An Integral Effect Test on the Feedwater Line Break of the APR1400 with the ATLAS Facility

Abstract

An integral effect test on the feedwater line break (FLB) was performed with the ATLAS facility for an APR1400 as a typical secondary system transient. The objectives of the present FLB tests are to understand the accident progression of the FLB scenario based on the APR1400 preliminary safety analysis report (PSAR) and to assess the prediction capability of system analysis codes such as the MARS, RELAP5, TRACE and SPACE. The main concern of the present FLB test is the peak RCS pressure and the major parameters affecting the peak RCS pressure are the break size, the break location, potential for reverse flow, initial pressurizer level and the initial SG level. The present test is performed for a break on the pipe connected to the economizer with a typical break size. The initial steady-state conditions and the sequence of event of FLB scenario for the APR1400 were successfully simulated with the ATLAS facility. In the present paper, major thermal-hydraulic phenomena such as the system pressures, the collapsed water levels, and the break flow rate are presented and discussed. It could be concluded that the APR1400 has the capability of coping with the hypothetical FLB scenario with an adequate set of controlling devices and proper setpoints. This integral effect test data could also be used to evaluate the prediction capability of existing safety analysis codes of MARS, RELAP5 and SPACE and to identify any code deficiency for an FLB simulation.