Experimental and analytical work on the fast depressurization transients at Aquitaine 2

The fast depressurisation of a vessel and piping simulating full or partial guillotine breaks in the primary loop of a pressurized water reactor was studied experimentally and analytically within the AQUITAINE II test program. The analytical work covered the calculation of the decompression wave and its propagation for direct comparison with pressure measurements, and the computation of the hydraulic loads to be employed as input for the mechanical analysis. The comparison between computed and measured pressure histories is satisfying considering the incertitude in the initial temperature distribution. The hydraulic forces are maximal during the subcooled blowdown phase due to pressure wave effects. During the saturated blowdown the thrust coefficient is about 1.05 for a full guillotine break. (orig.)