Nuclear Reactors

TNT (trinitrotoluene) is a conventional explosive used to trigger the beginning of a nuclear reaction in some nuclear weapons. When the TNT detonates, it generates the high temperatures and pressures needed to initiate the fission process in the nuclear material, causing a chain reaction to occur.

The primary purpose of the cooling water in a reactor is obvious, cool the reactor core by carrying heat away to someplace else. That someplace else is usually a heat exchanger/steam generator, which generates steam to turn the turbine generators that make electricity.

In light water moderated reactors, the cooling water also serves a secondary purpose as the moderator. The moderator is a material that slows the fast neutrons from the fission to slow thermal neutrons before too many are absorbed by the plentiful Uranium-238 isotope, which will not fission. These thermal neutrons then fission the rare Uranium-235 isotope to keep the reactor going.

Control rods absorb excess neutrons. By withdrawing them the power level of the reactor goes up. By inserting them the power level of the reactor goes down. They act similar to the throttle control on airplane engines.

Absorption of neutrons by an element depends on neutron cross-section data for that element at the energy of interest. The absorption cross-section gives the probability of a neutron being absorbed by an atom of the element. Measuring the absorptions at a certain neutron energy can help in determining the propensity of an element to absorb neutrons at that energy level.

Cadmium is used in nuclear reactors as a control rod material. Control rods are inserted into the reactor core to absorb neutrons and regulate the nuclear fission process. Cadmium has a high neutron absorption cross-section, making it effective for controlling the rate of nuclear reactions.

Helium is used as a coolant in nuclear gas reactors because it is chemically inert, meaning it does not react with other materials in the reactor. It has high thermal conductivity, which helps in transferring heat away from the reactor core efficiently. Helium also has low neutron capture cross-section, making it less likely to absorb neutrons and become radioactive.

Spent fuel rods are a concern because they contain highly radioactive materials that can pose a serious health and environmental risk if not handled properly. They must be safely stored and managed to prevent exposure to radiation and potential environmental contamination. Additionally, spent fuel rods are a long-term nuclear waste issue as they remain radioactive for thousands of years.

This part is the core of the nuclear reactor containing the nuclear fuel.

Most nuclear reactors are built to produce electric power. A single nuclear reactor can generate enough energy to power 1,200,000 homes around the clock. The vast minority of reactors around the world are operated by power or energy companies that are licensed by the government, or by the government itself.

Some smaller reactors are constructed for research, and for the production of nuclear materials used in industry and medicine. Plutonium can also be produced in reactors, and its application as a nuclear fuel or a material for a nuclear weapon is widely known.

When nuclear reactors are operated at high power levels the fission process produces a lot of heat, and the reactor coolant system removes that heat to prevent the heat from building up to the point that the fuel melts or is otherwise damaged. When the reactor coolant system develops a problem (perhaps one or all coolant pumps stop due to interruption of the electrical power supplied to them) the system detects this and automatically inserts control rods to turn off the fission process (a reactor SCRAM or TRIP). Unfortunately, this does not turn off the decay of fission products that were produced when the reactor was operating at power. Since the fission products already exist, and their decay is inevitable, the heat production is going to happen, regardless of the presence of a means to remove that heat. If the emergency cooling systems should fail (as they did at Fukushima following the earthquake and tidal wave) then the heat production could cause the fuel to eventually melt its way through the bottom of the reactor vessel and through the containment concrete below that and in to the environment. This would release large amounts of radioactivity into the environment that could be very dangerous to anyone in the vicinity.

Nuclear energy is produced in the core of a nuclear reactor, where controlled nuclear fission reactions occur. These reactions release heat energy, which is then used to generate electricity through steam turbines.

The inside of a nuclear power plant typically operates at temperatures ranging from 500 to 750 degrees Fahrenheit, depending on the specific design and type of reactor. Cooling systems are in place to manage these temperatures and prevent overheating.

By its cooling system, which consists of a series of coolant loops connected by heat exchangers. Some of the coolants that have been used in these loops have been: water, liquid metals, gasses, the reactor's fuel itself (in molten salt or slurry fueled reactors), etc. depending on the reactor's design. One or more loops is used to make steam to turn turbines to generate electricity. The final loop is open to the environment to dump the unusable waste heat either into the air or a river.

