RELAP5 ANALYSIS OF GRAVITY-DRIVEN CORE-COOLING EXPERIMENTS WITH PACTEL

The RELAP5 calculation results for a series of gravity-driven emergenc y core-cooling (ECC) experiments with the parallel channel test loop ( PACTEL) facility are provided. The simulated accident was a small-brea k loss-of-coolant accident with a break in one hot leg of the three lo ops of the facility. The ECC flow was provided from a core makeup tank (CMT) located at a higher elevation than the main part of the primary system. The CMT was pressurized with pipings from the pressurizer and a cold leg. The tests indicate that rapid condensation in the CMT inf luences the ECC flow. The experimental results are numerically analyze d using the RELAP5/MOD3.1 code. The calculations show good agreement w ith the tests except in the modeling of rapid condensation.