PRECRACKED PIPE UNDER WATERHAMMER ACTION

We numerically simulate a full scale test in several computational ste ps with the finite element method and compare all calculated data with the experimental findings. First, we compute the deflection under sta tic loading and the spectrum of eigenfrequencies of an integer piping, attached to a nuclear reactor pressure vessel (RPV). Then we consider a sudden pipe break at some distance from the vessel, immediately fol lowed by an undamped closure of a check valve close to the break on th e RPV side, and calculate the elastic and plastic transient dynamic re sponse of the integer piping part between the RPV and the break. Final ly, we consider a circumferential internal surface crack, fairly close to the vessel; after extensive testing of our fracture mechanics calc ulation procedure we investigate the stress in the crack region under the waterhammer action.