a device for transferring the heat released in a nuclear fission chain reaction from the nuclear reactor to the heat exchanger; it is a closed system of pipes through which a coolant circulates. In the heat exchanger, heat is used to produce power steam (in the case of a power reactor) or is transferred to process water that is released into a reservoir (in the case of a research reactor). The reactor coolant loop also includes a heat exchanger (steam generator), circulating pump, and fittings.
A power reactor usually is equipped with two to six identical coolant loops operating in parallel. Increasing the number of such loops complicates the design of the reactor plant; using one loop makes operation of the plant unreliable, since the required cooling of the reactor cannot be ensured if the loop is disabled. In a research reactor, the number and design peculiarities of the loops are determined by the nature of the experiments conducted.