Nuclear EnergyPRESENTATION

What is Nuclear Energy?

The large amount of energy released when heavy nucleus is break in the nuclear reactor. This energy is used for multipurposes as electricity generation or other mechanical works.

Nuclear Energy

The term includes nuclear fission, nuclear decay and nuclear fusion. Presently, the nuclear fission of elements in the actinide series of the periodic table produce the vast majority of nuclear energy in the direct service of humankind, with nuclear decay processes, primarily in the form of geothermal energy, and radioisotope thermoelectric generators, in niche uses making up the rest.

To get this energy some nuclear reaction are carried out. Given ahead.

Nuclear Reaction:

A nuclear reaction is a process in which atoms collide with other atoms and lose some of their original mass. Because of the principle of energy conservation the lost mass must reappear as generated energy, according to Einstein's equation E = mc².

The two types of nuclear reactions used to produce energy are

1) fission and 2) fusion .

Fission Reaction:

In a fission reaction, a heavy atomic nucleus is split into smaller nuclei, other particles and radiation.

For example : In a typical reaction, an atom of uranium 235 absorbs a neutron and splits into two lighter atoms, barium and krypton, emitting radiation and neutrons. Under special circumstances (the attainment of a "critical mass") the emitted neutrons can split further atoms, which in turn bring about more splitting, producing a very fast chain reaction. Nuclear power plants exploit the process of fission to create energy.

This reaction can be dangerous if it is not controlled (Uncontrolled Fission reaction) as in atom bomb. While when it is controlled (Controlled Fission Reaction) is used for electricity production.

Mechanism of reaction:

Uncontrolled Fission Reaction:

In a fission of 235U by slow neutrons, three more neutrons are created. The emitted neutrons can create further fission reactions. So the second stage fissioning of 235U will give rise to nine more neutrons. These 9 neutrons can further cause fissioning giving rise to 27 neutrons. This is the chain reaction. Each fission reaction gives out an enormous amount of energy. Now you can see how a chain reaction can give rise to explosive amount of heat energy.

A fission reaction whereby the reaction is allowed to proceed without any moderation (by removal of neutrons) is called an uncontrolled fission reaction.

An uncontrolled fission reaction is used for nuclear bombs.

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Controlled Fission Reaction:

In a fission reaction, if we can remove the emitted neutrons from the fissionable material, then we can control the rate at which the chain reaction proceeds.

In the nuclear fission reaction shown above, if we remove two of the three neutrons then, instead of having three more 235U to fission, we will have only one more of such a reaction. In this way, the rate of reaction can be controlled.

The neutrons can be removed by what are called moderators which are made up of materials which like to absorb neutrons. Cadmium (Cd) is one such material.

A nuclear fission reaction, whereby the rate of reaction can be moderated externally by allowing just enough number of neutrons to keep the fission reaction rate constant is called a controlled fission reaction.

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Fusion Reaction:

In nuclear physics, nuclear fusion is a nuclear reaction in which two or more atomic nuclei collide at a very high speed and join to form a new type of atomic nucleus. During this process, matter is not conserved because some of the matter of the fusing nuclei is converted to photons (energy).

The fusion of two nuclei with lower masses than iron (which, along with nickel, has the largest binding energy per nucleon) generally releases energy, while the fusion of nuclei heavier than iron absorbs energy.

Mechanism Of Reaction

About fusion:

Fusion within the cores of the sun and other stars generates their radiating energy by fusing two hydrogen atoms to produce a helium atom.

Current researchers are using magnetic vacuum chambers and laser beams in an attempt to generate the extreme high-temperatures necessary for the fusion process. If successful, the net energy gain would create a viable alternative energy option.

The main use of fusion is also energy production while it is also used for Hydrogen Bomb.

Nuclear Energy Production:

The main design is the pressurised water reactor (PWR) which has water in its primary cooling/heat transfer circuit, and generates steam in a secondary circuit. The less popular boiling water reactor (BWR) makes steam in the primary circuit above the reactor core, though it is still under considerable pressure. Both types use water as both coolant and moderator, to slow neutrons.

In the reactor the heat generated is delivered to water from which steam is formed .

This steam is used to run turbine from which electricity is produced.

Energy making Process:

Advantages:

The generation of electricity through nuclear energy reduces the amount of energy generated from fossil fuels (coal and oil). Less use of fossil fuels means lowering greenhouse gas emissions (CO2 and others).

Currently, fossil fuels are consumed faster than they are produced, so in the next future these resources may be reduced or the price may increase becoming inaccessible for most of the population.

Another advantage is the required amount of fuel: less fuel offers more energy. It represents a significant save on raw materials but also in transport, handling and extraction of nuclear fuel. The cost of nuclear fuel (overall uranium) is 20% of the cost of energy generated.

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The production of electric energy is continuous. A nuclear power plant is generating electricity for almost 90% of annual time. It reduces the price volatility of other fuels such as petrol.

This continuity benefits the electrical planning. Nuclear power does not depends on natural aspects. It's a solutions for the main disadvantage of renewable energy, because the hours of sun or wind does not always coincide with the hours with more energy demand.

