The Nuclear Option


An all-nuclear group photo from 1964.

The post about time, distance, and fuel consumption included an offhand comment about nuclear plants being able to sustain high speed. Questions were raised. I always had the intention of coming back to it, so let’s dig into it now.

In a nutshell, naval nuclear power relies on using the heat generated by radioactive decay to heat water and make steam. Instead of using coal to drive a steam engine, we use uranium. Once you get away from the reactor itself, it’s the same old steam that’s been in use for 200-plus years. But unlike coal, which is depleted as it is burned, the fuel rods stay hot and relatively intact for decades. A ship with a fifty-year service life will probably only be refueled once.

Aside from the ability to bypass the gas station, this steady power source also offers enormous amounts of energy on demand. Depending on the plant configuration and hull characteristics, it really can maintain a sprint across an ocean.

The navies of the United States and a few other countries – notably, Russia, China, France and the United Kingdom – have predominantly applied nuclear power toward submarines and aircraft carriers. The nuclear advantage is most pronounced in submarines. They never have to surface to recharge batteries with air-breathing diesels and, since drinking water and oxygen can be made from seawater, the only limit on their endurance is food. Nuclear power also enhances aircraft carriers by eliminating the vast amounts of fuel storage and ventilation that would serve a conventional plant, making that space available for aviation fuel and other supplies. Sustained high speed capabilities also help carriers when launching and recovering aircraft, since they have to make their own wind over the flight deck so their aircraft can generate extra lift.

Other smaller surface ships have been nuclear powered – Russia even maintains some nuclear icebreakers. But cruel economics have ended their careers in the United States. The construction costs of nuclear ships are higher than their conventional brethren, and end-of-life disposal costs are commensurately increased as well. In between, their fuel costs are obviously much, much lower than an oil-consuming ship, but the plants have to be overseen by nuclear-trained personnel.

If you want to enter a career field that pretty much guarantees you lifetime employment, be a nuclear engineer. They tend to get poached by the private sector, so the Navy has to spend a lot of bonus money to retain these guys, whose training wasn’t cheap to begin with. I’m sure there are other external factors that add to the cost of nuclear power, but manpower is definitely a dominant one. Expanding the nuclear manpower model to the entire fleet would require drastic paradigm-shifting reforms to be affordable; otherwise the cost would be prohibitive.

I did a bit of cursory research and found a couple tidbits that flesh out the bottom line of why nuclear has not retained its foothold in the surface fleet. First, in this Heritage Foundation report from 2007, they estimate that oil prices above $74/barrel make nuclear power competitive (they say it’s a Navy estimate but there’s no sourcing). Then, go to page 23 of this 2011 Congressional Budget Office analysis of nuclear power’s cost-effectiveness for surface ships. The history of oil prices since the early 1990s – when the last nuclear surface combatants were decommissioned – shows that prices high enough to justify nuclear ships are actually pretty rare, only about 2006 to 2008 and 2010 to 2015 (including recent history after the report was published). With OPEC keeping the spigots on, Iranian oil about to hit the market, and the American “fracklog” waiting to take advantage of any price jumps, cheap oil will be a reality for a while. Some commercial shippers are finding fuel costs to be so low that it is more economic to take extra-long trips around Africa instead of paying Suez Canal tolls, which might mean an extra ten days at sea by our calculations the other day. No need for nukes in this situation.

So, at the end of the day, nuclear plants only appear on the vessels where they offer a clear qualitative advantage – submarines and aircraft carriers.

In that case, you ask, how do we sustain a fuel-hungry non-nuclear force at sea? There’s a clue in the photo up top… stand by for more.


2 thoughts on “The Nuclear Option

  1. Pingback: The Domain of Professionals | The Salty Wog

  2. I wonder if future thorium reactors will change the numbers at all. They are supposed to more efficient, safer, and cleaner. ……

    Matt, thanks for the great explanation. It really did answer all my questions and once you laid it all out, it made perfect sense.


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