Now Generation III+ reactors are becoming a reality, with construction of the EPR well underway in Europe and plans to start building AP1000 units at Samen in China within the next month, therntime has come to look ahead to improved nuclear power plant designs. The High Pressure Boiling Water Reactor (HP-BWR) is one possibility. Based on operating experience with conventional BWRs and PWRs, the HP-BWR concept combines the advantages of each traditional design, but leaves out the troublesome components to give a safe, environmentally friendly and economical plant.rnCommon sense, public confidence and economic considerations demand that the new HP-BWR design should not be a big leap from presently operating reactors; however it should be a significant improvement on them. Therefore the parts of the older designs that have caused trouble in the past, for example PWR steam generators and BWR perforated reactor vessel bottoms, have been removed. Instead the HP-BWR design relies on proven componentsrnsuch as the pressure vessel and the control rod drive systems from the PWR, and the core internals, circulation pumps and steam-moisture separators from the BWR. The HP-BWR is shown in Figure 1.rnUnlike a conventional BWR, the control rods enter from the top and are gravity operated, as this system has served well in PWRs. However in the HP-BWR the shape is cruciform, as it is in BWRs. This assures a large clearance between the BWR type fuel assemblies. The bottom of the HP-BWR reactor vessel is also free of the numerous control rod penetrations, found in conventional BWRs.
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