environment and medical procedures does not result in any detectable health problems. However, if a person were exposed to significant amounts of radiation over a period of time, this exposure could damage body cells and lead to cancer. If a person were to be exposed to an acute dose of high-levels of radiation, the result would be radiation sickness. Radiation sickness is defined as illness caused by exposure to a large dose of radiation over a short period of time. Symptoms may include skin burns, nausea, vomiting, diarrhea, hair loss, general weakness and possibly death.
In addition to personal health concerns, there are also environmental health concerns associated with nuclear power generation. Nuclear power plants use water from local lakes and rivers for cooling. Local water sources are used to dissipate this heat, and the excess water used to cool the reactor is often released back into the waterway at very hot temperatures. This water can also be polluted with salts and heavy metals, and these high temperatures, along with water pollutants, can disrupt the aquatic life (flora and fauna) within the waterway.
Since the World Trade Centre attacks in New York City on September 11th, 2001, concerns have circulated that terrorists could target nuclear reactors with the purpose of releasing radioactive materials. While it cannot be completely predicted how a nuclear reactor would withstand a terrorist attack, it is worth noting that the containment walls that surround the nuclear reactor are typically constructed of an inner steel lining surrounded by two to five feet of reinforced concrete. Nuclear power plants within the United States are built to withstand hurricanes, tornadoes, earthquakes and small plane crashes, but the sad truth is that accidents still occur!
It is not only the use of fossil fuels that pollutes our surrounding but even the use of nuclear energy gives rise to pollutants and hence pollutes our environment. Also the pollution caused by the use of nuclear energy from fission process is much more damaging than pollution caused by burning fossil fuels.
The fuels like U-235 are radioactive substances which keep on emitting some nuclear radiations all the time. The dangerous nuclear radiations can enter into the environment if there is any leakage from nuclear reactors where fission of U-235 is going on. These nuclear radiations can cause damage to cells and in some cases even lead to death.
The waste material produced during the various stages of the nuclear energy production is collectively known as “nuclear waste”. If these radioactive wastes are dumped in garbage bins, they will emit nuclear radiations and pose a threat to life around that place. If they are dumped in rivers or sea, they will contaminate water and damage aquatic life.
For this purpose, a systematic approach has been adopted for proper nuclear waste disposal ‐
First the waste will be incorporated in stable and inert solid matrices. The conditioned waste will then be placed in canisters and kept in a retrieval store under cooling and constant surveillance. Ultimately, the canisters will be stored in suitable place.
Immobilization involves verification of radioactive waste which is coded at underground disposal. The canisters in storage are air cooked by natural convection and when the heat radioactivity decay to desired level; they are transported to a suitable geological formation for ultimate storage. A graveyard for storage of nuclear wastes has been established in Trombay.
Nuclear Power Plant Accidents
It occurred on April 26, 1986. It is considered as the worst accident in the history of nuclear power generation. It was caused due to the failure in cooling water. As a result, the reactor overheated, melting the Uranium fuel. Explosions blew up the roof of the reactor, producing a cloud of radioactive particles. A 30km zone surrounding Chernobyl was evacuated. The city of Prypyat that had a population of 48,000 at the time of accident is now a ghost city. As a consequence, cases of thyroid cancer increased in Belarus, Ukraine and the Russian Federation. Ultimately this led to the death of 16,000 people.
[UPDATE 2021: You should definitely consider watching the T.V. Mini-Series Chernobyl (2019) to get an insight into the exact events that happened during this disaster. ]
- Fukushima Daiichi:
It occurred on March 11, 2011. It is the second worst accident in the history of nuclear power generation. It was caused due to the failure in cooling water supply due to Tsunami. As a result three reactors overheated and there was a hydrogen-air explosion. 2 people were seriously injured and 37 people faced mild injuries. Although no causalities were encountered, it indirectly resulted in many causalities afterwards!
The greenhouse gas emissions from nuclear fission power are much smaller than those associated with coal, oil and gas, and the routine health risks are much smaller than those associated with coal. However, there is a "catastrophic risk" potential if containment fails, which in nuclear reactors can be brought about by overheated fuels melting and releasing large quantities of fission products into the environment. This potential risk overrides all of the other benefits of nuclear power generation. The most long-lived radioactive wastes, including spent nuclear fuel, must be contained and isolated from the environment for a long period of time. On the other side, spent nuclear fuel could be reused, yielding even more energy, and reducing the amount of waste to be contained. The public has been made sensitive to these risks and there has been considerable public opposition to nuclear power.
Despite all of this, scientists all around the world haven’t stopped and have come up with more refined and sophisticated techniques to harness nuclear energy. Scientist at University of California have come up with a much safer technique to harness nuclear energy using small modular reactors which are roughly the size of a heavy load carrying truck. Here is a video which briefly discusses this technique.
[UPDATE 2021: Many companies like TerraPower have come up with new designs & innovative solutions to the problems which are preventing nuclear power geenration to take off. Currently, there is a dire need for shift towards nuclear power generation owing to the increasing consumptioni of electricity around the world.]
The possibilities are endless, it’s we who have to decide whether we are ready to accept nuclear power or not! Here is another video which you should watch!
Want to discuss more? Feel free to comment below.