Nuclear Reactors

There are two radioisotopes that serve as fuel for a nuclear reactor. The first is uranium-235, which is a constituent of natural uranium. U-235 is a "fissile" isotope -- i.e., the one that splits when it absorbs a neutron of a certain energy. When a reactor starts up with a fresh load of fuel, all of the early activity involves U-235.

This splitting, or fissioning, of U-235 atoms releases energy in the form of heat. The production of heat is the whole purpose of certain types of nuclear reactors. This heat converts water into steam to turn a turbine generator and make electricity.

Fission also releases neutrons. These neutrons sometimes are absorbed into another uranium isotope, uranium-238, another constituent of natural uranium which is also present in nuclear fuel. When U-238 absorbs a neutron, it eventually becomes plutonium-239. Pu-239 is another fissile isotope, i.e., it also fissions when struck by a neutron of a certain energy.

So the two isotopes that are used as fuel for a nuclear reactor are uranium-235 and plutonium-239. The former gets the reactor going; the latter is made inside the reactor.

Some nuclear reactors are designed solely to produce neutrons. These are research reactors. Neutron interactions with other materials are of great interest to a great many scientists and engineers.

Small reactors for research, teaching, or radio-isotope production are usually open pool type reactors, with no electric output. You can read about these in the link below. The smaller power reactors are those built into submarines and other naval ships, these are small versions of PWR. No small reactors of this type are built for use in civilian plants as far as I know, but it would be possible to do so for an isolated community without a connection to the national grid system. The difficulty would be in licensing and ensuring suitable trained operating staff in such a location.

Neutron absorption in a nuclear reactor can help control the rate of fission reactions by absorbing excess neutrons to prevent them from causing further reactions. This process helps regulate the reactor's power output and overall stability. Additionally, some materials used for neutron absorption, like control rods, can also be used to shut down the reactor in emergency situations.

The fuel in a nuclear reactor is located in the fuel rods, which are typically made of materials such as enriched uranium or plutonium. These fuel rods are where the nuclear fission reaction takes place, producing heat that is used to generate electricity.

The Purity && The Shape

AND size density

Typically, the reactors in nuclear power plants are lined with zirconium alloys, such as Zircaloy, due to their high corrosion resistance and low neutron absorption properties. This lining helps to contain and protect the nuclear fuel rods within the reactor core.

1. very low power experimental reactors need no cooling system (e.g. CP-1 built as part of the Manhattan Project had a maximum power of half a watt and was entirely self cooling, it never even got noticeably warm at any time)
2. some experimental reactors have been deliberately built without a cooling system to aid in studying the effects of reactor meltdown, etc. (unfortunately these were also built without any containment facility, to aid in data collection and caused significant downwind contamination)
3. reactors designed for power production require a cooling system both to remove heat from the core as it is generated (thus preventing a meltdown) and to move that heat to the power generation building where it is used to make steam to turn the turbines that turn the generators that make the electricity
4. reactors designed for plutonium production require a cooling system only to remove heat from the core as it is generated (thus preventing a meltdown)
5. reactors designed for medical (and other) isotope production require a cooling system only to remove heat from the core as it is generated (thus preventing a meltdown)
6. reactors designed for direct nuclear propulsion systems(e.g. jet engine, rocket engine) require a cooling system both to remove heat from the core (thus preventing a meltdown in flight) and to heat their working fluid (e.g. air, hydrogen gas; respectively) prior to expelling it through the exhaust nozzle to generate thrust to move the vehicle
7. etc.

Currently, 100 nuclear power plants are operating the United States per the statistics of the International Atomic Energy Agency (IAEA) as of April 2004.

If the control rods in a nuclear reactor were somehow to be instantly "jerked" out of the reactor, the reactor would go supercritical. If they were pulled at a normal rate and all of the control rods were pulled out, the reactor would start up and heat up and would end up running far too hot. Any one of several safety systems would shut the reactor down before this could happen. If the safety systems were disabled, the reactor would overheat and a meltdown may occur.

