The reactor core is surrounded by water under pressure (about 100 times atmospheric) in the primary cooling circuit. This water is also the moderator. It must not boil because if it did the fission reaction would slow down.
Depending on the vertical relative positioning of floats 331 switch 330 may open check valve 340 (shown by an arrow) to prevent coolant leakage from ICS chamber 321. This is a safety function.
What is a Reactor?
A reactor is a large steel container that houses the nuclear fuel, control rods and moderator. It also has a primary coolant loop that is heated by the fission reaction to make steam to run turbines.
The primary coolant in most commercial nuclear reactors is water and it is pressurised to stop it boiling. Alternatively, some experimental reactor designs use helium or carbon dioxide – for example in the current British AGR nuclear power plants and in first generation French, Italian and Japanese plants. The resulting hot gas can be used to drive a steam turbine or in some cases – for the CANDU and RBMK types of reactor – it can directly power a gas turbine.
Unlike the lead in a PWR or PHWR reactor, these alternative fluids have the advantage of being able to handle much higher temperatures and they are not radioactive. The disadvantage is that they are more expensive, difficult to work with and pose a higher risk of explosion if the coolant leaks out.
Another safety feature of some reactors uses burnable poisons in the fuel or coolant to even out performance over a long period between refuellings. Gadolinium is the most common of these, but others include cobalt-60 and molybdenum-99. These poisons act as neutron absorbers and decrease in effectiveness over time as they decay, allowing the reactor to operate for longer periods between refuellings.
Reactors for Sale
We carry more than 1,000 used reactors for sale in a variety of shapes, sizes, and designs. Our inventory is a combination of gas, liquid, and batch reactors for use in a wide range of applications. Our stock of reactors includes carbon steel, glass lined, and stainless steel types with various shell pressure ratings, supported temperature ranges, and agitated or non-agitated configurations. Aaron Equipment also carries laboratory, pilot plant, bench scale, catalyst and Buss loop reactor vessels.
A nuclear reactor consists of a large tank, called a calandria, penetrated by several hundred horizontal pressure tubes that form channels for the fuel and which are surrounded by a primary coolant system (also known as a primary steam circuit) that provides moderator, cooling, and heat transfer to generate electricity. The reactor is encased in containment, which is designed to protect the public from radiation leaks and other failures that could occur inside.
Most reactors are cooled by a combination of water from a main feedwater line 120 and steam generated in a steam generator. The water in the reactor is kept at a temperature lower than its surroundings, using a heavy water (deuterium oxide) that circulates around the pressure tubes. The resulting steam is then used to drive the turbines, which create electrical power. If an emergency occurs, a control rod assembly may be inserted into the reactor core to reduce the amount of radioactive material released into the environment.
Used Reactors
If you are looking for a used reactor, surplusrecord has many types of industrial process reactors available. These include batch process reactors, continuous process reactors, plug flow and tubular flow reactors. These are commonly used in commercial production applications to mix a product, solids dissolution, liquid extraction, crystallization, and chemical reactions. Aaron Equipment has a large inventory of carbon steel, alloy, glass lined and stainless steel reactors for sale. buy reactors at the best price from surplusrecord.
During refuelling, the nuclear plant is shut down and the reactor vessel opens up to remove and replace the fuel rods. Refuelling is typically done every 3-4 years and is part of the overall maintenance cycle for the plant. Some reactors such as CANDU and RBMK reactors use pressure tubes rather than a vessel enclosing the core and can be refuelled on-load.
If a power station experiences a loss of feedwater from line 120, example embodiment isolation condenser systems 300 may provide emergency cooling to prevent any further overheating or damage to the reactor 142. The isolation condensers 310 and 320 may have varying capacities in the range of a full volume of steam produced by example embodiment lower power reactor 142 or an equivalent safety margin. The isolation condensers 310 may be outside containment, ICS pool 301, and/or other components of the nuclear plant. This allows them to be easily accessed for inspection, emergency refill and/or operation regardless of the plant state.
Condensers
A large heat exchanger that cools steam from a reactor below its boiling point. The cooled steam is then returned to the reactor (in a pressurized water reactor) or to the boiler in a boiling-water reactor. A portion of the steam is also used to generate electricity in a steam turbine generator.
The condenser has thousands of small tubes. A power plant must ensure that the tubes are not fouled with scale and other debris to maintain a high condenser vacuum to maximize power plant efficiency and capacity. Fouling causes a drop in the condenser vacuum which reduces fuel conversion efficiency and lowers capacity. An improvement of condenser vacuum by 0.35 inches Hg or 12 mBar can improve overall power plant capacity by 3 – 3.5%.
Isolation condenser systems are generally controlled by a pressure pulse transmitter and fluidic controls which have multiple water level setpoints. At one of the setpoints, floats in isolation condenser 310 or 320 will activate the system by opening an inlet and/or outlet to/from the reactor for coolant flow.
Another setpoint can be based on the detection of an abnormality such as an excessively hot or cold condition in the reactor core. A passive switch or other detector will detect the condition and may activate a shut ICS valve on an isolation condenser.
