Nuclear Reactors

• moderator, slows fast fission neutrons to thermal (near room temperature) energies rapidly enough to prevent their capture by uranium-238 before they can participate in the chain reaction and fission uranium-235
• control, remove excess neutrons so as to hold the reactor at exactly critical at all times, permit control of increases and decreases of operating power level

The element used as a fuel component in most nuclear reactors is uranium. Specifically, uranium-235 is the primary isotope used for nuclear fission reactions in nuclear power plants.

The nuclear reactor that exploded and burned in the 1980s was located near the town of Chernobyl in Ukraine. The Chernobyl disaster, which occurred in 1986, released a significant amount of radioactive material into the environment and is considered one of the worst nuclear accidents in history.

India's first nuclear reactor is situated in the ''Rajasthan, porbandar.''

Any fissile material would do, but Uranium is the most common.

The controlled release of nuclear energy in a reactor is accomplished by controlling the rate of fission reactions through the use of control rods. These rods absorb neutrons and regulate the nuclear chain reaction to maintain a constant and safe level of energy production. Additionally, the coolant in the reactor helps remove heat and regulate the temperature to prevent overheating.

The power required to start a nuclear reactor varies depending on the size and type of reactor, but typically ranges from a few hundred megawatts to several gigawatts. Once the reactor is operating, it generally requires a smaller amount of power to maintain criticality and sustain the fission chain reaction, usually around 1-5% of the total reactor power output.

• Nuclear power plants are more efficient than ever before. New technology has made them more reliable (they break down less often) and safer. People for nuclear power argue that this is evidenced by more and more nations (such as China) building nuclear power plants.
• Reduce greenhouse gas emissions. This is a contentious issue. Proponents of nuclear power argue that, as no coal or fossil fuels are burnt, no carbon dioxide is released into the air. However, uranium has to be mined and transported to the nuclear plant. Both these activities require burning of fuels, so carbon dioxide is released. Also, producing nuclear fuel from the uranium requires a lot of energy, which also contributes to the emission of greenhouse gases.
• Although the initial cost of building nuclear plants is high, the running costs are relatively low.
• One reason the costs are low is that nuclear plants need only a small amount of uranium to produce a lot of energy. In fact, if the cost of uranium doubled, costs would only be increased by 7%. 1 truck of uranium produces as much energy as 1000 trucks of coal!
• Reduces dependence on foreign oils and natural gas (like biofuels). America, for instance, imports a lot of oil and natural gas from other countries. The price of these products is volatile, and change very quickly. If the price increases quickly, consumers have to pay more for their electricity (which they may not be able to afford). Building more nuclear power plants means that Americans will not be susceptible to price rises in oil and gas. President Barack Obama supports this idea of 'energy independence'.
• Nuclear wastes can be safely stored underground (another debated issue).

The primary function of a moderator in a nuclear reactor is to slow down the fast neutrons produced during fission reactions, making them more likely to cause additional fission events. This helps sustain a chain reaction by ensuring a sufficient number of neutrons are available to continue the process. Common moderators include water, graphite, and heavy water.

It is not possible for a nuclear reactor to explode in the way a nuclear bomb does, because the fissionable part of the fuel is spread out through the reactor in a matrix, in a bomb a critical mass has to be formed very quickly to make the explosion happen.

What is possible is some sort of failure in the reactor's pressure circuit, releasing the coolant and causing fuel to melt thus leaking radioactivity to the environment. This is what happened at Chernobyl, a steam pressure surge blew the top of the reactor off, and some fuel was ejected, then the remains of the reactor caught fire (it was graphite moderated) and released even more activity. It must be emphasised however that this did not happen during normal operation. It was due to an experiment that was badly planned and carried out, together with some design faults that had not been assessed thoroughly enough.

PWR's and BWR's used in the US and elsewhere are very different. A massive disruptive failure of the pressure vessel can be discounted because of design overkill and thorough inspection before use. Some smaller coolant circuit failures are deemed credible and are allowed for in safety studies. The main protection is that the reactor has secondary containment, this is the large dome that is characteristic of reactors seen from outside the plant.(Chernobyl did not have this). In the Three Mile Island incident coolant did leak out through a valve that the operators did not know was open. This shows the necessity of better instrumentation and this has been taken into account in new designs. No significant radiation exposure happened to the nuclear staff or the public nearby, though the reactor was damaged and has never operated since.

Because "ordinary" uranium is mostly 238U, which won't fission and create a chain like its lighter cousin 235U will. When critical mass is achieved with the 235U isotope of uranium, fission will occur spontaneously. Or with a significantly enriched uranium fuel (one where the natural concentration of 235U has been increased a bunch so the fuel has a much higher percentage of this isotope), fission and a chain reaction is also possible. But with just natural uranium, a big pile of it will just sit there. It won't fission and create a chain reaction. Note that 238U is radioactive and decays over time because it is unstable, but it has a long half-life. Also, the fact that it's unstable (radioactive) doesn't mean it's fissile. It isn't.

