NANOSCIENCE AND NANOTECHNOLOGY
Nanoscience and Nanotechnology:
- It is the study of structures and materials on an ultra-small scale (in range of 1-100 nanometers).
- and the unique and interesting properties these materials demonstrate.
- It is the manipulation of matters at atomic level in order to produce novel materials and devices with new extraordinary properties.
- Basic concept of nanotechnology: Behavior of matters changes significantly when the surface area to volume ratio increases dramatically.
- Properties of materials are size dependent i.e. melting point, electrical conductivity, magnetic and chemical properties vary at nano scale range and follow “the laws of quantum physics”.
- Example: Some Polymers being insulators in the bulk form, they act like semiconductor in nanoscale.
|· Nanoscience is studying nanomaterials and their properties.
· Nanotechnology is using those materials and properties to create something new or different.
|· The development of nanoscience can be traced back to 5th Century B.C.
· Nobel laureate Richard Feynman introduces the concept of Nanotechnology in 1959 during a lecture entitled “There’s Plenty of Room at the Bottom”.
· Richard Feynman – Considered as Father of Modern Nanotechnology.
|· Also known as BUCKY BALL or Carbon 60.
· Carbon atoms connected to three others carbon atoms by covalent bonds in pentagons and hexagons pattern giving spherical shape.
· Bucky balls used in Composites to strengthen materials.
· Being a good electron acceptors, used in increasing efficiency of solar cells in transforming sunlight into electricity.
CARBON NANOTUBES (CNT):
|· CNTs are rolled graphene sheets in a cylindrical shape.
· Strongest and stiffest materials on earth in terms of tensile strength.
· Forms in either a seamless cylinder, known as Single-Walled CNTs or many cylinders stacked one inside the other, known as Multi-Walled CNTs.
· CNTs can carry 1000 times more electric current than equivalent copper and silver wire.
· Highest strength to weight ratio, used in light weight spacecrafts and ideal for bullet proof jackets.
· Flexible Electrical resistance, used in developing chemical vapours detection sensors.
· Easily penetrates cell membranes, helps in targeted drug delivery.
|· Extracted from graphite, an allotrope of carbon.
· Graphene is one single layer of graphite; a layer of sp2 bonded carbon atoms arranged in a honeycomb(hexagonal) lattice.
· Important properties: very good conductor of electricity and heat.
· 200 times stronger than steel, light-weight,
· Perfectly transparent, Impermeable to gases
· Allotropes: are different structural forms of same element and can exhibit quite different physical and chemical properties.
· Diamond, graphite and fullerenes are allotropes of carbon.
Zeolites or Molecular sieve:
|· Crystalline Alumino-silicates.
· Properties: Adsorption and Ion exchange.
· The unique structure allows the water of crystallization to be removed, leaving a porous crystalline.
· Used in petroleum industry to catalyse oil refinement.
|· Dendrimers polymer consists of molecular chains branched out from a common center (tree like structure).
· “dendritic box” used as vehicle for targeted drug delivery.
· Also used in environmental clean-up as they can trap metal ions.
Applications of Nanotechnology:
Health & Medicine:
|· Targeted drug delivery in destroying the cancer cells without harming healthy cells,
· Nano sponges (polymer) for absorbing toxins and removing them from bloodstreams.
· Gold nano cells for location and elimination of cancer cells.
· Antiviral Nano coating on Face mask and PPE kits.
· Nano robotics can acts as miniature surgeons.
|· CNTs membrane used for water desalination, nanoscale sensors for identifying water contaminations.
· Nano fabric “Paper-towel” used in oil for clean-up applications.
· Iron nanoparticles for remediation of contaminated ground water.
Food and Agriculture:
|· Titanium dioxide nanoparticles as antimicrobial agents.
· Anti-bacterial Silver nanoparticles in food packaging to increase shelf-life.
· Bio indicators to detect the bio magnification of pesticide and fertilizers.
Implications of Nanotechnology:
|Risks to Human Health:||Nano particles being slowly degradable, may accumulate into human body and affect regulatory mechanisms, compromise immune system response.|
|Environmental Issues:||Nano pollution created by toxic wastes from nano material manufacturing. Greater bioavailability and greater bioactivity may introduce new toxicity risk.|
GREY GOO: A hypothetical situation where self-replicating nano robots go out of control, and consumes all matter on the earth.
- It is a new carbon nanotube (CNT) based fiber that looks and acts like textile thread but is able to conduct heat and electricity.
- Behaves like both metal wires and strong carbon fibers.
- Used in field of aerospace, automotive, medical and smart-clothing markets.
