The reactor building has four levels, a seismic construction and its nucleus is a massive block of concrete that hosts the reactor and the auxiliary pools. The ETRR-2 is an open pool reactor. Its core has 30 fuel elements with 19 plates each, made up of 19,75% Enriched Uranium alloy, and a nominal power of 22 thermal MW.
The core is at 10 m depth inside the 4.5 diameter pool and surrounded by a zircalloy tower through which a flow of demineralized light water is forced upwards.
Core reactivity is controlled by means of six safety plates made of silver-indium-cadmium alloy. In case of LOCA, convective upward flow inside the tower is enough to dissipate decay heat, without the need to pump or invert the flow. This is an inherent safety feature.
Furthermore, the reactor has a protection system (RPS) that monitors five safety parameters simultaneously. The RPS automatically triggers shutdown if predefined limits are reached.