A nuclear fission reaction is controlled in a nuclear reactor by using control rods made of materials that absorb neutrons, such as boron or cadmium. By adjusting the position of these control rods within the reactor core, the rate of fission and thus the power output can be regulated. Inserting the control rods absorbs neutrons and reduces the number available for further fission reactions, helping to maintain a steady power level.

it comes from nuclear fission
Nuclear energy is the fission of certain, materials such as uranium or plutonium,within a nuclear reactor. This produces heat, which turns water into steam. This steam rises, driving a turbine which creates electricity for commercial and public use.

You don't need nuclear power, energy can be generated using other methods, fossil fuels, hydro-electric etc.

However nuclear power does reduce a countries reliance on fossil fuel, which can be particularly important for countries with few fossil fuel reserves of their own. Nuclear power stations do not release CO2 into the atmosphere so do not directly contribute to global warming. Many countries are looking at an investment in nuclear power to help meet CO2 emissions targets.

Nuclear power stations are also required to make plutonium for nuclear weapons. Plutonium does not occur naturally and can only be made from uranium in nuclear reactors. Any country with a nuclear weapons program will have a civilian nuclear power industry for this reason.

It's greener and safer than fossil fuel power plants, but produces far more energy than wind or solar power plants.

For example, coal power plants produce the same amount of radiation as Three Mile Island every few days, and produce extremely large amounts of particulate pollution, which kill the same number of people as Chernobyl every few weeks.

Wind turbines cost about the same amount as nuclear plants, per watt, but to produce the same amount of energy, they require 300 times as much land.

Spent uranium is usually reclaimed in thermal-neutron reactors.

This process is possible only in CANDU reactors and other similar types, which use heavey water as a moderator (a moderator slows neutrons to a speed at which they are more likely to be absorbed by a nuclei, as the neutrons impact the molecules of the moderator and are slowed).

Normal water (usually refered to as light water when dealing with nuclear reactors) is H20, H being a hydrogen atom, which does slow the neutrons, but it also sometimes absorbs neutrons that impact it. This means less neutrons are getting through to the reactor core, which means once a fuel bundle has less than a certain percentage of fissionable material left in it (idealy it should be about 5% for commercial reactors, that it, before it has been used. It can only continue to be productive in a light-water reactor above about 1- 2%.), not enough neutrons are getting through to keep the reactor critical (the point where enough neutrons are being released from fissions to sustain a chain reaction), and the fuel is discarded.

Heavy water, on the other hand, is D2O, with two deuterium atoms (an isotope of hydrogen which has 1 proton and 2 neutrons, instead of the regular 1 and 1). This means that the hydrogen atoms already have an extra neutron, making them less likely to absrob the neutrons they are supposed to be slowing down.

Thus more neutrons are getting through, and there are enough to cause fission in a significant portion of the remaining fissionable material, allowing such reactors to run on depleted uranium.

The energy in a nuclear reactor comes from nuclear reactions, specifically fission reactions where the nucleus of an atom is split into smaller parts. This process releases a large amount of energy in the form of heat, which is then used to produce steam to turn turbines and generate electricity.

The Open Pool Australian Lightwater (OPAL) reactor is mainly used to produce radioisotopes for medical use (nuclear medicine). It also performs irradiation services and is used for neutron beam research. Although the fission process does generate heat, the facility is not used to generate power mainly due to political reasons. Australia made the decision not to build power reactors, though there was at one time a proposal to build one at Jervis Bay.

Australia has a large amount of cheap black coal and generates most of it's power in coal burning power stations. The black coal is slightly more efficient than most of the world's brown coal.

The energy output of a nuclear reactor can vary greatly depending on its size and design. However, on average, a nuclear reactor can generate around 1-2 billion kilowatt-hours (kWh) of electricity in one day.

Mines, usually it is uranium, with only 0.7% (aproximately) U-235 (the isotope that is used for fission), the rest is U-238, known as depleted uranium, or natural uranium. Then it enriched to about 3-5% U-235, unless it is used in a CANDU reactor, in which case it can almost literaly be used straight out of the ground.

Using control rods that obsorb neutrons, and can be gradualy raised or lowered into the core. In emergencies, "neutron poisons" are used, which almost instantly stop most fission within the core.

Plasma is the form of matter found in lightning bolts, nuclear reactors, and stars. It is a state of matter that consists of charged particles, such as electrons and ions, and is characterized by its high energy and conductivity.