Abstract:
This research presents the implementation results of the RELAP5 Mod3.3 program to simulate the
Condensation Induced Water Hammer (CIWH) phenomenon. The phenomenon potentially induces a sharp
increase of pressure in a pipe system within a short period and occurs under heat exchanging between twophase
flows through a Direct Contact Condensation (DCC) process. The CIWH is experienced in the piping system
of various industrial plants, including the emergency cooling systems of nuclear power plants, which may
significantly damage piping systems. This study simulates three CIWH experimental systems of the previous
studies in which the experimental facility shape, size, and test conditions are varied. The experimental pressure
changes are then compared with the calculated results by RELAP5 Mod3.3. The comparisons results revealed
that RELAP5 Mod3.3 has a predictive capability to predict the CIWH phenomena. However, the calculated
results at some conditions differ from the experimental results in both magnitude and pressure change patterns.
These differences may be caused by improper heat transfer equations embedded in RELAP5 Mod3.3 and
inaccurate initial conditions used in the calculations. The research indicates the ability of the RELAP5 Mod 3.3
program to simulate the CIWH phenomenon and the opportunity to improve the accuracy of the program