The analysis of the characteristics of steam condensation and thermal mixing inside IRWST and flow through PZR discharge pipe

IRWST contains refueling water, provides coolant to SIS and CSS, and provides heat sink for condensating steam from PZR. For the proper function of IRWST, integrity of IRWST should be ensured and the function of IRWST should not be affected by operation of interfacing systems. The characteristics of steam condensation and thermal mixing inside IRWST are analyzed. Also, flow inside discharge pipe which connects PZR and IRWST is analyzed. These analyses lead following conclusions. 1. Analysis methodology which is able to predict choking location and its flow rate is improved to apply for merging piping system. 2. The characteristics of discharging steam is considered and is applied to develop preliminary analysis methodology for tank hydraulic load. 3. It is analyzed the characteristics of steam condensation, condensing mechanism, and unstable condensation. 4. For evaluation of IRWST function as heat sink and condensing steam, thermal mixing inside IRWST is analyzed. With these, physics of IRWST system is understood and relating analysis methodology is established, which are necessary for design of IRWST. 18 figs., 13 refs. (Author) .new