Nuclear Power Plants 5

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Nuclear Power Plants:

Nuclear Power Plants Nuclear power is generated using Uranium, which is a metal mined in various parts of the world. Some military ships and submarines have nuclear power plants for engines Nuclear power produces around 11% of the world's energy needs, and produces huge amounts of energy from small amounts of fuel, without the pollution that you'd get from burning fossil fuels.

How it Works:

How it Works The main bit to remember : Nuclear power stations work in pretty much the same way as fossil fuel-burning stations, except that a "chain reaction" inside a nuclear reactor makes the heat instead.

Nuclear Power Plants:

Nuclear Power Plants The pursuit of nuclear energy for electricity generation began soon after the discovery in the early 20th century that  radioactive  elements, such as  radium , released immense amounts of energy, according to the principle of  mass–energy equivalence . However, means of harnessing such energy was impractical, because intensely radioactive elements were, by their very nature, short-lived (high energy release is correlated with short  half-lives ). However, the dream of harnessing "atomic energy" was quite strong, even it was dismissed by such fathers of  nuclear physics  like  Ernest Rutherford  as "moonshine." This situation, however, changed in the late 1930s, with the discovery of  nuclear fission .

Nuclear Fuel:

Nuclear Fuel In order to give you an idea about the scale of fuel quantities involved in a nuclear power station vis-à-vis traditional power stations, I ask you to imagine that around a pound of nuclear fuel like say Uranium gives the energy equivalent to burning a million gallons of gasoline . This should not come as a surprise since we have already learned that the energy released in a nuclear reaction is the equivalent of the mass change which takes place during the process. It is therefore huge compared to energy which is released as a result of combustion and related chemical reactions during traditional fuel burning.

Nuclear Power:

Nuclear Power Nuclear power  is produced by controlled (i.e., non-explosive)  nuclear reactions . Commercial and utility plants currently use  nuclear fission  reactions to heat water to produce  steam , which is then used to generate  electricity . In 2009, 13-14% of the world's electricity came from nuclear power. Also, more than 150 naval vessels using  nuclear propulsion  have been built.

Nuclear Fusion:

Nuclear Fusion When the fusion reaction is a sustained uncontrolled chain, it can result in a  thermonuclear explosion , such as that generated by a hydrogen bomb . Non-self sustaining reactions can still release considerable energy, as well as large numbers of neutrons.

Fusion Energy:

Fusion Energy When  deuterium  and  tritium  fuse, the two  nuclei  come together to form a  helium  nucleus (an  alpha particle ) and a high energy neutron .

Nuclear Fission:

Nuclear Fission Simple diagram of nuclear fission. In the first frame, a neutron is about to be captured by the nucleus of a U-235 atom. In the second frame, the neutron has been absorbed and briefly turned the nucleus into a highly excited U-236 atom. In the third frame, the U-236 atom has fissioned, resulting in two fission fragments (Ba-141 and Kr-92) and three neutrons, all with large amounts of kinetic energy.

Nuclear Fission:

Nuclear Fission


Fission Nuclear fission produces energy for  nuclear power  and to drive the explosion of  nuclear weapons . Both uses are made possible because certain substances called  nuclear fuels  undergo fission when struck by free neutrons and in turn generate neutrons when they break apart. This makes possible a self-sustaining  chain reaction  that releases energy at a controlled rate in a  nuclear reactor  or at a very rapid uncontrolled rate in a  nuclear weapon .

Fission vs. Fusion:

Fission vs. Fusion

Fission vs. Fusion:

Fission vs. Fusion Both nuclear fission and nuclear fusion reactions can be used to generate large amounts of energy for destructive purposes. When an atom of 235U is bombarded by a neutron, it splits into atoms of cesium and rubidium, releasing a large amount of energy and three additional neutrons. These neutrons, if not controlled, can then cause more 235U atoms to split, leading rapidly to a nuclear explosion (A-bomb). Fusion reactions release energy when two light nuclei combine to make a heavier atom.

