SIR system description and development status

The objectives were to produce a reactor with the following features  

Enhance the public perception of safety Reduce the need for operator action Maximise system reliability and maintainability Make maximum use of existing technology Reduce the time needed for construction Competitive cost 

The reactor size was limited by the current diameter of pressure vessel which could be manufactured. This gave an electric power output of 320 MWe allowing for conservatism in the design margins. There is a prospect of increasing the power to 400 MWe. 

The reactor vessel contains the core, twelve once through steam generators, six canned rotor pumps at a high level in the vessel, and a control rod assembly in each of the 65 fuel assemblies. The top part of the vessel forms the pressuriser with its electric heaters. There is a passive spray system in the pressuriser which takes water from the riser region and sprays it into the steam space in the event of pressure rise in the core. The containment has a novel form of pressure suppression where the water for pressure control is contained in a tank farm connected to the reactor cavity by large diameter pipes. 

Although the module size is limited, a 1200 MWe station could be provided by having four reactor modules. Such an arrangement would take no more land space than a single large reactor. 

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