Nuclear Energy: Fission and Fusion

Renewable Energy: Nuclear Energy

• Nuclear energy involves the generation of energy from nuclear reactions.
• Nuclear reactions for energy include nuclear fission and nuclear fusion.
• Nuclear fission is splitting heavy nuclei of uranium, thorium, or plutonium into lighter nuclei.

Isotopes, Electrons and Protons

• Electrons, protons, and neutrons are the components of atoms.
• Isotopes are variants of an element with the same number of protons but different numbers of neutrons.
• Hydrogen isotopes include Protium, Deuterium, and Tritium.

Nuclear Fission vs Nuclear Fusion

• Nuclear fission involves splitting a heavy, unstable nucleus into two lighter nuclei, releasing energy.
• Nuclear fusion involves combining two light atomic nuclei to form a single, heavier nucleus, releasing significant energy.
• Nuclear fission is not common in nature, while nuclear fusion occurs in stars.
• Nuclear fission typically requires high-speed neutrons, while nuclear fusion requires high temperature and high-pressure conditions.
• Nuclear fission produces highly radioactive fission products, while nuclear fusion may not release energy from heavy nuclei reactions.
• Examples of nuclear fission include neutron bombardment of uranium-235 and radioactive decay in unstable isotopes.
• Examples of nuclear fusion include fusion between Deuterium and Tritium.

Nuclear Reactor Functionality

• A nuclear reactor is based on a controlled chain reaction and fusion.
• Reactor designs use a neutron moderator, such as regular water, solid graphite, or heavy water, to reduce the speed of fast neutrons.
• A coolant, like water or molten salt, is circulated past the reactor core to absorb the generated heat.
• Heat is then used to generate steam.
• Control rods made of neutron poisons like boron, silver, indium, and cadmium are used to absorb neutrons. This controls the rate of fission.
• Inserting the control rods deeper reduces the reactor's power output, and removing them increases it.
• Moderators slow down neutrons, while control rods absorb them.

Nuclear Fuel Cycle

• The nuclear fuel cycle consists of operations and facilities for nuclear power generation.
• The nuclear fuel cycle is divided into a front end (before generation) and a back end (after generation).

Front End of Nuclear Fuel Cycle

• The front end includes surveying and exploration done by the Atomic Minerals Directorate (AMD) in Hyderabad.
• Mining and milling occur at the Uranium Corporation of India Ltd. (UCIL) in Jaduguda, Singhbhum, Jharkhand, with new deposits found in Tummalapalle, Andhra Pradesh.
• New uranium sites are usually found in plateaus, including Domiasiat (Meghalaya), Rohil (Rajasthan), and the Gwalior Basin (Madhya Pradesh).
• Natural uranium contains only 0.7% U-235 (the fissionable isotope), with the remaining 99.3% as non-fissionable U-238.
• Uranium is typically enriched to 2.5-3.5% U-235 for light water reactors.
• Enrichment over 90% is needed for fast chain reactions in weapons applications.
• UCIL handles enrichment, which is usually 15-30% for breeder reactors.
• Enriched uranium is converted to solid yellow cakes, made into pellets and packed into fuel rods at the Nuclear Fuel Complex in Hyderabad.

Back End of Nuclear Fuel Cycle

• Reprocessing is done by the Bhabha Atomic Research Centre (BARC).
• Unused uranium is recovered, and radioisotopes are removed.
• Unused uranium goes to enrichment and fabrication
• Nuclear waste is vitrified, stored, and then dumped into deep geological formations like abandoned mines, oceans, or rocks.

International Atomic Energy Agency (IAEA)

• If a country has achieved a full fuel cycle with enrichment and reprocessing and has ENR technology, it is capable of developing both weapons and peaceful nuclear applications.
• IAEA is the nuclear watchdog of the UN.
• IAEA has its headquarters in Vienna, Austria.
• IAEA promotes the peaceful use of nuclear technology.
• Nuclear facilities are kept under IAEA safeguards if the uranium source, the fissile material for a nuclear reactor, is from outside the territory of India or because of new reactor plants from foreign collaboration.
• IAEA safeguards ensure that imported uranium is not diverted for military use and is for civilian energy production.
• IAEA was set up as the world's Atoms for Peace organization in 1957 within United Nations.
• IAEA is the international center for cooperation in the nuclear field.
• IAEA has 175 member states with India as a founding member.
• IAEA’s mandate to maximize contribution of nuclear technology to society while verifying its peaceful use.

Nuclear Safety

• Nuclear safeguards prevent diversion to military purposes (e.g., NPT, CTBT).

