Analysis of Failed Polymer Filter Cages

Several septa filters used in a demineralization process for a condensate water line at a nuclear power plant were found during a maintenance inspection to have catastrophically failed. The filters cages, composed of a polypropylene material, exhibited extensive cracking and deformation. The investigation into the failure coupled extensive fractographic analysis via light and SEM microscopy with evaluation of the base material through Raman and FTIR-ATR spectroscopy to identify damage and degradation mechanisms which led to the failure. Results indicated that increased crystallinity of the material combined with stresses induced from cleaning practices was the likely root cause of the failure.