Emergency coolant supply - for PWR through elbow directing flow of coolant in downcomer

摘要

Emergency cooling water is fed in the reflux space of the pressure vessel of a pressurised water reactor in case of a loss-of-coolant accident, using as a flow guide element an elbow at the end of an emergency feeder circuit. The end piece of the elbow points downward in the downcomer and can be convergent in shape. The pressure vessel (1) of a PWR has a "downcomer" (4) in the shape of a hollow cylinder between the pressure vessel wall (2) and the outer wall (3) of the core tank. The main coolant inflow and outflow (6) pipes terminate in the downcomer. If a crack occurs at the spot (10), emergncy coolant (11) is directed by elbows (12) at the end of the emergency circuit in a downward direction (f2) in the downcomer. ADVANTAGE - This prevents or minimises the cooling water loss both during the sudden pressure relief, when the main cooling pipe breaks, and during a core flooding phase.