|
|
| Fig. 1: Basic Nuclear Submarine Reactor/Engine System. (Source: Wikimedia Commons) |
The concept of a submarine is one that is relatively simple. A vessel that sits below the water, out of sight and detection of ships above. As submarine designs progressed, the biggest struggle submarines faced was the challenge of efficiently propelling the submarine both on and under the surface. The US submarines of 1945, the Balao and Tench classes, were powered by large gas engines on the surface and electric batteries and engines when submerged. The submarines were advanced for their time but were limited by their engines which hindered their dive depth, speed, and length of dive. The Balao reached a top speed of 8.75 knots while submerged (20.3 on the surface), but only cruised at 2, and had a range of 11,000 nautical miles. She could also only remain underwater for 48 hours at a time before the submarine was required to surface to use diesel engines to recharge the batteries. [1] These lacking abilities in the diesel/electric submarine left something to be desired and the potential of nuclear-powered submarines became more important.
The nuclear reactors on submarines (see Fig. 1) work just like every other nuclear reactor, but instead of producing electricity they work as a heat engine. The uranium fission releases energy that is used to heat up water. The water is heated in the reactor and pressurized to prevent boiling but is then used to heat up a separate secondary system that produces steam. This steam then acts like any other steam engine and is used to drive turbines that power the propellers and the electric generator. The steam condenses to water and returns back to the steam generator. The first nuclear submarine, the USS Nautilus (Fig. 2) was produced by the US Navy in 1955. The USS Nautilus had the capability of 2100 kilometers of submerged travel. The Nautilus top speed was 26 miles per hour both above and below the surface. [2] The USS Nautilus was a massive engineering achievement and paved the way for future nuclear submarines that would change the world.
 |
| Fig. 2: The USS Nautilus (Source: Wikimedia Commons) |
The USS Nautilus's 30 year career was highlighted by Operation Sunshine, the first ever submerged crossing of the polar ice cap and the north pole. Since the Nautilus, the United States has assembled the largest fleet of nuclear submarines in the world. Nuclear submarines have a massive role in our national defense, notably in the cold war and also now during peace time to maintain constant readiness around the world. At the end of 2014, the United States had 73 nuclear submarines in its fleet; 55 Fast-attack SSNs, 14 Ballistic missile SSBNs, and four guided missile SSGNs. The latter two submarines have the ability to launch nuclear missiles from under water onto land and have been in service since the 1980s. [3,4] The constant presence of these submarines around the world keep the United States prepared for anything. As the majority of these submarines, and others from around the world, continue to roam earths waters, they will have a constant impact.
© Dylan Woodhead. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. 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.
[1] J. Christley, US Submarines 1941-45 (Osprey Publishing, 2006).
[2] H.-J. Kim, "Nautilus: The First Nuclear Submarine," Physics 241, Stanford University, Winter 2018.
[3] "Report to Congress on the Annual Long-Range Plan for Construction of Naval Vessels for Fiscal Year 2019," U.S. Office of the Chief of Naval Operations, February 2018
[4] A. Yachanin, "The Future of U.S. Nuclear Submarines," Physics 241, Stanford University, Winter 2016.
