Experimental Investigation of Thermal Behavior of Concentric Tubes During a Severe Accident

Abstract

A pair of experiments were conceived and executed to provide data and a technical basis for investigating selected aspects of postuloted severe accidents in a pressure tube/calandria tube configuration. The response to core damage and debris relocation within the pressure rube was investigated experimentally. The experimental objectives of the two tests were: 1) to assess the potential for failure of an unflawed pair of concentric lubes when prototypic wall stress is produced while high temperature debris is resident within the inner tube and sub-cooled water is present outside the outer tube, and 2) to assess the dynamic and energetic interaction given the rupture of the concentric tubes and the discharge of molten debris under steam pressure into the surrounding sub-cooled water pool. These experiments provide an effective demonstration of the passive cooling mechanism which can prevent calandria tube failure and of the interaction between molten debris and water if a calundria tube were to fail.