As a favorite author of mine once wrote: "Any time someone asks 'why don't they...' the reason is almost always money." Nuclear power wouldn't be cost effective for most civilian operations. Not only is a nuclear power plant very expensive both to built and maintain, it would also cost a great deal more to hire nuclear qualified and certified personnel to run it. In short, the cost of using nuclear power for most civilian maritime uses would vastly outweigh any potential advantage. Shultz: Please read the answer carefully. There is much more cost involved in running a nuclear power plant for a ship than just the cost of fuel. In addition to what I already mentioned, there are the regulatory issues, which would be different for every country (and at least one, Japan, doesn't allow nuclear powered vessels in her national waters at all), making the cost of nuclear power for commercial vessels prohibitive. Trust me, if it was commercially feasible, it would be done. If you know some OTHER reason why commercial vessels don't use nuclear power, you should post a separate answer.

I originally asked this question because if submarines, aircraft carriers, and other military vessels get to use Nuclear power, why shouldn't Civilian ones use it as well? My hunch was because nuclear-powered Cruise Ships would be a possible health hazard for passengers. What if a curious 4-year-old went into the engine room and decided to swim in the pool housing the fuel rods? Curiosity would kill the cat by radiation poisoning, if not drowning. But not likely, since there would be doors requiring keycard access several rooms before the room with the fuel rods. Cargo ships would be run by trained personnel, so things may be safer there if they were nuclear-powered. I still asked this question anyway to confirm my hunch, and/or see what your answers would be. Not only would hiring nuclear power operators be rather expensive, it's also prohibitive to install and maintain nuclear reactors. Even though some companies could afford it, the safety issues plus the expense put together deters civilian companies from doing it in the first place. Money is not as much an object in the military, and it's better if a refueling comes only once every 20 years, so those are some of the reasons why some naval ships carry nuclear reactors on them.

You may also want to take into consideration that without military protection, terrorists would target these day in and day out for their chance to get a hold of some of that wonderfull plutonium. Who wants a nuclear arrrrrrrmed pirate? (bad pun, i know) Non-weapons grade Uranium is still deadly. Uranium-235 is the main isotope used for bombs and reactors. The "uranium enrichment" procedures used for most types of nuclear power reactors increase the percentage of u-235 in an sample of uranium. The "light water" reactor designs used in the United States need uranium "enriched" to about 3% u-235 (up from a natural level of 0.7%). Different isotopes of the same element are identical chemically. Separation requires techniques that exploit the subtle difference in weights between isotopes. The technologies of enrichment are extremely sophisticated and subject to stringent international control, since the processes that can enrich uranium to the levels needed by nuclear reactors can be repeated over and over to separate uranium-235 to the 90% levels useful in nuclear weapons. In other words, anyone making nuclear reactor grade uranium can easily make a nuclear weapon, which means the myth of "peaceful nuclear power" is a grotesque lie. Some more info: So-called "depleted" uranium is called this because the much of the uranium-235 isotope useful for nuclear power fuel and weapons has been separated, "depleted" does not mean that its biological hazards have been mitigated one iota. DU burns on impact, converting the uranium into lots of particles that are easily inhaled and can cause lung cancers. Uranium-238 has a half-life roughly as long as the Earth has been in existence. DU tipped weapons are the real "dirty bombs" and are a war crime to manufacture and use.

