Analysis of coolant flow on various hot gas plenum geometry of the Non Commercial Power Reactor (RDNK) (Muhammad Yunus a), Farisy Yogatama Sulistyo, Kiswanta and Muhammad Subekti

Abstract. On design criteria of cooling process in HTGR reactor, besides considering the structural strength of the
reactor core and gas mixing performance, the pressure drop in the core reactor as well as the bottom reflector, is
maintained as low as possible in order to avoid leakage or bypass flow. To investigate the effect of varying hot gas
plenum geometry to the coolant flow behavior in the bottom reflector structure of the RDNK reactor, computational
fluid dynamic simulation has been carried out. There are three variations of the hot gas plenum high that is 150 mm,
200 mm, and 250 mm. The models are simulated by using Fluent software. By simulating the cooling process in the
bottom reflector it was obtained differences in temperature and pressure drop of each model. As a result of pressure
drop, it was found that a model with a hot gas plenum height of 250 mm has the lowest pressure drop. Meanwhile, the
average temperature of the outlet channel of all simulation model is not significantly different.
Keywords: coolant flow, hot gas plenum, non-commercial power reactor