New Design Options Free from a Potential Sodium Freezing Issue for a Passive DHR System of KALIMER

To enhance the operational reliability of a purely passive decay heat removal system in KALIMER, which is named PDRC, three design options to prevent sodium freezing in an intermediate decay heat removal circuit were proposed, and their feasibilities have been studied for an entire plant operation mode. The potential candidates for the new design options are (a) the partially immersed DHX concept, (b) the cavity air cooling system-coupled PDRC concept, and (c) the advanced PDRC concept with alternative cooling medium. The design features of each concept are quantitatively evaluated in this study. For all the options, more specific design considerations were made to confirm their feasibility to properly materialize their concepts in a practical system design procedure, and the general definitions for a purely passive concept and its design features have been discussed as well.