Description
The aim is to have small nuclear reactors which run years without refuelling and can be transported by truck or tracked vehicle or even C-17 cargo aircraft. These would use a proven low-enriched uranium used type of reactor.
In a nuclear power plant, the reactor is housed in a reinforced concrete and steel pressure vessel. This prevents the core from melting or vaporising, and protects the surrounding environment from radiation in case of a nuclear accident.The water in the reactor core is heated to a high temperature and kept under 150 times atmospheric pressure by the natural circulation of the cooling system. This keeps the fission reaction at a safe level, since it would slow down if the water turned to steam.In addition, the reactor is protected by a shielding wall that can absorb neutrons and prevent a meltdown. Some newer Russian and other reactors install devices called 'core catchers' under the pressure vessel to catch any melted nuclear fuel in the event of an accident. These systems are designed to shut down the reactor automatically without the need for human intervention, thereby improving safety. Many existing nuclear plants were originally built to have 30 or 40-year operating lifetimes, but they are now being refurbished and extended to operate for 60 years or more.
The fuel in modern reactors is made up of small ceramic pellets of low-enriched uranium oxide. These are stacked vertically and encased in metallic cladding to form fuel rods. A fuel assembly is a bundle of 200-300 of these rods. They are immersed in water which acts as both a coolant and moderator. The uranium atoms fission to produce energy, and the neutrons in the moderator absorb them. This stops them escaping from the core and causing it to heat up.
The nuclear energy generated by the reactor is converted to steam for driving a turbine. A conventional PWR, PHWR or VVER type of reactor has the moderator and coolant in a large tank called a calandria. This contains a high-pressure primary coolant (often at 150 times atmospheric) that transfers the heat to a secondary circuit which generates steam for the turbines.The types of buy reactors have a pressure tube design which allows the reactor to be refuelled without shutting it down. This is because the tubes can be disconnected individually. Some used reactors use fuel with burnable poisons, mostly gadolinium, which can help increase the fuel’s refuelling interval by slowing its radioactive decay rate.Get the latest scoop on used reactors prices and promotions – click here or explore our official site.
