The measurement of void fraction by a differential pressure during a premixing stage in the TROI

Steam explosions are explosive processes in which a very rapid energy transfer occurs between a hot liquid and a volatile, colder liquid when the two liquids come into sudden contact. To quantify the risk of a prototypic steam explosion, TROI (Test for Real cOrium Interaction with water) experiments have been intensively performed at KAERI (Korea Atomic Energy Research Institute) since 2001. For a precise evaluation of the computer codes on the steam explosion characteristics, the void fraction should be appropriately measured during the premixing process, particularly, just before the triggering stage. This paper focuses on the validation process of the void fraction measured during the premixing process in TROI. A separate test, so-called scoping test, was first performed with the same size test section and differential pressure sensors with TROI tests. The void fractions measured by differential pressure sensors are compared with void fractions estimated by the level swell meter and by the level swell by the video images. The void fraction method using differential pressure sensors during the premixing process is then applied to TROI. The results in the TROI show that the void fraction method by a differential pressure during the premixing process is feasible.