Nuclear powered cargo ship question

[Somes J]

I was doing some internet research on the idea of using nuclear reactors for cargo ships, and a couple of sites I found discussed the possibility of building fast cargo ships (> 30 knots) that would run on nuclear power so that they wouldn't face the economic difficulties with fuel price. E.g. http://onlinepubs.trb.org/onlinepubs/archive/marineboard/fall08/cushing.pdf" 's an example of a conventional ~30 knot design that ran into trouble because of fuel costs.

I was wondering, suppose we did switch to nuclear powered cargo ships in the future (maybe when oil runs out), would one expect to see a general across the board decrease in ocean shipping times as a result? I understand the uranium is a very small part of the cost of a nuclear vessel (http://nuclearinfo.net/Nuclearpower/WebHomeAvailabilityOfUsableUranium" (thousands of dollars a day in fuel costs with oil).

Are the speeds of modern cargo ships limited mainly by fuel/energy costs, or other factors like the cost of equipping them with more powerful engines?

 

[SteamKing]

The economics of shipping and vessel operations involve many factors. The initial construction cost is a huge factor, as is the anticipated life of the vessel. Daily operating costs (wages for crew, fuel, food, maintenance of the vessel, insurance, etc.) are also significant.

Nuclear cargo ships have been constructed in the past (e.g., the NS SAVANNAH, and the OTTO HAHN), but the construction cost of the hull was minor compared to the acquisition cost of the nuclear reactor. The operation of both ships was heavily subsidized by the US and Fed. German govts., respectively, and both ships were laid up when the subsidies were ended, in the case of the SAVANNAH after less than 10 years operation.

Nuclear cargo ships are certainly feasible, but their economics have proven to be daunting. Given the aftermath of the recent earthquake in Japan and the Fukushima debacle, many ports would be reluctant to entertain visits by such vessels even with the tightest security available.

 

[quasi44]

I was doing some internet research on the idea of using nuclear reactors for cargo ships, and a couple of sites I found discussed the possibility of building fast cargo ships (> 30 knots) that would run on nuclear power so that they wouldn't face the economic difficulties with fuel price. E.g. http://onlinepubs.trb.org/onlinepubs/archive/marineboard/fall08/cushing.pdf" 's an example of a conventional ~30 knot design that ran into trouble because of fuel costs.

I was wondering, suppose we did switch to nuclear powered cargo ships in the future (maybe when oil runs out), would one expect to see a general across the board decrease in ocean shipping times as a result? I understand the uranium is a very small part of the cost of a nuclear vessel (http://nuclearinfo.net/Nuclearpower/WebHomeAvailabilityOfUsableUranium" (thousands of dollars a day in fuel costs with oil).

Are the speeds of modern cargo ships limited mainly by fuel/energy costs, or other factors like the cost of equipping them with more powerful engines?

A thorium fueled reactor based on the proven design at Oak Ridge National Laboratory is likely the most viable fission based option. The energy density of thorium is much higher than uranium, and the reactor is much safer.

 

[Somes J]

Honestly my question was less motivated by curiosity about the specific issues with using nuclear power and more by curiosity about how the design of these big ships might be different in a world where fuel cost wasn't a serious issue. I read about some fast container ships that ran into economic trouble because of high fuel prices (the http://www.globalsecurity.org/military/systems/ship/takr-287.htm" types), and I was wondering whether we'd see a lot more fast ships like that in such a world.

Any thoughts on that?

 

[russ_watters]

I'm not sure if container ships actually go this fast, but the water line length of a ship causes a pretty hard restriction on its maximum speed. For example, a 900 foot ship can go a max of about 40 knots: http://www.sailingusa.info/cal__hull_speed.htm

 

[Somes J]

I'm not sure if container ships actually go this fast, but the water line length of a ship causes a pretty hard restriction on its maximum speed. For example, a 900 foot ship can go a max of about 40 knots

While bigger ships tend to be faster they are usually well below theoretical hull speed IIRC.

http://www.globalsecurity.org/military/systems/ship/container-types.htm"

For ships in the size range of up to 1,500 teu, the speed is between 9 and 25 knots, with the majority of the ships (58%) sailing at some 15-19 knots. The most popular speed for the 1,500-2,500 teu ships is 18-21 knots, which applies to 70% of these ships. In the 2,500-4,000 teu range, 90% of the ships have a speed of 20-24 knots. 71% of the 4,000-6,000 teu ships have a speed of 23-25 knots. Finally, 80% of the ships that are larger than 6,000 teu have a speed of 24-26 knots.

http://www.sailingusa.info/cal__hull_speed.htm" gives hull speed of about 23 knots for a 100 meter hull, 33 knots for a 200 meter hull, and 40 knots for a 300 meter hull. I'm not sure what the average length is but in descriptions of individual ships it's usually in the ballpark of 250-400 meters.

 

[Bob S]

A nuclear powered cargo ship should be faster than the Somali pirates off the horn of Africa, or have a Navy escort. We don't want Somalia to have access to nuclear material.

Bob S