The nuclear reactor

Nuclear reactor is an devise use to initiate and sustained nuclear chain reaction.The reactor used for generate the electricity and propulsion of ships.In this video,will shows how an nuclear reactor works and the functions of each the component.In the second,video is all about how the nuclear reactor works,to deliver the energy to be used.

References
http://www.youtube.com/watch?v=ueainTAy7G0
http://www.youtube.com/watch?v=kc2DKSC9Mj8&feature=player_embedded#!

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An explanation on what went wrong in Fukushima Dai-chi.

Professor Cham Dallas of the University of Georgia, an expert on nuclear energy, walked Chris Wragge (host) through what exactly went wrong with the Fukushima Dai-ichi nuclear power station in Japan which experienced a partial meltdown.

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Nuclear Reactor Evolution

Figure below shows the type of nuclear reactor from Generation I to Generation IV, current commercial power reactors mostly from Generation II and III to III+ as the design change to better improved safety features together with new technologies implementation and also extended lifetime.

Reference : Introduction to Nuclear Technology MEHB 513 (UNITEN) Textbook, Author: Dr Nor Azlan Mostafa

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German police clear nuclear waste train protest

Police in Germany say they have cleared thousands of protesters who were trying to block a trainload of nuclear waste.

Protesters had blocked the tracks near the site in northern Germany where the spent nuclear fuel is to be stored. The 150 tonnes of uranium, originally from German nuclear plants, is being moved in 11 containers from Normandy, France, where it was reprocessed. It is the last of 12 such shipments from France because of a German move away from nuclear power. Reports said 1,300 people had been detained following the clearing of the protest.

A rescuer holds the unchained hand of an anti-nuclear protester being removed from the railway tracks before the arrival of the transport train in Hitzacker. The transport has to stop again and again because of the blockades - it takes longer than any such transport did before. It started on Wednesday, 4pm in Valognes, France and has to make 1,200 kilometres. Now it is on its final 20 kilometres (12 miles)

Anti-nuclear protesters in sleeping bags lay on the road to the final destination, Gorleben. The police expect a difficult last stage of the transport of the 11 nuclear waste containers. On the final leg the containers will be carried by trucks

One of the eleven Castor (Cask for Storage and Transport of Radioactive material) nuclear waste containers is seen behind a police ribbon and barbed Nato wire at Dannenberg on the route to Gorleben. A castor is six metres long, the diameter is more than two metres, and it weighs 117 tonnes

Anti-nuclear activists of the environmental group Greenpeace measure the radioactivity of the castor containers while they are moved from the train onto the low-loaders by a crane in Dannenberg. The 11 shipped castor containers contain the radioactivity of 44 Fukushima disasters, Greenpeace said

More info here: German police clear protester

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Advantages of using Nuclear Energy

Nuclear energy may be looked at in a negative light, but anyone who understands the process and production that goes into creating nuclear energy can see that there are advantages with the energy source as well. These advantages help make nuclear energy one of our best sources of energy and the question just depends on whether the good outweighs the bad and if nuclear energy is really worth it [1].

We should understand the way that nuclear energy and it’s advantages, you need to know the process that goes behind creating nuclear energy. First, uranium is taken from natural resources and then put through an enrichment process that makes the uranium ready for the nuclear reactor. Once the uranium is ready, it goes through a process known as "fission" [1].

Nuclear fission, this process splits one atom into two and that splitting causes a chain reaction through the whole element. This chain reaction creates heat energy that is used to boil water and create high pressured steam. The steam spins and powers a turbine connected to a generator that provides electricity.For example the energy it releases is 10 million times greater than is released by the burning of an atom of fossil fuel. Besides it would take many hectares of land covered with solar collectors,wind farms or hydro-electric dams to equal this power [1].

Next, advantage are the greenhouse gasses are not released by nuclear power plant. Even when accounting the is fossil fuel used in mining uranium,to processing it,the building and decommissioning of the nuclear plant, the picture remains good from this perspective. Less than one-hundredth of carbon dioxide gas is produced by nuclear power plants compared to coal or gas-fired energy plants. This means nuclear energy also emits less greenhouse gas than renewable energy sources such as hydro, wind, solar and biomass. Ofcourse, others have contrary views to these claims about the advantages of nuclear energy.From this, we can see the nuclear reactors do not burn any fossil fuels so the plants do not give off any emissions or pollution into the air. This is very beneficial because pollution and burning has caused a greenhouse effect that could dramatically affect future generations [2].

The ability availability of uranium is an advantage of using nuclear energy. Uranium is obtained from open-cut mines and is not expensive to mine. The world reserves are estimated to last anywhere between 6 to 150 years, to even hundreds of centuries, depending on who is the commentator, and depending on the type of reactor they have in mind. The present reactors only use some 1% of the energy available in uranium but in future fast breeder reactors could recycle spent fuel rods at a 99% efficiency rate. The potency and quantity of radio active waste material from such reactors is much less than that of current thermal reactors [2].

