Multi-Channel Thermal Hydraulic Model for LOCA Analysis of Heterogeneous BWR Core

Abstract

A multi-channel thermal hydraulic model for LOCA analysis of a heterogeneous core such as a HCBWR has been developed. This model solves integral formulations for basic equations based on a one-dimensional drift flux model. The core region is divided into several fuel channel groups which differ in their thermal power or geometry. The various flow patterns in the core are determined by calculating the redistribution of vapor generated in the lower plenum into the fuel channel groups. In order to verify the multi-channel model, a computer program FLORA was developed based on the multi-channel model and large and small break LOCA experiments conducted in the Two Bundle Loop (TBL) facility were analyzed by the FLORA program. As a result, the difference in thermal hydraulic behavior between two bundles with different power in the various break LOCA experiments were well simulated.

KEYWORDS:

• BWR type reactors
• HCBWR type reactors
• loss of coolant
• ECCS
• peak clad temperature
• safety
• two-phase flow
• drift-flux model
• multi-channel hydraulics
• computer programs