Preliminary analysis of the core design for Indonesia Micro Reactor (IMR-13)

Abstract

The development of microreactor technology can meet the energy needs of specific regions of Indonesia’s underdeveloped, foremost, and outermost areas. One of the latest microreactor designs is the Indonesia Micro Reactor (IMR-13), which has seed and blanket fuel and 5MWt power generation. The IMR-13 reactor has characteristic design features for operation for as many as ten years without refuelling. The reactor core comprises integral fuel elements consisting of a heat pipe, fuel matrix, fuel cladding, and graphite moderator. There are two fuel element types: seed fuel elements with 19.75 % low-enriched uranium oxide and blanket fuel elements with thorium oxide – graphite reflectors on the bottom, sides, and top surround the reactor core. Side reflectors have moving parts that function to regulate reactor power. There are no active components in this reactor. Heat transfer occurs by natural circulation in the heat pipe to the molten salt pool and then from the molten salt pool to the steam generator. This research focuses on the neutronic aspect of the reactor, particularly in calculating the seed and blanket ratio to allow the reactor to operate for ten years with minimal power peaking factor. The selected variant model has 979 seeds and 294 blankets. The variation model has a value of excess reactivity at the beginning of the life of 937 pcm. Each value of the shutdown margin for system first and system second sequentially is 3020 pcm and 2994 pcm. The temperature reactivity coefficient is negative, implying inherent safety. At the end of life, the burnup value was achieved at 4.97 GWd/MTU with an excess reactivity of 271 pcm. A parameter analysis of the burnup characteristics will follow in the selected variant model. The parameters examined were the core power distribution, delayed neutrons, the fast fission factor, conversion ratio, and decay heat.