It's an alternative to fossil fuels, so the consumption of fuels such as coal or oil is reduced. This reduction of coal and oil consumption benefits the situation of global warming and global climate change. By reducing the consumption of fossil fuels we also improve the quality of the air affecting the disease and quality of life.

Disadvantages:

One of the main disadvantages is the difficulty in the management of nuclear waste. It takes many years to eliminate its radioactivity and risks.

The constructed nuclear reactors have an expiration date. Then, they've to be dismantled, so that main countries producing nuclear energy could maintain a regular number of operating reactors. They've to built about 80 new nuclear reactors during the next ten years.

Nuclear plants have a limited life. The investment for the construction of a nuclear plant is very high and must be recovered as soon as possible, so it raises the cost of electricity generated. In other words, the energy generated is cheap compared to the cost of fuel, but the recovery of its construction is much more expensive.

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Nuclear power plants generate external dependence. Not many countries have uranium mines and not all the countries have nuclear technology, so they have to hire both things overseas.

Current nuclear reactors work by fission nuclear reactions. These chain reactions is generated in case control systems fail, generating continous reactions causing a radioactive explosion that would be virtually impossible to contain.

Probably the most alarming disadvantage is the use of the nuclear power in the military industry. The first use of nuclear power was the creation of two nuclear bombs dropped on Japan during World War II. This was the first and the last time that nuclear power was used in a military attack. Later, several countries signed the Nuclear Non-Proliferation Treaty, but the risk that nuclear weapons could be used in the future will always exist.

Scope Of Nuclear Energy:

The countries that need it the most will continue to use it. France gets 77 percent of its electricity from nuclear reactors, the rest being hydroelectric. Japan is close to 30 percent and increasing steadily. Japan has little domestic coal and no oil. We have plenty of coal and natural gas, can afford to import more than half of our oil. Therefore, we can afford delays caused by controversy unless we are zapped by the greenhouse effect. However, the counterculture generation is passing through the peak of its political power, and the next generations seem to be more rational about nuclear energy and many other issues.

Therefore, the U.S. is likely to resume building reactors before being driven to it by other countries getting economic advantages.

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Current fission reactors in operation around the world are second or third generation systems, with most of the first-generation systems having been retired some time ago. Research into advanced generation IV reactor types was officially started by the Generation IV International Forum (GIF) based on eight technology goals, including to improve nuclear safety,minimize waste, improve natural resource utilization, the ability to consume existing nuclear waste in the production of electricity, and decrease the cost to build and run such plants. Most of these reactors differ significantly from current operating light water reactors, and are generally not expected to be available for commercial construction before 2030.

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One disadvantage of any new reactor technology is that safety risks may be greater initially as reactor operators have little experience with the new design. Nuclear engineer David Loch baum has explained that almost all serious nuclear accidents have occurred with what was at the time the most recent technology. He argues that "the problem with new reactors and accidents is twofold: scenarios arise that are impossible to plan for in simulations; and humans make mistakes“.

Moreover danger of waste risk , human error , Negligence , and if heat losses are controlled than this will bring a new world .

Scope in Pakistan:

Nuclear power in Pakistan is provided by 3 licensed-commercial nuclear power plants, KANUPP, CHANUPP-1 and CHASNUPP-2.

The Pakistan Atomic Energy Commission (PAEC) is solely responsible for operating these power plants while Pakistan Nuclear Regulatory Authority (PNRA) is licenser, who devises, adopts, makes and enforces rules, regulations, orders or codes of practice for nuclear safety and radiation protection as may, in its opinion, be necessary.

As 1989 Pakistan became a member of World Association of Nuclear Operator (WANO), which is yet another international standard for safety and operational excellence. Additional measures have been taken by Pakistan’s nuclear operators as Fukushima Response Action Plan which includes immediate, short-term and long-term plans. Main elements of the action plan are re-assessment of external hazards, design basis of threat, additional sources of emergency power, diverse means of core cooling and a comprehensive emergency preparedness plan.

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Pakistan has long-term intergovernmental agreements with China for supply of nuclear power plants, fuel and O&M support. Pakistan is a pioneer developing country in using nuclear technology for producing electricity. Nuclear power can play a significant role in providing base-load electricity and minimizing imports of expensive fossil fuels. Despite international embargoes, nuclear power program in the country is moving forward slowly but steadily to achieve the target of 8,800 MW by 2030. However, safety and security will remain on top priority in the nuclear power program of Pakistan.

Nuclear reactors used in world:

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Comparison Between countries:

Nuclear Energy Requirements:

Comparison of energy generation:

References:

www.Wikipedia.org

http://scitechnol.com/scope-of-nuclear-power-in-Pakistan.

http://www.slideshare.net/pearloblivion/nuclear-energy-powerpoint

www.diffen.com/difference/Nuclear_Fission_vs_Nuclear_Fusion

www.tutorwista.org

www.world-nuclear.org/info/current.../outline-history-of-nuclear-energy

Physical Science by C. Lon Enloe.

Nuclear Energy by Charlas D. Ferguson.

Nuclear Energy Principles by David Bodansky.

That’s all from us.

Any Question?

Presenters

Muhammad Kashif (2013-CH-401) Muhammad Aleem (2013-CH-402) Usama Javaid (2013-CH-407) Ahsan Rafiq (2013-CH-412) Saddam Hussain (2013-CH-440)

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