Research On Whip Behavior Of The Secondary Circuit Main Pipe In AP1000 Nuclear Power Station

The studies of this paper bases on the first phase of the AP1000 nuclear power plant project in Haiyang, Shandong Province. The main steam pipe and main feedwater pipe of the nuclear power station’s conventional island across from nuclear island to conventional island. According to the American standard ANSI/ANS-58.2-1988, in order to remain the main pipe from destroying the reactor auxiliary building when double-end break condition happens with fluid jetting and pipe whip, it is necessary to analysis the harm of the broken main pipe and set the anti-whip restrain devices,for satisfying the safety requirements of the reactor auxiliary building. Because of the specification-based tradition method, the result is conservative and it is unable to analysis the dynamic process of pipe whip. This paper simulate the double-end break condition with or without the anti-whip restrain devices, in order to ensure the smooth analysis of pipe breaking and pipe whip, as well as the smooth design of the anti-whip restrain devices.The numerical analysis results show that the fluid dynamic thrust force calculated by RELAP5 is less than which calculated by tradition method, which proves that tradition method is conservative. Under the effect of the fluid dynamic thrust force calculated either by RELAP5 or by tradition method, the pipe whip would destroy the equipments and walls around, so it is forbidden to set important equipments or pipe around the main pipes without anti-whip restrain devices. As a kind of anti-whip restrain devices, U-bolt can restrain main pipes from destroying the equipments and walls by its own plastic deformation. The quantity and diameter of U-bolt should be considered when designing, because which would impact the U-bolt’s performance.