Development of one-dimensional computer code DESOPT for thermal hydraulic design of sodium-heated once through steam generators

Abstract

Once-through Steam Generator (SG) is a critical component of Liquid Metal Fast Breeder Reactor (LMFBR) plant. It is a counter current heat exchanger, in which heat is transferred from the hot sodium flowing on the shell side to water/steam in tube side. High pressure subcooled water enters the SG tube from bottom, gets heated up to saturation, goes through nucleate boiling, dry out and post dry out heat transfer, getting converted to saturated steam and finally gets superheated. For this the process design needs to be carried out accurately. A computer code DESOPT has been developed for the process design of straight vertical, serpentine and helical geometries and validated against reported designs in literature. Recently a test facility to test a 5.5 MWt sodium heated steam generator has been commissioned. The predictions of the code have been compared with the measurements and found satisfactory. This paper brings out different heat transfer mechanisms in SG and describes the one-dimensional code, its validation based on literature and in-house tests and presents the results of comparison between predicted and actual operation at different part loads.