EX-VESSEL BOILING EXPERIMENTS - LABORATORY-SCALE AND REACTOR-SCALE TESTING OF THE FLOODED CAVITY CONCEPT FOR IN-VESSEL CORE RETENTION .1. OBSERVATION OF QUENCHING OF DOWNWARD-FACING SURFACES

This paper presents the results of a series of quenching experiments t o examine the boiling curve of relative large downward-facing surfaces . The test masses are 61 cm in diameter and the downward-facing surfac e is either flat or curved. The work is motivated by the need to asses s the ex-vessel boiling process for in-vessel core retention. The crit ical heat flux is found to be approximately 50 W cm(-2). The nucleate boiling regime and the critical heat flux regime are found to be chara cterized by cyclic two-phase flow patterns. (C) 1997 Elsevier Science S.A.