This question touches on several issues and my answer has been broken down into two sections, with different emphasis. ------------------------------------------------------------ Economy ------------------------------------------------------------ There is one main reason reactors are not used in commercial ships: they are not economically viable. If there were significant advantages to using nuclear power, reactors would have entered commercial service decades ago. Commercial shipping is highly competitive and shipowners strive to keep expenses down. A ship represents a substantial investment, which is recouped by keeping the vessel in service for as many days of the year as possible and minimizing personnel costs. Lakers may overwinter in dock every year when the St. Lawrence Seaway freezes up, but ocean-going vessels do not. 1. Purchase Cost The initial cost of purchasing a reactor far exceeds that of a conventional naval propulsion system. Not only are reactors very expensive to design, build, and install, they require more sophisticated and more expensive components and control systems. Reactors produce heat, which is used to make steam, which drives a steam turbine. Turbines are also expensive. These factors make reactors commercially unfeasible. The military cares less about such expenses than they do for the logistical advantages of a nuclear-powered system, particularly in submarines. 2. Operation The cost of operating a nuclear reactor is much higher than conventional marine propulsion systems. Reactors and turbines require a high level of expertise to operate and maintain, as well as substantially more person-hours over their operational life. Their direct maintenance costs are much higher than conventional systems. The military accepts these costs for logistical reasons, investing heavily in personnel training and operational maintenance. On the other hand, a large cargo vessel would not have more than 25 or 30 crew members. Perhaps 10 are responsible for the vessel's propulsion, mechanical, and electrical systems while at sea, 24h/day. The number of personnel is kept as low as economically feasible. 3. Refuelling Although another poster mentioned refuelling at 20 years intervals, the majority of naval reactors require refuelling in less than 10. Refuelling is an expensive, time-consuming process that can take the ship out of service for weeks. I am only aware of one commercial system that can be refuelled during operation and it is not a naval system. There is also a safety issue refuelling was done at sea: handling the spent fuel rods, which are highly radioactive and extremely hot. 4. Lifespan The design lifespan of a naval reactor is typically 25 to 35 years. However, reactors often need major overhauls during their operating life and some do not reach their design life. This is party the effect of radiation on the reactor components: long-term exposure to high levels of radiation alters the mechanical properties of metals, often leading to premature failures. When the reactor has reached the end of its serviceable life, it is scrapped, along with all other contaminated parts of the vessel. This is not an issue with naval vessels, as the vessel is either scrapped, reroled, or upgraded at this time. Commercial vessels, on the other hand, are expected to last 50 years in service without major overhauls. The propulsion system may be upgraded, but it is rarely replaced. ------------------------------------------------------------ Security ------------------------------------------------------------ Another poster has raised the issue of security issues, such as terrorism. I do not feel that this is a significant issue for several reasons. Nuclear power would be restricted to the largest vessels, such as supertankers and super-container ships, because of the cost of nuclear power. It would not be cost-effective in smaller ships. The size of these vessels limits the number of ports they can access and make them impossible to hide. Most naval reactors use uranium-235 (U-235) to operate. The U-235 may be enriched, but not all reactor designs require enriched fuel. A naval reactor does not produce bomb-grade (fissionable) material. Modifying the reactor to do so would take several years, to implement the modifications and to create sufficient fissionable material. This leaves the potential to use the fuel rods or the complete reactor to build a "dirty" bomb: a weapon designed to contaminate an area with radioactive debris. This could be done by jacketing a large conventional bomb with radioactive material and detonating it in a city. A ship, however, is not well-suited for this task. If a nuclear-powered vessel were highjacked at sea, it would be extremely vulnerable to being recaptured, immobilized (e.g., damaging the rudder and/or screw), or sunk (e.g., air-to-ground missiles). If the highjackers did not want to use the ship itself as the weapon's delivery system, but only wanted the fuel bundles, they would either have to keep the reactor running to get the ship to a site where they could be removed or shut the reactor down and dismantle it on board. It takes time to shut down a reactor and cool the fuel bundles enough to allow them to be removed. Either situation leaves the ship vulnerable to attack. If the ship were used as a weapon, sufficient explosives would need to be brought on board. These would need to be placed so as to destroy both the reactor and much of the ship around it, in addition to ejecting sufficient radioactive material over the target area. Since the ship is vulnerable at sea, the 'bomb' would need to be assembled in port. This would be very difficult, as the highjackers would need to physically carry enough explosives on board to do the job properly. Failing to create a suitably large explosion would simply leave a 'dirty' ship, which would be towed out to sea for disposal, and possibly contaminate the local dock area. There are several scenarios that would be easier to accomplish. Highjacking a super-cargo vessel and, if recapture or sinking were avoided, scuttling it at the entrance to a port. Halifax harbour in Canada, for example, would be vulnerable to such an attack because of the narrow harbour entrance. The ship would create a barrier to navigation that would take time to be removed, possibly closing the port and, thus, negatively affecting economic activity. The other scenario is to steal spent fuel bundles from storage facilities to build a dirty bomb. There are almost 450 reactors in operation world-wide. Most of the spent fuel is stored above ground. When fuel bundles are removed from a reactor, they are extremely hot and highly radioactive. Typically, they are placed in large pools for five to ten years. Following the cooling process, the fuel is encased in large, heavily-reinforced concrete storage containers. These are expected to last about 100 years, after which they are replaced with new containers. We'll be doing this for some time to come. All of the fuel in above-ground storage is, technically, accessible to terrorists. It would be difficult to acquire enough to make a dirty bomb, but it is feasible. As for delivering a nuclear weapon or other weapon of mass destruction to an urban area, the simplest method would be to place it inside a shipping container, along with a power supply for the detonator. Very few cargo containers are physically inspected on arrival, because there are so many in service. A container could arrive by ship, by train, or by road. A terrorist would need only transmit the detonation code to the container from somewhere close. A container on a ship could be detonated before it reaches the unloading and inspection area.

