The idea that everything in the universe is made of atoms has existed for many centuries. But the understanding of the power residing in it has made revolutionary changes in approach of the mankind towards it. It was the Italian physicist Enrico Fermi in 1934 who showed that neutrons could split many kinds of atoms. This process in which the nucleus of an atom splits into two or more smaller, lighter nuclei is termed as nuclear fission. This is the process through which energy is produced in a nuclear power plant. The aim of the article is to formulate a basic idea about nuclear energy and nuclear power plants and to discuss the major issues related to it.
Nuclear Power Plant
Nuclear power plants are power plants that use the process of nuclear fission to generate electricity. In a nuclear reactor neutrons induces nuclear fission which results in the splitting of the elements like uranium nuclei into two lighter nuclei. As a result of this reaction large amount of energy in the order of 200 MeV is released. There is a release of extra neutron (s) in the fission process and this extra neutrons in turn can initiate fission processes, producing still more neutrons, and so on. This leads to a process of chain reaction. By controlling the chain reaction a steady amount of energy is produced. This energy is then used to boil water to steam which in turn is used to run turbines to produce electricity.
Demerits Of Nuclear Energy
Although nuclear power plants can produce enormous amount of energy, there are some demerits of this energy source. There occurs a long time lag between planning and operation of a nuclear power plant. Nuclear power plants take 10-19 years or more from their planning to operation which is very long period. For example Hinkley point nuclear plant had taken 17–19 years. The planning for 4 reactors in Ringhals, Sweden started in 1965 and one of them took 10 years, second took 11 years, third took 16 years and the fourth one took 18 years to complete. These power plants are highly expensive. From setting up a nuclear power plant to its maintenance to storing nuclear waste it costs very high. The growth of nuclear energy in many countries has increased the ability of nations to use Uranium, Plutonium which can be used to make nuclear weapons which is situation of global concern. The threat of melting down wraps the power plants. 1.5 % of all the nuclear power plants ever built have melted down to some degree till now. This is due to melting of overheated fuel. These have been either catastrophic such as in Chernobyl, Russia or have been damaging as occurred in three mile island. The uranium used in nuclear power plants for generating electricity is mined. But the uranium mines contain natural radon gas which may cause lung cancer or other lung diseases. So, the lives of miners are at a great risk of lung cancer. The setting up of power plants is mainly done onshore so that the water for cooling could be made available easily but this increases the chances of destruction due to flood or tsunami as happened in Fukushima nuclear plant and the worst accidents at nuclear power plants have resulted in severe environmental contamination.
The Nuclear Waste
Nuclear power plants produce a large amount of radio active wastes. It is a type of hazardous waste that contains radioactive materials. It emits radioactive particles, which if not properly managed can be a risk to human health and the environment and is a result of nuclear power generation and rare-earth mining. There are 3 types of radioactive wastes classified based on their radioactivity.
Low-level waste:- It contains small amounts of mostly short-lived radioactivity.
Intermediate- level waste:- It contains higher amounts of radioactivity and some requires shielding.
High-level waste:- It is highly radioactive and hot due to decay heat, so requires cooling and shielding.
Nuclear power reactors don't produce direct CO2 emissions. However, nuclear power plants use uranium as fuel. The process of mining uranium releases high amounts of CO2 into the environment. Carbon dioxide is additionally released into the environment when new atomic power plants are built. Finally, the transport of radioactive material also causes CO2 emissions. So, in overall process of generating electricity from nuclear power carbon emissions i.e. greenhouse gas emissions are there.
Nuclear Disasters
Chernobyl Disaster
The Chernobyl disaster occurred on Saturday 26 April 1986, and was caused by a nuclear accident at the No. 4 reactor within the Chernobyl atomic power Plant, situated near the town of Pripyat within the north of the Ukrainian SSR. Rated at seven—the maximum severity—on the International Nuclear Event Scale, it is one of the worst nuclear disaster in history.
The accident began during a security test on an RBMK-type reactor. The reactor power was decreased gradually in preparation for the electrical test. During the process the facility unexpectedly fall to a near-zero level. The operators only partially restored the required test power. This caused a potentially unstable condition in the reactor. The operators were not aware of the risk involved in this process, therefore proceeded with the electrical test. Upon test completion, the operators initiated a reactor shutdown, but due to unstable conditions and reactor design flaws, an uncontrolled nuclear chain reaction began.
Safety protocols were violated by the workers during the test which led to power surge inside the plant. Despite attempts to shut the reactor entirely, another power surge caused a sequence reaction of explosions inside. Finally, the nuclear core itself was exposed, discharging material into the atmosphere. It was reported that quite 6,000 children and adolescents developed thyroid cancer after being exposed to radiation from the incident. As an immediate effect of the accident, so many trees turned reddish-brown and died after absorbing high levels of radiation and an area of about four square miles became known as the “Red Forest”.
The economic and political toll quicken the end of the USSR and incited a global anti-nuclear movement. Belarus, which saw 23 percent of its territory contaminated by the accident, lost a few fifth of its agricultural land, and had to spent in 1991, 22 percent of its total budget handling Chernobyl. Today after more than 30 years after, scientists believe the zone around the chernobyl will not be habitable for up to 20,000 years.
