Modern life wouldn’t exist without the chemicals produced by the chemical industry. These substances are used to manufacture everything from food products and medicines to electronics, automobiles, and fuel. The industry uses reactors to speed up the reactions that produce these substances. The type of reactor that is best for a process depends on the reaction itself.
For example, a packed bed reactor can be used to perform a variety of reactions. This vessel is designed with a large number of catalyst particles to increase the speed and rate of reaction. The result is a high-yielding chemical process that saves time and money. Another type of reactor is a solid-fuel buy reactors. This type of reactor is a steel pressure vessel with a graphite moderator and carbon dioxide as the primary coolant. It has control rods and a safety system to prevent a meltdown. The uranium fuel is placed in stainless-steel tubes inside the reactor core.
The reactors in which chemicals are made in industry range from the small laboratory units to the vast structures depicted in photographs of industrial plants. They vary in size from a few cm3 to the large volume reactors like those used in the manufacture of colorants and margarine. Some of these reactors use a gaseous fuel such as lead-bismuth eutectic (45% Pb, 55% Bi) while others have a steam turbine to generate electricity. Currently, the world’s smallest commercial reactors are four barge-mounted units co-generation plant in a remote corner of Siberia. A new generation of small nuclear reactors is being developed. These are smaller, cheaper, and more flexible than conventional power reactors. They can be built to service local electricity grids, which avoids the need for expensive transmission lines. They can also be mass produced and shipped to their site, yielding significant cost savings. They are designed to be “inherently safe”, making a meltdown physically impossible in various complete failure scenarios, such as loss of coolant or power.
Uranium is the basic fuel, processed into small ceramic pellets arranged in tubes to form fuel rods. The fuel rods are bundled into fuel assemblies and are located in the reactor core. In a 1000 MWe class PWR there may be 51,000 such fuel assemblies. Fuel assemblies are cooled with water that is both a coolant and a moderator, slowing down neutrons to sustain the fission chain reaction. Control rods can be inserted into the assembly to decrease or increase the rate of fission.
A supplementary neutron source is often added, usually beryllium mixed with polonium or radium to give alpha particles that can initiate fission. This can also be used to provide a boost in the initial start-up of a reactor that has been shut down for some time. Once the fission process is complete, the fuel is highly radioactive and must be removed for temporary storage at the reactor site in a spent fuel pool. The spent fuel will continue to produce energy from its radioactive decay for several years after it has been withdrawn from the reactor.
Nuclear reactors are suited to remote locations as they provide electricity and heat much more cheaply than fossil fuel alternatives. Four small units are already operating in a remote corner. They are graphite moderated and CO2 cooled, using natural uranium in metal form. For the most reliable and affordable chemical reactors, click here or explore our official marketplace.