Nuclear Power Plant in Pakistan:

Nuclear Power Plant in Pakistan In Pakistan, nuclear power makes a small contribution to total energy production and requirements, supplying only 2.34% of the country's electricity.  Total generating capacity is 20 GW and in 2006, 98 billion kWh gross was produced, 37% of it from gas, 29% from oil. The Pakistan Atomic Energy Commission (PAEC) is responsible for all nuclear energy and research applications in the country. Its first nuclear power reactor is a small (125 MWe) Canadian pressurized heavy water reactor (PHWR) which started up in 1971 and which is under international safeguards - KANUPP near Karachi, which is operated at reduced power.

Nuclear Power Plant in Pakistan:

Nuclear Power Plant in Pakistan The second unit is Chashma-1 in Punjab, a 325 MWe (300 MWe net) pressurised water reactor (PWR) supplied by China's CNNC under safeguards. The main part of the plant was designed by Shanghai Nuclear Engineering Research and Design Institute (SNERDI), based on Qinshan-1.  It started up in May 2000 and is also known as CHASNUPP-1. Construction of its twin, Chashma-2, started in December 2005. It is reported to cost PKR 51.46 billion (US$ 860 million, with $350 million of this financed by China). A safeguards agreement with IAEA was signed in 2006 and grid connection was established in 2010 or in 2011.

Pakistan Nuclear Power Reactors :

Pakistan Nuclear Power Reactors Reactor Type MWe net Construction start Commercial operation Planned close Karachi   PHWR  125 1966 12/72   Chashma 1 PWR 300 1993 6/00   Chashma 2 PWR 300 2005 4/2011   Total   725     

Nuclear Power Plants:

Nuclear Power Plants

Idea of a Nuclear Power Plant:

Idea of a Nuclear Power Plant Spinning turbine blades and generator Boiling water Steam

Nuclear Heat :

Nuclear Heat Heat Steam produced Steam Turbine Generator Electricity

Nuclear Plant:

Nuclear Plant

Main Parts of Nuclear Power Plant:

Main Parts of Nuclear Power Plant The only two components are differs in Nuclear Power Plant with respect to Conventional Power Plant. Nuclear Reactor Heat Exchanger

Main Parts of Nuclear Reactor and Reactor Control:

Main Parts of Nuclear Reactor and Reactor Control Reactor core Moderator Reflector Shielding Control of Reactor Cooling System

Classification of Reactors:

Classification of Reactors According to type of Fuel According to type of Moderator According to type of Coolant

Types of Reactors:

Types of Reactors Thermal Reactor Calder Hall Reactor Boiling Water Reactor Pressurized Water Reactor Sodium- Graphite Reactor Fast Reactor Fast Breeder Reactor

Boiling Water Reactor (BWR) :

Boiling Water Reactor (BWR)


BOILING WATER REACTOR Boiling water reactors reactors. Inside a boiling water reactor, heat from the chain reaction boils the water and turns it to steam. The steam is piped from the reactor vessel directly to the turbine. The steam turns the turbine's propeller-like blades, which spins the shaft of a huge generator. Inside the generator, coils of wire and magnetic fields interact—and electricity is created.

Pressurized Water Reactor (PWR) :

Pressurized Water Reactor (PWR)

Pressurized Water Reactor (PWR):

Pressurized Water Reactor (PWR) Reactor core generates heat Pressurized-water in the primary coolant loop carries the heat to the steam generator Inside the steam generator heat from the primary coolant loop vaporizes the water in a secondary loop producing steam The steam line directs the steam to the main turbine causing it to turn the turbine generator, which produces electricity

Reactor Safety Design:

Reactor Safety Design Containment Vessel 1.5-inch thick steel Shield Building Wall 3 foot thick reinforced concrete Dry Well Wall 5 foot thick reinforced concrete Bio Shield 4 foot thick leaded concrete with 1.5-inch thick steel lining inside and out Reactor Vessel 4 to 8 inches thick steel Reactor Fuel Weir Wall 1.5 foot thick concrete

Slide 29:

Nuclear power plants use a series of physical barriers to make sure radioactive material cannot escape. In today’s water-cooled reactors, the first barrier is the fuel itself: the solid ceramic uranium pellets. Most of the radioactive by-products of the fission process remain inside the pellets. The pellets are sealed in zirconium rods, 12 feet long and half an inch in diameter. The fuel rods are placed inside a large steel reactor vessel, with walls 8 inches thick. The vessel is surrounded by 3 feet of concrete shielding. At most plants, a leak-tight steel liner covers the inside walls of the containment building. The containment building is a massive, reinforced concrete structure with walls 4 feet thick.