Smart Matter/ Smart Dust:
- Is the use of tiny wireless sensors and transponders to communicate the information they sense.
- Made by Hitachi, have GPS capabilities, they can be sprayed on us and absorbed or taken in foods, drinks and even injected to monitor health and activities.
- These are materials which have a conductivity between conductors (generally metals) and non-conductors or insulators (such as ceramics).
- Its resistance falls with rise in temperature, opposite to metals.
- Semiconductors acts like an insulator at Zero Kelvin.
- g.: pure metals such as silicon or germanium or compounds such as gallium arsenide or cadmium selenide.
|Types of Semiconductors|
|Intrinsic material:||Material made to be very pure chemically. It possesses a very low conductivity level having very few number of charge carriers, namely electrons and holes(in equal quantities). E.g.: germanium, silicon.|
|Extrinsic material:||Extrinsic material – Electrical conductivity is higher than Intrinsic material.
In this a small amount of impurity has been added to the basic intrinsic material. This creates either an excess or shortage of electrons. In this way, two types of semiconductors are available:
· N-type: has excess of electrons. Free electrons are available within the lattices and their overall movement in one direction under the influences of potential differences result in an electric current flows.
· P-type: has shortages of electrons, i.e. there are ‘holes’ in crystal lattice.
Plasmonic Semiconductor Nanomaterials
- PSN are metal-like materials with free electrons on the surface that oscillate collectively when hit by light.
- It uses solar light to increase the photocatalytic efficiency to degrade pollutants as well as generate renewable hydrogen.
- PSN can easily absorbs toxic ions like arsenic and fluoride, helps in remove water contamination.
Applications of Semiconductors:
|· Used in Transistors and Electric circuits.
· In calculators, solar plates, computers and other electronic devices,
· In microchips and self-driving cars,
· 3-D printing machines,
· To make temperature sensors.
- An Atom is made up of a Nucleus (Protons + Neutrons) and Electrons revolving around the nucleus.
- Atomic number (Z) = number of Protons.
- Atomic mass number (A) = number of Protons + Neutrons.
- Isotopes: an element with same number of protons but different numbers of neutrons in each atom. Ex: Hydrogen has 3 types of isotopes, Protium (light water), Deuterium (heavy water) & Tritium and Uranium-238, Uranium-235
- Nuclear Force: Acts between protons and neutrons of atoms and binds the protons and neutrons in a nucleus together. So, nuclear force is strongest in nuclei and weak between electrons and nuclei.
- Radioactive decay is the process by which an unstable atomic nucleus loses energy by radiation.
- It was discovered by Henri Becquerel in 1896.
- A material containing unstable nuclei is considered radioactive in nature.
- Three of the most common types of decay are alpha decay, beta decay, & gamma decay, all of which involve emitting one or more particles or photons.
- Half-life refers to the time for half the radioactive nuclei in any atom to undergo radioactive decay.
TYPES OF NUCLEAR REACTIONS:
- Nuclear Fission
- Nuclear Fusion reactions.
|Nuclear Fission||Nuclear Fusion|
|Definition||Fission is the splitting of a large atom into two or more smaller ones.||Fusion is the fusing of two or more lighter atoms into a larger one.|
|Natural occurrence||Does not normally occur in nature.||Yes. occurs in stars, such as the sun.|
|By-products||Produces many highly radioactive particles||Few radioactive particles are produced|
|Takes little energy to split atoms||Extremely high energy is required to bring two or more protons close enough that nuclear forces overcome their electrostatic repulsion.|
|Energy Released||Lower than Fusion reaction but higher than other chemical reactions||Higher than Fission reaction|
|Usage||In nuclear power generation, Atom bombs||In experimental stage for future power generation.|
- A nuclear reactor is a reactor where the nuclear chain reactions occur that produces energy.
- Theseare used at nuclear power plants for electricity generation & in nuclear marine propulsion.
- Nuclear reactors convert the energy released by controlled nuclear fission into thermal energy for further conversion to mechanical or electrical forms.
- Nuclear fuel is the fuel that is used in a nuclear reactor to sustain a nuclear chain reaction.
- U-233, U-235 & Pu-239 are fissile in naturee., they exhibit nuclear fission when targeted with a neutron.
- U-238 & Th-232 are fertile in naturee., when targeted with neutrons instead of breaking down, they change into new element. (U238àPu239, Th232àU233).
- The Natural Composition of Uranium extracted from earth is that 99.3% is U-238, which is fertile and remaining is U-235, which is fissile.
- When the percentage of U-235 is increased in mixture i.e., described as Uranium enrichment.