Finally, the nuclear energy is a compact fuel which makes it easy to transport easily It reduces dependency on the fossil fuel. In Medical also nuclear energy used in radiotherapy used in special medical conditions like cancer, where it weakens or destroys the particular cells. The advantages of Nuclear Energy are growing day by day with the new inventions as the scientists around the world are working on it so thoroughly.Even the with all of the benefits coming from nuclear power plants, there are still some big dangers. Explosions or meltdowns in plants can spread harmful radiation through the air, potentially causing diseases like cancer and sometimes death [3].

References
[1] - http://www.ehow.com/about_4579502_what-advantages-using-nuclear-energy.html
[2] - http://www.alternate-energy-sources.com/advantages-of-nuclear-energy.html
[3]- http://topissues21.blogspot.com/2011/08/advantages-of-nuclear-energy.html

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Nuclear Power Survey

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A Nuclear Blast In Space Would Wipe Out Satellites

Jon Titus's Nov.16 letter proposes the use of high-altitude electromagnetic pulse (HEMP), caused by detonating a nuclear weapon in space, to halt Iran's nascent nuclear program. Perhaps I am missing some subtle irony or humor on his part, but this is the most ill-advised idea I have ever heard seriously suggested.

A HEMP in space would cause irreparable damage not only to electronics in Iran, but throughout the region, if not the entire Eastern Hemisphere. (Eastern China is less than 800 miles from Iran, and U.S. troops in Afghanistan would also have their electronics knocked out.) It would instantly vaporize or render inoperable literally thousands of satellites already in orbit, potentially including any geosyncronous orbit (GEO) satellites within line of sight. This is because nuclear radiation in space travels much farther than in the lower atmosphere, due to the paucity of molecules to absorb it. This would destroy or degrade space-based communication, TV and radio, navigation and other capabilities upon which the modern world depends.

What's more, it would seriously degrade and disrupt our own global-positioning-system constellation, which requires a minimum of 24 satellites in a particular configuration to operate. Any GPS satellites in view of the burst would be destroyed or at least severely degraded. Banks, stock exchanges and many other time-sensitive enterprises world-wide, which depend upon precise time signals from GPS, would be thrown into disarray and panic, to say nothing of the millions of angry motorists who would have useless GPS receivers in their cars.

Most frightening would be the potential consequences to satellites in low-earth orbit, loosely defined as any orbit below 2,000 kilometers. This is an extremely crowded area of space. Assuming, charitably, that no orbital debris is generated by the proposed nuclear detonation, satellites in this orbit already have to contend not only with each other, but with tens of thousands of smaller pieces of debris, such as that created in 2007 by the Chinese anti-satellite test, or in 2009 by the collision of a defunct Russian spy satellite with an Iridium communications satellite.

It is precisely the ability to maneuver in orbit that prevented these mishaps from destroying even more satellites. But the thousands of dead satellites created by the HEMP could not be maneuvered.

In a nightmare scenario, we would have a "Kessler Syndrome," named after former NASA scientist Donald Kessler, who predicted in 1978 that orbital debris could reach a threshold in which colliding satellites created exponentially more debris, causing a chain reaction of orbital collisions until orbital space became literally unreachable and thus unusable.

Furthermore, those satellites not destroyed by the initial HEMP burst would find their solar panels and internal electronics degraded by the highly radioactive particles trapped in the Van Allen belts, particularly in the South Atlantic Anomaly, a portion of the Van Allen belts that dip into low-earth orbit due to the shape and inclination of the Earth's magnetic field. (Astronauts don't perform spacewalks when passing through it, for example, and many satellites shut down critical sensors and other electronics to avoid damage.)

These and other scenarios denying humans the critical use of space are what keep world leaders and space professionals such as myself up at night. We certainly don't need any of Mr. Titus's kind of help in this regard.

REFERENCES

http://online.wsj.com/article/SB10001424052970204531404577050403048374584.html

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Comparing Radioactive Waste To Industrial Toxic Waste.

In countries with nuclear power, radioactive wastes comprise less than 1% of total industrial toxic wastes, much of which remains hazardous indefinitely [1]. Overall, nuclear power produces far less waste material by volume than fossil-fuel based power plants. Coal burning plants are particularly noted for producing large amounts of toxic and mildly radioactive ash due to concentrating naturally occurring metals and mildly radioactive material from the coal. A recent report from Oak Ridge National Laboratory concludes that coal power actually results in more radioactivity being released into the environment than nuclear power operation, and that population effective dose equivalent from radiation from coal plants is 100 times as much as from ideal operation of nuclear plants [2]. Indeed, coal ash is much less radioactive than nuclear waste, but  ash is released directly into the environment ,whereas nuclear plants use shielding to protect the environment from the irradiated reactor vessel,fuel rods, and any radioactive waste on site [3].

