At this high temperature the pressure inside the reactor could be high enough

• At this high temperature, the pressure inside the reactor could be high enough to damage the containment structure – Radioactive steam is released in air

38 38 Generations of Reactors

39 39 Advanced Fission Reactor Concepts • Thermal reactors – Standard type, includes BWR, PWR etc. – Higher temperature designs allow higher Carnot efficiencies but require different fuel rod designs and different coolants – Examples: Very high temperature reactor (e.g., pebble bed reactor), supercritical water reactor • Fast reactors – Use fast neutrons instead of thermal neutrons – Make best use of energy content in fission fuel – Examples: Gas cooled fast reactors, lead/sodium (liquid metal) cooled fast, molten salt reactors • Liquid fluoride thorium reactor – Fast reactor – Breeds 232 Th into 233 U – Abundance of thorium sources

40 40 Very High Temperature Reactor

41 41 Pebble Bed Reactor to turbine cold fluid pump spent fuel pebbles reinforced new fuel pebbles cooling gas Pebble Bed Reactor scheme heated fluid from turbine concrete

42 42 Supercritical Water Cooled Reactor Electrical Power Generator Turbine Condenser Heat Sink Reactor Supercritical Water Control Rods Pump Reactor Core

43 43 Gas Cooled Fast Reactor Control rods Reactor Reactor core Heat sink Comp ressor Comp ressor Recupe rator Heat sink Pre cooler Intercooler Gene rator Electrical power Turbine Helium

44 44 Liquid Metal Cooled Fast Reactor

45 45 Lead Cooled Fast Reactor Heat sink Comp ressor Comp ressor Recupe rator Heat sink Pre cooler Intercooler Gene rator Electrical power Turbine Reactor Core Header U-Tube he at exchanger modules (4) Reactor module/ fuel cartridge (removable) Coolant module Coolant Inlet distributor Reactor Control rods

46 46 Sodium Cooled Fast Reactor Gene rator Electrical power Turbine Core Cold plenum Hot plenum Heat exchanger Primary sodium (cold) Seconda ry sodium Pump Pump Condenser Control rods Heat sink Steam gene rator Pump Primary sodium (hot)

47 47 Molten Salt Reactor Heat Sink Freeze Plug Pump Emergency Dump Tanks Chemical Processing Plant Purified Salt Reactor Control Rods Coolant Salt Generator Electrical Power Turbine Repuperator Pump Pre Cooler Compressor Intercooler Heat Sink Compressor Heat Exchanger Heat Exchanger Fuel Salt