TECHNOLOGY

Generation IV

GFR (Gas cooled Fast Reactor)

Figure 22.Schematic diagram of GFR concept
Source: "A technology Roadmap for Generation IV Nuclear Energy Systems", U.S. DOE Nuclear Energy Research Advisory Committee and Generation IV International Forum, 12.2002, http://www.gen-4.org/PDFs/GenIVRoadmap.pdf [55]

The GFR splits two ways of reactor development: fast neutron spectrum way and high temperature way. It is helium cooled reactor, that allow for operate at high temperatures. It is also fast reactor, making possible to manage nuclear wastes with actinides and breed the fuel. The GFR gives minimal amount of nuclear wastes, that have to be transport to repository for storage. Fuel use is much more efficient. In addition the GFR is depleted uranium capable. Exact sort of fuel has not been decided yet. It needs further studies because fuel assemblies have to withstand very high temperature in the core. However today, carbide, nitride or oxide fuel containing depleted uranium and other fertile or fissile material with 20% of plutonium are considered. Closed fuel cycle requires fuel reprocessing and actinides recycling. Its methods are adopted from the SFR. Advanced aqueous recycling method or metallurgical processing recycling method at local fuel conversion facilities are planned.

High temperature ensure high thermal efficiency of the cycle and gives opportunity for heat generation on purpose industrial use and hydrogen generation. However, like in case of the VHTR, high temperatures are difficult to control and they are serious challenge for materials. The reference reactor with total power of 1100 MWe and 2400 MWt consisting 3 loops of 800 MWt is envisaged with direct Brayton cycle and helium turbine. But owning to problems with such solution it is planned in the future. At first stage, the GFR could have indirect power conversion system with supercritical carbon dioxide secondary cycle (optionally with combined cycles). The reactor outlet temperature is 850ºC.

Although the GFR derives from many developments over the VHTR it is necessary to make further researches for the GFR only in area of core design, fuel form and safety. The GFR is the only generation IV concept totally first of a kind. There is neither operating antecedents of the GFR reactor nor prototype of it. First experimental GFR like ETDR or ALLEGRO without power conversion system will be building from 2014 by Euroatom, but serious, full functional demonstration unit is not going to be built until 2020, due to many problems that must be solved.

The GFR was qualified to reactor for electricity generation and actinide management with optional hydrogen production (as support). [50],[51],[52],[54],[55],[56],[57], [58],[59]

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