- For this purpose, most commonly used technology is of
- On the basis of enrichment, two types of Uranium: 1) Low Enriched uranium (LEU), 2) High enriched Uranium (HEU).
- LEU is use for peaceful purposes like fuel in nuclear reactors (Kudankulam (1.5%) & Jaitapur (5%) required enriched Uranium.
- HEU is weapon grade uranium used for conducting nuclear test and nuclear weapons.
U-233 (not found naturally) is produced in Thermal breeder reactors where Thorium-232 absorbs a neutron to form U-233 which is fissile.
Fissile Material Cut-off Treaty (FMCT):
- Proposed International agreement that would prohibit the production of two main components of nuclear weapons: highly enriched uranium (HEU) and Plutonium.
- FMCT would provide new restrictions for the five recognized nuclear weapon states (US, Russia, UK, France, China) and the four states that are not NPT members (Israel, India, Pakistan, & North Korea).
- Moderators are generally atoms with lighter nuclei and does not absorb neutron.
- Hence, these are used in nuclear reactors to slow down the neutron in a controlled chain reaction.
- Generally Ordinary Water, Heavy Water and Graphite rods are used as moderators.
- There are used in nuclear reactors to control the fission rate of uranium or plutonium.
- Control rods are made of neutron poisons& therefore absorb neutron This action results in fewer neutrons available to cause fission & reduces the reactor’s power output.
- Control rods absorb neutrons but do not release energy in the process.
- Their compositions include chemical elements such as Boron, Cadmium, Silver, or Indium, that are capable of absorbing many neutrons without themselves fissioning.
NUCLEAR REACTOR & ITS TYPES:
- The commercial power plants have several types of design. They vary depending on the type of heat transfer fluid that is used and other design elements.
- Fusion reactors: increasingly seen as the future of energy security due to following factors:
- Abundance of fuel (Hydrogen)
- Clean source of energy as it involves no release of CO2
- Elimination of risk from nuclear waste.
- But these Fusion reactors are still in experimental stage due to their complexity in its operational handling.
- Different types of fission reactors are as listed in the table below.
|Light Water-Graphite reactor||Light Water||Graphite||Enriched Uranium|
|Boiling Water Reactor||Light Water||Light Water||Enriched Uranium||Steam from boiling water fed to turbine.
have any steam generator)
|Pressurized Water Reactor||Light Water||Light Water||Enriched Uranium||Steam generated in secondary loop.|
|Pressurized Heavy Water (CANDU)Reactor||Heavy Water (D2O)||Heavy Water||Natural Uranium||D2O helps in better moderation & sustain chain reaction|
|Fast Breeder Reactors||liquid sodium||No moderator used||U-238||produce more fuel than they consume
|Gas-Cooled Reactors||CO2||Graphite||Natural / Enriched Uranium|
Why India Prefers Fast Breeder Reactors?
- FBRs are designed to produce more fissile material (plutonium) than they consume (Thorium Th-232).
- Enrichment and Re-processing technology (ENR) is not easy and costly, and FBRs Effectively utilizes the natural uranium (nearly 80%).
- Consumes the depleted fuel discharged from thermal reactors, FBRs is important from Waste management and environmental considerations.
- FBR technology can use Thorium (as fertile material) which gets converted to U-233, a fissile isotope. This holds great promise as India has one of the world’s largest deposit of Thorium (450,000 tons) in form of sand dunes in Kerala and chattarpur coast of Orissa.
INDIA’S THREE STAGE NUCLEAR PROGRAM
- India has consciously proceeded to explore the possibility of tapping nuclear energy for the purpose of power generation and the Atomic Energy Act was framed and implemented with the set objectives of using two naturally occurring elements Uranium & Thorium having good potential to be utilized as nuclear fuel in Indian Nuclear Power Reactors.
- The 3-stage nuclear programme is developed with the aim of utilizing the vast Thorium reserves in India (about 25% of the world) as India is a Uranium scarce country.
|Stage-1: Pressurized Heavy Water Reactor
· Natural UO2 as fuel matrix (contains 99.3% U-238 and 0.7% U-235)
· Heavy water as moderator and coolant.
Fast Breeder Reactor
|· Primarily based on Plutonium which was obtained from the first stage reactor operation, as the fuel core.
· A blanket of U-238 surrounding the fuel core will undergo nuclear transmutation to produce fresh Pu-239 as more and more Pu-239 is consumed during the operation.
· Besides a blanket of Th-232 around the FBR core also undergoes neutron capture reactions leading to the formation of U-233.
