Nuclear Technologies

Nuclear Technology is the technologies that involve nuclear reaction. Such reactions can generate tremendous amounts of energy. There are two types of Nuclear reactions – Nuclear fusion and Nuclear fission.  Fusion generally involves Hydrogen. It is the same mechanism by which the sun produces such tremendous amounts of energy. 

Applications  of Nuclear Technologies: 

1. Agriculture: Insect control, N-15 for nitrogen fixation, plant mutation breeding.
2. Food Processing: Food irradiation with Gamma rays for sterilization.
3. Manufacturing: Smoke detectors use americium, in watches radium is used etc.
4. Industrial uses: to detect flows, gauge wear and tear, quality control, check micro-cracks etc.
5. Water purification: desalination
6. Medical purposes: For example, Iodine therapy for thyroid treatments uses I-131.
7. Power generation: Nuclear power, generators in ships, submarines etc. In space missions, micro-reactors are used for example in Cassini, New Horizons, Curiosity Mars rovers etc.
8. Research: For archaeology, C-14 is used for carbonating, in exploration it is used for making sensors and detectors in satellites.
9. Environment: detection of pollutants, underground water resources etc.

The biggest advantage 

Importance as an energy Source:

1. Clean fuel.
2. Abundance of Thorium in India
3. Cost-effective: Takes less space.
4. Reliable: not erratic like Renewable energy
5. National & Energy security – deterrence. 
6. Already invested in 3 phase program.

Nuclear Energy

Binding Energy

The energy required to separate all the nucleons (protons and neutrons) in the nucleus of an atom. The binding energy per nucleon indicates the stability of a nucleus. Higher binding energy per nucleon indicates a more stable nucleus.

Mass-Energy Equivalence

The mass of a nucleus is always less than the sum of the masses of its individual protons and neutrons. The difference in mass is called the mass defect, and it is converted into binding energy as per Einstein’s equation:

Where Δm is the mass defect, c is the speed of light, and E is the binding energy.

Nuclear energy

Nuclear energy can be derived in two ways – Nuclear Fusion and Nuclear Fission.

Nuclear Fission

The process of splitting a heavy nucleus (e.g., uranium) into two smaller nuclei, releases a large amount of energy. This is the basis for nuclear reactors and atomic bombs.

Nuclear Fusion

The process of combining two light nuclei (e.g., hydrogen) to form a heavier nucleus, releases even more energy than fission. Fusion is the energy source of the sun and other stars.

Nuclear Bombs

A nuclear bomb is a weapon that derives its destructive power from nuclear reactions, either fission (splitting heavy atomic nuclei) or fusion (combining light atomic nuclei). These reactions release enormous amounts of energy, capable of causing massive destruction. Types of Nuclear Bombs: Atomic Bomb (Fission Bomb): The first type of nuclear bomb, developed during World War II, uses uranium-235 or plutonium-239. When the nuclei of these isotopes are split, they release vast amounts of energy. The bomb dropped on Hiroshima in 1945 was an atomic bomb. Hydrogen Bomb (Thermonuclear Bomb): A more powerful bomb, which combines fission and fusion. It uses a fission bomb to trigger the fusion of hydrogen isotopes (deuterium and tritium), releasing much greater energy. The first hydrogen bomb test was conducted by the United States in 1952. Effects: Blast: A powerful shockwave that flattens buildings and causes massive structural damage. Heat: Intense thermal radiation causes fires and burns over large areas. Radiation: Both immediate and long-term radiation can cause severe health issues, including radiation sickness and cancer. Fallout: Radioactive particles can spread over vast areas, causing long-term environmental damage. Nuclear weapons have been used twice in warfare (Hiroshima and Nagasaki) and continue to be a subject of global disarmament efforts due to their devastating consequences.

Nuclear Fission

Nuclear fission involves radioactive elements such as Radium, Plutonium, Uranium and Thorium. The government has taken several measures to enhance the generation of nuclear fission-based power plants in the country. The government follows a three-stage nuclear program. 

A Fission reactor uses four types of material in order to safely derive power from the radioactive material. Let’s understand by taking the example of the most common type of nuclear fission reactor.

