Experimental activities on a LBLOCA Reflood Phase in the ATLAS Facility

KAERI recently constructed a new thermal-hydraulic integral test facility for advanced pressurized water reactors (PWRs) - ATLAS. The ATLAS facility has the following characteristics: 1/2-height and length, 1/288-volume, and a full pressure simulation of APR1400, maintaining a geometrical similarity with APR1400 including 2(hot legs) x 4(cold legs) reactor coolant loops, a direct vessel injection (DVI) for an emergency core cooling water, integrated annular downcomer, etc., incorporation of specific design characteristics of OPR1000 such as cold leg injection and low-pressure safety injection pumps, maximum 8% of a scaled nominal core power. The ATLAS will mainly be used to simulate various accident and transient scenarios for evolutionary PWRs, OPR1000 and APR1400: the simulation capability of broad scenarios including the reflood phase of a large-break loss-of-coolant accident (LOCA), small-break LOCA scenarios including DVI line breaks, a steam generator tube rupture, a main steam line break, a feed line break, a mid-loop operation, etc. The ATLAS was used to simulate the LBLOCA reflood phase of the APR1400 in 2007. Three kinds of the LBLOCA reflood tests were performed, e. g. parametric effect test for the LBLOCA late reflood phase, the LBLOCA reflood tests and a separate effect test(SET) for lower reflooding rate