More than a dozen advanced reactor designs are in various stages of development. Some are evolutionary from the PWR, BWR and PHWR designs above, some are more radical departures. The former include the Advanced Boiling Water Reactor (ABWR), two of which are now operating with others under construction, and the planned passively safe ESBWR and AP1000 units (see Nuclear Power 2010 Program).
The Integral Fast Reactor (IFR) was built, tested and evaluated during the 1980s and then retired under the Clinton administration in the 1990s due to nuclear non-proliferation policies of the administration. Recycling spent fuel is the core of its design and it therefore produces only a fraction of the waste of current reactors.
The Pebble Bed Reactor, a High Temperature Gas Cooled Reactor (HTGCR), is designed so high temperatures reduce power output by doppler broadening of the fuel's neutron cross-section. It uses ceramic fuels so its safe operating temperatures exceed the power-reduction temperature range. Most designs are cooled by inert helium. Helium is not subject to steam explosions, resists neutron absorption leading to radioactivity, and does not dissolve contaminants that can become radioactive.
Typical designs have more layers (up to 7) of passive containment than light water reactors (usually 3). A unique feature that may aid safety is that the fuel-balls actually form the core's mechanism, and are replaced one-by-one as they age. The design of the fuel makes fuel reprocessing expensive.
The Small Sealed Transportable Autonomous Reactor (SSTAR) is being primarily researched and developed in the US, intended as a fast breeder reactor that is passively safe and could be remotely shut down in case the suspicion arises that it is being tampered with.
The Clean And Environmentally Safe Advanced Reactor (CAESAR) is a nuclear reactor concept that uses steam as a moderator � this design is still in development.
The Hydrogen Moderated Self-regulating Nuclear Power Module (HPM) is a reactor design emanating from the Los Alamos National Laboratory that uses uranium hydride as fuel.
Subcritical reactors are designed to be safer and more stable, but pose a number of engineering and economic difficulties. One example is the Energy amplifier.
Thorium based reactors. It is possible to convert Thorium-232 into U-233 in reactors specially designed for the purpose. In this way, thorium, which is more plentiful than uranium, can be used to breed U-233 nuclear fuel. U-233 is also believed to have favourable nuclear properties as compared to traditionally used U-235, including better neutron economy and lower production of long lived transuranic waste.
Advanced Heavy Water Reactor (AHWR)� A proposed heavy water moderated nuclear power reactor that will be the next generation design of the PHWR type. Under development in the Bhabha Atomic Research Centre (BARC), India.
KAMINI � A unique reactor using Uranium-233 isotope for fuel. Built in India by BARC and Indira Gandhi Center for Atomic Research (IGCAR).
India is also planning to build fast breeder reactors using the thorium � Uranium-233 fuel cycle. The FBTR (Fast Breeder Test Reactor) in operation at Kalpakkam (India) uses Plutonium as a fuel and liquid sodium as a coolant.
Source : http://nuclear-powerplants.blogspot.com/
There are many advantages and disadvantages of nuclear power. There are also ethical concerns as well as political concerns. The following article addresses many of the major advantages and disadvantages to nuclear power.
There are many advantages and disadvantages of nuclear power. There are also ethical concerns as well as political concerns. The following article addresses many of the major advantages and disadvantages to nuclear power.
Advantages of Nuclear Power:
* Nuclear power plants don't take up much space. This allows them to be placed in already developed areas and the power does not have to be transferred over long distances.
* It doesn't pollute in a very direct way. It is cleaner than many other forms of energy production. This is in reference to greenhouse gas emissions which are released into the atmosphere. There is a waste product as described below.
* Another advantage of nuclear power is that nuclear energy is by far the most concentrated form of energy, so it can be produced in large quantities over short periods of time.
* The possibility for long term production is great since new reactors, where costly can be made when the old ones wear out. Oil reserves and other fossil type fuels are likely to run out at some point.
Disadvantages of Nuclear Power:
* Nuclear Power generates radiation, which can be harmful or even fatal to infected people.
* A nuclear meltdown can often occur which will release massive amounts of radiation into the community.
* Extremely radioactive nuclear waste is produced by nuclear power plants. This stuff can�t be just thrown out. The US plans to move all its nuclear was to an underground dump by the year 2010. Currently it is stored in the plants.
* Nuclear waste dumps can spontaneously combust without warning.