References :

1.Waste management in the nuclear fuel cycle,information and issue briefs world nuclear association      .Retrieved 2006-11-09

2. Alex Gabbard , coal combustion: Nuclear resources or danger. Oak ridge nasional laboratory, retrieved 2008-01-31.


3. Coal Ash is not more radioactive than nuclear waste, CE Journal. 2008-12-31

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"Smoke" from Cooling Tower! Dont worry they only emit clean water vapor.

When we first heard about Nuclear, the first thing pop-out from our mind is some "smoke" coming out from the cooling towers. We all actually does thought the same as all of us didn't actually know what is the function of that tower at first. Some power plants, usually located on lakes or rivers, use cooling towers as a method of cooling the circulating water that has been heated in the condenser.A cooling tower is a heat rejection device, which extracts waste heat to the atmosphere though the cooling of a water stream to a lower temperature.

The type of heat rejection in a cooling tower is termed "evaporative" in that it allows a small portion of the water being cooled to evaporate into a moving air stream to provide significant cooling to the rest of that water stream. The heat from the water stream transferred to the air stream raises the air's temperature and its relative humidity to 100% and this air discharged to the atmosphere. Evaporative heat rejection devices such as cooling towers are commonly used to provide significantly lower water temperatures than achievable with "air cooled" or "dry" heat rejection devices, like radiator in a car to achieve more cost-effective and energy efficient operation of systems in need of cooling.

But when cooling towers are used, plant efficiency usually drops. One reason is that the cooling tower pumps and fans, if used consume a lot of power.

There are 2 types of towers - mechanical draft and natural draft.

Mechanical Draft Towers 

Mechanical draft cooling towers have long piping runs that spray the water downward. Large fans pull air across the dropping water to remove the heat. As the water drops downward onto the "fill" or slats in the cooling tower, the drops break up into a finer spray.

Natural Draft Towers

This picture shows a single natural draft cooling tower as used at a European plant. Natural draft towers are typically about 120 m high, depending on the differential pressure between cold outside air and the hot humid air on the inside of the tower as the driving force. No fans are used. 

More info here : Natural draft towers , Mechanical draft towers , Cooling tower , Components of Nuclear Reactors

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What is Nuclear Power?

Nuclear power is the use of sustained nuclear fission to generate heat and do useful work. Nuclear power plants provide about 6% of the world's energy and 13-14% of the world's electricity [1] with US, France and Japan together accounting for about 50% of nuclear generated electricity [2]. In 2007, the International Atomic Energy Agency (IAEA) reported there were 439 nuclear power reactors in operation in the world [3] operating in 31 countries [4]. Also, more than 150 Naval vessels using nuclear propulsion have been built.

There is an ongoing debate about the use of nuclear energy [5]. Proponents,such as the World Nuclear Association and IAEA,contend that nuclear power is a sustainable energy source that reduces carbon emission [6].Opponents ,such as Greenpeace International and NIRS, believe that nuclear power poses many threats to people and the environment [7]

Nuclear power plants accidents include the Chernobyl disaster(1986), Fukushima Daiichi nuclear disaster (2011), and the Three Mile Island accident (1979) [8]. There have also been some nuclear power submarine mishaps [9]. However, the safety record of nuclear power is good when compared with many other energy technologies. Research into safety improvements is continuing and nuclear fusion may be used in the future.

China has 25 nuclear power reactors under construction,with plans to build many more [9],while in the U.S the license almost half its reactors have been extended to 60 years, and plans to build another dozen are under serious consideration.However. Japan's 2011 Fukushima Daiichi nuclear disaster prompted a rethink of nuclear energy policy in many countries. Germany decided to close all its reactors by 2022, and Italy has banned nuclear power [10]. Following Fukushima, the International Energy halved its estimate of additional nuclear generating capacity to be built by 2035.

References

1. World Nuclear Association.Another drop in nuclear generation World Nuclear News, 5 May 2010

2. Key world energy Statistics 2007. International Energy Agency 2007. Retrieved 2008-06-21

3. U.S Energy Legislation May Be 'Renaissance'for Nuclear Power

4."Nuclear Waste Pools in North Carolina". Projectcensored.org. Retrieved 2010-08-24

5.The worst Nuclear Disasters

6. Strengthening the safety of radiation sources

7.World Nuclear Association (December 10,2010) , Nuclear Power In china

8.Sylvia westall and Fredrik dahl (June 24,2011). "IAEA Head Sees Wide for Stricter Nuclear Plant Safety". Scintific American. 

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