Test data and comparison to analysis for condensation induced water hammer

Full text of publication follows: In nuclear facilities, steam voids can form in service water lines at times of loss of offsite power (LOOP). Pumps coast down, and the corresponding loss of pump head reduces local water pressure to the saturated state at elevated points in the flow path. Steam is also generated by boiling in the heat exchangers in the containment structures. While the void is forming, void collapse can occur if the steam in the void rapidly condenses. This can occur in horizontal pipes and is a condensation induced water hammer (CIWH). Analytical methods for condensation induced water hammer are conservative and cannot accurately calculate the pressure magnitude of the CIWH in the specific conditions of the service water system. A testing program was conducted to characterize these water hammers. The testing also examined the effects of aeration of the water. The pressures determined in the testing were compared to the pressures that would be classically calculated. The tests showed that all the CIWH tests had relatively constant pressure impulse, determined as the area under the pressure-time curve. The impulse was independent of whether the water was aerated or deaerated. The test program included instrumented piping supports. The loads in the supports were also determined and compared to those that would be classically calculated. The effect of the constant impulse of the pressure pulse was evident in the support forces. The structural load at high pressures was limited by the constant impulse. (authors)