· U-233 is the nuclear reactor fuel for the third stage.
|· Fuel: U-233 is obtained from the nuclear transmutation of Th-232 in stage-2 programme.
· Since India has abundant Thorium reserves in the form of monazite sand, the 3rd stage is critical for India’s nuclear energy basket.
NUCLEAR POWER IN INDIA:
- Currently India has 22 nuclear reactors operating in 7plants generating about 6780 MW of power.
- Nuclear power contributes to 8% of the total energy basket of India.
- India’s nuclear energy target set at 63000MW of power by 2032.
NUCLEAR TECHNOLOGY REGULATION IN INDIA:
DEPARTMENT OF ATOMIC ENERGY (DoAE):
- It is apex body under the direct charge of Prime Minister working toward development & regulation of nuclear technology in India.
- Atomic Energy Commission is the governing body of
ATOMIC ENERGY REGULATORY BOARD (AERB):
- The Board was constituted on 15 November 1983.
- AERB is the regulatory authority responsible for safe operations of nuclear reactors as well as regulation at all other nuclear facilities in India.
- It derives its powers from Atomic Energy Act, 1962 &the Environmental (Protection) Act,
NUCLEAR WEAPON TESTS OF INDIA
- Smiling Buddha (Pokhran I) was a single nuclear test conducted in 1974. (Mrs. Indira Gandhi period)
- Shakti (Pokhran II) was a group of 2 nuclear tests conducted in 1998 (Mr. Atal Bihari Vajpayee period)
Nuclear Power Corporation of India Limited (NPCIL):
|· Under the Atomic Energy Act, 1962 NPCIL is responsible for design, construction, commissioning and operation of nuclear power reactors in India.
· The Atomic Energy (Amendment) Act, 2016 empowers NPCIL to form joint ventures with any government company to produce, develop, control, & use atomic energy.
Bharatiya Nabhikiya Vidyut Nigam Limited (BHAVINI):
|· Wholly owned Enterprise of Government of India under the DoAE, situated at Kalpakkam, Tamil Nadu
· BHAVINI, implements Fast Breeder Reactors programme in the country.
|Atomic Minerals Directorate for Exploration and Research:
|· Its prime mandate is to identify and evaluate Uranium resources required for the successful implementation of Atomic Energy Programme of the country.|
India–United States Civil Nuclear Agreement
- Also known as the 123 Agreement signed between the United States & India in 2008
- Under this agreement, India agreed to separate its Civil & Military nuclear facilities and to place all its civil nuclear facilities under IAEA
- With this India was also granted the waiver from the NSG protocols to get Nuclear supply & technologies.
|The INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)
|· International organization to promote the peaceful use of nuclear energy, and to inhibit its use for any military purpose, including nuclear weapons.
· Also known as the world’s “Atoms for Peace”.
· India is a member country of IAEA.
· Established through the IAEA Statute, the IAEA reports to both the United Nations General Assembly and Security Council.
THE WORLD ASSOCIATION OF NUCLEAR OPERATORS (WANO)
|· WANO is a not for profit, international organization with a mission to maximize the safety and reliability of the world’s commercial nuclear power plants.
· It was established on 15 May 1989 following the nuclear accident at Chernobyl (Ukraine).
· HQ: London, UK
· India is a member country of WANO.
IMPORTANT NUCLEAR NON-PROLIFERATION TREATIES:
PARTIAL TEST BAN TREATY (PTBT):
- PTBT is the abbreviated name of the 1963 Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space and Under Water, which prohibited all test detonations of nuclear weapons except for those conducted underground.
- The PTBT was signed by the governments of the Soviet Union, the United Kingdom, & the United States in Moscow on 5 August 1963.
- Since then, 123 other states have become party to the treaty. Ten states have signed but not ratified the treaty.
NON-PROLIFERATION OF NUCLEAR WEAPONS TREATY (NPT), 1968:
- NPT is an international treaty whose objective is to prevent the spread of nuclear weapons & weapons technology, to promote cooperation in the peaceful uses of nuclear energy, and to further the goal of achieving nuclear disarmament.
- Signed by 191 countries, the treaty restricts nuclear non-weapon states (countries which had no nuclear weapon till1968) from developing or acquiring nuclear weapons.
- 5 states recognized as nuclear-weapon states include the United States, Russia, the United Kingdom, France, and China.
- Four UN member states that have never joined the NPT are: India, Israel, Pakistan & South Sudan.
- North Korea had signed the NPT in 1985 later in 1993 it unilaterally withdrew from NPT.
- Though India is not a part of NPT, it has signed the Comprehensive Safeguards Agreement IAEA in 2009.
