BYP.ARAVIND

MECHANICAL

NUCLEAR ENERGY

What is nuclear energy?

Nuclear energy is a powerful source of energy, generated during a nuclear reaction, by change in the nucleus of an atom. The source of nuclear energy is the mass of the nucleus and energy generated during a nuclear reaction is due to conversion of mass into energy (Einstein's Theory).

TWO WAYS TO OBTAIN NUCLEAR ENERGY:1. Nuclear fission 2. Nuclear fusion

NUCLEAR FISSION

Nuclear fission reaction, the nucleus of a heavy radioactive element like uranium, plutonium or thorium splits up into smaller nuclei, when bombarded by low energy neutrons. A huge amount of heat is generated in this process, which is used in nuclear power plants to generate electricity.

NUCLEAR FUSION Nuclear fusion reaction involves the

combination or fusion of two light elements to form a heavier element and release uncontrollable energy. Thus it cannot be used to generate electricity, unlike fission reaction. Did you know that the sun’s energy is generated by nuclear fusion reaction? The heat and light that we get from Sun, is all due to the continuous reactions going on inside it. We can now imagine how much energy would be released in the nuclear fusion reaction, that it is the source of sun’s energy

BRIEF INTRO Nuclear power is the use of sustained

nuclear fission to generate heat and electricity. Nuclear power plants provide about 5.7% of the world's energy and 13% of the world's electricity.

There were 439 nuclear power reactors in operation in the world, operating in 31 countries.

Environmentalists for Nuclear Energy contend that nuclear power is a sustainable energy source that reduces carbon emissions.

Just as many conventional thermal power stations generate electricity by harnessing the thermal energy released from burning fossil fuels, nuclear power plants convert the energy released from the nucleus of an atom via nuclear fission that takes place in a nuclear reactor.

The heat is removed from the reactor core by a cooling system that uses the heat to generate steam, which drives a steam turbine connected to a generator producing electricity.

LIFE CYCLE A nuclear reactor is only part of the life-cycle

for nuclear power. The process starts with mining (see Uranium mining). Uranium mines are underground, open-pit, or in-situ leach mines.

The uranium ore is extracted, usually converted into a stable and compact form such as yellowcake, and then transported to a processing facility. The yellowcake is converted to uranium hexafluoride, which is then enriched using various techniques

The fuel rods will spend about 3 operational cycles (typically 6 years total now) inside the reactor, generally until about 3% of their uranium has been fission,

then they will be moved to a spent fuel pool where the short lived isotopes generated by fission can decay away.

After about 5 years in a spent fuel pool the spent fuel is radioactively and thermally cool enough to handle, and it can be moved to dry storage casks or reprocessed.

URANIUM Uranium is a fairly common element in the

Earth's crust. Uranium is approximately as common as tin or germanium in Earth's crust, and is about 40 times more common than silver.

Uranium is a constituent of most rocks, dirt, and of the oceans. The fact that uranium is so spread out is a problem because mining uranium is only economically feasible where there is a large concentration.

The cost of nuclear power lies for the most part in the construction of the power station.

Therefore the fuel's contribution to the overall cost of the electricity produced is relatively small, so even a large fuel price escalation will have relatively little effect on final price.

SCHEMATIC DIAGRAM OF A NUCLEAR REACTOR

ADVANTAGES Almost 0 emissions (very low greenhouse gas

emissions). They can be sited almost anywhere unlike oil which is

mostly imported. The plants almost never experience problems if not

from human error, which almost never happens anyway because the plant only needs like 10 people to operate it.

A small amount of matter creates a large amount of energy.

A lot of energy is generated from a single power plant. Current nuclear waste in the US is over 90% Uranium.

If reprocessing were made legal again in the US we would have enough nuclear material to last hundreds of years.

Modern reactors have two to ten times more efficiency than the old generation reactors currently in use around the US. New reactor types have been designed to make it physically impossible to melt down.

As the core gets hotter the reaction gets slower, hence a run-away reaction leading to a melt-down is not possible.

DISADVANTAGES Nuclear plants are more

expensive to build and maintain.

Waste products are dangerous and need to be carefully stored for long periods of time. The spent fuel is highly radioactive and has to be carefully stored for many years or decades after use. This adds to the costs.

There is presently no adequate safe long-term storage for radioactive and chemical waste produced from early reactors some of which will need to be safely sealed and stored for thousands of years.

Nuclear power plants can be dangerous to its surroundings and employees. It would cost a lot to clean in case of spillages.

There exist safety concerns if the plant is not operated correctly or conditions arise that were unforeseen when the plant was developed, as happened at the Fukushima plant in Japan.

nuclear plants can render hundreds of square miles of land uninhabitable and unsuitable for any use for years, decades or longer, and kill off entire river systems .

A lot of waste from early reactors was stored in containers meant for only a few decades, but is well past expiration and, resulting, leaks are furthering contamination.

Early nuclear research and experimentation has created massive contamination problems that are still uncontained.

INDIA’S NUCLEAR ENERGY

Nuclear power is the fourth-largest source of electricity in India after thermal, hydroelectric and renewable sources of electricity.

As of 2012, India has 20 nuclear reactors in operation in six nuclear power plants, generating 4,780 MW while seven other reactors are under construction and are expected to generate an additional 5,300  MW.

India has been making advances in the field of thorium-based fuels, working to design and develop a prototype for an atomic reactor.

The country has also recently re-initiated its involvement in the LENR research activities , in addition to supporting work done in the fusion power area through the ITER initiative.

Using thorium and low-enriched uranium, a key part of India's three stage nuclear power programme .

Madras Kaiga Kakrapar Rajasthan Narora Kanupp Chasnupp Tarapur Kudankulum

HISTORY OF NUCLEAR ENERGY IN INDIA

India emerged as a free and democratic country in 1947, and entered into the nuclear age in 1948 by establishing the Atomic Energy Commission (AEC), with Homi Bhabha as the chairman. Later on the Department of Atomic Energy (DAE) was created under the Office of the Prime Minister Jawahar Lal Nehru. Initially the AEC and DAE received international cooperation, and by 1963 India had two research reactors and four nuclear power reactors.

In spite of the humiliating defeat in the border war by China in 1962 and China's nuclear testing in 1964, India continued to adhere to the peaceful uses of nuclear energy).

On May 18, 1974 India performed a 15 kt Peaceful Nuclear Explosion (PNE).

The western powers considered it nuclear weapons proliferation and cut off all financial and technical help, even for the production of nuclear power. However, India used existing infrastructure to build nuclear power reactors and exploded both fission and fusion devices on May 11 and 13, 1998.

The international community viewed the later activity as a serious road block for the Non-Proliferation Treaty and the Comprehensive Test Ban Treaty; both deemed essential to stop the spread of nuclear weapons. India considers these treaties favoring nuclear states and is prepared to sign if genuine nuclear disarmament is included as an integral part of these treaties.