Analysis of the OSU-MASLWR-003A Natural Circulation Test by Using the TRACE Code

Today the international community shows a great interest in the use of advanced small modular integral reactors as part of energy mix of developing and developed countries. The designs of some advanced small modular reactors rely on natural circulation for removing of the core power during normal operation conditions. In this framework Oregon State University (OSU) has constructed a system-level test facility (OSU-MASLWR) to examine natural circulation phenomena of importance to integral reactors. The test facility is based on the Multi-Application Small Light Water Reactor (MASLWR) concept, a small modular integral Pressurized light Water Reactor (PWR) relying on natural circulation during both steady-state and transient operation. A first test campaign, under a US Department of Energy grant, has been conducted in the OSU-MASLWR test facility for characterizing the MASLWR prototype phenomena. In particular the OSU-MASLWR 003A test has been conducted in order to investigate its natural circulation phenomena. The single phase natural circulation and heat exchange from primary to secondary by helical coil Steam Generator (SG) with superheating on secondary side have been simulated by using the best estimate thermal hydraulic system code TRACE. The results of the calculated data show that the TRACE code is able to predict the phenomena typical of this transient.