Water Hammer Analysis of Piping Via Response Spectra

Abstract

Water hammer piping analysis at Ontario Power Generation (OPG) has been via time history methods. The method to be described here and compared with that tradition enables one to address the issue of “as built” vs “as designed” loading with their concomitant stresses.

Both approaches are within the STANPIPES suite of OPG piping analysis programs. These interface with the finite element package NASTRAN whose DMAP language facilitates creation of crucial connection matrices from the excitation points within the piping structure to apply the pressure time histories. What is new to this OPG application is transformation of the point-wise pressure time histories to catch natural force cancellations. These occur in time history - but will be missed in the most obvious response spectrum approach.

Comparison results obtained for time history and response spectrum analyses are presented for the (NE Quadrant) of the Primary Heat Transport (PHT) System at the Darlington Nuclear Station.