Water Hammer Analysis/Prevention/Mitigation in Fire Protection Systems at Power Plants

Abstract

Fire Protection water systems are typically piping networks where water is pumped from a low elevation reservoir at atmospheric pressure to higher elevations in the buildings served by the system. Because of this nature of their design, they are prone to water hammers due to water column separation & rejoining. A loss of pressure can lead to void formation at high elevations whose collapse can result in severe water hammer. A damaging water hammer event that occurred at a nuclear power plant (Arastu, et al, 1999) causing a catastrophic valve failure pointed to the need to prevent and mitigate such potential events at other plants. One important aspect of that event is that prior to it, several events of similar magnitude had occurred that did not apparently cause physical damage but degraded the system sufficiently to make it susceptible to damage. This paper discusses the causes of water hammer in Fire Protection Systems at power plants and identifies analysis, prevention, and mitigation strategies. Using a Method Of Characteristics based program, computer simulation results of the application of the mitigative measures are given for three large plant systems to demonstrate the effectiveness of the measures proposed at these plants.