Thermal hydraulics of a 600 MWth pebble bed type nuclear reactor

This paper deals with the core thermal hydraulic analysis of the conceptual design of the Indian 600 MWth High Temperature Reactor (IHTR). The comparative analyses are carried out with two primary coolants: Molten Salt (FLiNaK) and Lead Bismuth Eutectic (LBE). The 1-D natural circulation studies show that the pressure drop in the core is significantly lower for molten salt as coolant compared to LBE coolant. Melting of the salt coolant by surface heaters during start up of the reactor shows that melting is more efficient in the core geometry with tubular down comer than annular down comer. 2D CFD analysis is also carried out with the simplified geometry of the core to find flow and temperature distribution. Preliminary thermal design of a primary heat exchanger is carried out and discussed in the paper. (author)