What Is a Reactor Vessel?

A reactor vessel is the part of a nuclear power plant that safely houses the reactor core and contains harmful radiation. It is at the heart of the reactor coolant system and consists of a vertically mounted, cylindrical structure. On either end, there is a rounded edge called a closure head, the top one which features nuts and studs for the purpose of removing it. The reactor vessel can be opened to refuel the reactor and access components for control systems in instruments.

The vessel and closure head typically measure about 41 feet (12.5 meters) tall. General measurements include an inside diameter of 171 inches (434.3 cm), while the thickness of the shell wall is 8.4 inches (21.3 cm). A reactor vessel is comprised of an assembly that includes the reactor core, core rods, and other components, such as neutron monitors, steam separators, steam dryers, and jet pumps. Systems for circulating water and coolant are also contained in the pressure vessel.

In a nuclear power plant, a reactor vessel also features emergency core cooling systems. These provide water to prevent the core from overheating if it is exposed due to a rapid decrease in water level. The core plate and top guide serve to separate components at different levels of the vessel. Fuel rods are stored at the bottom, and within this section are control drives as well as hydraulic lines. The rods are protected during refueling by fuel channels, and new fuel rods are placed in the vessel from the bottom in order to regulate the nuclear core’s power.

Various inlets and outlets penetrate the housing of the reactor vessel. These primarily cover the need to bring steam and water in and out of the system to properly maintain it. Nuclear reactor vessels must always be kept in a state of equilibrium in order to function correctly as well as to avert dangerous meltdowns that can pollute the environment with fatal levels of radioactive material. The reactor vessel that is the single most important component for serving this purpose.

Every reactor vessel can be ordered from and built by commercial businesses with the knowledge and expertise needed to build these complex structures from specialized materials. There are various types, but all nuclear reactor vessels perform the same operations. Normal operation of them is what keeps nuclear power plants from becoming unsafe to people and the environment.