Ex-vessel boiling experiments: laboratory- and reactor-scale testing of the flooded cavity concept for in-vessel core retention Part I: Observation of quenching of downward-facing surfaces

Abstract

This paper presents the results of a series of quenching experiments to examine the boiling curve of relative large downward-facing surfaces. The test masses are 61 cm in diameter and the downward-facing surface is either flat or curved. The work is motivated by the need to assess the ex-vessel boiling process for in-vessel core retention. The critical 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 characterized by cyclic two-phase flow patterns.