The Nuclear Energy Institute lists 5 new reactor designs that should be appearing in the near future. Remember though, nuclear plant construction and licensing should be measured in half-lives, just like Plutonium-239, half-life of 24,000 years.
Areva's 1600 MWe PWR is a well-designed refinement of the pressurized water reactor used worldwide. It is light water, as opposed to heavy water and can be loaded with MOX fuel, which is a mixture of uranium and reprocessed plutonium. Construction time is 4 years from first concrete pour, and a special neutron deflector protects the pressure vessel from radiation-induced brittleness. It has a fuel capacity of 24 months and can be refueled in about 10 days.
GE Hitachi have an Advanced Boiling Water Reactor (AWBR) producing about 1400 MWe. It too, is light water operation and construction time of 39 months was achieved in a Japanese installation. A boiling water reactor generally powers the electrical turbines with steam produced directly in the reactor core, whereas the PWRs have a heat exchanger. Obviously this means the turbines will be exposed to radiation-induced metal fatigue and the turbines must be serviced with radiation protective gear.
GE was one of the originators of the boiling water reactor design, and the GE Hitachi Economic Simplified Boiling Water Reactor (ESBWR) is designed for faster construction and lower operating costs. It appears to be further evolution of their boiling water product line. A sound bite - the elimination of greenhouse gases for a fossil-fueled plant is equivalent to taking 1.5 million automobiles from the road.
The Mitusubishi Advanced PWR Plant is a 1530 MWe redesign of their PWR product constructed at 23 sites. They argue that the increased complexity of the 4-loop PWR is actually defense-in-depth, providing better safety. Like the other designs, this too, will take the MOX fuel and also has a neutron reflector structure to protect that precious pressure vessel with 1/3 of traditional irradiation.
Last, but not least, is the Westinghouse AP1000, which a 1154 MWe pressurized water reactor design. It has an 18 month fuel cycle, with a 60 year plant life. Like some of the other designs, it uses gravity and natural circulation to protect the reactor in a significant event. The operator can flood the outside of the reactor vessel with water, preventing the core from melting the pressure vessel. Georgia Power has a contract to construct two of the plants near Waynesboro, Georgia.