There was one nuclear cruise ship and it had no problems at all. http://content.hamptonroads.com/story.cfm?story=109976&ran=166119

well,in the past, certainly nuclear was far expensive, but as of now, that has tipped the balance and especially if our free markets remove all of the red tape and start using nuclear energy for all passenger ships.all of them could be built safely for all passengers and it would be cost-effective as long as all of the lobbyists from boeing and airbuss are kept out of the equation by law.all of the airlines needs, economical competition or all form of international travel will grind to a halt and thus drag down several of the major businesses as well,soon,all of america's international airports will share in storing, sealing and parking thousands of planes as destinations drop off during this really severe economic chaos

They tried it with the ship savannah http://gcaptain.com/maritime/blog/the-worlds-first-nuclear-merchant-ship-ns-savannah/ and later with the Sturgis but the only country to do it sucessfully is russia... but theya re having problems disposing of the old nulear waste properly. You can find lots more on this topic here: http://gcaptain.com/maritime/blog/tag/nuclear/

Short answer: Money. Diesel propulsion is vastly cheaper. Diesel engines are far easier and cheaper to build, maintain, and operate. One 18 year-old with a vo-tech training could keep one going, as opposed to a couple dozen specialists and watch-officers, includiing several with degrees in nuclear engineering, needed to operated a nuclear powerplant. Diesels also are virtually indestructable, while a reactor, a steam turbine or its reduction gears would be utterly destroyed if you dropped a washer or paper clip in them, or if you lost coolant, lubricant or had to stop and lock the turbines while still hot. Additionally, a single grain of salt in the primary or secondary coollant would corrode and ruin the reactor, heat-exchanger and turbine in a few days. Finally, Diesels don't tend to explode; nor do they suffer steam leaks that kill everyone in the engineroom or boilerroom. Diesel engines, including the fuel needed for a trans-Pacific voyage at 10-5 knots, still take up far less space, and weigh far less, than would a nuclear power-plant, allowing greater capacity for cargo. The Savannah was built in the waning days of STEAM ships, and was an attempt to find a more economic way of generating the steam. (The reactor is just an extremely hi-tech boiler) But diesel-engines supplanted ALL steam power plants (other than warships that need to attain speeds that only steam engines (and later gas-turbines) could achieve) once the variable pitch propeller blade was developed. (Ship diesels turn at a fairly constant rpm rate, and the propeller shafts and propellers with them; the variable pitch propeller blades increase, decrease, and reverse thrust by changing their pitch, rather than their rotation rates, eliminating the need for the massive tripple expansion steam turbines and incredibly expensive and sensitive reduction gears that come with steam-turbines.

Large warships and many submarines do use nuclear power. Some countries choose not to use nuclear power for their military either for economic reasons or philisophical ones (Japan-which still allows nuclear warships to sail in Japanese waters). However as to why commercial ships don't, I would venture that it is most likely just a matter of economics and the expenses of building a nuclear powered ship (although in the 21st century security does become an issue I suppose). However, there was a nuclear powered merchant ship in the 60's and 70's. It was the NS Savannah. If you're really interested in the subject, look up information on it sometime.

Well, your hunch concerning the safety issue is not the reason why. The NS Savannah was built by the United States as a concept ship to demonstrate the feasibility of using nuclear power for commercial ships. It was an extremely successful concept in terms of operability, but it failed for a couple of good reasons: Number one was the fact that she wasn't designed to be an optimal commercial vessel. She was designed for looks and dual purpose: passenger AND cargo. As a result, she couldn't carry nearly as much cargo as a commercial cargo vessel and she couldn't carry nearly as many passengers as passenger liners. Not by far. And the designs that went into the visual aesthetics further reduced her commercial use. She was a FINE looking vessel indeed, but what works well for looks doesn't work well for maximizing cargo space. So she lost revenue because of that. Second, there was the cost of operating her. It's expensive to train and pay the people required to operate and maintain her. Add to that the fact that the crew requirements are significantly larger for a nuclear powered vessel than a conventionally powered vessel and not only does the cost go up as a result, but the increased space required for the additional crew further limits the cargo and passenger space available. Ironically, 2 years after she was decomissioned the rising fossil fuel costs would have made her break even on these expenses! There are other nuclear powered non-military vessels, though. See the answer I provided here for more info and some links: http://www.answerbag.com/a_view/8001077

their funded, in other words, they have real pride. Nothing to a lowly crew