Energy is the most fundamental requirement of every society or nation as it progresses through the ladder of development.
In recent times, the world has been dealing with a power and energy crisis. While the factors that caused this emergency differ country to country, the upshot has been a clamour to reduce dependence on fossil fuels and look for viable alternatives.
In this context, Nuclear Energy has a lot to offer. On one side, it may be the cheapest, greenest and safest source of energy currently known to man. On the other, it has also been responsible for some of the worst disasters in the history of mankind
Nuclear energy is a form of energy released from the nucleus, the core of atoms, made up of protons and neutrons. This source of energy can be produced in two ways: fission – when nuclei of atoms split into several parts – or fusion – when nuclei fuse together.
The nuclear energy harnessed around the world today to produce electricity is through nuclear fission, while the technology to generate electricity from fusion is in the R&D phase.
- Nuclear Fission:
- The nucleus of an atom splits into two daughter nuclei.
- This decay can be natural spontaneous splitting by radioactive decay, or can actually be simulated in a lab by achieving necessary conditions (bombarding with neutrons, alpha particles, etc.).
- The resulting fragments tend to have a combined mass which is less than the original. The missing mass is usually converted into nuclear energy.
- Currently, all commercial nuclear reactors are based on nuclear fission.
- Nuclear Fusion:
- Nuclear Fusion is defined as the combining of two lighter nuclei into a heavier one.
- Such nuclear fusion reactions are the source of energy in the Sun and other stars.
- It takes considerable energy to force the nuclei to fuse. The conditions needed for this process are extreme – millions of degrees of temperature and millions of pascals of pressure.
- The hydrogen bomb is based on a thermonuclear fusion reaction. However, a nuclear bomb based on the fission of uranium or plutonium is placed at the core of the hydrogen bomb to provide initial energy.
- Criticality is the first step towards power production. A nuclear reactor is said to be critical when the nuclear fuel inside a reactor sustains a fission chain reaction.
- Each fission reaction releases a sufficient number of neutrons to sustain a series of reactions. Heat is produced in the event, which is used to generate steam that spins a turbine to create electricity.
- Fission is a process in which the nucleus of an atom splits into two or more smaller nuclei, and some byproducts.
- When the nucleus splits, the kinetic energy of the fission fragments (primary nuclei) is transferred to other atoms in the fuel as heat energy, which is eventually used to produce steam to drive the turbines.
Fissile and Fertile materials
- Fissile material is one that can sustain a chain reaction upon bombardment by neutrons.
- Fertile meaning that it can transmute into a fissile radioisotope (U-233) but cannot itself keep a chain reaction going.
- Thorium is by itself fertile.
- In a thorium reactor, a fissile material like uranium or plutonium is blanketed by thorium.
- The fissile material, also called a driver in this case, drives the chain reaction to produce energy while simultaneously transmuting the fertile material into fissile material.
- Atoms and elements are made of protons, neutrons, and electrons. The nucleus is made of protons and neutrons, and the electrons surround the nucleus. The sum of the number of protons and the number of neutrons is equal to the atomic mass.
- Isotopes are atoms with the same number of protons but that have a different number of neutrons. Since the atomic number is equal to the number of protons and the atomic mass is the sum of protons and neutrons, we can also say that isotopes are elements with the same atomic number but different mass numbers.
- For example: U-233, U-235, U-238 (U – Uranium)
- Out of these three U-233 and U-235 are fissile whereas U-238 is fertile.
- The first two breakdowns to produce heat and neutrons as well as 2 lighter nuclei whereas the third-one changes into Pu-239 which is fissile substance. Similarly, Th-232 is also a fertile element, it changes into U-233.
- A nuclear reactor, or power plant, is a series of machines that can control nuclear fission to produce electricity. The fuel that nuclear reactors use to produce nuclear fission is pellets of the element uranium. In a nuclear reactor, atoms of uranium are forced to break apart. As they split, the atoms release tiny particles called fission products. Fission products cause other uranium atoms to split, starting a chain reaction. The energy released from this chain reaction creates heat.
- The heat created by nuclear fission warms the reactor’s cooling agent. A cooling agent is usually water, but some nuclear reactors use liquid metal or molten salt. The cooling agent, heated by nuclear fission, produces steam. The steam turns turbines, or wheels turned by a flowing current. The turbines drive generators or engines that create electricity.
- Rods of material called nuclear poison can adjust how much electricity is produced. Nuclear poisons are materials, such as a type of the element xenon, that absorb some of the fission products created by nuclear fission. The more rods of nuclear poison that are present during the chain reaction, the slower and more controlled the reaction will be. Removing the rods will allow a stronger chain reaction and create more electricity.
Components of a nuclear power plant
- Uranium is the basic fuel. Usually pellets of uranium oxide (UO2) are arranged in tubes to form fuel rods. The rods are arranged into fuel assemblies in the reactor core.* In a 1000 MWe class PWR there might be 51,000 fuel rods with over 18 million pellets.
- Material in the core which slows down the neutrons released from fission so that they cause more fission. It is usually water, but may be heavy water or graphite.
- Control rods or blades
- These are made with neutron-absorbing material such as cadmium, hafnium or boron, and are inserted or withdrawn from the core to control the rate of reaction, or to halt it.
- A fluid circulating through the core so as to transfer the heat from it. In light water reactors the water moderator functions also as primary coolant
- Pressure vessel or pressure tubes
- Usually a robust steel vessel containing the reactor core and moderator/coolant, but it may be a series of tubes holding the fuel and conveying the coolant through the surrounding moderator.
- Steam generator
- Part of the cooling system of pressurised water reactors (PWR & PHWR) where the high-pressure primary coolant bringing heat from the reactor is used to make steam for the turbine, in a secondary circuit.
