|Fig. 1: Nuclear Powered Aircraft Carrier USS Ronald Reagan. (Source: Wikimedia Commons)|
In the US Navys current fleet, all of the aircraft carriers are nuclear powered. However, none of its other surface ships such as cruisers and destroyers are nuclear powered. They are conventionally powered, which means they get power from burning petroleum based fuel. This supplies all of the power for the ship. Nuclear powered ships have an onboard nuclear reactor generating power.
Destroyers play the role of defending larger ships such as aircraft carriers and amphibious assault ships from threats by air and sea. They provide most of the defense in fleets and also can attack land targets with missiles. Part of its defense is the ability to protect agains ballistic missiles.  Amphibious assault ships are the other type of surface ship that has potential to be nuclear powered. These ships are larger, with the LHA-6 displacing around 45,000 tons versus destroyers displacing about 10,000. Their main goal is to carry helicopters or Harrier jump jets, as well as transport marines and their equipment. This approximates to about 1000 marines, and up to 30 helicopter or 20 Harrier jets. 
The main drawbacks from using conventional powered ships is the need to refuel. Currently, a destroyer in the Navy has a range of about 4,400 nautical miles, while traveling at 20 knots.  A cruiser traveling at 20 knots will have a range of about 6,000 nautical miles.  This can become problematic for these ships traveling some routes because they wont be able to make it without stopping to refuel. For example, it is 5,933 nautical miles from San Diego to just east of Taiwan.  A destroyer would not be able to make that route without refueling. Although this would just be a small burden during peacetime, this becomes a dangerous burden during wartime where ships wasting time to refuel could be very detrimental.
The main argument against nuclear powered ships is going to be cost compared to conventionally powered ships. Some added expenses regarding these nuclear powered ships include bigger crews to operate the more advanced propulsion system and a much higher disposal cost at the end of the ships life. The biggest cost is the actual building of the ship, for although the Navy would save all the money on fuel that they are spending, it is not nearly equal to the added price of building nuclear powered ships. The estimated cost of refitting the entire surface fleet with conventional powered ships would be about 100 billion for 56 ships, while it would be closer to 120 billion for nuclear powered ships. Where it would make sense for the fleet to become nuclear powered would be a sharp rise in oil prices. However, this would require oil to rise at about 3.4 percent per year from 2012-2084, which would create a rate around $223 per barrel by 2040. The Congressional Budget Office predicts that oil will be only about $114 per barrel by 2040, at a growth rate of 1 percent. Total cost estimates would therefore be almost 20% higher than conventionally powered ships. 
So is it worth the cost? Although nuclear ships are more expensive, this may be a worthy investment. Nuclear power gives the ships more range and faster, as well as the ability to operate greater equipment such as larger radars. Since all aircraft carriers are already nuclear, missions would not have to be hindered by destroyers or other surface ships needing to refuel, and can have more flexible operating schedules. Although the cost of new and better ships is expensive, this could be a worthy upgrade to make for the US Navy.
© Brandon Wu. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 "The Cost-Effectiveness of Nuclear Power for Navy Surface Ships," U.S. Congressional Budget Office, Publication No. 4028, May 2011.
 R. O'Rourke,"Navy Nuclear-Powered Surface Ships: Background, Issues, and Options for Congress," Congressional Research Service, RL33946, May 2009.