Types of Radiation:

Types of Radiation

Types of Radiation:

Types of Radiation Alpha radiation Cannot penetrate the skin Blocked out by a sheet of paper Dangerous in the lung Beta radiation Can penetrate into the body Can be blocked out by a sheet of aluminum foil Gamma radiation Can go right through the body Requires several inches of lead or concrete, or a yard or so of water, to block it. Neutron radiation Normally found only inside a nuclear reactor

Measuring Radioactivity:

Measuring Radioactivity Half-Life The time for a radioactive source to lose 50% of its radioactivity For each half-life time period, radioactivity drops by 50% 1/2; 1/4; 1/8; 1/16; 1/32; 1/64; 1/128; 1/256; … A half-life of 1 year means that radioactivity drops to <1% of its original intensity in seven years Intensity vs. half-life Intense radiation has a short half life, so decays more rapidly

Nuclear Fuel Cycle:

Nuclear Fuel Cycle

Slide 35:

The nuclear fuel cycle for typical light-water reactors. The cycle consists of "front end" steps that lead to the preparation of uranium for use as fuel for reactor operation and "back end" steps that are necessary to safely manage, prepare, and dispose of the highly radioactive spent nuclear fuel. Chemical processing of the spent fuel material to recover the remaining fractions of fissionable products, 235U and 239Pu, for use in fresh fuel assemblies is technically feasible. Reprocessing of spent commercial-reactor nuclear fuel is not permitted .

Nuclear Waste Reprocessing:

Nuclear Waste Reprocessing Separates usable elements (uranium, plutonium) from spent nuclear reactor fuels Usable elements are then reused in a nuclear reactor Other waste products (e.g., radioactive isotopes) must be disposed of

Nuclear Waste Disposal:

Nuclear Waste Disposal Cooled in a spent fuel pool 10 to 20 years Onsite temporary dry storage Until permanent site becomes available Central permanent buried disposal

Spent Fuel Cooling Pool:

Spent Fuel Cooling Pool

Fuel Rod Storage:

Fuel Rod Storage

Dry Storage Cask:

Dry Storage Cask

Dry Storage On Site:

Dry Storage On Site

Dry Cask Construction:

Dry Cask Construction

Dry Cask Durability:

Dry Cask Durability

Waste Burial:

Waste Burial Immobilize waste in an insoluble matrix E.g. borosilicate glass, Synroc (or leave them as uranium oxide fuel pellets - a ceramic) Seal inside a corrosion-resistant container Usualy stainless steel Locate deep underground in stable rock Site the repository in a remote location. Most radioactivity decays within 1,000 years Remaining radioactivity similar to that of the naturally-occurring uranium ore, though more concentrated

Advantages :

Advantages Nuclear power costs about the same as coal, so it's not expensive to make. Does not produce smoke or carbon dioxide, so it does not contribute to the greenhouse effect. Produces huge amounts of energy from small amounts of fuel…so cheaper logistics Produces small amounts of waste. Nuclear power is reliable.

Disadvantages :

Disadvantages Although not much waste is produced, it is very, very dangerous. It must be sealed up and buried for many thousands of years to allow the radioactivity to die away. For all that time it must be kept safe from earthquakes, flooding, terrorists and everything else. This is difficult. Nuclear power is reliable, but a lot of money has to be spent on safety - if it does go wrong, a nuclear accident can be a major disaster. People are increasingly concerned about this - in the 1990's nuclear power was the fastest-growing source of power in much of the world. In 2005 it was the second slowest-growing.

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