CFD analysis on temperature homogenisation performance in experimental power reactor bottom plenum

Abstract

An issue concerning Experimental Power Reactor (Reaktor Daya Eksperimental/RDE), an HTGR-based experimental-scale nuclear power reactor proposed by National Nuclear Energy Agency (Badan Tenaga Nuklir Nasional/BATAN), is hot gas temperature deviation. To prevent safety-related problems caused by such deviation, RDE employs two levels of gas mixing for the heated coolant gas; the first level is bottom plenum and the second is hot gas chamber. Unlike the latter, bottom plenum is a simple empty column where the heated gas is mixed, but not homogeneous enough to be considered safe to be flown into the heat exchanger. To understand the mixing phenomena better, this paper will analyse the temperature homogenisation on the RDE bottom plenum, employing computational fluid dynamics-based method using FLUENT software. Simulation result shows that the coolant gas heterogeneity is reduced by 139.98°C, implying temperature homogeneity degree of 55.99%. This value provides insight on coolant gas parameter to perform more accurate calculation on the hot gas chamber. Temperature deviation pattern at the outlet channels is also discussed.