Nuclear Reactors

Since the continued chain reaction of a nuclear fission reactor depends upon at least one neutron from each fission being absorbed by another fissionable nucleus, the reaction can be controlled by using control rods of material which absorbs neutrons. Cadmium and boron are strong neutron absorbers and are the most common materials used in control rods. A typical neutron absorption reaction in boron is In the operation of a nuclear reactor, fuel assemblies are put into place and then the control rods are slowly lifted until a chain reaction can just be sustained. As the reaction proceeds, the number of uranium-235 nuclei decreases and fission by- products which absorb neutrons build up. To keep the chain reaction going, the control rods must be withdrawn further. At some point, the chain reaction cannot be maintained and the fuel must be replenished

To slow down the chain reaction in a nuclear reactor, you would insert the control rods. Control rods absorb neutrons and reduce the number available to sustain the chain reaction, thus slowing down the rate of fission reactions occurring in the reactor core.

The first line of shielding is to limit the neutron bombardment of the pressure vessel, to give it a safe life of 40 or more years. Then you need to protect personnel who have to go into areas close to the reactor for maintenance, and also to limit the exposure of equipment which may need maintanance done during the life of the plant

Natural uranium consists of mainly U238 with about 0.7 percent U235, which is the fissile one, so enrichment is to raise the proportion of U235, which can be done by diffusion or by centrifuging, because of the slight difference in density, using uranium hexafluoride which is gaseous.

Boron and/or Cadmium control rods. They are inserted into the core to slow the reaction and withdrawn from the core to speed up the reaction. Both elements have a very high neutron capture crosssection, the more in the core the more excess neutrons they remove from the chain reaction.

Cooling water bathes the control rods and fuel bundles of a nuclear reactor to remove excess heat generated during fission. It helps regulate the temperature within the reactor core, preventing overheating and ensuring safe operation.

Nuclear reactors do not typically use lasers as a primary component in their operation. Lasers are more commonly used in research, industry, and medical applications. Nuclear reactors rely on controlled nuclear fission reactions to generate heat for electricity production.

This depends very much on the type of reactor. PWR's operate at a high pressure in the primary circuit to prevent boiling, and the outlet water temperature is about 315 degC. In BWR's in contrast, boiling is allowed and the outlet temperature is about 285 degC.

Gas cooled reactors can operate at much higher temperatures. In the AGR for example (CO2 cooled, graphite moderated) the gas outlet temperature is designed to be about 540 degC, which allows steam to be produced at conditions the same as in a modern coal fired station, in fact at the last two built the steam turbines were exactly the same as installed in coal fired stations at that time. At these temperatures all steel components in the reactor have to be austenitic, as CO2 oxidises normal steel, and re-entrant gas flow has to be arranged to keep the graphite moderator cool, the gas inlet being at about 300degC.

Designs exist for helium cooled gas reactors which could operate even hotter and drive a gas turbine directly, without a steam circuit. These may or may not be commercially exploited.

Well, scientists have been researching fusion reactors for over 50 years, but nuclear fusion is much more difficult to achieve than nuclear fission, which is what current nuclear power technology is based on. There are many reasons for this, but while there have been tests and advancements in the field, scientists have yet to a) create a sustainable and stable nuclear fusion reaction and b) create a reaction that has a greater output than input.

This is used in the nuclear reactor that is known as Boiling Water Reactor (BWR) in which heat produced by the nuclear fission in the nuclear fuel allows the light water reactor coolant to boil. Then, the nuclear reactor moisture separator is used to increase the dryness of the produced steam before it goes to the reactor steam turbines.

Nuclear fission occurs in the reactor core of a nuclear reactor. This is where nuclear fuel, typically uranium, is arranged in such a way that it sustains a chain reaction of splitting atoms, releasing energy in the process.

A lamp or an X-ray tube cannot be used to "add neutrons" to other nuclei because lamps and X-ray tubes are not neutron sources.

