Pipe whip experiments involving impacts between pipes

Dynamic pipe impact tests were performed in order to determine the impact conditions for which a 2 inch Schedule 80 carbon steel target pipe would not be broken if it were impacted during a pipe whip event created by a postulated break of an adjacent larger parallel pipe. Such pipe/pipe impact scenarios are of special interest for the feeder pipes of a CANDU reactor because the large number of closely spaced parallel feeder pipes that carry coolant between large primary system pipes and individual fuel channels in the reactor core makes it impractical to consider providing feeder pipe whip restraints. The testing which was performed involved simulating the behaviour of 3 inch and larger whipping pipes in order to study their impact with 2 inch target pipes pressurized at about 9 MPa with water at a temperature of about 2900C. In a conservative simulation of the worst pipe/pipe impact event which it has been predicted could occur for adjacent parallel feeder pipes (when a whipping pipe has a kinetic energy of about 10 kJ just before it impacts a 2 inch pipe), it was demonstrated that the target feeder pipe does not experience more than a 26% local reduction in its diameter. The target pipe impact conditions were also made sufficiently severe that a target pipe would rupture in order to estimate the safety factor associated with not having a feeder pipe rupture during the worst plausible feeder pipe whip event. (orig./RW)