15.4.4.1 Steam generator cassette

SMART has eight identical SGs which are located on the annulus formed by the RPV and the core support barrel (CSB) (see Figure 15.7). Each SG is of a once-through

design with a number of helically coiled tubes. The primary reactor coolant flows downward in the shell side of the SG tubes, while the secondary feedwater flows upward through the inside of the tube. The secondary feedwater is evaporated in the tube and exits the SG cassette nozzle header at a 30 °C superheated steam condition of 5.2 MPa. In the case of an abnormal shutdown of the reactor, the SG is used as the heat exchanger for the PRHRS, which permits an independent operation of the PRHRS from the hydraulic condition of the primary system. The design temperature and design pressure of the SG cassette are 360 °C and 17 MPa, respectively.

15.4.4.2 RCP

SMART has four RCPs horizontally installed on the upper shell of the RPV (see Figure 15.8). Each RCP is an integral unit consisting of a canned asynchronous three phase motor. The rotational speed of the pump rotor, 1800 rpm, is measured by a sensor installed in the upper part of the motor.

Being a canned motor pump which does not require pump seals, its characteristic basically eliminates a SB LOCA associated with a pump seal failure which is one of the design basis events for conventional reactors.