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The Integral Molten Salt Reactor (IMSR) is a small modular reactor (SMR) that employs molten salt reactor technology. Its design is based closely on the DMSR design from Oak Ridge National Laboratory, TN, USA and incorporates elements found in the SmAHTR, a later design from the same laboratory. The IMSR is being developed by Terrestrial Energy Inc. (TEI), headquartered in Oakville, Canada. The IMSR belongs to the DMSR class of MSR and hence is “burner” reactor that employs a liquid fuel rather than a conventional solid fuel; this liquid contains the nuclear fuel and also serves as primary coolant. ==Design== The IMSR “integrates” into a compact, sealed and replaceable nuclear reactor unit (the IMSR Core-unit) all the primary components of the nuclear reactor that operate on the liquid molten fluoride salt fuel: moderator, primary heat exchangers, pumps and control rods. The IMSR belongs to the DMSR class of MSR. It therefore employs a uranium dominant fuel with a simple converter (also known as a “burner”) fuel cycle objective. This is unlike the majority of other molten salt reactor designs that employ the thorium fuel cycle, which requires the more complex breeder objective. Therefore the design uses the well-known uranium fuel cycle and low enriched uranium fuel, as most of today's operating power reactors do. The IMSR fuel itself is in the form of uranium tetrafluoride (UF4). This fuel is blended with carrier salts, which are also fluorides, such as lithium fluoride (LiF), sodium fluoride (NaF) and/or beryllium fluoride (BeF2). These carrier salts increase the heat capacity of the fuel (coolant) and lower the melting point of the uranium fluoride fuel. This liquid fuel-coolant mixture is pumped through a critical nuclear reactor core that is moderated by graphite elements, making this a thermal neutron reactor. After heating up in the core, pumps force the liquid fuel through heat exchangers positioned inside the reactor vessel. The reactor’s “integrated” architecture (all the primary components, heat exchangers etc. are positioned inside the reactor vessel) avoids the use of external piping that could leak or break. The piping external to the reactor vessel contains a secondary, nonradioactive coolant salt. This salt acts as an additional containment barrier and heat sink, and transfers its energy to either a standard industrial grade steam turbine plant, which generates electricity or to a process heat application, or to a combination of the two. The IMSR Core-unit is designed to be fully replaceable in normal operation as described below. During the power operations period, small fresh fuel salt batches are periodically melted and added to the reactor system. This online refueling process does not require the mechanical refueling machinery required for solid fuel reactor systems. These design features are based heavily on two previous molten salt designs from Oak Ridge National Laboratory (ORNL) – the ORNL denatured molten salt reactor (DMSR) from 1980 and the solid fuelled but liquid salt cooled, small modular advanced high temperature reactor (SmAHTR), a 2010 design. The DMSR, as carried into the IMSR design, proposed to use molten salt fuel and graphite moderator in a simplified converter design using LEU (in combination with thorium, which may be used in the IMSR), with periodic additions of LEU fuel. Most previous proposals for molten salt reactors all bred more fuel than needed to operate, so were called breeders. Converter or “burner” reactors like the IMSR and DMSR can also utilize plutonium from existing spent fuel as their makeup fuel source. The more recent SmAHTR proposal was for a small, modular, molten salt cooled but solid TRISO fuelled reactor. Terrestrial Energy is currently working on 3 different unit sizes, 80 megawatts-thermal (MWth), 300 MWth and 600 MWth, generating 33, 141, and 291 electrical megawatts (MWe) of electricity respectively using standard industrial grade steam turbines. As standard industrial grade steam turbines are used, cogeneration, or combined heat and power, is also possible. TEI’s goal is to have the IMSR licensed and ready for commercial rollout by early next decade. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「IMSR」の詳細全文を読む スポンサード リンク
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