Nuclear reactors split uranium atoms in a process called nuclear fission to release energy. This process generates heat that is used to produce steam, which then drives turbines to generate electricity. Burning uranium would involve a chemical reaction, while nuclear fission is a nuclear reaction.

Yes, plutonium is used as a fuel in certain types of nuclear reactors, such as breeder reactors. These reactors are designed to produce more plutonium than they consume, as a way to generate energy and also produce more fuel for future use.

A moderator is necessary in a reactor to slow down fast-moving neutrons produced during nuclear fission. This helps control the rate of reaction and enables more neutrons to be captured by other atoms, sustaining the chain reaction. Additionally, the moderator helps manage the temperature and pressure within the reactor to prevent overheating and maintain stability.

The nuclear fuel is typically contained in the reactor core, which is a central part of the nuclear reactor where the fission reaction takes place. The fuel rods, which contain the nuclear fuel pellets, are inserted into the reactor core during operation.

Neutrons are the forms of radiation used to directly increase the temperature of water in a nuclear reactor. When neutrons collide with water molecules, they transfer kinetic energy, increasing the temperature of the water.

In a nuclear reactor, the fission process splits heavy atomic nuclei, releasing energy and additional neutrons. These neutrons can then collide with other nuclei, causing them to split and release more neutrons, creating a self-sustaining chain reaction. Controlling the number of neutrons and their interactions is crucial to the operation and safety of a nuclear reactor.

Yes, nuclear fission reactors produce plutonium.

92238U + 01N --> 92239U (Uranium-238 + Neutron = Uranium-239)

92239U --> 93239Np + e- + v-e (Uranium-239 beta decays to Neptunium-239)

93239Np --> 94239 Pu + e- + v-e (Neptunium-239 beta decays to plutonium-239)

Some alternatives to uranium for nuclear energy include thorium, which is more abundant; plutonium, which can be produced as a byproduct in uranium reactors; and fusion reactions, which use hydrogen isotopes like deuterium and tritium. Each of these alternatives carries its own set of challenges and benefits for nuclear energy generation.

Moderation slows or reduces the energy of neutrons in a nuclear reactor. By doing this, moderation allows continuation of the chain reaction. Neutrons will only cause more fission events when they have a specific range of energy, but they have too much energy when they are first emitted from their precipitating event, hence the need for moderation.

Moderation also regulates the reaction. In the light water moderated reactor, for instance, a common design, water is the moderator. Water is also the heat sink, carrying away the energy of the reaction to make steam which spins turbines and makes electricity. If reactivity were to increase, temperature would also increase, causing an increase in the number of voids in the water. This reduces the effectiveness of the moderator and tends to decrease reactivity. Similarly, if reactivity were to decrease, temperature would decrease, causing voids to decrease, ultimately causing reactivity to increase. Conversely, if the load changes, that will reflect back into the water temperature, causing reactivity to adjust accordingly. It is a self-stabilizing situation.

It is also a safety designed system. If there were a sudden loss of heat sink, such as a turbine load rejection, temperature would go up, causing a decrease in reactivity. If there were a steam line break, causing a depressurization incident, the water would flash to steam and the reactor would go instantly subcritical. In both of these scenarios, there would be time to insert the control rods, forcing the reactor further subcritical, and giving the emergency core cooling systems time to startup.

The control rods include some material that strongly absorbs neutrons-boron is the most common though others like cadmium are also effective. The safety function of the rods is to quickly shut the reactor down should conditions require it. This would most likely be a loss of coolant flow, whether water flow or gas flow, which would cause a rapid rise in fuel temperature, so the best way to kill this quickly is to insert the rods (in a few seconds) so that the reactor power is immediately shut off (except for the decay heat which requires some emergency cooling flow). During steady operation or power changes the rods are used to maintain the reactor just critical, so that the chain reaction is maintained steady or changed at a slow controlled rate. Changes in the reactors reactivity state are caused by variations in neutron absorption by some fission products, notably Xenon 135, which varies in concentration with power level, and by fuel burn up during the period between refuelling outages, so that control rod adjustments are needed to accommodate these changes. If the reactor maintains a steady power level for several days, the xenon reaches an equilibrium level and the rods will move very little from then on, just gradually coming out to offset the fuel burn up.

Uranium is the primary fuel used in nuclear power plants. Specifically, uranium-235 is the isotope that undergoes nuclear fission to generate heat in these plants.