* Nuclear reactors only last for about forty to fifty years, so where they are extremely productive, they break down and are costly to replace.
* There are international dangers too. Some reactors produce plutonium which can be used to make nuclear weapons. If the whole world were to use these, they would have unlimited access to nuclear weapons.
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Earlier in the discussion about advantages and disadvantages of nuclear energy we saw how nuclear energy is beneficial, if used in the right manner and its scope utilised to the fullest.
However, there is a great deal of radiation danger associated with Nuclear energy. It is capable of causing genetic disorders, thus once exposed, can affect generations to come adversely. Another drawback is the storage of nuclear wastes, as it too can lead to disastrous effects if not disposed or stored in the right manner.
A well known nuclear disaster was the attack on Hiroshima and Nagasaki by the United States during World War II. An experiment, as described by some, was a grave event in the history of nuclear energy and its effects. It was the first of its kind. Another infamous event is the Chernobyl disaster. Although an accident, it made the world realize that controlling such a potentially great power is not entirely in our hands. The accident happened during a test in a nuclear power plant. The extent of damage was controlled as the plant was shut down immediately, and the residents relocated. Even now, the city is in ruins, a pale picture of its past.
The most recent nuclear mishap was the Fukushima Accident in Japan. It was caused by an earthquake-generated tsunami. The nuclear reactor was seismically robust, however could not sustain the effect of the gallons of sea water that went inside the reactor, thus leading to power failure which in turn led to overheating. This ultimately resulted in a hydrogen explosion and subsequent events led to the discharge of radioactive materials into the atmosphere.
Disadvantages of Nuclear Energy
1) Radioactive minerals are unevenly distributed around the world and are found in limited quantities.
2) Supply of high quality uranium, one of the raw material, will last only for few decades.
3) Nuclear waste from nuclear power plant creates thermal(heat) pollution which may damage the environment.
4) A large amount of nuclear waste is also created and disposal of this waste is a major problem.
5) The danger of accidental discharge of radio activity also exists.
6) Starting a nuclear plant requires huge capital investment and advanced technology.
7) Nuclear plants are opposed on moral grounds, by many groups, because of their close linkage with development of nuclear weapons.
8) There are number of restrictions on the export or import of nuclear technology,fuels etc.
9) Nuclear power stations are always at the risk from terrorist attack.
10) Aftermaths of Chernobyl cannot be forgotten easily.
11) Safety issues associated with nuclear power are hard to be overlooked.
12) Proliferation of nuclear technology increases the risk of nuclear war too.
13) The waste produced remains 'active' over many years and disposing it safely is a an issue which needs to be addressed properly.
14) Nuclear power is not a renewable source of energy. Uranium is a metal that is mined from the ground in much the same way as coal is mined. It is a scarce metal and the supply of uranium will one day run out making all the nuclear power plants obsolete.
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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)
There are two ways to obtain nuclear energy:
1) Nuclear fission and
2) Nuclear fusion.
In a 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 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.
Let�s cut out the technical part behind nuclear power and discuss advantages and disadvantages of nuclear energy, starting with advantages.
Advantages of Nuclear Energy
1) As compared to other conventional energy sources, Nuclear power produces very less amount of pollution.
2) Very small amount of raw material is required to generate huge amount of nuclear energy. To put it into perspective, about 28gm of Uranium releases as much amount of energy as is generated by 100 metric tonnes of coal.
3) Since they are required in small quantities, atomic materials can be easily transported to far-off places even at a global scale. Thus transportation is easy unless you are considering security part of it.
4) If nuclear power stations are operated up to their full capacity they can produce cheap electricity and gain from other benefits of Nuclear energy.
5) The quantity of nuclear waste produced is also small. Cons of this advantage are discussed in Disadvantages of Nuclear Energy.
6) It is a very reliable source of energy. The average life span of a nuclear reactor is approx. 40 years which can be extended up to 60 years.
7) Nuclear power stations are usually very compact compared to thermal stations.
8) Although the initial capital cost of building a nuclear plant is high, the maintenance and running costs are relatively low.
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More than a dozen advanced reactor designs are in various stages of development. Some are evolutionary from the PWR, BWR and PHWR designs above, some are more radical departures. The former include the Advanced Boiling Water Reactor (ABWR), two of which are now operating with others under construction, and the planned passively safe ESBWR and AP1000 units (see Nuclear Power 2010 Program).
