Summary of Denting Mechanism and Kinetic Studies with Seawater

Abstract

Studies at Commissariat à l’Energie Atomique (CEA) have been under way for three years in an attempt to find methods for preventing and stopping denting. Tests have been performed in 28 model boilers (Ajax with U tubes and Clarinette with straight tubes). In these boilers, with continuous injection and blowdown, and heat flux is ∼40 W·cm⁻² (126 900 Btu/ft²·h). The kinetics of denting has been studied with different levels of faulting. Some high-temperature electrochemical measurements established the mechanism of denting in the boiler tests. Denting kinetics can be rationalized in terms of three main parameters: faulting level, heat flux, and relative mechanical strength of the tube compared to the support plate.