1. The Radioactive Fuel whose reaction rate can be accelerated by a chain reaction. For example, When U-235 (Uranium – 235) is triggered with a neutron, it splits to produce 2-3 slow-moving neutrons while decaying. These neutrons can be absorbed by other U-235 nuclei to become unstable, creating a chain reaction.

U-235 + n → Barium + Krypton + 3n + Energy

1. Moderator: A moderator is a material used in a nuclear reactor to slow down fast neutrons, increasing the likelihood of fission. Most moderators in Uranium-based power plants slow down neutrons or absorb them to increase the rate of reaction. For example, water, heavy water (D2O) and Graphite.
2. Coolant: The coolant in a nuclear reactor is a substance that removes or transfers heat from the reactor core. Running Water is often used as a coolant. Molten Salt or Molten metal also works amazingly well as a coolant. 
3. Control Rods: In the absence of control Rods, the nuclear reaction may run uncontrollably and may lead to a nuclear disaster. Luckily, since nuclear power plants use fuel of much lower purity (just 2-5%), it can never explode like a nuclear bomb.

Processing of Nuclear fuel

Natural uranium consists mostly of Uranium-238 (U-238) (about 99.3%) and only a small fraction of Uranium-235 (U-235) (about 0.7%). While U-235 is the isotope that is most readily fissionable, and not U-238. In order to use uranium as nuclear fuel, it needs to be enriched to increase the concentration of U-235. 

Uranium Enrichment

Uranium enrichment via centrifuges involves the following steps:

1. Conversion of Uranium to Uranium Hexafluoride (UF6): Uranium ore is first mined and processed into yellowcake (U3O8). This yellowcake is then converted into uranium hexafluoride (UF6) gas, which is suitable for the centrifuge process.
2. Centrifugal operations: Centrifuges are vertical machines that spin at very high speeds (thousands of RPMs). The UF6 gas is injected into these centrifuges, where it is subjected to a strong centrifugal force. Because U-235 is slightly lighter than U-238, the centrifugal force causes the heavier U-238 to move toward the outer edge of the centrifuge, and is separated.

We get two types of material through this process:

1. Depleted Uranium – with a higher concentration of U-238.
2. Enriched Uranium – with a higher concentration of U-235.

Enriched Uranium can be used in several different types of processes depending on the enrichment level:

1. Low-enriched uranium (LEU): Typically around 3-5% U-235, which is used in most nuclear reactors for electricity generation.
2. Highly enriched uranium (HEU): Above 20% U-235, and can be used in nuclear weapons or certain specialized reactors. 

Fission Waste

The next big challenge in nuclear fission reactors is to deal with the products of fission reactions. The used nuclear fuel that has gone through a nuclear reactor’s fission process is referred to as the ‘Spent Fuel’. 

• After being irradiated, it contains a mix of isotopes, including radioactive elements.
• Spent fuel remains highly radioactive and requires careful storage or reprocessing to manage its long-term environmental and health risks.

Generally, the spent fuel is kept in water pools which cools them down convectively. Once they are sufficiently cooled, the fuel is then stored in deep mines and is then sealed.

For example, the Uranium spent fuel primarily consists of:

1. Uranium-238 (U-238) – The majority of the spent fuel remains as U-238, which is less fissile.
2. Plutonium (Pu) – Produced by neutron absorption in U-238, plutonium isotopes (especially Pu-239) are highly fissile.
3. Fission products – These include various radioactive elements like iodine-131, cesium-137, and strontium-90, resulting from the fission of uranium atoms.
4. Minor actinides – Including neptunium, americium, and curium, which are also radioactive and contribute to the fuel’s long-term radioactivity.

However, spent fuel is a potential environmental hazard, which if leaked into the environment, can act as a carcinogen.

Closed Fuel Cycle

A closed nuclear fuel cycle is a process that reprocesses and reuses spent nuclear fuel, rather than storing it for disposal. This process helps to reduce waste volume, long-term radiotoxicity, and the need for geological isolation.

Types of Nuclear Fission Reactors

Nucleus of radioactive heavy metals are fissioned to derive energy. 

Uranium Based Power

Only the Fission of U-235 provides thermal Neutrons which can create a chain reaction. However, natural Uranium contains less than 1% of U-235. The largest reserve and exporter – is Kazakhistan; Then Canada and the US – in terms of exports. 