- Accordingly, India has kept 20 of its 22 civilian nuclear facilities under IAEA safeguards
COMPREHENSIVE TEST BAN TREATY (CTBT)
- CTBT was negotiated at the Conference on Disarmament in Geneva and adopted by the United Nations General Assembly in 1996.
- The Treaty intends toban all nuclear explosions- everywhere, by everyone.
- So far it has been signed by 184 states, of which 168 have ratified the treaty. However, the treaty has not come into force
- China, Egypt, Iran, Israel, &USA have signed but not ratified the NPT.
- India, Pakistan and North Korea haven’t signed the NPT.
EXPORT CONTROL REGIMES
The NUCLEAR SUPPLIERS GROUP (NSG):
- NSG is a multilateral export control regime& a group of nuclear supplier countries that seek to prevent nuclear proliferation by controlling the export of materials, equipment & technology that can be used to manufacture nuclear weapons.
- The NSG was founded in response to the Indian nuclear test in May 1974.
- It is a 48-member export-control regime that regulates export of nuclear technology and fuel.
- Nuclear non-weapon states who have signed NPT can have access to items listed in NPT.
- Though India is not a member of NSG, in 2008 India was granted a special waiver by NSG for supply of nuclear fuel and technology to India.
- Thus, India became the first & only non-NPT signatory to have this privilege.
- Was established in response to Chemical Weapon use in Iran-Iraq war in 1984.
- There are around 43 members at present including India, USA.
- Objective: is to control exports of biological & chemical agents used as weapons.
MISSILE TECHNOLOGY CONTROL REGIME (MTCR):
- The MTCR is a multilateral export control regime. Established in 1987by the G-7 industrialized countries.
- It is an informal political understanding among 35 member states that seek to limit the proliferation of missiles & missile technology.
- Accordingly, weapons delivery system carrying more than500 kg payload for over 300 km is restricted under MTCR.
- In 2018 India joined MTCR, which enabled India to:
- Increase the range of brahmos from 290KM to 450KM.
- Get access to predator drones from different countries
- It is the successor to the Cold War-era Coordinating Committee for Multilateral Export Controls (COCOM), and was established on 12 July 1996, in Wassenaar, the Netherlands.
- Objective: is to contribute to regional and international security and stability by promoting transparency and greater responsibility in transfers of conventional arms and dual-use goods & technologies.
- Currently, it has 42 members including India, US, Canada, Mexico, Argentina, Australia, Japan, Russia, South Africa etc.
NATIONAL & INTERNATIONAL DEVELOPMENTS
INTERNATIONAL THERMONUCLEAR EXPERIMENTAL REACTOR (ITER):
|· ITER is an international nuclear fusion research & engineering megaproject, which will be the world’s largest magnetic confinement plasma physics experiment.
· Headquarters:-Saint-Paul-lez-Durance, France.
· ITER was launched in 1985 &is expected to be completed by 2025.
· It is a joint collaboration of 35 countries with the following members China, the EU, India, Japan, South Korea, Russia & the US.
|· It is a branch of non-invasive medical imaging that uses small amounts of radioactive materials to diagnose & determine the severity of diseases or treat a variety of diseases including cancers, heart disease, gastrointestinal, endocrine, neurological disorders etc
· For example, Radio-isotopes such as Cobalt-60, Arsenic-74 are used in treating Thyroid disorders & various types of Cancer.
ROOPPUR NUCLEAR POWER PROJECT (RNPP):
- This will be a 4 GWe nuclear power plant in Bangladesh on the banks of the river Padma, 87 miles (140 km) west of Dhaka.
- RNPP is the collaboration project between the India, Russia & Bangladesh.
- The Hindustan Construction Company of India is being involved in the construction of “Non-critical” infrastructure.
- The Nuclear reactor & “Critical infrastructure” are being built by the Russian Rosatom State Atomic Energy Corporation.
USA to Set Up 6 Light Water Reactors in Kovvada, Andhra Pradesh
- Under the agreement, the US Company Westinghouse Electric will sell Six AP-1000 nuclear reactors to India.
- NPCIL will be responsible for construction and operation of the plant.
- Note: Fuel used here is U-235& ordinary water as coolant and moderator.
GLOBAL CENTRE FOR NUCLEAR ENERGY PARTNERSHIP (GCNEP):
- GCNEP is the World’s first nuclear energy partnership center at Kheri Jasaur village of Haryana state in India.
- GCNEP will help in capacity building, in association with the interested countries & the IAEA, involving technology, human resource development, education & training and giving a momentum to R&D in enlisted areas.