Blowdown thrust force and pipe whip analyses of large diameter pipes under LWR LOCA conditions

An instantaneous pipe rupture is postulated as a hypothetical accident in the design of the nuclear power plants. The ruptured pipe at double ended guillotine break would move rapidly and impact surrounding structures. This dynamic motion is called a pipe whip. Pipe whip restraints and other protective structures are installed to limit the pipe whip motion in the nuclear power plants. In order to design such protective structures, it is necessary to evaluate the blowdown thrust force for a ruptured large diameter pipe under the loss of coolant accident (LOCA) conditions. The present paper shows the verification of the thermal-hydraulic analysis code RELAP4/MOD6 and its post-processor BLOWDOWN for the blowdown thrust force analysis under both BWR and PWR LOCA conditions by comparison between analytical and experimental results, pipe whip analysis of an 8 inch diameter pipe using the general purpose finite element code ADINA with analytical blowdown thrust force under PWR LOCA conditions, and blowdown thrust force analyses for various diameters of pipes under both BWR and PWR LOCA conditions.