• Pressurized heavy water reactor. 

• Enriched URANIUM(3-5% U-235) ->  Electricity + Plutonium-239 +  Depleted U (U-238).

• The end product is hot. It is impossible to enrich it for the next cycle.

Small Modular Reactors

DW

Plutonium based Power

• 2nd Stage reactor: Pu fuelled fast breeder reactor: [Fast: Fast moving neutrons]

1. It generates more fissile material than what it consumes.

1. No moderator is required.
2. Plutonium-239(+ depleted U) + Natural Uranium-238 -> Plutonium-239 + Energy

Thorium Based Power

• 3rd Stage reactor: Thorium Fuelled stage, U-233 fuelled breeder.

• self-sustaining series of thorium-232-uranium-233 fuelled reactors
• Thermal breeder reactor, which in principle can be refuelled – after its initial fuel charge – using only naturally occurring thorium.
• Pu  +   Thorium   -> U -233.
• U-233 + Thorium -> U-233.

Indian Nuclear Power Program

Homi Bhabha envisioned India’s nuclear power program in 3 stages to suit the country’s low uranium resource profile.

In the first stage, enriched uranium breaks to produce Plutonium depleted Uranium and a large amount of energy. In the second stage, depleted Uranium is again depleted to produce Plutonium and a large amount of energy. In the third stage, Thorium reacts with U-233 to produce more U-233. This is therefore called the fuelled breeder reaction.

India has a large amount of Thorium deposits. As a result, if India sets up several third-stage reactors then India would easily become energy-independent and fuel its growth. This is what Homi Jahangir Bhabha envisioned when he designed the three-stage nuclear program.

DAE’s 3-stage Nuclear Program:

Pressurized heavy water reactor (PHWR):

The PHWR uses unenriched natural uranium as fuel, and heavy water (deuterium oxide D2O) as coolant and moderator.

The present installed nuclear power capacity in the country is 6,780 MW and the share of nuclear power in the total electricity generation in 2020-21 is about 3.1%.

India has several PHWRs throughout India, as listed below: 

1. 1. Kudankulam Nuclear power plant: in Tirunelveli distt. Of TN.
      • There is a plan to build a total of six 1000MW reactors with Russian help. One is already operational with India having its full operational control.
      • It is the first plant to have post-fukushima safety enhancement requirements.
      • Built by NPCIL and Russia’s Atomstroyexport company.
   2. Gorakhpur Haryana Anu Vidhyut Pariyojana(GHAVP) Units  1 & 2 (2X700MW).
   3. Kakrapara Atomic Power Project Units 3 &4, Gujarat
      • Unit 3: 700MWe: biggest indigenously built.
      • The first two were based on Canadian tech.
   4. Rajasthan Atomic Power Project Units 7 & 8, in RawatBhata.
   5. Jaitapur (Ratnagiri, Maharashtra): -Technical cooperation from France – 6 nuclear power reactors with 1,650 MW capacity each will be set up.  It will be the country’s largest nuclear power generating site with a total capacity of 9,900 MW.

• Kaiga Atomic power station, Karnataka: 4X220MW; Phase III with 2X700MW is planned.

Problem with Uranium based power:

• Nuclear waste’s half-life is 4 billion years.
• A complex system is required to maintain stability and therefore it is liable for nuclear accidents. Fukushima and Chernobyl.

Heavy water production: done by the Atomic Minerals Directorate for Research and Exploration.

Prototype fast breeder reactor (PFBR): 

Prototype fast breeder reactor (PFBR): 

• 1st indigenously built 500MW @ Kalpakkam – Criticality to be achieved in 2019. The Nuclear chain reaction is self-sustaining. It produces neutrons to sustain the reaction.
  • A total of 4 FBRs have been sanctioned. One more in Kalpakkam and two elsewhere.
  • A new PSU: Bhartiya Nabhikiya Vidhyut Nigam(BHAVINI) Ltd. under DAE is implementing the project. It is wholly owned by GoI and under the administrative control of DAE.
  • It is 2nd power utility in India after NPCIL.
• Indira Gandhi Centre for Atomic Research Uses fast breeder reactor.

