Shipboard Nuclear Reactor Operation
The operation of a nuclear reactor to raise steam outlined above is similar to a shipboard one. The main differences being as follows,
As we have seen the normal fuel used in the reactor is enriched uranium known as UO2, however the fuel used by the PWR for ships propulsion has a different form.
This fuel is still uranium based but alloyed with different percentages of aluminum or zirconium.
The UO2 fuel is normally enriched with 3-5% of U235. The uranium alloy has been enriched to contain up to 90% U235, but is normally used at between 45-75% U235 enrichment in PWR for ships propulsion.
The internal neutron shield is designed to contain the aggressive neutrons movement occurring within the narrow compact pressure vessel containing the reactor core. The neutron shield is fabricated from a high mass/density material which provides a good source of neutron absorption. This prolongs the reactors core life by preventing the embrittlement of the steel of the pressure vessel, with some reactors being designed to last between 40 and 50 years.
The shipboard nuclear reactor is very compact compared to the normal power plant reactor.
This compact plant is normally about 4m high with a diameter of 2m. This makes these plants particularly suitable for submarines, where space is at a premium
The power output from ships nuclear energy plants ranges from 200MWt for submarine propulsion to 300MWt for larger warships such as aircraft carriers.