Neutron activation is generally something we do in an operating nuclear reactor. In the core of the reactor, there is a high neutron flux. Many, many neutrons are being released in the fissions that are going on in the nuclear core. Materials that are to be activated are lowered through ports and brought down into the neutron flux. Activation occurs. Lamps or X-rays do not produce neutrons, and cannot be used in neutron activation activities. No neutrons means no neutron activation.

The five key elements used in nuclear power plants are uranium fuel rods, control rods, coolant (such as water or gas), reactor pressure vessel, and steam turbine. These elements work together to initiate and sustain the nuclear fission process, produce heat, and generate electricity.

The moderator in a nuclear reactor is usually made of graphite, which is used to slow down neutrons. So, the correct answer is "all of the above".

particle accelerators. These methods involve bombarding target elements with high-energy particles to induce nuclear reactions that form new elements. The elements produced in this way are usually radioactive and have short half-lives.

Graphite rods are used as moderators in a nuclear reactor with natural uranium. Graphite slows down the fast neutrons released during fission reactions, allowing them to cause further reactions and sustain the chain reaction. This is necessary because natural uranium is not as efficient at sustaining a chain reaction without a moderator.

Materials commonly used in nuclear reactors for canning purposes include zirconium alloys for fuel cladding and stainless steels for structural support and containment. These materials are chosen for their corrosion resistance, mechanical strength, and ability to withstand high temperatures and radiation exposure. Special coatings or treatments may also be applied to enhance their performance in reactor conditions.

The fuel rod in a nuclear reactor contains enriched uranium pellets that undergo fission, producing heat that is used to generate electricity. The fission process releases energy in the form of heat, which is used to heat water to produce steam that drives turbines connected to generators, producing electricity.

A control rod is made of a neutron absorbing material. Boron is common. When the control rod is withdrawn (pulled out) of the reactor, the fission reaction rate increases. When that control rod is inserted, the reaction rate decreases. There are other factors that control the reaction rate, but the rods can be considered as the way to start up or shut down the reactor by pulling or inserting them.

Lowering control rods in a nuclear reactor will result in the absorption of more neutrons, which decreases the rate of fission reactions and slows down the nuclear chain reaction. This helps to control and regulate the power output of the reactor.

Helium-3 can be found on the moon and has the potential to be used in nuclear fusion reactors. It is an ideal fuel source due to its abundance on the moon and its efficiency in producing energy through fusion reactions.

Breeder reactors are designed to produce both heat and Pu-239 as a byproduct. These reactors use fertile material such as uranium-238 to breed plutonium-239 through neutron capture, resulting in a self-sustaining chain reaction. The produced Pu-239 can then be used as fuel in nuclear reactors or for nuclear weapons.

Having redundancy and diversity in nuclear reactors helps to improve safety and minimize the risk of accidents. Redundancy ensures that critical systems have backups in case of failures, while diversity involves using different designs or technologies to provide additional layers of protection. This helps to maintain the integrity of the reactor and prevent the potential for catastrophic events.

The nuclear chain reaction is controlled using neutron absorbing control rods containing boron, and in PWR's by also using soluble boron when necessary. Nuclear engineers use a term called reactivity, which just means the surplus of neutrons from one generation to another, and in steady operation this is zero. During the fission reactions fission products are produced, some of these are neutron absorbers like Xenon131, and their concentration changes with power changes, so that adjustments with the control rods are necessary following such changes. On start-up with new fuel for example it takes some hours before equilibrium xenon is reached, and if power has to be reduced the xenon rises again as a delayed action, so enough control to overcome the increased poisoning has to retained, or the reactor will shut itself down. The reactivity with new fuel loaded is higher than at the end of the fuel life, and this is where boric acid added to the reactor water circuit is useful.

The reactor power (neutron flux level) is constantly monitored with instruments so that the control room staff know what is happening and can respond. In addition automatic safety circuits are triggered if there is an increase in flux beyond a certain point which the operators don't react to, and this inserts the control rods fully (scram or trip) which shuts the reactor down and holds it down. So there is no chance of a runaway.