Advantages of Plutonium-based PFBR

• • Utilization of Nuclear waste from 1st phase. Reduced heat and toxicity.
  • Creating Pu-stockpile for 3rd phase: once a sufficient amount of plutonium-239 is built up, thorium will be used in the reactor, to produce Uranium-233.
  • Generates more fissile material than it consumes: In FBRs, plutonium-239 undergoes fission to produce energy, while the uranium-238 present in the fuel transmutes to additional plutonium-239. 
  • Easy to sustain chain reactions: Breeder reactors use a small core, which is important to sustain chain reactions. 
  • Don’t use moderators: do not even need moderators for slowing down neutrons for sustaining reactions, as they use fast neutrons.
  • 100 times more efficient than thermal reactors.

• Commerce in the fissile material such as Plutonium.  Such buying would elevate pressure from countries like Japan and the UK which are looking to reduce Pu stockpile. 

Challenges:

We only have a limited choice of fuel

Advanced Heavy Water Reactor (AHWR): 

AHWR forms the 3rd stage of India’s Civil Nuclear program. It is based on the U-233 cycle. It mainly utilises Thorium to sustain the reaction in a closed fuel cycle. 

However, many more decades would be required to build sufficient fissile material for the 3rd stage to use Thorium.

Advantages of AHWR

• • Thorium-based AHWR produces far less waste than present-day reactors.
  • Significantly less waste produced: Output is used as input.
  • Waste is toxic for 300 to 400 years only.
  • It is cheaper and we have in abundant quantities in India in monazite sand in Kerala.
  • It is easy to detect as it contains U-233 which is gama radiative. Therefore its movement can be traced and its movement can be easily monitored.
  • NPT allows the transfer of Plutonium under adequate safeguards.

• Resource utilization: Thorium is abundant in India. 

Limitations:

Plutonium stockpile is low in India.  The earliest projection for the Thorium utilisation is the late 2040s.

As there is a long delay before direct thorium utilization in the 3-stage program, the country is now looking at reactor designs that allow more direct use of thorium in parallel with a sequential 3-stage program. Advanced Heavy Water Reactor (AHWR) is such an option under consideration.

Nuclear Fusion: 

The nucleus of Hydrogen atoms is fused to form helium and other heavier nuclei which gives energy. No Fusion plant has ever achieved criticality, i.e. produced more energy than what is required to initiate the reaction.

• Tokamak
• Intertial confinement
• Magnetic mirror

Significance of Fusion Energy: 

• It promises to be low-carbon, 
• Safer than fission nuclear energy is now produced 
• Has an efficiency that can technically exceed 100%.

Experiments: 

• Jan 2022: China’s Experimental Advanced Superconducting Tokamak (EAST) sustained the plasma at 70 million degrees Celsius for 1,056 seconds in January 2022. The EAST project is part of the ITER project.
• Feb 2022: Joint European Torus (JET) fusion experiment in Oxfordshire, U.K., produced 59 megajoules (MJ) of energy from thermonuclear fusion. 
• These are dress rehearsals for the upcoming International Thermonuclear Experimental Reactor (ITER), a global experiment to generate 500 MW of power by fusing hydrogen atoms into helium atoms by 2035.

The International Thermonuclear Experimental Reactor (ITER):  

ITER is an unprecedented international scientific and technological collaboration representing more than half the world’s population is presently involved towards construction.

• Thirty-five countries, including India, Russia, USA, UK, China, EU, Japan & S. Korea are collaborating to jointly build the largest Tokamak as part of the ITER.
• ITER will be built mostly through in-kind contributions from the participant countries (Parties) in the form of components manufactured by the Parties and delivered/installed at ITER.
• The idea germinated in 1985. After years of ups and downs since March 2020, the machine assembly is underway at Saint Paul-lez-Durance, southern France. 
• ITER-India is the Indian Domestic Agency (DA), formed with the responsibility to provide ITER with the Indian contribution. India is contributing to the manufacturing of the Cryostat.
  • The 3,800-ton ITER cryostat will be the largest stainless steel vacuum chamber in the world. It will encase the entire vacuum vessel and all the superconducting magnets, ensuring an ultra-cool, protective environment.
  • With the installation of the Cryostat covering the assembly is slated to be completed by 2025. If all goes well, the first plasma will be produced at the end of 2025 or early 2026. 
  • After testing and troubleshooting, energy production will commence in 2035.
• The Future: The plant is expected to generate 500 MW of power and consume 50 MW for its operation, resulting in a net 450 MW power generation. 
  • Although there are many experimental tokamaks worldwide, including one in India, none has demonstrated net energy production more than the input. 
  • The main task of the experimental ITER reactor is to get operational experience and train human resources. 

