Safety improvement of pool type FBR against loss of flow accident

Among the various loss of flow situations possible in a fast reactor, rupture of coolant pipe is very important due to the rapid reduction in coolant flow resulted under this condition. This event dictates the number of coolant loops in primary circuit. Safety demonstration of two loop medium size fast reactor design is a challenging task due to large reduction in core flow caused during this event. This difficulty can be overcome by increasing number of coolant pipes. The pros and cons of this option are investigated in this paper. Thermal hydraulic benefits of increasing the number of coolant pipes are presented through plant dynamic studies. The main difficulty of this option lies in layout of pipes due to the space constraints. An option to overcome this is by reducing the gird plate size. The associated hydraulic issues have been investigated to ensure core safety. Parametric studies covering pipe size, hydraulic resistance of various parts and cavitation characteristics of pumps have also been performed to identity cliff edge effects.