Nuclear Reactors

• Nuclear reactor is based on a controlled chain reaction and fusion.
• Types of nuclear reactors include Boiling Water Reactors (BWR) and Pressurized Heavy Water Reactors (PHWR)
• Moderators slow down neutrons, control rods absorb neutrons
• Moderators are like accelerators, control rods are like brakes

Boiling Water Reactor

• A first-generation reactor that uses normal water to boil and create steam in the core which produces a water-steam mixture.
• Steam is separated and used to run a turbine generator to produce electricity.
• Steam is then converted back to liquid water and reheated.
• The Fukushima nuclear plant is an example of a BWR.
• There is direct water conversion and no heat exchange, thus more power, and a simple design.
• The core contains radioactive water, so leakage can contaminate, and risks are difficult to control.
• Can be negatively affected by an earthquake

Pressurized Heavy Water Reactor

• PHWR use heavy water (D2O) as both a moderator and coolant in the first cycle.
• High-pressure keeps the heavy water super hot without converting it into steam.
• The heavy water exchanges heat to a second cycle containing water which runs a turbine to produce electricity.
• India is a large producer of heavy water and utilizes PHWRs.
• PHWR efficiency is higher, can be condensed and recycled and safer because of no steam in core, BUT costly and complex design

Fast Breeder Reactor

• Fast breeder reactors convert U-238 into fissile Pu-239 using fast neutrons, generating more fuel than consumed and is generally liquid sodium
• Do not require a moderator.
• U-238 converts to Pu-239 in the reactor, thorium can be used to get U- 233
• Are cost effective (no heavy water) and Pu-239 can be reprocessed but the more control is difficult

Thorium based Reactor

• It uses a Uranium-233 and Thorium mixture and used normal water into steam and heavy water as the moderator
• Thorium is 4 times more abundant than Uranium

India's Nuclear program

• It meets the countries energy needs by utilizing its 25% Thorium, Atomic Energy Act was passed in 1962 and conceptualized by Homi Mhabha. It involves a 3-stage nuclear program

3 stages

• First stage reactors are PHWR & BWR using natural Uranium as well as heavy water but provide Plutonium
• Second level, converts U-238 and Thorium used in the first stage into extra fuel is done using a Fast Breeder Reactor e.g. The Kalpakkam.
• Third stage is the Advanced Heavy water reactor which light water as the moderator

India's Nuclear Doctrine

• "No First use"
• "Credible minimum deterrence"
• Retaliation to chemical weapons is OK"

Global International Biofuel Alliance (GIBA)

• launched by India during India Energy Week 2023 to create a global eco system for biofuels

Nuclear Fusion

• Nuclear fusion is a process where two light atomic nuclei, combine to form a single heavier nucleus and releases large amounts of energy
• the two nuclei need to be able to outweigh the repulsive (Electrostatic) force
• Fusion reactions take place in plasma, a hot, charged gas of positive ions and free-moving electrons and requires 100 million degrees Celcius

Fusion vs Fission: (2 types of Nuclear fusion)

• Inertial: laser or ion beams are focused very precisely onto the surface of a target
• Magnetic: hundreds of cubic meters of plasma at a density of less than a milligram per.
• Advantages: High Energy and wide fuel availability, zero CO2 waste and low radioactive
• Cons: Plasma extremely difficult to store, fusion reactions are difficult to control at high temp

Small Modules

• SMRS are advanced nuclear reactors up to 300MW, affordable (prefabricated) more save in cost and space

Biofuels

• Is fuel thats made from plants, it reduces less carbon dioxide and is considered an biofuel e.g., Biogas
• Types include: Solid, Liquid, and gas
• first gen biofuels uses food crops to produce oil
• second gen biofuels are are wood, biomass, food or crap waste
• Third gen biofuels are engineered energy like algae
• Generation biofuels: captures biomass while growing, and are converted into fuel

Biofuel Advantages

• Increases life of vehicle engine, made from different renewable sources, lower levels of pollution

Biofuel Disadvantages

• Expensive, debate, emits large amounts of emissions, encourage monoculture, are les suitable in low temperature

National Policy on Biofuels (2018)

• revised document on Biofuels to increase use of biofuels in the energy and transportation and set up 20 -5 ethanol production

Ehtanol

• Also produced by fermentation, low environmental pollution to produce C02 and water, and higher octane
• Made with raw material
• Methanol blended Diesel uses 755 blend of Diesel and is clean fuel

compressed Natural gas (CBG)

• compressed and purified bio-gas from agricultural residue
• Benefits is Reduces/ solves stubble burning and production of organic burning

Biomass Co firing

• SAMARTH Mission is the National Mission on Use of Biomass, advantage is its better than traditional coal powered plants due to lower price etc.

National Bioenergy programme (NBP)

• NBP will use waste to energy and biomass energy

Geothermal energy

• Uses water and head or hot water from underground via hydrothermal
• Carbon free, continuous and located specfically

Three scheme:

• Waste from Energy Programme
• Biomass Programme
• Biogas Programme The compressed b.

Wave Energy

• High tide

Wind: - The more of the land

OTEC (Them Ocean thermal energy conservation)

• It uses temperature and pressure

India has the following

• Bhabha

Fast Breeder reactor

• The first prototype has now been in Kalapakkam

Nuclear safegaurds and policy

• It comes through fuel. India must do it

Methanol

• Has the advantage of creating polygeneration

Hydrogen

• The ability to store

National green hydrogen mission and renewable energy with the UNFCC

• 500GW Capacity of fossil energy -50 power percent of the required