ADITYA: 

It is India’s first indigenously designed and built experimental tokamak of the country. It was commissioned in 1989. ADITYA, a medium size Tokamak, has been operating for over a decade. It has a major radius of 0.75m and a minor radius of the plasma is 0.25 m. A maximum of 1.2 T toroidal magnetic field is generated with the help of 20 toroidal field coils spaced symmetrically in the toroidal direction.

India’s Nuclear Capacity:

1. 2% of TOTAL INSTALLED CAPACITY in India

1. India has 22 nuclear reactors in operation in 7 nuclear power plants, having a total installed capacity of 7 GW.

Defence Nuclear doctrine:

• Uranium enrichment was started in the late 1960s.
• The Smiling Buddha, 1972: Indira Gandhi (after the Bangladesh Liberation War) authorised the Bhabha Atomic Research Centre (BARC) to manufacture a nuclear device and prepare it for a test which was done in Pokharan.
  • This led to International condemnation and a series of counteractive measures such as the Comprehensive Test Ban Treaty(CTBT) and Non-Proliferation Treaty (NPT).
• Pokharan -II/Operation Shakti, 1998: This too invited sanctions from the USA and the next year Pakistan tested its own nuclear weapon.
• No First Use Policy(NFU: 2003): ‘India’s nuclear weapons were based on staggering and punitive retaliation, in case deterrence failed. The retaliation to a nuclear strike, whether by tactical or theatre weapons or something bigger, would be crushing enough to deter the possible use of nuclear weapons by an adversary.
• India’s Nuclear triad:  nuclear weapons delivery of a strategic nuclear arsenal which consists of three components: 

• Strategic bombers, 
• intercontinental ballistic missiles (ICBMs): Agni series.
• Submarine-launched ballistic missiles (SLBMs): K Series.

2014 Aim: GoI has announced tripling of the then existing capacity of 4780MW in the next ten years, i.e. by 2024

ISSUES

1. CIVIL

1. 2011 Fukushima Disaster – risk involved
2. ALTERNATIVE – solar energy has become cheap
3. In India – Delays in Expansion

• nuclear liability law

• Protests by people – KUDANKULAM in TN

1. Bankruptcy of Westinghouse

• India is NOT a member of the NPT

• MILITARY

• The 9/11 attack on the US discards the argument for deterrence

1. Cyber Warfare – easy to inflict and does brainwash  thousands, much more disastrous

• International relation issues

• Disposal of Spent fuel storage – Half-life 24000 years

1. Nuclear Proliferation: Why countries still have it

1. INSECURITY – even if one has it, others feel insecure
2. Clean fuel
3. Three Pillars of the Non-Proliferation Treaty

• non-proliferation

• Disarmament

• nuclear energy for peaceful purposes

Multipurpose fast research reactor project (MBIR): 

The Multipurpose Fast Research Reactor (MBIR) is a cutting-edge nuclear research reactor under construction in Russia (Dimitrovgrad, in Ulyanovsk region), designed for a wide range of applications, including material testing, nuclear fuel development, and the study of nuclear technologies. 

• MBIR is a pool-type fast neutron reactor, operating with a sodium coolant and using MOX (mixed oxide) fuel. 
• Objective: Its primary purpose is to provide a platform for researching advanced nuclear fuels, reactor materials, and waste management techniques, supporting both civil nuclear energy and nuclear safety research, with particular emphasis on:
  • Nuclear energy based on the closed fuel cycle with fast neutron reactors. 
  • A design that includes three independent loops that can be used to test different coolants like gas, lead, molten salt, among others, and therefore it will be possible to conduct material testing research in those different environments.”
  • A sodium-cooled Generation 4 fast reactor to design an advanced fast neutron reactor for use in nuclear power plants

It is expected to start operations in the early 2020s. MBIR will significantly contribute to the development of next-generation nuclear reactors.  

Russia has invited India to participate in its fast reactor research project.