Fukushima Daiichi nuclear disaster
The Fukushima Daiichi nuclear disaster, was a 2011 nuclear accident at the Fukushima Daiichi atomic power Plant in Okuma, fukushima prefecture, Japan. it had been the foremost severe nuclear accident since the Chernobyl disaster in 1986. it had been classified as Level 7 on the International nuclear event scale.
The accident was started by the tohoku earthquake and tsunami on Friday, 11 March 2011. On detecting the earthquake, the active reactors automatically pack up their normal power generating fission reactions thanks to which the reactors' electricity supplies failed, and their emergency diesel generators automatically started. However, the earthquake had also generated a tsunami 46 m high and swept over the plant's seawall then flooded the lower parts of reactors. This caused the failure of the emergency generators and power loss to the circulating pumps. The resultant loss of reactor core cooling led to 3 nuclear meltdowns, three hydrogen explosions, and therefore the release of radioactive contamination in various units between 12 and 15 March.
The government declared an ever-larger evacuation zone round the plant, culminating in an evacuation zone with a 20 km radius. Almost 154,000 residents were evacuated from the communities surrounding the plant.
As workers continued their attempts to chill the reactors, the looks of increased levels of radiation in some local food and water supplies prompted Japanese and international officials to issue warnings about their consumption. At the top of March, the evacuation zone was expanded to 30 km round the plant, and ocean water near the plant was discovered to possess been contaminated with high levels of iodine-131. This was resulted from leakage of radioactive water through cracks in trenches and tunnels between the plant and therefore the ocean.
During and after the disaster a large amounts of water contaminated with radioactive isotopes were released into the Pacific. it's estimated that 18,000 terabecquerel (TBq) of radioactive Cs-137 were released into the Pacific during the accident. In 2013, 30 gigabecquerel (GBq) of Cs-137 were still flowing into the ocean a day.
Later the plant’s operators built new walls along the coast and has created a 1.5 km long "ice wall" of frozen earth to prevent the flow of contaminated water.
Nuclear Decommissioning
Nuclear decommissioning is the process through which a nuclear facility is dismantled to the extend that it no longer requires measures for radiation protection.
Decommissioning is both an administrative as well as a technical process. It includes clean-up of radioactive materials and gradual demolition of the facility. No radiological danger should persist after the decommissioning of a plant. The costs of decommissioning saved in a decommissioning fund are generally spread over the lifetime of a facility. The plant is released from regulatory control after it’s complete decommissioning and the plant licensee is no longer responsible for its nuclear safety. Decommissioning may proceed all the way to restoring the place to the conditions existing before the construction of the plant (“greenfield status”).
Reduction Of Nuclear Issues
The agency responsible for safety of nuclear power plants at international level is International Atomic Energy Agency (IAEA).
we need to improve our technological approach so that we could
minimize the time gap between planning and operation of power plants.
minimize the cost of setting up a nuclear power plant.
make more accurate and safer back-up plans so that in case of any accident the leakage or explosion chances could be reduced.
reduce the meltdown risks at nuclear power plants and lung cancer risks during mining of uranium.
Proper agreements should be made to reduce the problem of weapon proliferation and military or cyber-attacks.
Treatment and conditioning of nuclear waste should be effective as it is one of the major issue of nuclear power. To do this some treatment and conditioning processes are used that converts a wide variety of radioactive waste materials (low-level, high-level) into other forms that can be managed properly including their transportation, storage and final disposal. The principal aims are to
minimize the volume of waste that requires management via treatment processes.
reduce the potential hazards of the waste by conditioning it into a stable solid form that immobilises it and provides its dispersion to the surrounding environment. Conditioning process includes cementation and vitrification.
After treatment and packaging the waste need to be disposed properly so that it could not affect the environment. Some wastes can be disposed off like other normal wastes after treatment but some requires proper management. For this some disposal sites are made around the world mainly for low-level waste but some sites are under construction for high-level radioactive waste.
Importance Of Nuclear Energy
We know most of the electricity demand, which is increasing day by day, is completed using coal which is a non-renewable source of energy and produces a lot of pollution and greenhouse gas like carbon dioxide. So, we need to look for other cleaner methods for electricity generation. One such effective method is nuclear power/energy.
There are numerous advantages for nuclear energy. Nuclear Power stations have a long lifetime after their construction and Nuclear power is a reliable source. It only requires low quantity of fuel to generate a high quantity of electricity. Due to this mining and transportation effects on environment gets reduced. Though setting up of a nuclear power plant take a high cost but it’s operational cost is very less as it requires a lesser amount of fuel.
In comparison to many other energy sources, nuclear energy stands out as an environment friendly source. Though there are carbon emissions in plant construction and fuel treatment but it produces zero carbon emissions while generating electricity. And so does not contribute to global warming. It is stable, safer, renewable source of energy having lowest carbon footprint. Nuclear Power has a promising future.
Conclusion
The discovery of nuclear energy is undoubtedly one of the major foot print in the history of mankind. When we compare nuclear energy with conventional form of energy such as coal, the amount of energy produced through nuclear fission is huge. Environmental degradation due to nuclear energy is also very low, hence can contribute towards the long term goals like sustainable development. However we should be able to address the issues arising from this energy source, most importantly the issues concerning the disposal of radio active wastes. Power plants must be made in a way that disasters such as chernobyl won’t repeat. By taking necessary precautions we can effectively utilise nuclear energy for our energy requirements cost effectively.
By Goutham Gopal K V
gouthamgopal03@gmail.com
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