Flow Instabilities in Boiling Two-Phase Natural Circulation Systems: A Review

Abstract

Several decades have been spent on the study of flow instabilities in boiling two-phase natural circulation systems. It is felt to have a review and summarize the state-of-the-art research carried out in this area, which would be quite useful to the design and safety of current and future light water reactors with natural circulation core cooling. With that purpose, a review of flow instabilities in boiling natural circulation systems has been carried out. An attempt has been made to classify the instabilities occurring in natural circulation systems similar to that in forced convection boiling systems. The mechanism of instabilities occurring in two-phase natural circulation systems have been explained based on these classifications. The characteristics of different instabilities as well as the effects of different operating and geometric parameters on them have been reviewed.

Experimental investigation on the flow instability behavior of a multi-channel boiling natural circulation loop at low-pressures

“…Many researchers have analyzed this instability in context of nuclear reactors (BWR). A review and classification of instabilities was presented by Boure et al [1] and recently by Nayak and Vijayan [2]. Fukuda and Kobori [3] have classified the density-wave instability as Type-I and Type-II for the low-power and high-power instabilities respectively.…”

A review: passive system reliability analysis – accomplishments and unresolved issues

“…So far, several attempts have been made to model Frontiers in Energy Research | Nuclear Energy flow instabilities using different two-phase flow models, which range from the simplest HEM to more rigorous two fluid models. There are concerns for using the models since the void velocity and their distributions and the two-phase frictional pressure drops, are found to affect the stability characteristics significantly (Nayak and Vijayan, 2008). The most difficult part is to ensure the applicability of best estimate codes like RELAP5 for modeling the flow stability in natural circulation systems.…”

Use of sophisticated heat exchanger simulation models for investigation of possible design and operational pitfalls in LNG processes

“…The largest area of research in this field is probably safety aspects of nuclear reactors and flow instabilities in natural circulation boiling loop Nayak and Vijayan (2008). Many of the instability phenomena described in Nayak and Vijayan (2008) can also be present in cryogenic processes and especially in boiling services which will be discussed later. Recent review article by Kakac and Bon (2008) and Tadrist (2007) discuss various categories of flow instabilities.…”