Kewaunee and Point Beach. See NRC link below

Baffles in reactors help to promote uniform mixing of reactants, improve heat transfer efficiency, and prevent the formation of stagnant zones within the reactor vessel. This is important for maintaining optimal reaction conditions and maximizing the conversion of reactants into products.

The energy in a nuclear reactor comes from the process of nuclear fission. This process involves splitting atoms of uranium or plutonium, which releases a large amount of heat energy. This heat is then used to generate steam, which drives turbines connected to generators to produce electricity.

Nuclear power plants provide a reliable and consistent source of energy without producing greenhouse gas emissions, making them a cleaner alternative to fossil fuels. They also have the capability to generate large amounts of electricity efficiently, which can help meet high energy demands. Additionally, nuclear power plants can contribute to energy security by reducing dependence on imported fossil fuels.

The first nuclear reactor became operational in 1942 as a part of the Manhattan Project, which was a research and development project during World War II that produced the first nuclear weapons. This marked the beginning of the nuclear age, leading to the development of nuclear power for electricity generation and revolutionizing the field of nuclear physics.

There is no fixed number, but most nuclear stations have two reactors. These are usually run quite separately, with separate generating equipment, so that whilst one reactor is being refuelled the other can continue to produce power. Some stations have more than two reactors, but usually then they have been built over a long time period and the later ones may be of an improved design.

The amount of uranium-235 used in a nuclear reactor depends on the design and size of the reactor. Typically, a reactor core contains several tons of uranium fuel, with the concentration of uranium-235 ranging from 3-5%. The fuel is arranged in fuel assemblies to sustain a controlled nuclear fission chain reaction.

Nuclear reactors produce very low greenhouse gas emissions during operation, as they do not burn fossil fuels. However, there are some emissions associated with the mining and processing of uranium fuel, construction of the facilities, and potential accidents. Overall, the emissions from nuclear power are significantly lower than those from fossil fuel-based energy sources.

You can work out the gas flow from the gas circulator characteristics, and measure the reactor inlet and outlet temperatures, so you can work out the reactor thermal output. Then you can measure the thermal conditions in the steam circuit from feed flow and temperature and steam temperature and pressure, this will give the reactor thermal output together with the gas circulator heat input. From all this data work out the best estimate for the reactor output. The generator output is straightforward, then you have to subtract the power being used on the plant for driving the gas circulators and feed pumps etc, to get the net electrical output, then it is just the ratio of that to the reactor thermal output.

Lightning bolts are discharges of electricity. Nuclear reactors contain mainly uranium. Stars contain light elements undergoing nuclear fusion. I don't see any common form of matter.

Actually, plasma is found in all of them.

In a nuclear reactor, materials such as water or graphite are commonly used as neutron moderators to slow down fast-moving neutrons to speeds where they are more likely to induce fission in uranium or plutonium atoms. Slowed down neutrons are termed thermal neutrons and are key to sustaining a nuclear chain reaction.

Fission of Uranium-235, splitting of this atom into two smaller atoms of different elements. A neutron must hit the nucleus at just the right speed to cause the Uranium-235 to undergo fission. When the Uranium atom is split into smaller atoms called fission products, free neutrons are released which can split more Uranium atoms. The fission product atoms separate at high speed, transferring lots of energy to its surroundings making them very hot. This heat is used to boil water, making steam which is used to turn turbines. The turbines turn generators which produce electricity.

They are used in nuclear reactor to control the rate of fission of uranium and plutonium. Because these elements have different capture cross sections for neutrons of varying energies, the compositions of the control rods must be designed for the neutron spectrum of the reactor it is supposed to control.

Reactors can be fueled by uranium or many of the transuranic elements, but uranium is the only element that occurs naturally with large enough levels of its fissionable isotope uranium-235 for practical use.

Plutonium is also a good reactor fuel, but must be produced first from the plentiful but nonfissionable uranium-238 in a reactor as it only occurs naturally at trace levels.

While thorium cannot be directly used as fuel, the fissionable isotope uraniuum-233 which can be used as fuel can be produced from it in a nuclear reactor.

For transuranics other than plutonium (and maybe americium) specially designed fast neutron reactors are required to effectively use them as fuel, but they too can be used.