Reactor modules are housed in reinforced concrete structures designed to resist various threats, both natural (earthquake) and man-made (aircraft impact) and also internal failure. Part of the building where the modules are located can be below ground level which increases safety.

Small modular reactors are defined as advanced reactors with individual modules having generating capacity of up to 300 MW. These reactors provide a significant increase in nuclear safety, primarily through the implementation of passive safety systems. The components of these reactors and their entire modules can be manufactured and finished at the manufacturing plant and transported in a standard manner to the installation site.

A stainless steel-lined, reinforced concrete pool located in the reactor building below plant-grade level. The ultimate heat sink consists of a reactor pool area where reactor modules are submerged, the refuelling pool area, and the spent fuel pool area. It has the capacity to absorb all the decaying heat produced by all modules for more than 30 days.

Modules are covered by a biological shield that serves as an additional barrier that reduces potential radiation leakage in case of failure.

Fuel handling equipment designed for refuelling operations. An SMR based plant may require refuelling between approx 2 - 7 years. During the process, the module is lifted via an overhead crane and transported to a common refuelling area adjacent to the spent fuel pool following disassembly. While the core is being refuelled by a fuel loading machine, the upper module section is moved to a partial dry-dock facility for inspection and maintenance.

Spent fuel withdrawn from the core is stored under the water. The water acts as radioprotective shielding and as a coolant.

An overhead crane inside the reactor building can lift reactor modules and move them during installation, refuelling or decommissioning.

The reactor core consists of an array of 37 half-height typical LWR fuel and 16 control rod assemblies. Naturally circulating light water provides cooling and also acts as a moderator slowing down neutrons.

The fuel assembly of an SMR is similar to the fuel assembly used in a classic nuclear power plant, but usually at half-height with an active fuel length of approximately 2 meters. Fuel assembly consists of a set of fuel rods in a support lattice. Some of the fuel assemblies also contain the control rods.

Control rods (also called regulating rods) made of steel alloyed with boron and containing cadmium or hafnium, are inserted in between the fuel bundles in a nuclear reactor. The absorber concentration is decreased by pulling the rods out of the reactor core, causing the reactor power to increase. Inserting more control rods causes the reaction to be inhibited and the power output decreases.

The core is surrounded by a stainless steel heavy neutron reflector that reflects back neutrons that would otherwise escape. Additionally, as an envelope to the core, it directs the coolant flow through it.

Feedwater is pumped into the steam generator where it boils to generate superheated steam.

A cylindrical vessel-type containment made from stainless steel houses the reactor pressure vessel and steam supply piping and components.

Movement of cooling water in the primary circuit is ensured not by pumps, but only by natural phenomena. Water is heated in the core and then rises through the tube called a riser due to a chimney effect. Two helical coil steam generators are wrapped around the riser and as the heat is passed to the coolant of the secondary circuit and the water cools down, its density increases. Denser water than falls down back to the reactor core.

The steam generator consists of two independent sets of helical tube bundles wrapped around the outside of the riser. After contact with the heat of the primary coolant rising through the riser, the feedwater in the tubes boils producing superheated steam.

The pressurizer is located in the upper head of the reactor pressure vessel and maintains pressure in the primary circuit. The pressurizer is partially filled with water which is heated to the saturation temperature (boiling point) for the desired pressure by submerged electrical heaters.

The steam generator helical coils wrapped around the outside of the riser transfers heat from the primary coolant to the water of the secondary circuit producing superheated steam.

Steam generator output, leading superheated steam to a turbogenerator where the electricity is produced. The steam could be also used for industrial purposes.

A stainless-steel vessel housing the nuclear core, pressurizer and steam generator.