Generation IV reactors

Significant advances have also been made in reactor safety. Earlier reactors rely on a series of active measures, such as water pumps, that come into play to keep the reactor core cool in the event of an accident. A major drawback is that these safety devices are subject to failure, thereby requiring backups and, in some cases, backups to the backups The Generation IV reactor designs provide for what is called passive stability, in which natural processes, such as evaporation, are used to keep the reactor core cool. Furthermore, the core has a negative temperature coefficient, which means the reactor shuts itself down as its temperature rises owing to a number of physical effects, such as any swelling of the control rods. 

Brady, D., et al. (2007), Generation IV Reactor Development in Canada , 3rd Int. Symposium on SCWR, Shanghai, China, 12-15 March. 

It is notable that all Generation IV reactors aim to operate at higher coolant temperatures than those of the FWRs, thereby increasing the efficiency of thermal-to-electrical-energy conversion. The main characteristics of some of the reactors mentioned here and others are given in Table G-3. 

Ion, S. et al., Pebble Bed Modular Reactor The First Generation IV Reactor to Be Constructed, paper presented at the World Nuclear Association Annual Symposium, London, September 3-5. 

Development of a one-step electrochemical process to reduce LWR spent fuel (UO2) to metallic form is under development at Argonne National Laboratory The transuranic metals are separated by pyroproces-sing technology. This reduces waste that requires repository disposal. The transuranic metals could be cast into fuel suitable for the Generation IV reactors or transmuted reducing them to fission products. 

In terms of neutron spectrum and fuel cycle, there are two options of the SCWR the first is a thermal neutron reactor, and the second is an FR-based closed fuel cycle coupled with full actinide recycle based on advanced aqueous processing. Using last neutrons will be advantageous for achieving sustainability to be aimed for the Generation IV reactor because of their potential to produce at least as much fissile material as it consumes. 

Future Issues and Developments 24.3.8.1 Generation IV Reactors and GNEP... 

Innovation options in the nuclear sector include the development of small to medium capacity plants (200-500 megawatts [MW]), evolutionary concepts for the European pressurized water reactor (EPR), Generation IV reactors that reduce waste production, and alternatives to uranium. 

GREENSPAN, E., et al.. The encapsulated nuclear heat source reactor - a generation IV reactor, GLOBAL-2001 (Paper presented at Int. Conf, Paris, France, September 2001), ANSENS. 

GREENSPAN, E., Generation-IV reactors and nuclear waste minimization, (Proc. of the 14 Pacific Basin Nuclear Conference, pp 032, Honolulu, Hawaii, March 21-25, 2004). 

The AHTR is part of the U.S. DOE Generation IV reactor programme and is being actively investigated. If the AHTR is selected for large-scale deployment, the goal would be to have an operating test reactor by 2012. 

Regarding the potential to share design and technology development with reactors of other types, a remarkable example is provided by the AHTR, a pre-conceptual system that is part of the U S. Department of Energy Generation IV reactor programme. About 70% of the R D required for the AHTR is shared with that for helium cooled high temperature reactors. This includes fuel development, materials development, and Brayton power cycles. Annex XXVI. 

In longer-term innovative designs, such as Generation IV reactors an inherent safety feature is defined as the intrinsic physical capability of the installation, which should encompass the abovementioned protection systems. 

Proven at coolant temperature of 950°C, the highest among the Generation IV reactors, the VHTR enables not only high-efficiency electric power generation, but also broad cogeneration and industrial heat applications. 

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