Benefits of Nuclear Energy
- Nuclear energy offers many advantages as the emissions-free workhorse of our energy grid. Its unique value cannot be found in any other energy source.
- Nuclear protects national security.
- U.S. leadership in nuclear energy maintains safety and nonproliferation standards globally, supports a resilient electrical grid at home, and fuels a strong navy.
- Nuclear fights climate change.
- Nuclear energy provides large amounts of 24/7 carbon-free electricity now, which is irreplaceable in protecting the environment.
- Nuclear ensures U.S. leadership in technology.
- The United States pioneered nuclear energy for the world and, with continued leadership, can respond to growing clean energy demand worldwide with advanced reactors.
- Nuclear produces electricity reliably.
- Around-the-clock electricity is a must for our nation to prosper in the 21st century. Clean, reliable nuclear energy is a critical part of U.S. infrastructure because it runs nonstop for 18-24 months at a time.
- Nuclear generates jobs.
- Nuclear energy provides more than 100,000 well-paid, long-term jobs and supports local economies with millions of dollars in state and local tax revenues.
- Nuclear protects our air.
- Nitrogen oxide, sulfur dioxide, particulate matter, and mercury: all things you don’t want in the air you breathe. Nuclear energy provides power 24/7 without a trace of those pollutants.
- Nuclear boosts international development.
- Nuclear energy helps developing nations meet sustainable development goals.
- Nuclear power electric vehicles. Electrified transportation promises to reduce carbon emissions. When powered by carbon-free nuclear energy, electric vehicles can reach their full potential.
Why Nuclear Energy?
- Availability of Thorium: India is the leader of the new resource of nuclear fuel called Thorium, which is considered to be the nuclear fuel of the future.
- With the availability of Thorium, India has the potential to be the first nation to realise the dream of a fossil fuel-free nation.
- Cuts Import Bills: Nuclear energy will also relieve the nation of about $100 billion annually which we spend on importing petroleum and coal.
- Stable and Reliable Source: The greenest sources of power are definitely solar and wind. But solar and wind power, despite all their advantages, are not stable and are dependent excessively on weather and sunshine conditions.
- Nuclear power, on the other hand, provides a relatively clean, high-density source of reliable energy with an international presence.
- Cheaper to Run: Nuclear power plants are cheaper to run than their coal or gas rivals. It has been estimated that even factoring in costs such as managing radioactive fuel and disposal nuclear plants cost between 33 to 50% of a coal plant and 20 to 25% of a gas combined-cycle plant.
Challenges to Adoption of Nuclear Energy
- Capital Intensive: Nuclear power plants are capital intensive and recent nuclear builds have suffered major cost overruns. An illustrative example is the V.C. Summer nuclear project in South Carolina (U.S.) where costs rose so sharply that the project was abandoned — after an expenditure of over $9 billion.
- Insufficient Nuclear Installed Capacity: In 2008, the Atomic Energy Commission projected that India would have 650GW of installed capacity by 2050; the current installed capacity is only 6.78 GW.
- Such targets were based on the expectation that India would import many light-water reactors after the India-U.S. civil nuclear deal. But, the deal has not led to the establishment of a single new nuclear plant, over 13 years after it was concluded.
- Lack of Public Funding: Nuclear power has never received the quantum of generous subsidy the fossil fuel received in the past and renewable is receiving currently.
- In absence of public funding, nuclear power will find it tough to compete against natural gas and renewables in the future.
- Acquisition of Land: Land acquisition and selection of location for Nuclear Power Plant (NPP) is also a major problem in the country.
- NPP’s like Kudankulam in Tamil Nadu and Kovvada in Andhra Pradesh have met with several delays due to the land acquisition related challenges.
- Impact of Climate Change: Climate change will increase the risk of nuclear reactor accidents. During the world’s increasingly hot summers, several nuclear power plants have already had to be temporarily shut down or taken off the grid.
- Further, nuclear power plants depend on nearby water sources to cool their reactors, and with many rivers drying up, those sources of water are no longer guaranteed.
- The frequency of such extreme weather events is likely to increase in the future.
- Deployment at Insufficient Scale: It might not be the appropriate choice for mitigating India’s carbon emissions since it cannot be deployed at the necessary scale.
- Nuclear Waste: Another side effect of nuclear power is the amount of nuclear waste it produces. Nuclear waste can have drastically bad effects on life, causing cancerous growths, for instance, or causing genetic problems for many generations of animals and plants.
- In a densely populated country such as India, land is at a premium and emergency health care is far from uniformly available.
India’s Initiatives Regarding Nuclear Energy
- India has consciously proceeded to explore the possibility of tapping nuclear energy for the purpose of power generation.
- In this direction a three-stage nuclear power programme was formulated by Homi Bhabha in the 1950s.
- The Atomic Energy Act, 1962 was framed and implemented with the set objectives of using two naturally occurring elements Uranium and Thorium as nuclear fuel in Indian Nuclear Power Reactors.
- In December, 2021, the Government of India informed Parliament about building ten indigenous Pressurised Heavy Water Reactors (PHWRs) to be set up in fleet mode and had granted “in principle approval” for 28 additional reactors, including 24 to be imported from France, the U.S. and Russia.
- Recently, the Centre has given in-principle (first step ) approval for setting up of six nuclear power reactors at Jaitapur in Maharashtra.
- Jaitapur would be the world’s most powerful nuclear power plant. There would be six state-of-the-art Evolutionary Power Reactors (EPRs) with an installed capacity of 9.6 GWe that will produce low carbon electricity.
- The six nuclear power reactors, which will have a capacity of 1,650 MW each, will be set up with technical cooperation from France.