Hugoniot analysis of energetic molten lead-water interaction

Abstract

Steam generator tube rupture and/or leakage (SGTR/L) is one of the least studied and dangerous safety issues in pool-type lead-cooled fast reactors (LFRs). During this accident, high-pressure water from the secondary circuit is injected into the primary circuit with relatively low-pressure molten lead. One of the possible consequences of SGTR/L is multiphase flow formation consisting water droplets inside vapor bubbles in lead, which could engender a potential explosive coolant-coolant interaction (CCI). The present paper is devoted to the analysis of energetic molten lead-water interaction during SGTR/L in LFRs using Hugoniot adiabats. A review of literature addressing multiphase thermal detonations using Hugoniot adiabats is carried out. Calculations for CCIs are performed which are compared with earlier works and experimental data. Hugoniot analysis is applied to the case of SGTR/L in Russian BREST reactor and detonation velocities and pressures in the Chapman-Jouguet plane are estimated. The mechanical expansion work of the explosion products and the conversion ratios are calculated for typical values of initial void fractions in two-phase water-steam mixture; lead volume fractions and temperatures. Dependencies of the expansion work potential on the void fraction, initial melt volume fraction, and melt temperature are addressed. It is shown that for typical low void fractions for the case of SGTR/L in LFRs the expansion work has a limited value.