High pressure injection piping waterhammer and resolution

High Pressure Coolant Injection (HPCI) system is the major safeguard of a GE BWR/4 Reactor. However, it doesn't have a specific injection nozzle on the Reactor. In order to inject coolant into the Reactor, it must use a connection on the FeedWater (FW) System. The FW system is a hot running system, but HPCI is a cold standby system. The connection of the two (2) systems with different fluid temperatures can cause trouble. NRC Information Notice No. 89-80 recognized this fact. Unfortunately, just like, the events described in NRC Notice No. 89-80, their Chin-Shan Nuclear Power Station (GE BWR/4) HPCI system had experienced several waterhammers during system Scheduled Surveillance testing and Cold Quick Start testing. The waterhammers had damaged several valves, some pipe supports and damaged some concrete surfaces near the support attachment points. The trigger of all issues are two (2) malfunctioning valves: injection valve (F006) and the test return valve (F008). Some practical measures are taken to alleviate the situation, and they have resulted in satisfactory success. This paper is going to review the how-and-why of the above issues. Suggestions for design rules are provided