Author:James Asaro
Course:EEE 460
Date:Spring 2002

Nuclear powered aircraft carriers have been the backbone of the United States Navy since 1961, when the U.S.S. Enterprise was deployed. These ships have steamed hundreds of thousands of hours, fought in several conflicts, and have given America three acres of mobile sovereign territory without major incident for 40 years.

 

Why nuclear powered aircraft carriers? Conventional powered carries have existed since 1910 when the first U.S. carrier, the U.S.S. Langley, was deployed. The technology for steaming a conventional carrier was tried and true. Also, conventional carriers produce 280,000-shaft horsepower [1], while the Enterprise class nuclear carrier produces 260,000-shaft horsepower [2], 20,000 less. Is there a difference between the efficiency of a conventional carrier vs. a nuclear carrier? Also, what is the difference in the fuel consumed while steaming each type of carrier?

 

When discussing efficiency, it turns out that a conventional carrier is more efficient than a nuclear carrier. This is surprising to people, since it is a popular misnomer that more efficient implies superior in some way. Efficiency is actually the difference in energy produced when a fuel is burned in a power plant compared to the energy output of the plant. This takes into account mechanical and thermodynamic losses. In conventional power generation plants, the difference in energy is about 60%, while in a nuclear power plant, the difference is 66% [3]. This is to say that in a conventional power plant, 2/5 of the fuel is turned into useful power, while in a nuclear power plant, 1/3 of the fuel is turned into useful energy. This occurs because conventional power plants can generate steam at a higher temperature [4], therefore providing more force to the turbines.

 

If a conventional carrier is more efficient, the benefit of building nuclear carriers must be in the amount of fuel consumed. Looking at the numbers, if each type of carrier were required to produce 200,000-shaft horsepower for a time of one week, a conventional carrier would require 5.125 X 106 kilo-grams of fuel, while a nuclear carrier would require from 4.094 kilo-grams to 136.476 kilo-grams of enriched Uranium (see Calculations). From these numbers, it is seen that nuclear carriers consume as little as .00008% of the fuel that conventional carriers consume.

 

In conclusion, the use of nuclear carriers has given the U.S. navy a great advantage over the use of conventional carriers. Nuclear carriers can carry more fuel for planes, as opposed for propulsion. They can also be operated without having to be refueled for years at a time. These advantages will keep U.S. Navy carriers operational for many more years to come.